The Honest Broker works the Boiler Room
Ethon dropped by with a big grin on his beak. It's been an unhappy time with not much fresh liver available in Boulder, the old place is dry and dusty without Dano and the old bunny to stir things up, and even newcomers like Jon soon recognize that the Honest Broker Boiler Room is selling penny stocks. But just this weekend Pielke Jr. provided a wonderful sampler of cherry pickled liver dumplings from the old place. A big Roger special of proving that this is the best of all possible worlds followed by a very serious admonition that climate change is real, even though this is the very best of all possible world and nothing is happening anyhow, stirred up three comments.
Bunny University is going to feature Roger's tour de force in Eli's new textbook, "RTFR or get snookered". Crowing about the recently issued CCSP Extremes Report, Roger thumbs his way to the back pages:
1. Over the long-term U.S. hurricane landfalls have been declining.
Yes, you read that correctly. From the appendix (p. 132, emphases added):
The final example is a time series of U.S. landfalling hurricanes for 1851-2006 . . . A linear trend was fitted to the full series and also for the following subseries: 1861-2006, 1871-2006, and so on up to 1921-2006. As in preceding examples, the model fitted was ARMA (p,q) with linear trend, with p and q identified by AIC.Of course, he started reading from the back. If he makes it to page 5, he might have found
For 1871-2006, the optimal model was AR(4), for which the slope was -.00229, standard error .00089, significant at p=.01. For 1881-2006, the optimal model was AR(4), for which the slope was -.00212, standard error .00100, significant at p=.03. For all other cases, the estimated trend was negative, but not statistically significant.
Atlantic tropical storm and hurricane destructive potential as measured by the Power Dissipation Index (which combines storm intensity, duration, and frequency) has increased (see Table ES.1). This increase is substantial since about 1970, and is likely substantial since the 1950s and 60s, in association with warming Atlantic sea surface temperatures (Figure ES.6) (Chapter 2, section 18.104.22.168).And, oh yes, you will find the same information in the three cited chapters.
There have been fluctuations in the number of tropical storms and hurricanes from decade to decade and data uncertainty is larger in the early part of the record compared to the satellite era beginning in 1965. Even taking these factors into account, it is likely that the annual numbers of tropical storms, hurricanes and major hurricanes in the North Atlantic have increased over the past 100 years, a time in which Atlantic sea surface temperatures also increased. The evidence is not compelling for significant trends beginning in the late 1800s.
Uncertainty in the data increases as one proceeds back in time. There is no observational evidence for an increase in North American mainland land-falling hurricanes since the late 1800s (Chapter 2, section 22.214.171.124). There is evidence for an increase in extreme wave height characteristics over the past couple of decades, associated with more frequent and more intense hurricanes (Chapter 2 section 126.96.36.199.2).
Hurricane intensity shows some increasing tendency in the western north Pacific since 1980. It has decreased since 1980 in the eastern Pacific, affecting the Mexican west coast and shipping lanes. However, coastal station observations show that rainfall from hurricanes has nearly doubled since 1950, in part due to slower moving storms (Chapter 2, section 188.8.131.52).
Attribution of Changes
It is very likely that the human induced increase in greenhouse gases has contributed to the increase in sea surface temperatures in the hurricane formation regions. Over the past 50 years there has been a strong statistical connection between tropical Atlantic sea surface temperatures and Atlantic hurricane activity as measured by the Power Dissipation Index (which combines storm intensity, duration, and frequency). This evidence suggests a human contribution to recent hurricane activity. However, a confident assessment of human influence on hurricanes will require further studies using models and observations, with emphasis on distinguishing natural from human induced changes in hurricane activity through their influence on factors such as historical sea surface temperatures, wind shear, and atmospheric vertical stability (Chapter 3, section 184.108.40.206).
Roger of the Breakdown Institute continues his merry way
Hmm, so he DID read page 5, but somehow skipped over the part about hurricanes. If he was a broker, you gotta wonder which market he traded in, but agin, our hero suffers from attention deficit disorder an manages to leave out what follows the . . .
2. Nationwide there have been no long-term increases in drought.
Yes, you read that correctly. From p. 5:Averaged over the continental U.S. and southern Canada the most severe droughts occurred in the 1930s and there is no indication of an overall trend in the observational record . . .
However, it is more meaningful to consider drought at a regional scale, because as one area of the continent is dry, often another is wet. In Mexico and the U.S. Southwest, the 1950s were the driest period, though droughts in the past 10 years now rival the 1950s drought. There are also recent regional tendencies toward more severe droughts in parts of Canada and Alaska (Chapter 2, section 220.127.116.11).There is more, but we leave the rest of the evisceration to the peanut gallery. Might rip another piece out later
Attribution of Changes
No formal attribution studies for greenhouse warming and changes in drought severity in North America have been attempted. Other attribution studies have been completed that link the location and severity of droughts to the geographic pattern of sea surface temperature variations, which appears to have been a factor in the severe droughts of the 1930s and 1950s (Chapter 3, section 3.2.3).
A contributing factor to droughts becoming more frequent and severe is higher air temperatures increasing evaporation when water is available. It is likely that droughts will become more severe in the southwestern U.S. and parts of Mexico in part because precipitation in the winter rainy season is projected to decrease (see Table ES.1). In other places where the increase in precipitation cannot keep pace with increased evaporation, droughts are also likely to become more severe (Chapter 3, section 3.3.7).