Eli Can Retire Part XII: The Australian Department of Climate Change and Energy Efficiency Responds to Ian Plimer's 101 Questions

Worldwide, energy and environmental agencies are contributing to Eli's retirement fund by whacking the moles.  Today the Australian Department of Climate Change and Energy Efficiency offs Ian Plimer's 101 questions.  Eli has had a whack at a few of them, but really, this was a job for the real climate scientists.

This document provides answers to the 101 questions on climate change posed by Professor Ian Plimer in his latest book, How to get expelled from school: a guide to climate change for pupils, parents and punters (2011). Many of the questions and answers in Professor Plimer’s book are misleading and are based on inaccurate or selective interpretation of the science. The answers and comments provided in this document are intended to provide clear and accurate answers to Professor Plimer’s questions. The answers are based on up-to-date peer reviewed science, and have been reviewed by a number of Australian climate scientists.

Plimer asks

8. If global warming is human in origin, when will we feel it and when will it be dangerous?

And the AU Department of Climate Change Responds

Climate change becomes dangerous when it takes natural and human systems beyond environmental thresholds to which they can easily adapt. The more rapid the change, the less likely that adaptation can occur. Projections indicate that without action to reduce greenhouse gas emissions:

»temperatures in Australia could increase by up to 5 degrees by 2070;

»sea levels could rise by up to 80 cm by the end of the century (baseline of 1990), with larger increases possible; and

»we are likely to see more severe and intense extreme climatic events.

World governments have agreed that limiting temperature increases to 2 degrees Celsius above pre-industrial temperatures would help to reduce many of the most dangerous impacts of future climate change.

and, this could be a dangerous drinking game, 99

99.  Why do those advocating human-induced global warming vilify scientists who disagree rather than addressing genuine scientific questions?

And: Genuine scientific disputes are normally addressed through publication of alternative theories in peer-reviewed scientific journals. However, the scientists and others disagreeing with the consensus on human-induced climate change have rarely published in such journals, therefore avoiding critical scientific assessment of their work.

There is no single paper, or set of papers, that provides a plausible alternative explanation of recent warming. The few papers that do exist have been demonstrated to be flawed by the weight of peer-reviewed literature. There is now a vast body of literature supporting the mainstream understanding of climate change.

And a bit of optimism from the first comment

Eli can retire: Part II - so much for Miskolczi

In Eli's continuing series from the replies to the EPA endangerment finding for CO2 pollution, we get the final work on Miskolczi and the majic humidifier. As Nick Stokes said, you can sum up Miskolczi as "the greenhouse effect doesn't exist, the proof is left as an exercise for the reader.

Comment (3-34):
Commenter (3701.1) requests that EPA analyze Miskolczi's theory (Miskolczi 2007) that water vapor balances out CO2 forcing. Commenter 3535 submits a statement by Miskolczi that claims that the National Oceanic and Atmospheric Administration (NOAA) National Centers for Environmental Protection (NCEP)/National Center for Atmospheric Research (NCAR) reanalysis data show a slight decrease in global average absolute humidity in the past 61 years, which compensates for increases in GHGs.

Another commenter submits Paltridge et al. (2009), which also found decreasing absolute humidity at high altitudes from the NCEP data. Some (0798, 2982) cite Miskolczi (2007), which theorizes that water vapor will condense or evaporate as needed to maintain a constant greenhouse effect, citing a finite atmosphere used in calculations and observed decline in upper atmosphere humidity as validating factors. A number of other commenters (3323.1, 4003, 4041.1, 4932.1, and 5158) state that the lack of observed constant humidity levels are contrary to anthropogenic global warming theory and the IPCC
computer models.

Response (3-34):
The hypothesis that increased CO2 forcing will lead to a counterbalancing decrease in water vapor is highly speculative, and is not supported by the vast body of scientific literature. Miskolczi claims that the greenhouse effect should maintain a balance, so that every increase in a GHG should lead to a corresponding decrease in water vapor (and vice versa), effectively implying a climate sensitivity of zero.

A climate sensitivity of zero is completely incompatible with historical temperature variations, as it would imply an unchanging climate in direct contrast to historically recorded temperatures changes on all timescales. Miskolczi also claims that “On global scale, however, there can not be any direct water vapor feedback mechanism, working against the total energy balance requirement of the system. Runaway greenhouse theories contradict to the energy balance equations and therefore, can not work.” This demonstrates a lack of understanding of feedback mechanisms in the climate (see response in Volume 4 for a discussion of runaway climate).

Several commenters also cite evidence for decreasing absolute humidity, in contrast to the IPCC conclusions (cited in the TSD) that “[a]lthough surface specific humidity globally has generally increased after 1976 in close association with higher temperatures over both land and ocean, observations suggest that relative humidity has remained about the same overall, from the surface throughout the troposphere (Trenberth et al., 2007).” The data from the NOAA NCEP/NCAR reanalysis for humidity has been questioned in other papers (Soden et al., 2005) (especially for the pre-satellite period), and a Dessler et al. (2009) review also contradicts this data. Even Paltridge et al. (2009), which relied on the NCEP reanalysis data, recognized that “[i]t is accepted that radiosonde-derived humidity data must be treated with great caution, particularly at altitudes above the 500 hPa [hectopascal] pressure level.”

Falling absolute humidity during a period of warming is also difficult to reconcile with theoretical understanding, model results, and historical temperature trends. The analysis in the IPCC (Trenberth et al., 2007) stated: “Due to instrumental limitations, long-term changes in water vapour in the upper troposphere are difficult to assess,” but nonetheless concluded: “To summarise, the available data do not indicate a detectable trend in upper-tropospheric relative humidity. However, there is now evidence for global increases in upper-tropospheric specific humidity over the past two decades, which is consistent with the observed increases in tropospheric temperatures and the absence of any change in relative humidity.”

No trend in upper- tropospheric relative humidity, and evidence for increases in specific humidity, are consistent with model predictions that relative humidity should stay fairly constant, implying increasing absolute humidity with increasing temperature, and therefore a positive feedback (see response on Volume 4 for more responses on relative humidity predictions in models).

Comments?

Eli can Retire Part XI - A bunch of denial denied

Eli is really lazy, he is letting Cthulhu do the looking up for goodies in the US EPA responses to challenges to its Endangerment Finding for increasing CO2 concentrations.

Comment (2-19):
Some commenters write that CO2 is a weak GHG compared to other gases (0425, 0498, 0639.1, 1187.1, 1217.1, 2759, 10595); they note that CH4’s potency is 1000 times greater (0425) or that water is 95% of total greenhouse effect (10158, several others), implying that CO2 emissions can not have a large effect on the earth’s climate.

Other commenters write that CO2 is a weak GHG because it is limited as to how much radiation it can absorb. For example, a commenter asks why Mars is not warm despite a 95% CO2 atmosphere (2895), and another states that doubling CO2 would only have a small (0.4°C) effect (2759). One commenter states that as CO2 concentrations increase, the forcing does not increase—CO2 “has a forcing limit of 325 ppm” (0582). Another cites Plimer, who states that it has a maximum threshold (11454), and another states that CO2 does not absorb infrared (286).

Others point out that CO2 is less than 0.05% of the atmosphere (0153, 0455, 0498, 2885, 3214.1), and therefore presumably has a very small effect. A commenter (3722) claims that because of logarithmic forcing, 75% of the warming due to CO2 doubling should have already happened, therefore future warming due to CO2 will be small. A commenter (1009.1) notes that increased CO2 will not lead to much increase in temperature because of the logarithmic relationship and saturation.

Response (2-19):
Although it is true that CO2 has a smaller warming effect per kilogram or per molecule than a gas like CH4, it plays a larger role in the warming of the atmosphere. For example, Table 2.14 of Forster et al. (2007) lists radiative effects per ppb, lifetimes, and global warming potentials for a number of gases. CH4 is 73 times as potent as CO2 per kilogram in the atmosphere, 26 times as potent per molecule, or 25 times as potent using the Global Warming Potential metric. However, the concentration by volume of CH4 is 210 times less than that of CO2, and the emissions in kilograms of CH4 are about two orders of magnitude less. Thus, the TSD does not characterize various GHGs as “weak” or “strong,” and we do not find such characterizations useful. Note also that we are unclear the source for the claim that CH4’s potency is 1,000 times greater than CO2’s. We are not aware of such an estimate.

We also find no support for the assertion that water is responsible for 90% or 95% of the greenhouse effect in the scientific literature. Calculations by Kiehl and Trenberth (1997) suggest that water contributes about 60% of the greenhouse effect in clear sky conditions and 75% in cloudy conditions (including the cloud contribution). CO2 contributes about 26% of the greenhouse effect in clear sky 14 conditions, and 15% in cloudy conditions. Because the mass of water in the atmosphere is much larger than the mass of CO2, this implies that per ton or per molecule, CO2 is actually a much more effective GHG than water vapor.

The total effect of increasing CO2 concentrations can be best addressed by actually calculating the radiative forcing resulting from changes in those concentrations. Section 4(a) of the TSD discusses changes in radiative forcing due to increases in CO2 concentrations in the context of other changes in radiative forcing over the last 250 years. This also puts in context how a gas that composes 0.04% of the atmosphere can actually have a large radiative effect.

We disagree with assertions by commenters about a number of the radiative characteristics of CO2. We do agree that the forcing due to increases in CO2 concentrations is roughly logarithmic (Forster et al., 2007). This logarithmic relationship holds over a wide range of concentrations; commenters provided no peerreviewed literature to support the contentions that CO2 has a forcing limit of 325 ppm, a maximum threshold, or no infrared absorption, and we find that these assertions are not consistent with the scientific literature (Forster et al., 2007). Current forcing is almost half (not 75%) of the expected doubling due to the logarithmic relationship cited by one commenter, and because of the inertia of the climate system not all the warming has been realized, so it is not possible to extrapolate future temperature change merely by doubling the past 50 years of change. Comments on future temperature projections are covered in detail in
Volume 4.

Regarding Mars, see the response in Section 3.2.3 of Volume 3 of the Response to Comments document.

For these reasons, we have found no support for the commenters’ conclusions that CO2 does not have a large effect on the Earth’s climate. They provided no literature to support their assertions, and we have determined that our discussion of these issues in Section 4(a) of the TSD is reasonable and scientifically sound.

Carrots to the first to figure out where the 75% of the warming due to CO2 doubling should have already happened comes from

Comments?

Eli can retire Part XII - The commenters get something right

Another in our series, but this time the EPA and the commenters get it right

Comment (6-44):
Commenters (e.g., 2791, 10298) state their support for the Findings, noting the potential for increased stress from heat, drought, insects, and disease on plant and tree populations. Others (2599, 10081) from the western United States voice their support for the Findings and describe their experiences with hot summers and serious wildfires. Other commenters (e.g., 3421, 4748, 6894) state their support for the Findings and express concern about the effects of current and future extreme weather events on the forestry industry, including heat waves, droughts, floods, wildfires, and hurricanes. One commenter (5844) describes how projected climate impacts, particularly the increased risk of wildfire on forestry and forest biodiversity will affect him personally given his enjoyment of hiking, camping, and communing with nature in the forests of the Pacific Northwest.

A commenter (3501) states his support for the Findings, indicating that the western United States and Canada are already seeing widespread changes in the natural landscape due to climate change. Hotter temperatures are causing more frequent and persistent drought in the West, which contribute to forest fires and pine beetle infestations. A weather-related pine beetle infestation has decimated millions of acres of forest in the western United States Western US and Canada. At the current rate of destruction, 80% of the forests of British Columbia will have been destroyed within five years and the rest of the West will lose 50% of its forests by mid-century. The forest fire season in the West is now 78 days longer than 25 years ago and it is well recognized that our forest fires have become more frequent, more intense and more destructive.

Response (6-44):
We reviewed the comments provided and note they are generally consistent with the discussion of climate impacts on forestry in the TSD, although commenters do not provide specific references to support their claims. As summarized in the TSD and in our responses to previous comments in this volume, disturbances like wildfire and insect outbreaks are increasing and are likely to intensify in a warmer future with drier soils and longer growing seasons.

The Technical Support Document provides the background for this, of which Eli will quote a bit

10(d) Insects and Diseases
Insects and diseases are a natural part of forested ecosystems and outbreaks often have complex causes. The effects of insects and diseases can vary from defoliation and retarded growth, to timber damage, to massive forest diebacks. Insect life cycles can be a factor in pest outbreaks; and insect life cycles are sensitive to climate change. Many northern insects have a two-year life cycle, and warmer winter temperatures allow a larger fraction of overwintering larvae to survive. Recently, spruce budworm in Alaska has completed its life cycle in one year, rather than the previously observed duration of two years (Field et al., 2007). Recent warming trends in the United States have led to earlier spring activity of insects and proliferation of some species, such as the mountain pine beetle (Easterling et al., 2007).

During the 1990s, Alaska’s Kenai Peninsula experienced an outbreak of spruce bark beetle over 6,200 square miles (16,000 km2) with 10 to 20% tree mortality (Anisimov et al., 2007). Also following recent warming in Alaska, spruce budworm has reproduced farther north reaching problematic numbers (Anisimov et al., 2007). Climate change may indirectly affect insect outbreaks by affecting the overall health and productivity of trees. For example, susceptibility of trees to insects is increased when multi-year droughts degrade the trees’ ability to generate defensive chemicals (Field, et al., 2007). Warmer temperatures have already enhanced the opportunities for insect spread across the landscape in the United States and other world regions (Easterling et al., 2007).

The IPCC (Easterling et al., 2007) stated that modeling of future climate change impacts on insect and pathogen outbreaks remains limited. Nevertheless, the IPCC (Field et al., 2007) states with high confidence that, across North America, impacts of climate change on commercial forestry potential are likely to be sensitive to changes in disturbances from insects and diseases, as well as wildfires.

The CCSP report (Ryan et al., 2008) states that the ranges of the mountain pine beetle and southern pine beetle are projected to expand northward as a result of average temperature increases. Increased probability of spruce beetle outbreak as well as increase in climate suitability for mountain pine beetle attack in high-elevation ecosystems has also been projected in response to warming (Ryan et al., 2008).

Climate change can shift the current boundaries of insects and pathogens and modify tree physiology and tree defense. An increase in climate extremes may also promote plant disease and pest outbreaks (Easterling et al., 2007).

And so, we get to the scary bits To be continued. . .

Eli can retire Part XIV - Death, no taxes

Continuing Eli's lazy stroll through the US EPA responses to comments. They are serious folks.

Comment (5-11):
A commenter (8320) submits information and references on the potential health effects of global climate change. The commenter discusses the following topics: extreme heat events, wildfires, vector-borne diseases, water-borne diseases, air quality and human heath, aeroallergens and allergies, environmental justice, and the vulnerability of children to effects from air quality. The commenter stresses that “climate change will alter the global environment and present major challenges to the health and welfare of children.”

Response (5-11):
EPA has reviewed the submitted comments and associated references, and finds that they include several very recent and relevant studies (e.g., St. Louis and Hess, 2008; Patz et al., 2008; Jerret et al., 2009) that confirm the scientific support for health related impacts summarized in the TSD.

In one example, Luber and McGeehin (2008) call extreme heat events “the most prominent cause” of weather-related human mortality in the United States, noting that they are responsible for more deaths annually than hurricanes, lightning, tornadoes, floods, and earthquakes combined. We note that the recently released U.S. Global Change Research Program (USGCRP) report (Karl et al., 2009) also concludes that mortality from heat is the number one weather-related cause of death and cites an analysis of nine U.S. cities showing that deaths rise with increases in temperature and humidity with no confounding or effect modification due to air pollution (Zanobetti and Schwartz, 2008).

Another recent study (Jerret et al., 2009) provided by the commenter indicates that high levels of ground-level ozone can increase the risk of asthma-related hospital visits and premature mortality and that the effect of long-term exposure to ozone on air pollution–related mortality was not known. The study indicates that ozone exposure is associated with the risk of death from respiratory causes, and that long-term, low-level exposure can be lethal. Researchers studied the outcomes of almost 500,000 adults in 96 metropolitan regions who enrolled in the American Cancer Society Cancer Prevention Study in 1982 and 1983 and were tracked for an average of 18 years. In addition, the study by Jerrett et al. (2009) looked at associations between ozone concentrations and the risk of death, in a single-pollutant model and in a two-pollutant model with fine particulate matter (PM2.5). In two-pollutant models, researchers demonstrated a significant increase in the risk of death from respiratory causes in association with an increase in ozone concentration. The study found that every increase in 10 parts per billion (ppb) in average ozone concentrations was associated with a roughly 4% increase in mortality from respiratory causes. This translated in Los Angeles to a 43% increase in the risk of dying from respiratory causes. Eastern cities like New York and Washington had an average increased risk of about 25% to 27%. EPA concludes this study fills important knowledge gaps in health impact literature from increases in ozone exposure (at low levels).

Another study provided by the commenter provides evidence of vector-borne disease shift attributed to climate. For example, in Europe, geographic shifts in the tick’s distribution have been attributed to climate change. An expansion of the tick’s range into higher elevations in the Czech Republic corresponded to rising temperatures. A shift toward higher latitudes in Sweden corresponded to a reduction in the number of very cold winter days (Gage et al., 2008).

Based on review of the cited literature from the commenter, we conclude that the information provided is generally consistent with, and in several cases even stronger than the assessment literature summarized in the TSD.

Eli can retire: Part III - Svensmark circles the drain

One of the bunnies said why bother posting these, the blogs have been all over this stuff. . . Well, for one thing Eli doesn't have to write them, for another, picking out the gems is fun and for anther, if anyone is looking for a good answer to one of the everbrowns, well Eli is happy to oblige. Today it's Svensmarks turn in the barrel, and there is a neat, new point down there in bold.

UPDATE: But before we start, in the comments, the AGW Observer, Ari Jokimäki, points to his article on a 2007 paper by Evan, et al., which claims that viewing angle has a strong effect on the cloud data (ISCCP) that Svensmark and Friis Christensen used. If corrected, most of the variation in cloudiness with time vanishes, and so does any claimed correlation with cosmic ray flux. UPDATED: The Evan result is not without its doubters, a summary is here but there is more reading to do. On the one hand there are problems with the ISCCP data set, on the other the problems may not be as deep as the critics maintain

Back to Eli's post

Comment (3-36):
Many commenters (0153, 0245, 0509, 0591, 1017.1, 1187, 2953, 3722, 3729.1) claim that temperature is better correlated with solar activity patterns than with greenhouse forcing, some of whom reference researchers such as Svensmark or Shaviv that attribute the mechanism not to solar irradiance but rather solar wind or solar-magnetic flux (2917, 3205.1, 3324.1, 4632, 5058) and interactions with cosmic rays seeding low-lying clouds (0542, 0646, 0798, 1616.1), or length of solar cycles (0543) or sunspots (1219.1).

One commenter (7031) indicates that solar impacts on climate have received scant research attention and are minimized in the IPCC Fourth Assessment Report (2007a) and the climate model community, even though the IPCC authors rank the level of scientific understanding of solar-climate interactions as very low. The assumption is that variations in TSI are the only significant solar impact on global climate. The commenter also posits:

------------------------------------------
Recent studies have shown strong correlations between solar-modulated cosmic ray fluxes and low-level cloud cover and its subsequent impact on global temperatures. Experimental verification of a cosmic-ray cloud seeding mechanism was recently completed by Svensmark et al. [1997], and the CLOUD (Cosmics Leaving OUtdoor Droplets) experiments at CERN (the European Organization for Nuclear Research) over the next few years will provide definitive measurements of cloud seeding by cosmic rays.
---------------------------------------

The commenter concludes it is clear that solar variations have much larger impacts on global climate than what is estimated based solely on TSI variations.

One commenter (3446.2) requests that the TSD include a rigorous presentation of sunspot activity and temperature over the past century, and notes objection to the lack of sunspot discussion in Karl et al. (2009). Another (3397) requests more discussion of solar activity as a climate forcer.

Response (3-36):
The contention that cosmic rays could provide the mechanism by which changes in solar activity affect climate is not supported by the literature. Solomon et al. (2007) address this topic, noting that “the cosmic ray time series does not appear to correspond to global total cloud cover after 1991 or to global low-level cloud cover after 1994.” More recent research continues to question the ability of this mechanism to play a significant role in climate change. Pierce and Adams (2009) use calculations to show that potential impacts on clouds from cosmic rays and “conclude that the hypothesized effect is too small to play a significant role in current climate change.” Erlykin et al. (2009) found that the evidence showed that connections between solar variation and climate were more likely to be mediated by direct variation of insolation rather than cosmic rays, and concluded: “Hence within our assumptions, the effect of varying solar activity, either by direct solar irradiance or by varying cosmic ray rates, must be less than 0.07 ◦C since 1956, i.e. less than 14% of the observed global warming.” Carslaw (2009) and Pittock (2009) review the recent and historical literature in this field and continue to find that the link between cosmic rays and climate is tenuous, though they encourage continued research.

The CLOUD experiments at CERN are interesting research but do not provide conclusive evidence that cosmic rays can serve as a major source of cloud seeding. Preliminary results from the experiment (Duplissy et al., 2009) suggest that though there was some evidence of ion mediated nucleation, for most of the nucleation events observed the contribution of ion processes appeared to be minor. These experiments also showed the difficulty in maintaining sufficiently clean conditions and stable temperatures to prevent spurious aerosol bursts. There is no indication that the earlier Svensmark experiments could even have matched the controlled conditions of the CERN experiment. We find that the Svensmark results on cloud seeding have not yet been shown to be robust or sufficient to materially alter the conclusions of the assessment literature, especially given the abundance of recent literature that is skeptical of the cosmic ray-climate linkage reviewed in the previous paragraph.

Therefore the TSD summary of the assessment literature on this issue is well founded: that the lack of a proven physical mechanism and the plausibility of other causal factors make the association between galactic cosmic ray-induced changes in aerosol and cloud formation controversial.

Comments?

Eli can retire Part VIII - The EPA reads Rabett Run

Well, well, well, Eli discovers that the EPA reads everything, including Rabett Run. We are honored. From the US EPA responses to challenges to its Endangerment Finding for increasing CO2 concentrations

Comment (3-45):
A number of commenters believe that anthropogenic global warming is impossible, many citing arguments made by Gerlich and Tscheuschner (2009). Several commenters (e.g., 0430) note that the greenhouse effect is not like a real greenhouse. Several claim that it is thermodynamically impossible because heat cannot be transferred from a cool substance to a warmer substance (0430, 2210.5): for example, blankets cannot make you warmer than body temperature (1707, 0183.1,). Another thermodynamic argument for the impossibility of the greenhouse effect was proposed by two commenters (2210.3, 4509) citing Gerlich and Tscheuschner (2009) who states that the greenhouse effect as commonly formulated violates the Second Law of Thermodynamics. Another commenter (0711.1) requests evidence of any peer reviewed climate change paper that does not rely on computer simulation. Another theory (2887.1) holds that long-wave radiation will cause increased evaporation of the surface ocean, negating any heat increase. One commenter (0535) submitted a non-peer reviewed paper providing a different explanation for the net energy budget of the Earth, with no role for warming by CO2.

Response (3-45):

The evidence for the atmospheric greenhouse effect is well supported by the scientific literature.

The objections raised by a number of commenters to the basic thermodynamics are without grounds. We are well aware that the greenhouse effect is not at all like a real greenhouse. However, the analogy of a blanket is a little bit better: and indeed, sufficiently insulating blankets can cause overheating. GHGs (blankets) will, by reducing the rate of heat loss, raise the surface temperature of the Earth (body) until a new thermodynamic balance is achieved between incoming solar radiation (internal body heating) and outgoing thermal radiation (in the case of a blanket, including convection and non-radiative processes). This process works regardless of whether the atmosphere (blanket) is cooler than the surface (body). We are aware of the paper by Gerlich and Tscheuschner, and we have determined that the conclusions of the paper are inconsistent with the well-supported literature regarding the mechanism of the greenhouse effect. For example, as a disproof of the greenhouse effect, the paper by Gerlich and Tscheuschner presents the example of a pot of water, noting that the bottom of the pot will be cooler if it is filled with water than if it is empty. Contrary to the assertion in the paper, the primary thermal effect of adding water to the pot is not a reduction in heat transfer, but rather an increase of thermal mass. We assert that a more appropriate example for the paper to have examined would have been the addition of a lid to a pot of water, which reduces the rate of heat loss, and leads to an increase of heating of the water compared to a case with no lid. The paper by Gerlich and Tscheuschner is also inconsistent with the scientific literature with regards to the interpretation of radiative balance diagrams and the assertion that there is no “mean temperature” of the Earth, in contrast to the hundreds of peer-reviewed publications and many assessment reports which use both concepts.

You read it first at Rabett Run

This, of course, neglects the latent heat carried away from the pot and thus the heating element by evaporation of the water in the pot. Since it is well known that people who are physics obsessed are often forgetful, we postulate that the housewife forgets that she has put the pot on the range, and all the water boils away. At that point, when all the water has evaporated, measurements show that the heating element rises to a higher temperature than it was before the tea pot was placed on it.

and, of course, there are the famous Rabett blanket posts

EPA Rocks!!

Eli can retire Part X - The grim reaper is a hot head

The US EPA responses to challenges to its Endangerment Finding for increasing CO2 concentrations blows hot and cold.

Comment (5-24):
Several commenters (e.g., 3347.3, 11453.1, 3187.3) note that the April 2009 TSD indicated that cold-related deaths presently exceed heat-related deaths in the United States and that this provides evidence that a warming climate will have beneficial effects on temperature-related mortality. Commenters note that on page 70 of the April 2009 TSD, EPA states that 5,983 heat-related deaths were reported in the United States between 1979 and 2002. In the same timeframe, 16,555 people died of extreme cold. A commenter (3187.3) provides a paper by Goklany (2007), which indicates that death from extreme cold exceed death from extreme heat.

Response (5-24):
We have revised the TSD’s estimates of heat-related deaths based on the latest findings of the assessment literature (Karl et al., 2009). Based on these results, other supporting evidence presented in the TSD, and additional evidence cited below, we have determined that the available literature strongly supports the conclusion that extreme heat is, on an average annual base, the leading cause of weather-related death in the United States. We agree that the April 2009 TSD contained statistics that could be interpreted as suggesting that cold-related mortality has recently been higher in the United States than heat-related mortality. The cold-related mortality statistics in the TSD from Ebi et al. (2008) are similar to those cited by Goklany (2007). However, the methods and data for estimating heat-related mortality were recently updated and these revised values are presented in Karl et al. (2009).

The more recent heat-related mortality numbers from Karl et al. (2009) reflect results from the Centers for Disease Control and Prevention (CDC). CDC (2006) reports more than 3,400 deaths from 1999 to 2003 for which exposure to extreme heat was listed as either a contributing factor or the underlying cause of death. This result of roughly 680 heat-related deaths per year is almost identical to the 689 deaths per year from cold exposure reported by Ebi et al. (2008) and summarized in the TSD. CDC (2006) suggests that even the revised heat-related mortality numbers may underestimate total heat-related mortality, noting: “Because heat-related illnesses can exacerbate existing medical conditions and death from heat exposure can be preceded by various symptoms, heat-related deaths can be difficult to identify when illness onset or death is not witnessed by a clinician. In addition, the criteria used to determine heat-related causes of death vary among states. This can lead to underreporting heat-related deaths or to reporting heat as a factor contributing to death rather than the underlying cause.” This issue has long been recognized in attempting to estimate the mortality impact of extreme heat using information from death certificates (American Medical Association Council on Scientific Affairs, 1997). As noted in a subsequent response (5-29), cold-related deaths are likely also underestimated. One complication with these death certificate–based estimates of extreme cold and heat is they are not limited to periods that would be considered heat waves or cold snaps in the location where the death occurs. Therefore, while these results are based in a consistent methodology and data source, they have an uncertain overlap with the occurrence of the weather events of primary interest to the TSD, cold snaps and heat waves. As a result, these data alone do not provide strong evidence the heat-related mortality is presently greater than cold-related mortality.

However, we note that alternative and much higher estimates of heat-related mortality come from analyses of daily urban summertime mortality patterns in Kalkstein and Greene (1997) and Davis et al. (2003a), which use a different methodology to compute heat-related deaths compared to CDC (2006). These studies first define extreme heat events by identifying threshold conditions for an event in a location and then calculate the number of extreme heat–attributable deaths based on differences in daily deaths on extreme heat days compared to longer-term averages. In these studies, heat’s mortality impact is quantified in terms of the excess deaths that result during the extreme heat conditions. By evaluating changes in daily deaths attributable to all causes, this approach also effectively eliminates differences or restriction in using certain causes of death as potential sources of bias in estimating the extreme heat’s mortality impact. This method is also more consistent with the view that heat waves are effectively identified through exceptional weather conditions that result in increases in daily mortality (e.g., Confalonieri et al., 2007; U.S. EPA, 2006a). Although differences in the time series, definitions of urban populations, and other analytical methods prevent an exact comparison of the results in these two studies, both studies (Kalkstein and Greene, 1997; Davis et al., 2003a) estimate that there are approximately 1,700–1,800 excess deaths per year during extreme heat events based on an evaluation of a subset of approximately 40 U.S. metropolitan areas (see U.S. EPA, 2006a). These estimates of extreme heat’s mortality impact are much higher than the corresponding death certificate–based estimates for heat as well as the Ebi et al. (2008) estimate for cold-related mortality summarized in the TSD.

We also note that Davis et al. (2004) find that the net impact of the observed temperature increase from 1964 to 1998 (considering both reduced temperature mortality in winter and increased temperature mortality in summer) was an extra 2.9 deaths (per standard million) per city per year in 28 major U.S. cities. This indicates that extreme heat has been the larger cause of mortality in the recently observed record when temperatures have warmed.
Furthermore, we note that the USGCRP assessment (Karl et al., 2009) specifically refers to a recent study by Borden and Cutter (2008), which concludes heat is the most deadly natural hazard in the United States. It also cites Medina-Ramon and Schwartz (2007), which found that in 50 U.S. cities between 1989 and 2000, extreme heat increased death rates 5.7% while extreme cold increased death rates by only 1.6%. These results are summarized in the TSD.

Though we are aware of a recent study by Andersen and Bell (2009) that finds a similar mortality risk for extremely hot and cold days based on the synthesis of results from 107 U.S. communities (contrasting with Medina-Ramon and Schwartz), Andersen and Bell are clear that cold temperatures more indirectly affect mortality than heat. In addition to the longer lag times for exposure incorporated for the effects of extreme cold (up to 25 days, compared a one-day lag for heat), they note that infectious diseases, which are more common in industrialized countries during colder weather (when people spend more time indoors and in proximity) could account for a substantial portion of the cold-related effect.

Summarizing, both recent studies and the assessment literature provide strong evidence that heat-related mortality presently exceeds cold-related mortality in the United States

Comments?

Eli can retire Part IV - Essex, Beenstock, Reingewertz and VS take it on the chin

Continuing Rabett Run's excerpts from the US EPA responses to challenges to its Endangerment Finding for increasing CO2 concentrations, Eli has it in for Essex, Beenstock, Reingewertz (really go to Our Changing Climate for this) and VS, Bart's little Mrs. Calabash.

Comment (2-26):
A commenter (3722) suggests that average global temperature is not an adequate “starting point” as an indicator of climate change “[c]onsidering the multitude of physical processes that control climate.” The comment indicates that “global temperature systems are not homogeneous, and are indeed characterized by large differences and variability.” The comment refers to Essex et al. (2007), who conclude “Physical, mathematical, and observational grounds are employed to show that there is no physically meaningful global temperature for the Earth in the context of the issue of global warming to support this notion.”

Response (2-26):
We have reviewed the paper by Essex and considered the commenter’s view regarding the usefulness of global temperature as a “starting point” and we disagree that it is not a useful indicator. We note that the TSD does not rank the importance of any individual indicator or suggest that global average temperature is the most important indicator. Rather, it summarizes the scientific literature on a large set of indicators (including changes in sea level and ocean heat content, glaciers, snow cover, precipitation, and a large number of physical and biological systems).

With respect to the Essex et al. study, the authors claim that “physical, mathematical, and observational grounds are employed to show that there is no physically meaningful global temperature for the Earth in the context of the issue of global warming.” We do not dispute that a single global average temperature may not be particularly meaningful to understanding global warming and concur that global temperature systems are not homogeneous. But Essex et al. are neglecting the fact that climate scientists are not particularly interested in a single average value, but rather the change or variation in temperature expressed as anomalies over time at a range of spatial scales, from local to regional to global. Analysis of temperature anomalies is a legitimate, extensively peer-reviewed, expertly assessed methodology for understanding temperature trends at all scales.

Thus, the TSD appropriately summarizes the literature and that its discussion of global temperature is reasonable, informs our understanding of climate change, and is consistent with the scientific literature.

Comments?

Eli can retire 1

Thanks to Marcus, Eli has a ready source of pre-written posts, the EPA Endangerment Response to Comments. The rest of you keep your hands off.

Comment (2-4):
A commenter (0740.1) states that ice core CO2 measurements are impacted by water contamination, and that there are no other methods of measuring historical CO2 (commenter 3722 also objects to ice core record manipulation). Several commenters (0339, 0714.1, 2210.5, 3722) have cited either Beck (2007) or Jaworowski to support a contention that CO2 was at high concentrations in the recent past immediately before the Mauna Loa record started, or during past interglacials (0655).

Response (2-4):
We disagree with the assertion by several commenters that estimates of historical CO2 concentrations are incorrect. According to IPCC (Jansen et al., 2007), “it is possible to derive time series of atmospheric trace gases and aerosols for the period from about 650 kyr [thousand years] to the present from air trapped in polar ice and from the ice itself.” This methodology has been “verified against recent (i.e., post-1950) measurements made by direct instrumental sampling.” Additionally, these measurements are consistent with various less accurate methods such as using the size of stomatal pores on tree leaves, boron isotope measurements in plankton buried under the ocean, or carbon isotope ratios in algae buried in the ocean floors, moss samples, and foraminefera carbonate shells. Therefore, there is extremely high confidence in the CO2 values determined from the ice core records, and we disagree that there is any evidence that water contamination or other manipulations reduce the confidence in the ice core estimates.

The commenters cited a theory from Jaworowski that water contamination in the ice core record reduces its reliability, and that the IPCC CO2 historical estimates require shifting the ice core records an arbitrary number of years in order to make them line up with the instrumental record. The critiques of Jaworowski on the shift were addressed by Hans Oeschger (1995), who pointed out that the ice core record shift was done in accordance with theoretical estimates of the rate of diffusion in gases in firn, and that these theoretical estimates were confirmed by isotopic enrichment in line with theory. Güllük et al. (1998) also rebutted Jaworowski on contamination, stating that “Jaworowski et al. [1992, 1994] suggested that CO2 measurements may be subject to fractionation due to clathrate formation and destruction. The good agreement of our CO2 measurements with those made by LGGE using the milling extraction procedure makes this artefact unlikely.” Similarly, Raynaud et al. (1993) found that the objections by Jaworowski were unfounded, demonstrating that the changes in CO2 and methane (CH4) are similar for different interglacial periods, regardless of depth, and that ice cores from different locations give the same values regardless of different “brittle zone” conditions between the different locations.

With respect to the citations of Beck (2007) and Jaworowski (1992, 1994) on pre–Mauna Loa CO2 records, these papers rely on chemical measurements that were taken in many environments which were not far enough away from sources and sinks of CO2 in order to measure the background concentration.

Beck himself (2007) notes that many of his measurements were taken from the “periphery of towns” and shows temporal CO2 plots that have large (210 ppm) variability over a time period of two months. He recognizes that some of these data points need to be corrected by 10 to 70 ppm to take into account nearby cities. This large variability is in contrast to the relatively smooth year after year increase in the Mauna Loa and other modern instrumental records. The pattern of CO2 changes in the Mauna Loa records are much more consistent with the ice core records than with the Beck estimates. Therefore, we find that these historical CO2 estimates by Beck and Jaworowski are not reliable alternatives to the conclusions of the assessment literature on historical background CO2 levels.

Therefore, EPA has determined that the assessment literature estimates of historical CO2 concentrations over the past 800,000 years are of high quality and the most reliable estimates available.

Easy blogging

Eli can retire Part XV - Bart blushes

Hi gang, the EPA has made sure that Eli will never have to go back to work, dumping another load on the petitioners for reconsideration. Remember the great scandal about only 26% of the Netherlands being below sea level while the WGII report said 55%, wonder where that came from?
-------------------------------
2.1.2 Accuracy of Statement on Percent of the Netherlands Below Sea Level

Comment (2-1):
Peabody Energy and the State of Texas contend that the IPCC erroneously stated (in Working Group II’s contribution to the AR4) that 55% of the Netherlands is below sea level, whereas the actual number is much lower according to Dutch materials (26%).

Response (2-1):
The statistic quoted in the IPCC AR4 is inaccurate. When this error was identified, PBL (2010b) published a correction:

In the 2007 IPCC report by the Working Group 2 (Climate change 2007: Impacts, Adaptation and Vulnerability) a mistake has entered the text that was supplied by the Netherlands Environmental Assessment Agency, regarding the risks of flooding for the Netherlands. In the chapter on Europe, on page 547, it says that 55 per cent of the Netherlands is below sea level (‘The Netherlands is an example of a country highly susceptible to both sea level rise and river flooding because 55% of its territory is below sea level’). This should have read that 55 per cent of the Netherlands is at risk of flooding; 26 per cent of the country is below sea level, and 29 per cent is susceptible to river flooding. Examples of the latter are the near floodings, in the mid-1990s, of areas along the rivers Meuse and Waal – areas that are well above sea level.

The IPCC agrees that this statistic is incorrect in the AR4, and also notes that the same mistake was made by other reputable groups (Reuters, 2010). For example, the IPCC—in a written statement provided to Reuters—indicated that a report from the Dutch Ministry of Transport had stated “‘about 60%’ of the country is below sea level,” and referred to a European Commission study saying “about half” (Reuters, 2010). As noted by the IPCC statement, the error was not made by authors of the AR4, but originated with PBL, which supplied the text. To correct the mistake, the IPCC published an official erratum (IPCC, 2010d):

2) Page 547. Section 12.2.3. Line 20: Delete “below sea level” and replace with “at risk flooding”.

The IPCC was further quoted as saying (Reuters, 2010): “The sea level statistic was used for background information only, and the updated information remains consistent with the overall conclusions.”

In its independent report Assessing an IPCC Assessment (PBL, 2010a), PBL, which was responsible for the error, states:

We acknowledge that this error was not the fault of the IPCC (Coordinating) Lead Authors or Co-Chairs. The error was made by a Contributing Author from the PBL, and the (Coordinating) Lead Authors [of the IPCC] are not to blame for relying on Dutch information provided by a Dutch agency.

--------------------------------------------

Oh yes, what did this all mean, the EPA says nothing much

EPA concludes that this error is minor and inconsequential to the Administrator’s Endangerment Finding. EPA does not refer to or rely on this statistic in the Endangerment Finding or supporting documents, and this information does not pertain to endangerment of public health and welfare in the United States in any meaningful way. It does not call into question the integrity of the IPCC, and it has no impact on the scientific support for EPA’s Endangerment Finding. Furthermore, as the error pertains to a statistic outside the United States, it is not relevant to the Endangerment Finding. As noted in Subsection 2.1.1, the Endangerment Finding states (Section III.D): “The Administrator looked first at impacts in the United States itself, and determined that these impacts are reasonably anticipated to endanger the public health and the welfare of the U.S. population. That remains the Administrator’s position, and by itself supports her determination of endangerment.”

Eli can retire Part VI - Going where the sun don't shine

Ms. Rabett told Eli to get off his tired old well the bunnies know what, and go where the sun don't shine. So the Rabett dialed up the US EPA responses to challenges to its Endangerment Finding for increasing CO2 concentrations and considered the matter of solar influences

Comment (3-35):
A number of commenters (e.g., 0670) argue that the sun is the primary driver of global temperature changes. Several commenters (3323.1, 4003, 4041.1, 4932.1, and 5158) referred to a new 2009 paper by Scafetta and Willson suggesting that the IPCC used faulty solar data in dismissing the direct effect of solar variability on global temperatures. Commenters also cite other research by Scafetta and others that suggests that solar variability could account for up to 68% of the increase in Earth’s global temperatures. One commenter (1616.1) attributes 0.14°C of the warming since 1950 to increased solar irradiance, and another 25% of warming since 1979, as in Scafetta and West (2006) (3596.1). Another commenter (7031) states that the correlation between solar variations such as sunspots and global climate has been pointed out by several scientists, such as Scafetta and West (2008). A number of specific climate-related regional phenomena have been related by commenters (e.g., 3596.1) to solar variability, such as sea surface temperature, floods, droughts, monsoons, and North Atlantic drift ice.

Response (3-35):
We have reviewed the comments and the literature submitted and have determined that changes in solar irradiance are not a sufficient explanation for recent climate change. The contention that direct solar variability can explain recent warming is not supported by the bulk of the scientific literature. As the TSD notes, the IPCC Fourth Assessment Report estimates that changes in solar irradiance since 1750 are estimated to cause a radiative forcing of +0.12 (+0.06 to +0.30) W/m², or approximately 5% of the combined radiative forcing due to the cumulative (1750–2005) increase in atmospheric concentrations of CO2, CH4, and N2O (2.30 W/m2 with an uncertainty range of +2.07 to +2.53 W/m²). The natural 11-year cycle of solar irradiance has a magnitude of less than 2 W/m² at the distance of the Earth—which, once corrected for albedo and distribution over the surface area of the planet, is a magnitude of less than 0.35 W/m².

In addition, Karl et al. (2009) state that “if most of the observed temperature change had been due to an increase in solar output rather than an increase in GHGs, Earth’s atmosphere would have warmed throughout its full vertical extent, including the stratosphere. The observed pattern of atmospheric temperature changes, with its pronounced cooling in the stratosphere, is therefore inconsistent with the hypothesis that changes in the Sun can explain the warming of recent decades. Moreover, direct satellite measurements of solar output show slight decreases during the recent period of warming.” A number of other recent studies also show results that contrast with the interpretation that solar variability is driving recent warming. Both Lockwood and Fröhlich (2008) and Lean and Rind (2009) show that the solar contribution to warming in recent decades has been small or negative, consistent with the IPCC attribution of most of the warming in recent decades to anthropogenic GHGs.

The attribution of components historical climate change to solar activity involves a number of issues. The first is the actual reconstruction of historical solar activity: even for the last three decades there is some controversy, as is evident in the differences between Scafetta and Willson (2009), which uses a total solar irradiance composite from the Active Cavity Radiometer Irradiance Monitor (ACRIM) analysis of satellite data, and Lockwood and Fröhlich (2008), which uses a composite based on the Physikalisch- Meteorologisches Observatorium Davos (PMOD) analysis of satellite data. These two composites don’t even agree on the sign of the solar irradiance trend over this time period.

Lockwood and Frolich analyze both datasets and find that the ACRIM dataset is inconsistent with methods of historical reconstructions that have shown correlations between historical solar activity and climate. Krivova, Solanki, and Wenzler (2009) also find no evidence of an increase in total solar irradiance (TSI) from 1986 and 1996 using an analysis based on magnetograms. Scafetta and Willson, on the other hand, claim that the PMOD approach requires a correction of the data from the earth radiation budget (ERB) system on the NIMBUS7 satellite, and this correction has been rejected by one of the scientists on the NIMBUS team (D.V. Hoyt, personal communication to Scafetta, 2008). Neither dataset shows an increase of solar irradiance between the minima of 1986 and 2008, which would be required in order to explain warming over that period.

Therefore, reconstructions of recent solar variability do not agree, but in one case show no trend, and in the case of the Lockwood and Fröhlich reconstruction the solar contribution during this period would have been a cooling, not warming, influence.

The second issue is that in order for solar irradiance to be a major driver of recent warming, there must be an amplification effect that is active for solar irradiance that is not active for forcing due to GHGs. Studies such as Scafetta (2009) often rely on a significantly different factor for solar irradiance than is used for GHG climate sensitivity. Additionally, the Scafetta study relies on a “slow lag” solar response and the timescale chosen has itself been the subject of dispute. The climate sensitivity for this slow lag response used by Scafetta is 0.46° K/Wm^-2. Note that this is compared to the total solar irradiance: therefore, the effective sensitivity to the average solar irradiance according to Scafetta would be (4*0.46)/0.7 = 2.6° K/Wm^-2. This can be compared to a climate sensitivity range of 2 to 4.5, or about 0.5° K/Wm^-2 to 1.2° K/Wm^-2. Additionally, Scafetta claims that solar variability accounts for most of the recent warming and that GHG sensitivity is on the low end of the range: this means that Scafetta is effectively claiming that sensitivity to solar variability is on the order of five times the sensitivity to forcing by GHGs, without a good mechanism to explain this extreme difference. Although it is not impossible that there are differences between solar and GHG induced changes, the evidence for an amplification of the magnitude needed to explain recent warming is weak. For example, while Meehl et al. (2009) find an amplification of the solar cycle variability is needed to explain certain patterns of tropical Pacific climate response, the authors note: “This response also cannot be used to explain recent global warming because the 11-year solar cycle has not shown a measurable trend over the past 30 years.”

Moreover, the sensitivity needed is nowhere near as large as the Scafetta sensitivity, and the behavior explained is geographically localized, which is different from a global increase in sensitivity. Therefore, the evidence for an amplification of the magnitude needed to explain recent warming is weak.

Some other authors also show some correlations between solar variability and regional trends. Eichler et al. (2009) find a strong correlation between solar activity (as reconstructed by carbon-14 and beryllium-10 proxies) and temperatures in the Siberian Altai region. However, the authors note that “underlying physical processes are still not yet understood” in terms of amplifying a weak solar signal (in terms of radiative forcing) in order to see larger effects, and also that “[i]n large spatial scale hemispheric or global reconstructions the solar signal may therefore even vanish” because the “main effect of solar forcing is presumably on location, routes, and stability of atmospheric pressure systems, which all act on regional scales.” The conclusion of the Eichler work is that while solar activity was a main driver for temperature variations in the Altai region preindustrially, during the industrial period they found that only CO2 concentrations show a significant correlation with the temperature record. They did find agreement with the northern hemisphere (NH) temperature reconstruction of Scafetta and West (2007) in that they found that only up to approximately 50% of the observed global warming in the last 100 years can be explained by the sun. Note that this conclusion provides 50% as an upper limit to the explanatory power of solar variability, and this is for the full century. Therefore, for the last 50 years, this conclusion is still consistent with the IPCC (2007b) statement that “[m]ost of the observed increase in global average temperatures since the mid-20th century is very likely due to the observed increase in anthropogenic greenhouse gas concentrations.”

Therefore, to summarize: attempting to attribute late-20th century temperature change mainly to solar variability requires choosing a specific solar dataset, assuming a simplified model with different “fast” and “slow lag” responses based on timescales from a controversial paper, and assuming that the climate system is several times more sensitive to changes in solar irradiance (or other, non-radiative changes in the sun) than it is to changes in GHG forcing. All three of these assumptions are counter to the conclusions of the IPCC and CCSP assessments and not viewed as established conclusions in the literature. While science in this area will continue to evolve, our review did not uncover any compelling alternatives to the science represented in the assessment literature, and summarized in the TSD.

Ho Ho Hummmm.

Eli can retire Part XIII - Tom Segalstad is an old buddy

In which the EPA explains to Judith Curry why Tom Segalstad is wrong, wrong, wrong.

Comment (2-3):
Several commenters state that CO2 has a short lifetime in the atmosphere (0711.1, 0714.1): for example, a commenter (1616) claims that the lifetime of CO2 can be at most 20 years based on the 12% annual exchange of CO2 with the surface ocean and 10% exchange between the surface and deep ocean as shown in the National Aeronautics and Space Administration (NASA) carbon cycle diagram, and two commenters (3440.1, 3722) state that the overwhelming majority of scientific papers support a residence time of seven years in contrast to the TSD and IPCC. Several commenters (e.g. 3722) cite Professor Segalstad who has stated, based on his work on CO2 residence times (Segalstad 1997), that the assumption of a 50- to 200-year lifetime by IPCC results in a “missing sink” of 3 Gt of carbon a year, which is evidence that IPCC is mistaken.

Another commenter submitted Essenhigh (2009), which developed a box model and also found that the lifetime of CO2 was on the order of a few years.

Response (2-3):
EPA reviewed the information presented, as well as the work by Segalstad, and finds that it does not address the lifetime of a change in atmospheric concentration of CO2, but rather the lifetime in the atmosphere of an individual molecule of CO2. These are two different concepts. As stated in the First IPCC Scientific Assessment, “The turnover time of CO2 in the atmosphere, measured as the ratio of the content to the fluxes through it, is about 4 years. This means that on average it takes only a few years before a CO2 molecule in the atmosphere is taken up by plants or dissolved in the ocean. This short time scale must not be confused with the time it takes for the atmospheric CO2 level to adjust to a new equilibrium if sources or sinks change.

This adjustment time ... is of the order of 50–200 years, determined mainly by the slow exchange of carbon between surface waters and the deep ocean” (Watson et al., 1990). The magnitudes of these large balanced sources and sinks are addressed in response 2-2, and are similar to those represented in the NASA carbon cycle diagram. Newer research has only extended and confirmed this statement from the first IPCC assessment report (Denman et al., 2007). A recent approximation for this perturbation lifetime is sometimes represented as the sum of decay functions with timescales of 1.9 years for a quarter of the CO2 emissions, 18.5 years for a third of the CO2, 173 years for a fifth of the CO2, and a constant term representing a nearly permanent increase for the remaining fifth (Forster et al., 2007).

The “missing sink” that was referred to by a commenter is also addressed in response 2-2, and is now called the “residual land sink.” The magnitude of this sink is about 2.6 Gt of carbon per year, with significant uncertainty. Denman et al. (2007) included a hypothesis that a portion of this sink is due to the increased growth of undisturbed tropical forest due to CO2 fertilization, but the carbon accumulation of natural systems is hard to quantify directly. The uncertainty in determining the size and nature of this residual sink does not contradict the assessment literature conclusions about the perturbation lifetime of CO2 concentration changes in the atmosphere, but is reflected in the carbon cycle uncertainty for future projections of CO2 (see responses regarding carbon cycle uncertainty in Volume 4 on future projections).

The box model in Essenhigh (2009) is clearly flawed: the results from this model as reported in the paper include a lifetime for CO2 containing the 14C isotope that is a factor of 3 different from the lifetime of CO2 containing the 12C isotope. This difference in lifetimes is not scientifically compatible with the immense difficulty involved in isotope separation. The model assumes that each “control volume” (each volume represents either the ecosystem, the surface ocean, or the deep ocean) is perfectly mixed, which is contrary to the observations of oceanic CO2 which show that storage of carbon in the ocean is only at 15% of the equilibrium value, and that the mixing time between the surface ocean and intermediate and deep oceans is on the order of years to centuries (Field and Raupach, 2004). Additionally, the paper uses only historical fossil fuel emissions of CO2, without including land use change CO2, and contains the same confusion about “residence lifetime” and “adjustment lifetime” that has been addressed above.

A common analogy used for CO2 concentrations is water in a bathtub. If the drain and the spigot are both large and perfectly balanced, then the time than any individual water molecule spends in the bathtub is short. But if a cup of water is added to the bathtub, the change in volume in the bathtub will persist even when all the water molecules originally from that cup have flowed out the drain. This is not a perfect analogy: in the case of CO2, there are several linked bathtubs, and the increased pressure of water in one bathtub from an extra cup will actually lead to a small increase in flow through the drain, so eventually the cup of water will be spread throughout the bathtubs leading to a small increase in each, but the point remains that the "residence time" of a molecule of water will be very different from the "adjustment time" of the bathtub as a whole.

This analogy does not hold for other GHGs: methane, HFCs, and N2O are actually destroyed chemically in the atmosphere, unlike CO2 where the carbon is not destroyed but merely shifted from one reservoir to another, and therefore the residence lifetime of these gases is fairly close to the adjustment lifetime of their concentrations in the atmosphere.

Similarly, any given molecule of CO2 is only expected to stay in the atmosphere for a few years before it moves into the oceans or ecosystem, but the change in atmospheric concentration due to combustion of fossil fuels can persist for much longer. Indeed, because the oceans and ecosystems are finite, some small fraction of CO2 emissions will have a perturbation lifetime in the atmosphere of thousands of years (Karl et al., 2009).

Next

Eli can retire, the EPA on Africa Gate

Stoat has arisen to contemplate the libel suit that Irene Meichsner brought (and won two out of three falls) from Stefan Rahmstorf. This showed up in a post on Klima Zwiebel, and, of course, at the non-innocent Roger Pielke's. Not innocent because Roger was deep into this thing early on.

It arises from some mischief that Eli's friends Jonathan Leake and Richard North had got up to, accusing the IPCC AR4 of making unjustified accusations about how climate change coule lead to decreased ag yields in Africa. IM, simply adopted their frame. Stoat makes the important point that no one is looking at whether SR was right or wrong on the science. The point he won is that the court agreed that his statement

Reading helps, if the author of the article, IM, herself had once looked in the IPCC report, she would have found out that the accusations were completely false.

was an allowable difference of opinion. But of course there is more

Turns out that the EPA and it's various friends in the denialsphere had already read the IPCC report AND the background information (this is long folks)
-------------------------------------------------

Comment (2-10):
The Competitive Enterprise Institute, the Ohio Coal Association, Peabody Energy, and the Southeastern Legal Foundation take issue with a statement in Section 16(b) of the TSD that: “In some countries, yields from rain-fed agriculture could be reduced by up to 50% by 2020.” They claim the statement originated from gray literature in the IPCC AR4 and is therefore illegitimate. Southeastern Legal Foundation concludes: “The African Crop Yields claim stands as another example of the IPCC making a claim of imminent disaster that inappropriately relied on non-peer-reviewed literature…”

Response (2-10):
The IPCC statement cites a report by Dr. Ali Agoumi, a climate expert from Morocco (Agoumi, 2003) that was published by the International Institute for Sustainable Development (IISD) and funded by the government of Canada, the U.S. Agency for International Development, and other public and private institutions. Based on EPA’s review of the report, it appears that the 50% number was not obtained from the peer-reviewed literature but rather from “vulnerability studies on three North African countries (Algeria, Morocco and Tunisia) with respect to climatic changes.” These vulnerability studies were prepared under the U.N. Environment Programme Global Environment Fund and included in the National Communications of these three countries to the U.N. Framework Convention on Climate Change (Ministry of Territory Development and Environment, 2001, Kingdom of Morocco, 2001 and Republic of Tunisia, 2001).

In response to publicity regarding this purportedly unsubstantiated statement in the IPCC report, Dr. Coleen Vogel, a contributing lead author of the IPCC chapter on Africa impacts, described the context in which Dr. Agoumi’s research was used. She explained that Agoumi’s report received rigorous scrutiny by her fellow authors and was thoroughly discussed during development of the chapter (Kretzmann, 2010). She explained that the decision to include this (gray literature) study was based on the paucity of peer-reviewed material relating to some parts of the world, particularly Africa, and the desire of the authors of the report to provide balanced information. The process described by Dr. Vogel is consistent with the IPCC’s guidance on the use of gray literature, as previously described in Volume 1 of the RTC document and further discussed in Subsection 2.2.4.4 of this Response to Petitions (RTP) document.

Finally, we note that this statement relates to impacts outside the United States, and it did not materially impact the determination of endangerment of public health and welfare in the United States. As noted in Subsection 2.1.1, the Endangerment Finding states (Section III.D): “The Administrator looked first at impacts in the United States itself, and determined that these impacts are reasonably anticipated to endanger the public health and the welfare of the U.S. population. That remains the Administrator’s position, and by itself supports her determination of endangerment.”

Comment (2-11):




Referring to an analysis published by Ben Pile, co-editor of the blog climateresistance.org on the blog of Roger Pielke, Jr. (Pile, 2010), the Southeastern Legal Foundation states that the primary reference supporting the IPCC’s statement on African crop yields “Vulnerability of North African Countries to Climatic Changes” (Agoumi, 2003) was from IISD, an advocacy group.

Regarding the IISD reference, Peabody Energy states:

Thus, the EPA based its findings on the IPCC WGII report, which based its findings on a report [the IISD report] published by an organization with a declared political interest in climate change that based its findings from an assessment of other non-peer reviewed national studies. This is not the way EPA science should be carried out.

Response (2-11):
The implication that the credibility of IPCC’s statement on African crop yields is diminished because the IPCC’s source (Agoumi, 2003) for the statement was published by an advocacy organization or an organization with a “declared political interest in climate change” is unsupported. The organization in question is IISD, which describes itself as follows:

The International Institute for Sustainable Development contributes to sustainable development by advancing policy recommendations on international trade and investment, economic policy, climate change, measurement and indicators, and natural resource management. By using Internet communications, we report on international negotiations and broker knowledge gained through collaborative projects with global partners, resulting in more rigorous research, capacity building in developing countries and better dialogue between North and South.

IISD’s vision is better living for all—sustainably; its mission is to champion innovation, enabling societies to live sustainably. IISD receives operating grant support from the Government of Canada, provided through the Canadian International Development Agency (CIDA) and Environment Canada, and from the Province of Manitoba. The institute receives project funding from the Government of Canada, the Province of Manitoba, other national governments, United Nations agencies, foundations and the private sector. IISD is registered as a charitable organization in Canada and has 501(c)(3) status in the United States.

We find no reason to question the credibility and legitimacy of information produced by this organization on the basis of either its mission or funding sources. Moreover, neither the Southeastern Legal Foundation nor Peabody Energy provide any support for the implication that work by an organization such as IISD is automatically suspect or flawed.

Finally, Peabody Energy’s statement that EPA’s findings are based on this material is incorrect. As noted in Subsection 2.1.1, the Endangerment Finding states (Section III.D): “The Administrator looked first at impacts in the United States itself, and determined that these impacts are reasonably anticipated to endanger the public health and the welfare of the U.S. population. That remains the Administrator’s position, and by itself supports her determination of endangerment.”

We discuss the legitimacy of the science and underlying references for the African crop yields statement in Response 2-12.

Comment (2-12):
The Southeastern Legal Foundation alleges that EPA uncritically adopted the IPCC’s “faulty conclusion” with respect to crop yields. It refers to a blog by writer/commentator Richard North (North, 2010) to conclude the Agoumi (2003) reference cited by the IPCC on the issue of rain-fed agricultural yields in Africa relies on studies that “do not support the proposition for which they are cited.”

Relying on Richard North’s blog, the Southeastern Legal Foundation summarizes the vulnerability studies cited by Agoumi (2003) from the National Communications of Morocco, Tunisia, and Algeria. The Southeastern Legal Foundation notes that the Morocco National Communication “lends some support [to the Agoumi reference], saying that by 2020 during drought conditions cereal yields would decline up to 50%” but that “the data apply to cereal yields only, not crops in general as is implied by the IPCC.” The Southeastern Legal Foundation further states that “Algeria’s report said their yields would double, and be trimmed only slightly by ‘climate change’” and “Tunisia’s submission concluded the picture was mixed, but they could have an increase in rain and agricultural production.”

Response (2-12):
The IPCC’s statement on rain-fed agriculture in Northern Africa is not “faulty” and the Southeastern Legal Foundation presents no evidence that it was included uncritically in EPA’s TSD. Furthermore, the Southeastern Legal Foundation’s portrayal of findings on climate and crop yields from the National Communications of Morocco, Tunisia, and Algeria derived from Richard North’s blog is not complete. When all of the information in these National Communications is considered, we find there is broad support for Agoumi’s (2003) statements on North African rain-fed agriculture, which are:

• “Some of the key statistics regarding water, soil, urban areas and coastal zones are outlined below. . . . Decreasing rain-based agricultural yields with grain yields reduced by up to 50 percent in periods of drought.”
• “Studies on the future of vital agriculture in the region have shown the following risks, which are linked to climate change: . . . deficient yields from rain-based agriculture of up to 50 percent during the 2000–2020 period.”

PBL, in its report Assessing an IPCC Assessment (PBL, 2010a), makes the following important point with respect to IPCC’s statement on rain-fed agriculture in Africa:

This statement is not directly a statement on climate change, but on climate variability: in individual years, droughts can cause up to 50% in yield reductions. The implicit message here is that when droughts would become more frequent due to climate change, more years with up to 50% in yield reductions would occur. The statement could easily mislead readers into thinking that average annual yields could be reduced by up to 50% due to climate change. In the Summary for Policymakers of the Working Group II Report, the paragraph that contains this statement starts with a sentence introducing the notion of climate variability, which puts the statement more into context.

It is possible that petitioners misinterpreted the IPCC’s statement as suggesting that the IPCC’s projection was on the basis of climate change alone, given the Southeastern Legal Foundation’s assertion, for example, that IPCC was projecting “imminent disaster.” While we agree with PBL that the IPCC’s statement could easily mislead readers without the proper context, we note that, before quoting the IPCC’s projection on rain-fed agriculture, EPA’s TSD includes the statement “Agricultural production, including access to food, in many African countries and regions is projected to be severely compromised by climate variability [emphasis added] and change.” Therefore, EPA provided the proper context for the IPCC’s conclusion.

With respect to the basis for the conclusion itself, the following excerpts from the three countries’ National Communication reports on the issues of climate variability and change, precipitation, and crop yields provide broad support for the Agoumi (2003) statements along with accompanying discussion:

• The National Communication of Morocco states (Kingdom of Morocco, 2001):

The development of climate scenarios for Morocco according to IPCC methodology reveals the following results: . . .

• A trend towards a decrease in average annual rainfall volume by about 4% in 2020 compared to 2000 levels. . . .
• An increase in the frequency and intensity of droughts in the south and the east of the country.

The first quantitative estimate of possible CC [climate change] impacts on water resources in 2020 points to the fact that there would be an average and general decrease in water resources (in the order of 10 to 15 %...).

The study of CC [climate change] impacts on agriculture (dominated by cereal cultivation) in 2020 unfolds the following results: A decrease in cereal yields by 50% in dry years and 10% in normal years.

As the Southeastern Legal Foundation admits, the numbers from Morocco’s National Communication lend support to the statement in Agoumi (2003) that “studies on the future of vital agriculture in the region have shown the following risks, which are linked to climate change: . . . deficient yields from rain-based agriculture of up to 50 per cent during the 2000–2020 period.”

Richard North’s contention (North, 2010, as referred to by the Southeastern Legal Foundation) that “the data apply to cereal yields only, not crops in general as is implied by the IPCC” is arguable considering that Morocco’s National Communication indicates that agriculture is “dominated by cereal cultivation.” Thus, it is not unreasonable to use cereal cultivation as a proxy for all of agriculture in this cereal-crop-dominated region.

• The National Communication of Algeria (Ministry of Territory Development and Environment, 2001) states: ¹

Because of global warming, we must brace ourselves for chronic climate instability and greater frequency of droughts and floods. Droughts damage soils and floods destroy ground cover and contribute to the erosion of soils. With longer spans of time between dry and wet spells comes an even greater impact due to erosion. The southern regions of the country will be most directly impacted by increased temperatures and will be subject to the numerous consequences of accelerated desertification. The increased risk of drought presents the greatest challenge as a result of climate change. The Intergovernmental Panel on Climate Change (IPCC) expect that the desert regions will extend northward in the Maghreb.

The above text provides a clear qualitative description of the risks climate change pose to agriculture in Algeria. In addition, this information from the National Communication of Algeria provides quantitative output from a model known as CROPWAT, which estimates changes in crop yields using climate change projections obtained from two general circulation models. The National Communication of Algeria reports:

… one can consider an average reduction in the output cereal of about 5.5 to 6.8%, corresponding mainly to instances of climate change [in 2020]( Ministry of Territory Development and Environment, 2001)

When considering these quantitative cereal yield changes, it is very important to note that these percentages refer to changes in cereal yields resulting primarily from climate change alone and not climate variability and change combined. The climate and hence precipitation variability in northern Africa can be quite large. For example, in the report Assessing an IPCC Assessment (PBL, 2010a), PBL states “…the [IPCC] authors made plausible that, due to current climate variability, the yields in Algeria, Morocco and Tunisia have been varying annually, including yield reductions of nearly 70% in individual years, in the period between 2000 and 2006.”

In other words, if these yield reductions resulting from greenhouse gas–induced climate change were superimposed on the yield reductions that might occur during a particularly dry period arising from the region’s characteristic precipitation variability, they would be higher and comparable with the results from the Morocco National Communication.

Finally, the Southeastern Legal Foundation’s reference to the Algeria National Communication’s projections for net increases in cereal projections in 2020 (relative to prior decades) is irrelevant and misleading. These increases are related not to climate variability and change but to changing agricultural practices and technology. Algeria’s National Communication makes clear that the effect of climate change on cereal yields is projected to be negative.

• The National Communication of Tunisia states (Republic of Tunisia, 2001):

…Tunisia is in a hydrous stress situation close to a shortage, sharpened by a high anthropic pressure. So minor they be, the Climate Changes can so, result in harmful consequences on water resources, on ecosystems depending of water, and on the different economic activities that need large quantities of water such as agriculture and tourism.

By modifying the evaporation and precipitation rate, the global warming will probably affect the hydrous climate balance and therefore the Tunisian water resources. In this way, if the intensification of the evaporation can lead to a possible important increase of the rain falls, it might not be sufficient to offset the decrease of the sweet water resources. Moreover, due to the global warming, the rain situation can be characterized by a bigger frequency of rains resulting from torrential storms and downpours, disappearing generally in streaming waters rather than be absorbed by the soils.

This information in the Tunesian National Communication does not provide any quantitative estimates of climate variability and/or change on rain-fed agriculture, but the clear qualitative implication is that climate changes—both drought and heavy precipitation events—will stress agriculture in Tunisia. We, therefore, find that the Southeastern Legal Foundation’s statement that “Tunisia’s submission concluded the picture was mixed, but they could have an increase in rain and agricultural production” is an overly optimistic interpretation of clearly expressed negative impacts.

Overall, these three National Communications (Morocco, Algeria, and Tunisia) provide qualitative support for the fact the climate change will likely stress rain-fed agriculture in northern Africa, consistent with the portrayal of Agoumi (2003) and the IPCC. The National Communication of Morocco presents quantitative information consistent with what is reported by Agoumi (2003) and the IPCC (and hence the TSD), while the National Communication of Algeria provides quantitative information that is consistent with these sources when factoring in precipitation variability in addition to climate change. The National Communication of Tunisia does not provide quantitative information.

Our view of the literature behind Agoumi (2003) provides considerable evidence that the scientific basis for the IPCC’s conclusion is legitimate. The PBL assessment of the IPCC notes that “…additional explanations could have provided further foundations for the statement, had they been included in [IPCC’s Working Group II] Chapter 9.” We concur, but the Southeastern Legal Foundation conclusion that “…there is no support for the IPCC’s dramatic pronouncement on African crop yields” is significantly overstated.

Comment (2-13):
The Southeastern Legal Foundation provides the following reaction to the African rain-fed agriculture projection, which appeared in the Sunday Times (Leake, 2010a) and comes from former IPCC chair Robert Watson: “Any such projection [pertaining to African crop yields] should be based on peer-reviewed literature from computer modeling of how agricultural yields would respond to climate change. I can see no such data supporting the IPCC report.”

Response (2-13):
Watson may not have appreciated that peer-reviewed modeling studies of climate change impacts on agriculture in parts of Africa are limited. As the IPCC’s AR4 WGI report states (Christensen et al., 2007): “Several climate change projections based on RCM (regional climate model) simulations are available for southern Africa, but are much scarcer for other regions.” Accordingly, as we discuss in Subsection 2.2.4.4 of this RTP document, the IPCC references gray literature in these circumstances. We also note in Response 2-10 that these studies are not central to the TSD or the Endangerment Finding. Finally, though we discuss some additional modeling studies pertinent to Africa in RTP 2-15, those modeling studies (Parry et al., 2005 and Hulme et al., 2001) were conducted at the global and continental scales and contain limited results pertinent to northern Africa specifically.

Comment (2-14):
The Southeastern Legal Foundation states that EPA ignored contrary peer-reviewed literature and submits literature that the Sahel is greening (from National Geographic and several studies) in contrast to “IPCC horror stories” (projecting reductions in rain-fed agriculture).

Response (2-14):
EPA is aware of the literature cited by the petitioner that suggests greening in parts of the Sahara and Sahel (e.g., Seaquisti, et al., 2009; Anyamba, and Tucker, 2005; Hutchinson et al., 2005; Olsson et al., 2005). The issue raised by petitioners is not new and was raised and responded to through the public comment process (see Response 2-73 in Volume 2 of the RTC document). Thus, these objections do not meet the test in Clean Air Act (CAA) Section 307(d)(7)(B) that it be impracticable to raise the objection during the public comment period or the reasons for the objection arose between June 24, 2009, and February 16, 2010. Nonetheless, we have reviewed these arguments and respond once again.

The fact that precipitation has increased recently in this region, as we note in our TSD in Section 4(d), does not mean that a combination of climate variability and change could not substantially reduce rain-fed agriculture in the future. The climate in this region is highly variable and while it has been relatively wet over the past decade or so, severe drought impacted the region for several decades from the 1960s to the 1990s and dry patterns could return to the region. As one of the studies (Nicholson, 2005) cited by the petitioner states: “The fluctuations between ‘wet’ and ‘dry’ in the Sahel/Soudan zones are extreme even on decadal and multi-decadal time scales.” Therefore, if the current wet period reverses to a dry period, the impacts of rain-fed agriculture on the region could be profound, especially when considering the potential enhancement of the drying from human-induced warming (i.e., climate change).

Finally, we note that the literature presented relates to impacts outside the United States, and it did not materially impact the determination of endangerment of public health and welfare in the United States. As noted in Subsection 2.1.1, the Endangerment Finding states (Section III.D): “The Administrator looked first at impacts in the United States itself, and determined that these impacts are reasonably anticipated to endanger the public health and the welfare of the U.S. population. That remains the Administrator’s position, and by itself supports her determination of endangerment.”

Comment (2-15):
The Southeastern Legal Foundation suggests that the IPCC ignored literature that drew different conclusions on the issue of rain-fed agriculture projections in Africa, specifically referring to two studies: Parry et al., 2005 and Hulme et al., 2001. The Southeastern Legal Foundation states: “Both Parry’s own paper and Hulme’s paper were known to and available to Professor Parry [co-chair of IPCC Working Group II] in composing the WGII Report and the Synthesis Report. Yet, Parry’s WGII report ignored his own paper and that of Hulme, which did not predict disaster, and instead relied on one that did, the Agoumi paper, even though it did so incorrectly and improperly and was not peer-reviewed.” The Southeastern Legal Foundation further notes that Hulme et al. (2001) were careful to note uncertainties in understanding African climate change, and implies that the IPCC was not as careful.

Response (2-15):
We have reviewed these papers (Parry et al., 2005, and Hulme et al., 2001) and find that, while not directly comparable with Agoumi (2003), they do not contradict that source. We also find, contrary to the Southeastern Legal Foundation’s assertion, that both of these studies were in fact cited by the IPCC, although not always in the same section or context as Agoumi (2003).

The Parry et al. (2005) study reports the results of a series of research projects that aimed to evaluate the implications of climate change for food production and risk of hunger. The analysis in this study is performed at global and continental scales rather than the regional scale. This is likely why it is not discussed in Chapter 5 of Working Group II’s contribution to the AR4 (Easterling et al., 2007), where Agoumi (2003) is cited in a section focusing on regional impacts in Africa (specifically on Morocco, Algeria, and Tunisia). The Parry et al. (2005) study is cited multiple times in Chapter 5 of Working Group II’s contribution (“Food, Fiber, and Forest Products,” Easterling et al., 2007), which provides a global perspective. Therefore, Parry did not “ignore his own paper” as stated by the Southeastern Legal Foundation.

One of the primary conclusions of Parry et al. is that “the region of greatest risk [of losses in food production, and hunger due to climate change] is Africa.” Parry et al. (2005) provide specific cereal yield projections for the 2020s and 2080s resulting from different GHG emission scenarios. They state for the globe: “By the 2020s, small changes in cereal yield are evident in all scenarios, but these fluctuations are within historical variations.” For the 2080s, Parry et al. (2005) provide projections specific to Africa – but not northern Africa specifically, stating that climate change could reduce cereal yields by up to 30%. Importantly, the changes in cereal yield projected for the 2020s and 2080s are driven by GHG-induced climate change and likely do not fully capture interannual precipitation variability which can result in large yield reductions during dry periods, as the IPCC (Christensen et al., 2007) states: “…there is less confidence in the ability of the AOGCMs (atmosphere-ocean general circulation models) to generate interannual variability in the SSTs (sea surface temperatures) of the type known to affect African rainfall, as evidenced by the fact that very few AOGCMs produce droughts comparable in magnitude to the Sahel droughts of the 1970s and 1980s.” Given the different scopes of the two analyses, it is misleading to state that the Parry et al. projections are inconsistent with the Agoumi (2003) yield projections.

The Hulme et al. (2001) study, which reviews observed (1900–2000) and possible future (2000–2100) continent-wide changes in temperature and rainfall over Africa, is also not ignored by the IPCC, contrary to the assertion of the petitioner. In fact, it is cited twice in IPCC’s Working Group II Chapter 9 on Africa (Boko et al., 2007):

• Hulme et al. (2001) is cited in a statement about the complexity of African climatology: “Other factors that complicate African climatology include dust aerosol concentrations and sea-surface temperature anomalies, which are particularly important in the Sahel region (Hulme et al., 2001; Prospero and Lamb, 2003) and southern Africa (Reason, 2002), deforestation in the equatorial region (Semazzi and Song, 2001; Bounoua et al., 2002)…”
• Hulme et al. (2001) is also cited in a statement pertaining to uncertainties in precipitation projections in the western Sahel (Boko et al., 2007): “For the western Sahel (10 to 18°N, 17.5°W to 20°E), there are still discrepancies between the models: some projecting a significant drying (e.g., Hulme et al., 2001; Jenkins et al., 2005) and others simulating a progressive wetting with an expansion of vegetation into the Sahara (Brovkin, 2002; Maynard et al., 2002; Claussen et al., 2003; Wang et al., 2004; Haarsma et al., 2005; Kamga et al., 2005; Hoerling et al., 2006).”

These examples demonstrate that the IPCC both cited Hulme et al. (2001) and transparently discussed the complexity of Africa’s climate and the uncertainty in African climate projections. This treatment is appropriate and reasonable, contrary to the petitioner’s implication.

Even in light of the complexities and uncertainties, Hulme et al. (2001) state that a “warming climate will nevertheless place additional stresses on water resources [in Africa], whether or not future rainfall is significantly altered” and they project reduced precipitation over Tunisia. Hulme et al. (2001) do not, however, provide projections for changes in cereal yields (from changes in rain-fed agriculture), so their results cannot be compared directly with Agoumi (2003) or its supporting documents (discussed in Response 2-12).

Overall, the IPCC does not ignore either the Parry et al. (2005) or Hulme et al. (2001) studies. The findings of these studies, while not directly comparable with Agoumi (2003), are broadly consistent. Hulme et al. (2001) project increased drying over northern Africa while Parry et al. (2005) project an increased risk of reduced cereal yields over all of Africa. The petitioner’s claim that IPCC was not careful or acted inappropriately in this regard is not confirmed by careful review of the material.
-------------------------------------

Eli can retire