For the first time, the U.S. Environmental Protection Agency is prepared to regulate carbon dioxide and other heat-trapping gases, which it says threaten public health and welfare. Atmospheric sciences professor Don Wuebbles, a co-author of several national and international assessments of climate change, reports that the changing climate will likely have significant effects in the United States. Wuebbles was interviewed by News Bureau Life Sciences Editor Diana Yates.
You and your colleagues are working on an assessment for the federal government of potential climate change impacts in the U.S. Can you describe some of the possible impacts?
We are currently waiting for the government agencies to sign off on the final version of the report, but I think I can safely state that it builds upon previous research suggesting that climate changes are already occurring in the United States and that the climate throughout the U.S. is projected to continue to change significantly throughout the century as the result of the effects of human activities. There are a number of potential impacts expected to result from these changes. I will just highlight a few of them.
Water is likely to be an issue in every region of the U.S., but the nature of the potential impacts will vary across our country. In the Midwest, we have concerns about an increasing probability of both floods and droughts. With higher precipitation expected in the spring and more of the precipitation likely to come as larger events, more probability of floods is projected. But the potential for decreasing summer precipitation also increases the probability of droughts in those months.
Threats to human health from the projected climate changes include concerns about heat stress, water-borne diseases, poor air quality, extreme weather events, and diseases transmitted by insects and rodents. One of the key concerns in the Midwest is the increased likelihood of multi-day heat waves; our studies suggest that week-long heat waves like the one in 1995 that resulted in hundreds of deaths in the Chicago area will become much more common. However, adaptation through robust public health measures can reduce the potential for negative impacts.
Agriculture is considered one of the sectors most adaptable to changes in climate. However, it is expected that increased heat, pests, water availability, diseases, and weather extremes will pose adaptation challenges for crop and livestock production.
It is also important to recognize that climate change is not happening in a vacuum - it will likely combine with other stresses on society such as pollution, population growth, overuse of resources, and urbanization to create larger impacts than from any of these factors alone.
Are there regional differences in these impacts?
There are very significant differences expected across the U.S. For example, as the century progresses, coastal areas are expected to be increasingly at risk of flooding and erosion from the effects of sea-level rise and storm surges. Concerns about significant drought, related to reduced precipitation and increasing evaporation (from increasing temperatures) is likely to be a major issue for the West and Southwest. On the other hand, the Northeast is likely to be more concerned about the excess water resulting from sea level rise and the increased likelihood of heavy downpours.
Are there any potential benefits of climate change?
Yes, definitely. Not all of the changes are bad. For example, warmer winters in the Midwest would be expected to decrease energy demand during that time of year, and there would likely be less cold-related mortality. However, a number of studies suggest that the negative aspects of the projected changes in climate are likely to far outweigh the benefits.
You had a leadership role in the early assessments of the United Nations-led Intergovernmental Panel on Climate Change, which won the 2007 Nobel Peace Prize with former Vice President Al Gore. How has the IPCC view on climate change evolved since then?
The analyses in the IPCC science assessments have evolved greatly over the years as our understanding of the science affecting Earth's climate system has evolved. From a public perspective, the largest change has been the significant increase in certainty about the role of human activities in affecting the climate on our planet. In the latest assessment, published in 2007, the science community came to the conclusion that current warming of the climate system is unequivocal, as is now evident from many observations, including increases in global air and ocean temperatures, widespread melting of snow and ice, and rising global mean sea level. Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (greater than a 90 percent probability) a result of the observed increases in concentrations of carbon dioxide and other heat-trapping atmospheric constituents that are being heavily influenced by human activities.