global warming


May 20, 2014

Global warming refers to the continuing rise in the average temperature of the Earth’s climate.  Since the early 20th century, the global air and sea surface temperature has increased about 1.4 degrees F with about 2/3 of that increase occurring within the last 30-35 years.  Global warming is caused by increasing levels of greenhouse gases produced by human activities (primarily the burning of fossil fuels, like coal, oil, and gas) and deforestation (tearing down Earth’s forests).