Climate change 101
Climate change is the term that describes an increase in the average temperature of the Earth's atmosphere and oceans. The natural greenhouse effect keeps the Earth 30° C warmer than it otherwise would be. Scientific opinion on climate change, as expressed by the UN Intergovernmental Panel on Climate Change (IPCC) and endorsed by the national science academies of the G8 nations, is that the average global temperature has risen between 0.6 and 0.2° C since the late 19th century. These increasing temperatures are the result of a strengthening greenhouse effect caused primarily by man-made increases in carbon and other greenhouse gases. A small minority of scientists contest the view that humanity's actions have played a significant role in recent temperature increases.
Based on basic science, observational sensitivity studies, and the climate models referenced by the IPCC, temperatures may increase by 1.4 to 5.8° C between 1990 and 2100.
Higher temperatures will have dramatic effects on our world.
The implications of a rise in the global temperature are sobering. Already, snow cover and ice have decreased in the coldest parts of the world. There has been widespread retreat of mountain glaciers during the 20th century, and there is an estimated decrease of 40% in the arctic ice thickness in recent years. If the warming trend continues, as it is expected to, the consequences are predicted to be severe.
A rise in sea level
The Arctic region warmed significantly in the 1990s compared to the 1980s, as did other regions with large ice stores. Global mean sea level is projected to rise from 0.29 to 2.88 feet between 1990 and 2100, and to continue rising at an even faster rate after that. Rising sea levels could cause significant amounts of coastline and many islands to become submerged.
Severe weather
The World Meteorological Organization reports that climate change will continue to disrupt global weather patterns, causing extreme weather conditions such as drought, flooding, and severe heat and cold. There has been a marked increase in the number of tropical storms since 1990. In fact, the 2005 hurricane season was the worst on record.
Agricultural impact
According to the Columbia University Center for International Earth Science's Information Network, climate change would lead to adverse impacts on crop yields and water resources. This increases the risk of international food insecurity triggered by drought, flooding, and migration due to environmental changes.
Species extinction
Significant climate change could potentially cause the extinction of large numbers of plants and animals. The National Wildlife Fund reports that some species are shifting their ranges north, or bearing young earlier.