Climate change
Climate change refers to any significant change in Earth’s climate systems (temperature, precipitation levels, wind, etc.) which lasts over time. Natural factors often affect the climate. The sun may become slightly more or less intense, the speed of the Earth’s orbit may vary or ocean circulation may change, thus altering world temperatures.
The most recent climate change has been global warming. Beginning late in the 18th century, human activities associated with the Industrial Revolution (specifically, greenhouse gas emissions from fossil fuel use) have changed the composition of the atmosphere. Scientists have concluded that these activities are very likely influencing the Earth's climate. Caused by deforestation, industrialization and urbanization, recent climate changes have been sharp and sudden (in terms of natural climate processes, which normally occur over millennia).
In 2007, the Intergovernmental Panel on Climate Change (IPCC) issued a series of reports describing the latest results of worldwide scientific research into global warming. The panel found that “warming of the climate system is unequivocal, as is now evident from observations of increases in global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.”
The panel noted that temperatures had increased 0.76 degrees Celsius (1.3 degrees Fahrenheit) between 1850 and 2005.
While this change seems small, scientists warn that if temperatures continue to rise at such a same rate, floods, droughts, severe storms, wildfires and excessive heat waves may occur more frequently and sea levels could rise, threatening coastal communities. The IPCC projects a temperature increase of 1.98-11.5 degrees Fahrenheit by 2099. (See also "Global Warming")
Sources:
-- “Climate Change: Basic Information,” EPA Web site. Accessed Sept. 6, 2007. http://www.epa.gov/climatechange/basicinfo.html
-- “Climate Change 2007: The Physical Science Basis (Summary for Policymakers).” Intergovernmental Panel on Climate Change. Available online at http://ipcc-wg1.ucar.edu/wg1/wg1-report.html
