What Are the Effects of Climate Change?

Global climate change has already had observable effects on the environment. Effects that scientists had predicted in the past would result from global climate change are now occurring: loss of sea ice, accelerated sea level rise, and longer, more intense heat waves.

Small temperature rise, big impact

Earth's average temperature has increased about 2 degrees Fahrenheit during the 20th century. Small changes in Earth's temperature correspond to enormous changes in the environment. For example, at the end of the last ice age, when the northeast United States was covered by more than 3,000 feet of ice, average temperatures were only 5 to 9 degrees cooler than today.

Scientists have high confidence that global temperatures will continue to rise for decades to come, largely because of greenhouse gases produced by human activities. The Intergovernmental Panel on Climate Change (IPCC), which includes more than 1,300 scientists from the United States and other countries, forecasts a temperature rise of 2.5 to 10 degrees Fahrenheit over the next century.

According to the IPCC, the extent of climate change effects on individual regions will vary over time and depend upon the ability of different societal and environmental systems to mitigate or adapt to change.

Some of the long-term effects of global climate change in the United States, according to the Third and Fourth National Climate Assessment Reports:

• Temperatures will continue to rise
• Lengthened frost-free season (and growing season)
• Changes in precipitation patterns
• More droughts and heat waves
• Stronger and more intense hurricanes
• Sea level rise of 1–8 feet by 2100
• Arctic likely to become ice free

Read more about these consequences and U.S. regional effects on climate.nasa.gov.