 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
 |
The U.S. National Climate Change Assessment: Do the Climate Models Project a Useful Picture of Regional Climate?
Subcommittee on Oversight and Investigations
Prepared Statement of The Honorable Jim Greenwood Good morning and welcome. This morning we will stand at the intersection of science, policymaking, and public concern about climate change to consider if an influential report provides the guidance necessary to navigate this often-confusing, uncertain territory. At issue is the use of climate models to create the regional climate-change scenarios that frame the discussion in what is called, in shorthand, the U.S. National Assessment on climate change. A national report about this assessment, prepared by scientists and researchers under a federal advisory committee known as the National Assessment Synthesis Team - two co-chairs of which are before us today -- seeks to provide policymakers and the public with "plausible" pictures of regional climate, fifty to 100 years from now, under the impact of global warming. Now, let me note, as we head into this, a couple of points about my perspective. First, I tend to agree with the view expressed in some of the testimony we will hear this morning that there are some reasonable mitigation measures and other policy strategies we can take to address climate change risks, and that these do not depend upon the scientific dispute before us. Indeed, this dispute should not be used to avoid decisions on such policies. Of course, there continues to be much debate about some of these policy decisions - how much can or should we do, when should we do it - and the debate has engaged many Members of the Energy and Commerce Committee, on both sides of the aisle. The hearing today, though it will help inform the debate, is not the appropriate forum to conduct that debate, which would only distract us from the important questions before us. Second, this is not to suggest we should glide over questions of science, and the scientific validity of the tools and methods used to drive understanding of inherently science-based issues. We need sound science to inform our decisions and to ensure our actions in the name of science aren't misguided because we were more confident than we should have been. So we begin today with a straightforward question: do the climate models project a useful picture of regional climate? And we have asked our panelists today - all scientists and all quite familiar with controversies about climate, climate variability and impacts, and the National Assessment - to comment on this, and speak to the role and suitability of the models used in this report. In the U.S. Climate Action Report, released to the United Nations this past May, reference to the National Assessment discussed the use of the models this way: "Use of these models is not meant to imply that they provide accurate predictions of the specific changes in climate that will occur over the next 100 years. Rather, the models are considered plausible projections of potential changes for the 21rst century." Two initial questions come to my mind when I read this - and I hope the witnesses can assist us in answering these questions this morning. The first has to do with the "plausibility" of the picture painted by the models. And this is basically a science question, which I'm sure the experts here can sort out for this layman. And this is: How reliable are the predictions of plausible regional outcomes given the admitted limitations of the modeling? And what would this mean for the usefulness of the report? And given the wide variations in the projections, results that oppose each other in one area but are similar in others, is it reasonable to rely upon them to take specific actions or to adopt specific policies? This appears to be a thoughful report. And I believe the authors sincerely attempted to work through describing some of the uncertainty for policymakers and the public. Was it sufficient? How did the models work in the full picture here? The second question relates to the problem of communicating the uncertainty. The reference above makes a rather nuanced description of predictions versus the projections. Yet The New York Times, which reported the Climate Action Report's reference to the Assessement, wrote this, back in May: ".the report says the United States will be substantially changed in the next few decades - 'very likely' seeing the disruptions of snow-fed water supplies, more stifling heat waves and the permanent disappearance of Rocky Mountain meadows and coastal marshes." Was this the message the authors want the public to take away? we must come to grips with the fact that a scientific assessment such as this is more than an academic exercise - read by the few who can grasp all the complexities. It is a document meant to guide us - policymakers and the public -- through complicated policy intersections, where we rely on science as much as we can. The stakes here are as high as any could be - the very inhabitability of our planet. The cost of reducing the stakes is also high. For both of these reasons, the reliability of our predictive models must be high indeed. I thank the witnesses again, especially those who traveled so far to testify this morning.
|
|||||||||||
|
