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The Earth’s climate is predicted to change because of human activities are altering the chemical composition of the atmosphere. The buildup of greenhouse gases primarily carbon dioxide, methane, nitrous oxide and chlorofluorocarbons is changing the radiation balance of the planet.
Water Resources
Changes in precipitation and increased evaporation from higher temperatures can affect water supplies and water quality, posing threats to hydropower, irrigation, fisheries, and drinking water. (Water Withdrawal and Consumption in the US Map)
Floods are more likely because the frequency of intense rainfall is predicted to increase. In addition, warm air holds more moisture causing higher intensity rainfalls.
Droughts are likely to be more severe because warmer temperatures increase evaporation rates and thereby lead to drier soils during periods of little or no rain.
Climate change would be likely to add to the stress in several U.S. river basins such as the Great Basin, California, Missouri, Arkansas, Texas Gulf, Rio Grande, and Lower Colorado.
Water scarcity in Middle Eastern and African countries is also likely to be exacerbated by climate change.
Coastal Resources
A 50 cm rise in sea level by the year 2100, which is within the range projected by the IPCC, could inundate more than 5,000 mi2 of dryland and an additional 4000 mi2 of wetlands in the U.S. if no protective actions are taken.
Areas at highest risk from sea level rise are areas currently experiencing high erosion rates and those with very low elevations, such as parts of the U.S. Atlantic and Gulf coasts.
Internationally, many low- lying areas such as parts of the Maldives, Egypt, and Bangladesh would be completely inundated and uninhabitable by a similar sea level rise.
Health
Climate change may shift the range of infectious diseases, with likely increased risks of malaria and dengue in the United States. Changing temperatures and precipitation patterns may produce new breeding sites for pests and pathogens.
Climate change may increase heat-stress mortality, particularly in the very young and very old. Agriculture
Agriculture
Large areas of the eastern and central United States face moderate to severe drying. Drought could become more frequent, particularly in the Great Plains.
Changes in management practices and technological advances might reduce or eliminate many of the potentially negative impacts of climate change in the agricultural sector.
Agriculture production in developing countries is likely to be more vulnerable to climate change given that they have relatively fewer economic resources.
Forests
Climate change over the next several decades might shift the ideal range for some North American forest species by as much as 300 miles to the north, exceeding the ability of forests and other ecological communities to migrate. (Current and Projected Ranges of Beech Trees in the US Map)
Forest damage from fire and diebacks driven by drought, insects and disease could increase.
The most vulnerable forest resources are those in regions subject to increased moisture stress, as in the dry continental interiors.
Energy & Transportation
Warmer temperatures will increase cooling demand but decrease heating requirements.
Changes in water availability may affect reliability of hydropower output.
Warming should lead to fewer disruptions of winter transportation, but increased droughts and floods may interfere with water transport.
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