Global climate change has already had observable effects on the environment. Glaciers have shrunk, ice on rivers and lakes is breaking up earlier, plant and animal ranges have shifted and trees are flowering sooner.
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.
Taken as a whole, the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time.
Scientists have high confidence that global temperatures will continue to rise for decades to come, largely due to 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 with the ability of different societal and environmental systems to mitigate or adapt to change.
The IPCC predicts that increases in global mean temperature of less than 1.8 to 5.4 degrees Fahrenheit (1 to 3 degrees Celsius) above 1990 levels will produce beneficial impacts in some regions and harmful ones in others. Net annual costs will increase over time as global temperatures increase.
“Taken as a whole,” the IPCC states, “the range of published evidence indicates that the net damage costs of climate change are likely to be significant and to increase over time.” 1
Some of the long-term effects of global climate change in the United States are as follows, according to the Third National Climate Assessment Report:
Change will continue through this century and beyond
Global climate is projected to continue to change over this century and beyond. The magnitude of climate change beyond the next few decades depends primarily on the amount of heat-trapping gases emitted globally, and how sensitive the Earth’s climate is to those emissions.
An indicator of current global sea level as measured by satellites; updated monthly.
NASA visualizations of future precipitation scenarios.
Go backward and forward in time with this interactive visualization that illustrates how the Earth’s climate has changed in recent history.
Temperatures will continue to rise
Because human-induced warming is superimposed on a naturally varying climate, the temperature rise has not been, and will not be, uniform or smooth across the country or over time.