Over the next century, global climate change is expected to have substantial consequences for the United States. While scientists continue to narrow remaining uncertainties about the magnitude and timing of future warming, these two new reports detail likely impacts on the U.S. economy, its diverse natural resources and the welfare of its citizens.
The first report, A Synthesis of Potential Climate Change Impacts on the United States, by Joel Smith of Stratus Consulting Inc., concludes a series of Pew Center reports examining the impacts of climate change on several economic sectors and natural resources in the United States. The companion report, U.S. Market Consequences of Global Climate Change, by a team of authors led by Dale Jorgenson of Harvard University and Richard Goettle of Northeastern University used analysis by Stratus Consulting based on the published literature to offer an in-depth analysis of the effects of climate change on the U.S. economy.
These studies find that natural systems are more vulnerable to climate change than societal systems. Any species or ecosystem that is less able to adapt--for example, coral reefs, coastal wetlands, already endangered species, and alpine forests--is at the greatest risk. In contrast to natural systems, economic sectors that are managed--for example, forestry and agriculture--may be less vulnerable to the effects of climate change provided that timely and potentially substantial investments are made.
The U.S. economy as a whole appears to be resilient to a gradual change in climate for a moderate increase in temperature (up to 2-4ºC). For a range of scenarios of climate change and related impacts, the U.S. may experience a 0.7-1.0% gain (under optimistic assumptions), or a 0.6-3.0% loss (under pessimistic assumptions) in GDP by year 2100. However, the economic impact on individual sectors are far more pronounced.
A critical finding in these reports is that as climate change continues past critical thresholds, any benefits diminish and, ultimately, reverse as the U.S. economy struggles to adapt to the changing climate. While some sectors may enjoy gains at low levels of warming (for example improvements in agriculture), beyond critical temperature thresholds, these benefits diminish and eventually become costs.
Just as with individual sectors, different U.S. regions will experience different impacts. The Southeast and the Southern Great Plains are at most risk due to their low-lying coasts and the impacts of warmer conditions on agriculture. Sectors with long-lived infrastructure and investments, such as water resources and coastal communities, will have the most difficulty adjusting.
"What is important to keep in mind about these studies, said Eileen Claussen, President of the Pew Center on Global Climate Change, “'is that ultimately all credible scenarios lead to negative impacts and costs. Taken together, these reports build the case that when it comes to climate change, policy inaction is costly--costly to certain sectors and regions of our economy, and costly to our environment,” said Claussen. “And without near-term action to address climate change, the U.S. is likely to face the need for more expensive and dramatic measures in the future.”
Pew is no longer active in this line of work, but for more information, visit the Center for Climate and Energy Solutions site.