Q&As: Climate Change Effects

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-How will climate change affect ecosystems?
Some ecosystems have already been affected by changes in climate. As the climate continues to warm, major changes may occur in ecosystem structure and function, species’ ecological interactions, and species’ geographic ranges, with predominantly negative consequences for biodiversity. In addition, climate changes such as increased floods and droughts are predicted to increase the risk of extinction for some plant and animal species, many of which are already at-risk due to other non-climate related factors.
Source: EPA Climate Change Effects

-How will climate change affect human health?
The prevalence of some diseases and other threats to human health depend largely on local climate. Extremely warm temperatures can lead directly to loss of life or heat-related illness, while less-severe winters could reduce the number of cold-related deaths. Climate-related disturbances in ecological systems, such as changes in the range of some parasites, can indirectly affect the incidence of serious infectious diseases. Climate change has already caused an earlier onset of the spring pollen season in Europe and North America. In addition, warm temperatures can increase air and water pollution, which in turn harm human health.
Source: EPA Climate Change Effects, Health

-How will climate change affect agriculture?
Agriculture is highly sensitive to climate variability and weather extremes, such as droughts, floods, and severe storms. The forces that shape our climate are also critical to farm productivity. Some aspects of projected climate change are predicted to increase food production (e.g., longer growing season, increased precipitation), but weather extremes (increased potential for droughts, floods, and heat waves) will likely have adverse effects, so the net effect on agriculture will vary depending on how these factors play out at a regional scale.
Source: EPA Climate Change Effects, Agriculture and Food Supply

-How will climate change affect precipitation?
Researchers estimate that rising global temperatures in the past century have led to about a 5 percent increase of atmospheric water vapor over the oceans. Because precipitation is generated mainly by weather systems that feed on the water vapor stored in the atmosphere, this has generally increased the intensity of precipitation and the risk of heavy rain and snow events. As the climate continues to warm, atmospheric concentrations of water vapor are predicted to continue to rise, leading to an increase in the global average amount of precipitation, at least partly through less frequent, more intense storm systems. Higher temperatures also increase evaporation, accelerating the drying of land surfaces and leading to droughts in some areas. A warmer climate may reduce snowpacks in mountains such as those in western North America, also leading to seasonal droughts. Thus, climate change increases the risks of both droughts and floods, albeit at different times and places.
Source: EPA Climate Change Science, Future Precipitation and Storm Changes

-How will climate change affect sea level?
Sea levels are rising worldwide and along much of the U.S. coast. Tide gauge measurements and satellite altimetry suggest that sea level has risen worldwide approximately 4.8-8.8 inches during the last century. A significant amount of sea level rise has likely resulted from the observed warming of the atmosphere and the oceans. The primary factors driving current sea level rise include the expansion of ocean water caused by warmer ocean temperatures (warmer water is less dense), melting of mountain glaciers and small ice caps (resulting in more water in the oceans and less on land), and - to a lesser extent - the melting of the Greenland Ice Sheet and the Antarctic Ice Sheet. Scientists predict that the global average sea level will rise by 7 to 24 inches by 2100 due to thermal expansion alone. The contribution of melting ice sheets, which is very uncertain, could add substantially to this estimate.
Source: EPA Climate Change Effects, Coastal Zones and Sea Level Rise