Global warming is the gradual heating of the Earth's surface, oceans and atmosphere. Scientists have documented the rise in average temperatures worldwide since the late 1800s. Earth's average temperature has risen by 1.4 degrees over the past century, according to the Environmental Protection Agency (EPA). Average temperatures are projected to rise another 11.5 degrees over the next 100 years.
Most scientific organisations acknowledge the existence of global warming as fact. A vast amount of literature on this subject that was reviewed, documents that the rate of global warming trends, are not a natural occurrence, but primarily the result of human activity. This consensus was made clear in a major climate report released in September 2013 by the Intergovernmental Panel on Climate Change (IPCC). In that
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Levels of CO2 have not been that high since the Pliocene Epoch, which was between 3 million and 5 million years ago, according to the Scripps Institution of Oceanography.
CO2 makes its way into the atmosphere through a variety of routes. Burning fossil fuels release CO2. Deforestation is also a large contributor to excessive CO2 in the atmosphere. When trees are destroyed, they release carbon they have stored for photosynthesis. According to the 2010 Global Forest Resources Assessment, deforestation releases nearly a billion tons of carbon into the atmosphere per year.
Methane is the second most common greenhouse gas, but it is much more destructive. There may be less methane in the atmosphere, but this gas is much more efficient at trapping radiation. The EPA reports that methane has 20 times more impact on climate change over a 100-year period.
Methane can come from many natural sources, but humans cause a large portion of methane emissions through mining, the use of natural gas, the mass raising of livestock and the use of landfills.
1.2.2 Effects of global