Thursday, December 21, 2006

RTFR...the WHOLE FR....

Somewhere down in the comments, anonymous says....

Speaking of inconvenient truths:
1. Though there is evidence both for and against the existence of a detectable anthropogenic signal in the tropical cyclone climate record to date, no firm conclusion can be made on this point.
2. No individual tropical cyclone can be directly attributed to climate change.
Point 1, is the WMO trying to avoid open warfare, which fails. This being the same document that the Boulder Staked Out On The Rocks Society referred to and comes from the summary statement. However, that is the classic comics edition. If you read the full version (RTFR like the bunny tells you), among other things you get (Eli pulled the references to save space, RTFR)
6. The climatological conditions under which tropical cyclones occur have been well established over decades of research. These include a requirement for warm sea surface temperatures, low vertical wind shear and high values of large scale relative vorticity in the lower layers of the troposphere .
7. It is also well established observationally that over the past several decades the sea surface temperatures over most tropical ocean basins have increased in magnitude by between 0.25 – 0.5 degrees C .
8. It is well accepted by most researchers within the field of climate science that the most likely primary cause of the observed increase of global mean surface temperature is a long term increase in greenhouse gas concentrations. It is likely that most tropical ocean basins have warmed significantly due to this same cause. If anthropogenic increases in greenhouse gases are the primary cause, then it would be expected that tropical sea surface temperatures will increase by an even greater amount in the 21st century than during the 20th century, as described in the climate projections of the IPCC (2001).
9. Globally the major factor affecting tropical cyclone frequency and tracks on an
interannual (e.g., 2-7 year) time scale is the ENSO phenomenon.
They go on to talk about the Emmanuel and Webster papers and the push back from Gray, et Landsea, and hit the bottom lines fairly quickly
13. The scientific debate concerning the Webster et al and Emanuel papers is not as to whether global warming can cause a trend in tropical cyclone intensities. The more relevant question is how large a change: a relatively small one several decades into the future or large changes occurring today? Currently published theory and numerical modeling results suggest the former, which is inconsistent with the observational studies of Emanuel (2005) and Webster et al. (2005) by a factor of 5 to 8 (for the Emanuel study).
This puts the shoes on the other feet when it comes to theory or observation
The debate is on this important quantification as to whether such a signal can be detected in the historical data base, and whether it is possible to isolate the forced response of the climate system in the presence of substantial decadal and multi-decadal natural variability. This is still hotly debated area for which we can provide no definitive conclusion.
14. Through the work of many researchers there is a developing theory governing maximum tropical cyclone intensity. The key concept is that for a given ocean temperature and atmospheric thermodynamic environment there is an upper bound on the intensity a tropical cyclone may achieve. This upper bound is referred to as the Maximum Potential Intensity (or MPI).......Given, however, that only a small percentage of tropical cyclones attain their MPI and that the sensitivity of hurricane intensity to CO2-induced warming is 3-5% per degree Celsius in these simulations and theories, Knutson and Tuleya (2004) have speculated that CO2 induced tropical cyclone intensity changes are unlikely to be detectable in historic observations and will probably not be detectable for decades to come.

18. Given the consistency between high resolution global models, regional hurricane models and MPI theories, it is likely that some increase in tropical cyclone intensity will occur if the climate continues to warm.
19. A robust result in model simulations of tropical cyclones in a warmer climate is that there will be an increase in precipitation associated with these systems....

21. There is general agreement that no individual events in those years can be attributed directly to the recent warming of the global oceans. A more appropriate question is whether the probability of an event happening in a particular basin has been increased by the ocean warming, as for example the probability of cyclone development can change according to the phase of ENSO or of the Madden Julian Oscillation.
They agree that most damage costs are due to sea side development, and that things will get worse
25. Projected rises in global sea level are a cause for concern in the context of society’s vulnerability to tropical cyclone induced storm surges.
The Rabett agrees strongly with the last point, he does. Now go read the full statement like good folk do right before class. There will be a test.


Anonymous said...

Wow - you really feel strongly about this subject don't you? Take it easy - no need to get all wound up...

Lab Lemming said...

So will global warming increase or decreae wind shear?

Anonymous said...

I think Eli gets "wound up" for the same reason that other scientists do.

At some point, one gets tired of the BS coming from the political scientists and others who 1) have no clue what they are talking about or 2) have a clue but knowingly misrepresent through cherry picking.

Political scientists should stick with what they know. I forget what that is, but there must be something -- and they should stick with it.

Anonymous said...

one thing about the gw tropical cyclone debate that puzzles me is the suggestion by some that there is no relationship between hurricane frequency and warmer ocean temperatures.
this seems counterintuitive, given that there does seem to be a minimum temperature at which hurricanes develop.

i can understand that if the minimum temperature condition were already being met in every place where the other conditions necessary for hurricane formation are found, then an increase in temperature (that occurred above this minimum) would not increase the likelihood of formation.

but it is far from clear that this is the case. presumably, as ocean temperatures increase, one starts to get the minimum temp condition in regions of the ocean that previously fell below the minimum. if the total area of ocean meeting the min temp condition increases, presumably the probability of a hurricane starting also increases.

the fact that no such increase in frequency has occurred to date does not mean that it will not occur in the future.

it is conceivable, at least, that there may be ocean regions 'almost ripe' for hurricane formation that are close to (but still below) the min temp. condition.

stevesadlov said...

Maybe the behavior of ocean heat content will surprise us. Maybe it already has.

Anonymous said...

Yes, perhaps we will be surprised.

Sometimes things do seem counterintuitive because we do not properly understand them.

But logic based on what one knows about physical processes (in this case thermodynamics) can also take one a long way toward predicting how nature will behave under particular circumstances if those circumstances have not yet been satisfied but yet could be satisfied in the future.

If something seems counterintuitive based upon everything one knows, one must at least explain why things do not behave in the way one expects.

Too often we see the argument that "because it has not happened yet, it will not happen or at least is unlikely to happen."

This is true only if it would violate physical law or if the necessary conditions are not likely to ever be met.