Wednesday, July 25, 2007

Betting on Droughts I: A Little Science

This is going to take a couple posts, so get a feel for where this might be going.

First from TerraDaily:

La Nina Pattern Likely To Play Havoc
With Global Weather

The UN's weather agency on Friday said a disruptive La Nina climate pattern was taking shape in the Pacific, raising the prospect of an active Atlantic hurricane season and strong monsoons in Asia. The World Meteorological Organisation (WMO) said in a statement that the development of La Nina in the second half of 2007 was now "more likely than not" after an initial hesitation in the past two months.

"Now things seem to be on track for the development of La Nina, but it is likely to be a weak La Nina event rather than a strong one." More

Warning: Anthropogenic Causation Skeptics Ahead

From CO2 Science, a discussion of U.S. drought history:

"Recent advances in the reconstruction of past drought over North America," in the words of Cook et al., "have revealed the occurrence of a number of unprecedented megadroughts over the past millennium that clearly exceed any found in the instrumental records." Indeed, they state that "these past megadroughts dwarf [our italics] the famous droughts of the 20th century, such as the Dust Bowl drought of the 1930s, the southern Great Plains drought of the 1950s, and the current one in the West that began in 1999," all of which dramatic droughts fade into almost total insignificance when compared to the granddaddy of them all, which they describe as "an epoch of significantly elevated aridity that persisted for almost 400 years over the AD 900-1300 period."

Our little friend makes another appearance:

...Of central importance to North American drought formation, in the words of the four researchers, "is the development of cool 'La Niña-like' SSTs in the eastern tropical Pacific." Paradoxically, as they describe the situation, "warmer conditions over the tropical Pacific region lead to the development of cool La Niña-like SSTs there, which is drought inducing over North America."

...In further explaining the mechanics of this phenomenon, on which both "model and data agree," Cook et al. state that "if there is a heating over the entire tropics [our italics] then the Pacific will warm more in the west than in the east because the strong upwelling and surface divergence in the east moves some of the heat poleward," with the result that "the east-west temperature gradient will strengthen, so the winds will also strengthen, so the temperature gradient will increase further ... leading to a more La Niña-like state." What is more, they add that "La Niña-like conditions were apparently the norm [our italics] during much of the Medieval period when the West was in a protracted period of elevated aridity and solar irradiance was unusually high."

If I should forget to follow up on this in the next weak or so send an email with your favorite memory-enhancing pills, potions or programs. For now take a look at the hurricane futures and go to bed thinking about oil being in backwardation.