What is Climate Change?
Climate change is any significant change in measures of climate (such as temperature or precipitation) lasting for an extended period of time (typically decades).
The United Nations Framework Convention on Climate Change (UNFCCC) further defines climate change as "a change of climate which is attributed directly or indirectly to human activity that alters the composition of the global atmosphere."
Scientists around the world have stated that climate change is real and it is happening now. The Intergovernmental Panel on Climate Change (IPCC) a group of thousands of scientists convened by the United Nations, issued the following statements in their Nobel Prize-winning 2007 report:
"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."
A look at some of the most significant signs that climate change is occurring:
- Increasing global temperatures - Average global temperature has increased 0.74degreesCsince 1850; 11 of the last 12 years have been the warmest on record since 1850.
- Changes in precipitation patterns - Precipitation has increased in the eastern regions of North and South America, Northern Europe, and Northern and Central Asia, but has decreased in the Sahel, the Mediterranean, Southern Africa, and parts of Southern Asia.
- More extreme weather events - More intense storms, droughts, heat waves, and rains occur more frequently.
- Rising sea levels - Sea levels are rising due to thermal expansion and melting glaciers and ice caps. Average global sea levels have risen 17 cm during the 20th century and may rise 28-58 cm by 2100.
- Decreasing snow cover and melting glaciers -
Mt. Kilimanjaro in February 1993 (top) and again in February 2000 (bottom)
- Warming poles and loss of sea ice - Arctic sea loss: greater than land area of Texas, California, and Maryland combined. Watch the ice decline on Nasa's Satellites.
- Warming and acidification of oceans - Ocean temperatures have increased around the world which leads to coral bleaching. Additionally, increased CO2 uptake by oceans leads to acidification which further impacts marine animals.
- Changes in ecosystems - Early timing of spring events, poleward and upward shifts in plant and animal communities, loss of polar and montane habitats.