6. The following pages provide a summary of the atmosphere and climate changes observed during the Industrial Era and, where possible, current understanding of why the changes have occurred .
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8. Greenhouse Gases Greenhouse gas concentrations in the atmosphere have historically varied as a result of many natural processes (e.g. volcanic activity, changes in temperature). However, since the Industrial Revolution humans have added a significant amount of greenhouse gases in the atmosphere by burning fossil fuels, cutting down forests and other activities. Because greenhouse gases absorb and emit heat, increasing their concentrations in the atmosphere will tend to have a warming effect. But the rate and amount of temperature increase is not known with absolute certainty.
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10. Sea Level Changes Sea levels are rising worldwide and along much of the U.S. coast. Tide gauge measurements suggest that sea level has risen worldwide approximately 6-8 inches (15-20 cm) during the last century . A significant amount of sea level rise has likely resulted from the observed warming of the atmosphere and the oceans.
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13. To stop global warming we should make immediate and continual efforts. I hope the situation will soon change. Global warming catches and holds our concern, for it affects us and will affect our later generations. We cannot wait any longer. Do it. Do it right. Do it right now.
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