November 06, 2005

Dark and Unhappy Expectations

A team of scientists at Purdue University's Climate Change Research Center has predicted a dramatic deterioration of the weather for the United States over the next 100 years.

"This is the most detailed projection of climate change that we have for the U.S.," said team leader Noah S. Diffenbaugh, an assistant professor of earth and atmospheric sciences in Purdue's College of Science and a member of the Purdue Climate Change Research Center. "And the changes our model predicts are large enough to substantially disrupt our economy and infrastructure."

"The climate model, run on supercomputers at Purdue University, takes into account a large number of factors that have been incompletely incorporated in past studies, such as the effects of snow reflecting solar energy back into space and of high mountain ranges blocking weather fronts from traveling across them," he said.

Diffenbaugh said a better understanding of these factors – coupled with a more powerful computer system on which to run the analysis – allowed the team to generate a far more coherent image of what weather we can expect to encounter in the continental United States for the next century. Those expectations, he said, paint a very different climate picture for most parts of the country.

Some of the unhappy expectations reached in the team's research include:

• The desert Southwest will experience more heat waves of greater intensity, combined with less summer precipitation. Water is already at a premium in the four-corners states and southern Nevada and, as years pass, even less water will be available for the region's burgeoning populations, with extreme hot events increasing in frequency by as much as 500 percent.

• The Gulf Coast will be hotter and will receive its precipitation in greater volumes over shorter time periods.

• In the northeastern United States – roughly the region east of Illinois and north of Kentucky – summers will be longer and hotter.

•Similarly, the continental United States will experience an overall warming trend: Temperatures now experienced during the coldest two weeks of the year will be a past memory, and winter's length will diminish as well, according to the model.

Commenting on the study, Stanford University's Stephen H. Schneider said the results confirm scientists' suspicions about the future of climate change. "This study is the latest and most detailed simulation of climatic change in the United States," said Schneider, who is Stanford's Melvin and Joan Lane Professor for Interdisciplinary Environmental Studies. "Critics have asserted that the coarse resolution of previous studies made their sometimes dire predictions suspect, but this new result with a very high resolution grid over the United States shows potential climatic impacts at least as significant as previous results with lower resolution model. As the authors wisely note, such potential impacts certainly should not be glibly dismissed."

In response to questions posed by Orwell's Grave, two Purdue University professors reflected on the study.

From Gerald Shively, Professor of Agricultural Economics

Anticipating economic impacts and making good public policy decisions requires good science. One of the reasons that it has been difficult to reliably forecast economic and social impacts arising from climate change is that there has been considerable uncertainty about the range of physical changes that will take place in our environment over the next 50-100 years. The value of Noah's work is that it narrows this band of uncertainty and provides better information for those of us working in the realm of economic and social science. It will now be possible for us to develop better forecasts of likely economic changes. To a large extent, our work can now begin.

I'm not prepared to attach dollar values to potential impacts or to speculate as to who might be most affected by climate changes. That said, the scenarios Noah's team highlights -- regional changes in temperature, rainfall, the length of growing seasons, etc. -- will clearly have economic impacts. Noah's work will help us to identify and anticipate likely changes and begin to think about ways to adapt to them (or mitigate their negative effects) sooner rather than later. In this way we may be able to avoid large scale disruptions to the agricultural sector, our general economy and society at large. I think adaptation is the operative word here – for example, I would highlight new crop varieties that are robust to climate variability and pest pressure, new approaches to water management that are sensitive to drought and rainfall variability, and enhanced “early warning systems” that allow the global community to respond more quickly to climate-induced crises in food production in vulnerable areas of the globe. My sense from reading the literature is that the climate has a lot of inertia and therefore it might be overly optimistic for us to think we can “undo” the changes underway.

From Leigh Raymond, Professor of Political Science, Purdue University

If our society wants to take steps to limit global warming impacts, it seems clear from the preponderance of science that I've read that we need to reduce our greenhouse gas emissions substantially, particularly in countries like the U.S. where per capita emissions of CO2 are an order of magnitude higher than many other nations.
I think higher fuel and energy taxes are a very good idea if implemented in a "revenue neutral" way by reducing regressive taxes on labor like the payroll tax. This also can minimize the impact on poorer individuals of higher fuel costs. This idea of "tax shifting" doesn't get enough serious attention in my view.
I also think we have to get serious about negotiating or agreeing upon a global distribution of emissions rights, so that countries like China and India are convinced to participate in future climate agreements. I am already on record (in Science, Baer et al 2000) as supporting the idea of equal per capita emissions rights as a basis for such an international agreement as a long-term goal to be achieved gradually in a very incremental manner (although I have some concerns about a strict equal per capita distribution compared to one that distinguishes between "subsistence" and "luxury" emissions, as Henry Shue has put it. Strict equality might not actually make the most sense, but it is still a worthwhile place to start the discussion).
I am intrigued by Peter Barnes idea of a "sky trust" as another approach within the U.S., although I think tax shifting might achieve many of the same goals with less trouble. But I like his approach as well in many ways and think it, too, deserves serious consideration.
In general, we have to find creative ways, in my view, to take advantage of what we know about the strengths of market-based approaches to environmental policy in general, while paying very careful attention to issues of distributive equity and political reality. The EU emissions trading system, for example, is a good step in the right direction. But it is just a small step.

There is an MP3 here of a talk given by Prof. Raymond entitled "State of Fear or State of Denial: The Increasing Isolation of the US Federal Government on Climate Change."

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