Optimists or Pessimists — what is it with those IPCC types?

I’m a self-described optimistic pessimist (or was it a pessimistic optimist, I simply can’t recall). I can see the dark clouds but believe that, somehow, we can figure out paths to a better situation. But, perhaps like the military, I like to have a clear understanding of the “worst case” (at least the reasonable worst case), seek to prepare for that, and feel relieved (and very well prepared) when that “worst” case doesn’t emerge. 

So, when it comes to climate science, what is it about the Intergovernmental Panel on Climate Change (IPCC)?  Are they incredibly pessimistic doomsday kooks, as Senator Inhofe seems to want us to believe, or are they overly optimistic, not adequately describing plausible ‘worst case’ scenario environments? Scientific American has weighed into this discussion …

In Conservative Climate, David Biello examines the question as to whether the IPCC reports are too conservative (e.g., their scenarios are too optimistic and understate the potential impact of Global Warming)  or too aggressive (pessimistic in overstating potential impact).    As some people are gleefully citing the IPCC as a clear proof that Al Gore, in talking about possibilities, has overstated the case, it is worth thinking this through.

 Biello points to the bureaucratic nature of the process and the need for consensus.  Right now, flying around skeptic conversation is a focus on solar activity and global warming.  Why isn’t this discussed in the report?

“after objections by Saudi Arabia and China, the report dropped a sentence stating that the impact of human activity on the earth’s heat budget exceeds that of the sun by fivefold. “

Saudi Arabia and China, such great bastions of open scientific thought forced the dropping of a sentence from the report.  Was that sentence right? Well, according to a top expert, no, the fivefold figure was probably wrong.

“The difference is really a factor of 10,” says lead author Piers Forster of the University of Leeds in England: compared with its historical output, the sun currently contributes an extra 0.12 watt of energy for each square meter of the earth’s surface, whereas man-made sources trap an additional 1.6 watts per square meter.

Oops … actually, should we point out that Foster was being generous, as the difference would be more like by a multiple of 13.3 …

So, absence of quantifying solar activity versus manmade was driven by Saudi Arabia and China … two of the environment’s greatest friends in the community of nations.

And, well, what about sea-level rise of 18-59 centimeters (7-23 inches) in the IPCC report?  Well, the models don’t include potential contributions from glacier melt — because it was poorly understood, too difficult to model, and new information came to light about ice activity after the report’s information cut-off dates.

As glaciologist Richard Alley of Pennsylvania State University notes: “The ice sheet is losing mass, this loss has increased over time, [and] it is not the dominant term in sea-level rise–but it matters.” In fact, many variables come into play in Greenland’s ice sheet. “You’re trying to figure out what is going on with an immense, remote and complex beast, and it isn’t easy,”

For example, the report did not model “positive feedback cycles” — that the very process of melting can lead to increased melting for ice now surrounded by water.  Nor did it account for water rise potentially lifting ice currently resting on rock well below the water line and surrounding it by water, increasing its melt rate. Nor did it account …

“By excluding statements that provoked disagreement and adhering strictly to data published in peer-reviewed journals, the IPCC has generated a conservative document that may underestimate the changes that will result from a warming world, much as its 2001 report did.”

Thus, the IPCC report is clearly conservative — extremely conservative — in its science.  Why can’t Senator Inhofe and other American conservatives therefore embrace its conclusion that humanity’s activity is the principle cause of current Global Warming?


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