Global Climate Change

I got this information in a email by a friend. And I was really interested to share it with the class, how the global temperature is increasing in some places and decreasing in other places.

"Scientists estimate that mean global temperatures have increased by 0.5 to 1.0 °F (0.3 to 0.6 °C) in the last 100 years." The temperature change has not been consistent across the planet. In fact, the temperature change has not been consistent across the United States. In the last 50 years, temperatures in the western United States have warmed. At the same time, temperatures in the eastern United States have cooled. The cooling in the southeastern United States may be due to excessive sulfates in the air. Sulfates can scatter the sun's light before it reaches the earth's surface. Without heat from the sun, the earth's surface will cool.

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
temperatures have hardly changed. Rates of temperature change even vary according to the time of day. Throughout the world, nighttime lows are rising about twice as quickly as daytime highs.

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.

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.

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.