Monday, March 21, 2005

Backing the IPCC

I’m becoming more and more convinced that climate advocates can concede that climate models are not perfect and still win the debate. Acknowledging that past IPCC reports have been slightly off in their predictions does not belittle the overwhelming scientific consensus on the issue. The continued support (from qualified sources) for the IPCC conclusions is undeniable. For example, in October 2003, more than 1,000 scientists from around the nation signed the State of Climate Science letter confirming that the major findings of the 2001 IPCC report were accurate and continue to reflect scientific consensus on the issue. Here are the main claims in the letter:

1) Anthropogenic climate change, driven by emissions of greenhouse gases, is already under way and likely responsible for most of the observed warming over the last 50 years—warming that has produced the highest temperatures in the Northern Hemisphere during at least the past 1,000 years;

2) Over the course of this century, the Earth is expected to warm an additional 2.5 to 10.5 °F, depending on future emissions levels and on the climate sensitivity—a sustained global rate of change exceeding any in the last 10,000 years;

3) Temperature increases in most areas of the United States are expected to be considerably higher than these global means because of our nation's northerly location and large average distance from the oceans;

4) Even under mid-range emissions assumptions, the projected warming could cause substantial impacts in different regions of the U.S., including an increased likelihood of heavy and extreme precipitation events, exacerbated drought, and sea level rise;

5) Almost all plausible emissions scenarios result in projected temperatures that continue to increase well beyond the end of this century; and,

6) Due to the long lifetimes of greenhouse gases in the atmosphere, the longer emissions increase, the faster they will ultimately have to be decreased in order to avoid dangerous interference with the climate system.

Consensus like that is pretty tough for skeptics to poke holes in, try as they may.



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