'Authoritative' Assessment of U.S. Climate Change Impacts

The White House released a new report today called Global Climate Change Impacts in the United States. The report represents a consensus of 13 federal agencies, was developed over a year and half and, in the words of John Holdren, President Obama’s science and technology guru, is “By far the most up to date, comprehensive and authoritative assessment of climate change impacts on the United States.” Definitely worth checking out.

As John Holdren exclaimed, this report is very comprehensive and provides the best, most rigorous assessment of the science of climate change. Also worth noting is the prevalence of water in the report's key findings. The report is targeted toward policy makers and is surprisingly easy to read. It is chock full of tables, graphs and illustrations that make many of the report's findings easily adaptable for presentations or other education efforts.

If you aren't the reading type and would like to view the press conference for the reports release, check out this YouTube video below.

Outlined in the report are ten key findings, and sure enough, stresses on water resources are one of the key findings highlighted by the report. In fact, if you look closely at the list of key findings below you'll notice that water is specifically mentioned in eight of the ten key findings:

1. Global warming is unequivocal and primarily human-induced. Global temperature has increased over the past 50 years. This observed increase is due primarily to human-induced emissions of heat-trapping gases. (p. 13)

2. Climate changes are underway in the United States and are projected to grow. Climate-related changes are already observed in the United States and its coastal waters. These include increases in heavy downpours, rising temperature and sea level, rapidly retreating glaciers, thawing permafrost, lengthening growing seasons, lengthening ice-free seasons in the ocean and on lakes and rivers, earlier snowmelt, and alterations in river flows. These changes are projected to grow. (p. 27)

3. Widespread climate-related impacts are occurring now and are expected to increase. Climate changes are already affecting water, energy, transportation, agriculture, ecosystems, and health. These impacts are different from region to region and will grow under projected climate change. (p. 41-106, 107-152)

4. Climate change will stress water resources. Water is an issue in every region, but the nature of the potential impacts varies. Drought, related to reduced precipitation, increased evaporation, and increased water loss from plants, is an important issue in many regions, especially in the West. Floods and water quality problems are likely to be amplified by climate change in most regions. Declines in mountain snowpack are important in the West and Alaska where snowpack provides vital natural water storage. (p. 41, 129, 135, 139)

5. Crop and livestock production will be increasingly challenged. Agriculture is considered one of the sectors most adaptable to changes in climate. However, increased heat, pests, water stress, diseases, and weather extremes will pose adaptation challenges for crop and livestock production. (p. 71)

6. Coastal areas are at increasing risk from sea-level rise and storm surge. Sea-level rise and storm surge place many U.S. coastal areas at increasing risk of erosion and flooding, especially along the Atlantic and Gulf Coasts, Pacific Islands, and parts of Alaska. Energy and transportation infrastructure and other property in coastal areas are very likely to be adversely affected. (p. 111, 139, 145, 149)

7. Threats to human health will increase. Health impacts of climate change are related to heat stress, waterborne diseases, poor air quality, extreme weather events, and diseases transmitted by insects and rodents. Robust public health infrastructure can reduce the potential for negative impacts. (p. 89)

8. Climate change will interact with many social and environmental stresses. Climate change will combine with pollution, population growth, overuse of resources, urbanization, and other social, economic, and environmental stresses to create larger impacts than from any of these factors alone. (p. 99)

9. Thresholds will be crossed, leading to large changes in climate and ecosystems.There are a variety of thresholds in the climate system and ecosystems. These thresholds determine, for example, the presence of sea ice and permafrost, and the survival of species, from fish to insect pests, with implications for society. With further climate change, the crossing of additional thresholds is expected. (p. 76, 82, 115, 137, 142)

10. Future climate change and its impacts depend on choices made today. The amount and rate of future climate change depend primarily on current and future human-caused emissions of heat-trapping gases and airborne particles. Responses involve reducing emissions to limit future warming, and adapting to the changes that are unavoidable. (p. 25, 29)

At 192 pages, the report is pretty big and it took me a while to download the full 13 MB file. If you don't have the time (or the bandwidth) to download the full report, be sure to at least check out the Water Resources (1.4MB) section. Most of the findings are not new to many of us, however, there are some good graphics, and because the report expresses the consensus of 13 very different federal agencies, they should be met with little controversy (ok, I'm optimistic). Here's the list of "key messages" from the water section:

• Climate change has already altered, and will continue to alter, the water cycle,affecting where, when, and how much water is available for all uses.

• Floods and droughts are likely to become more common and more intense as regional and seasonal precipitation patterns change, and rainfall becomes more concentrated into heavy events (with longer, hotter dry periods in between).

• Precipitation and runoff are likely to increase in the Northeast and Midwest in winter and spring, and decrease in the West, especially the Southwest, in spring and summer.

• In areas where snowpack dominates, the timing of runoff will continue to shift to earlier in the spring and flows will be lower in late summer.

• Surface water quality and groundwater quantity will be affected by a changing climate.

• Climate change will place additional burdens on already stressed water systems.

• The past century is no longer a reasonable guide to the future for water management.