Thursday, March 15, 2012

Why We Need More Dynamic Downscaling in Climate Research

I usually share very few of the views, or accept little of the research published by Roger A. Pielke, Sr., but his recent paper (Regional Climate Downscaling: What's the Point?) in Eos Transactions (Vol. 93, No. 5, p. 52)bears more than a passing comment, and maybe even a kudo or two.

The reason, as suggested by the attached table from Pielke's paper, is that we need a better interface in terms of climate-meteorological predictions to connect downsaling input Types 1, 2, 3 and 4. as Pielke notes, "both statistical and dynamical downscaling of multidecadal global climate models provide finer spatial resolution information for climate impact assessments."

More disturbing:

"Because real world observational constraints diminish from type 1 to type 4 downscaling, uncertainty grows as more climate variables must be predicted from models rather than obtained from observations".

Indeed, but let's bear in mind there ARE observations from many sources being made, e.g. in respect of the melting rate of Arctic sea ice,

The trick then, so far as I can see, is to improven selection or identification of what specific subset of current observations can best allow a practical integration between the downscaling inputs to maximize usefulness for climate models and attain specific practical objectives.

As an example, up to now most of the media and many meteorological “experts’” have failed to integrate El Nino and La Nina into the unfolding panorama of global warming. This is because they subscribe to an archaic view that these are mostly oceanic phenomena. However, as climatologist S. George Philander has noted (EOS, March 31, 1998, ‘Who is El Nino?’) , this is erroneous. Recent scientific results disclose these are both atmospheric and oceanic phenomena. Since global warming upsets atmospheric dynamics, via excess heat being trapped, it must impact on El Nino and La Nina as well. (Especially as more and more heat, as well as CO2, is being absorbed in the oceans - making them warmer and more acidic...see e.g. )

Thus, if correct and detailed observations are available, we already have a possible integration between type 3 and type 4 inputs to downscaling.

A more recent phenomenon which I think bears examining is the retraction of the jet stream far north resulting in the putative effect of much warmer recent winter temperatures for the U.S. Almost every night recently, when the network talking heads present the news of the "mild winter" they invariably show the elevated jet stream - hovering somewhere around northern Canada. But HOW is this happening?

I surmise that it has something to do with the very much more intense warming of the Arctic and sea ice retreat and so acts as a kind of energy balancing agent, i.e. so that the cold air needed to maintain some semblance of Arctic ice pack isn't dispersed to far southerly latitudes so the ice pack melts even faster. If this were to happen, we already know the planetary albedo would be changed, altered as more ground terrain is exposed and this aborbs more infrared radiation than refecting it.

Thus, retreating polar ice = decreased albedo or reflectance, leading to a darker Earth surface - with more IR absorbed - reinforcing the closure while enhancing global warming. As more ice melts from the polar regions, entropy increases - and positive feedback proceeds faster. Even Carl Sagan, the original proponent of the runaway greenhouse model (for Venus, in his Ph.D. thesis) noted that such a positive feedback cycle would ultimately lead directly into the maw of the runaway.

What we need then, are observations to test this hypothesis: that the actions of the jet stream are in reality "entropy minimizing" in respect of the Arctic - which after all, is the freezer of the planet. If it "defrosts" we're basically all for the high jump. So, in this sense, perhaps the "riding high " jet stream is the climatic "canary in the coal mine".

Preferably each observational subset for such a test, will be identified within the downscaling type framework that Pielke suggests.

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