For more information on changes in global temperature, visit: EPA Global Warming Site: Trends
The map at the right displays temperature trends across the United States over the last 100 years. Red circles represent temperature increases, while blue circles represent temperature decreases. Large circles represent a 3°C change, medium circles represent a 2°C change, and small circles represent a 1°C change. Map courtesy of the United States Environmental Protection Agency.
The increase in temperature has not been consistent through
time, either. Some periods during the year have experienced greater and faster temperature increases than others. Average winter temperatures in
areas between 50 and 70 ° North latitude have been increasing quickly, while summer
Changes in temperature appear to be closely related to concentrations of atmospheric carbon dioxide (CO2). The figure below displays the concentration of atmospheric CO2 as well as temperature changes observed during the past 160 thousand years and predicted during the next 10 thousand years.
Graph: Atmospheric carbon dioxide concentration (ppmv) and temperature change (°C) observed during the past 160 thousand years and predicted during the next 10 thousand years. Historical carbon dioxide data was collected from Antarctic ice cores; temperature changes through time are relative to the present temperature. Graph adapted from the Whitehouse Initiative on Global Climate Change.
As concentrations of CO2 in the air decrease, so does the temperature. As concentrations of CO2 in the air increase, so does the temperature. Concentrations of atmospheric CO2 are expected to increase dramatically in the future. Even if emissions of CO2 stay the same as they are now, concentrations of atmospheric CO2 will increase to 700 ppm by 2100 (see Remote Sensing: Carbon Dioxide. As a result, mean global temperatures will increase by 3.5 °F (1.9 °C) over the next 100 years.
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