ntil the last few centuries in Earth's approximate 4.5 billion year
history, climate change has occurred as a result of natural forces, mostly
at a very slow pace. The evidence of a few catastrophic exceptions shows
the devastating effects on many species that were caught in a sudden,
cataclysmic climate change. For the first time in history, humans are
altering the atmosphere in ways that the majority of scientists think
could fuel a new round of climatic disruptions and extremes. Since the
Industrial Revolution, human activities have been adding carbon dioxide
and other greenhouse gases to the atmosphere at an ever increasing rate.
This dramatic, accelerating build-up of carbon dioxide in the air, 25%
greater than 200 years ago, is caused by burning fossil fuels--coal, oil
and natural gas.
ntil the last few centuries in Earth's approximate 4.5 billion year
history, climate change has occurred as a result of natural forces, mostly
at a very slow pace. The evidence of a few catastrophic exceptions shows
the devastating effects on many species that were caught in a sudden,
cataclysmic climate change. For the first time in history, humans are
altering the atmosphere in ways that the majority of scientists think
could fuel a new round of climatic disruptions and extremes. Since the
Industrial Revolution, human activities have been adding carbon dioxide
and other greenhouse gases to the atmosphere at an ever increasing rate.
This dramatic, accelerating build-up of carbon dioxide in the air, 25%
greater than 200 years ago, is caused by burning fossil fuels--coal, oil
and natural gas. 
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