Global Warming to Worsen Without Counteraction, U.N. Report Says
The observed increase in average global temperature since the mid-20th century is very likely – more than 90 percent — due to the increase in greenhouse gas concentrations, according to a new report.
The observed increase in average global temperature since the mid-20th century is very likely — more than 90 percent — due to the increase in greenhouse gas concentrations, according to a new report.
The report, “Climate Change 2007: The Physical Science Basis,” released by the
United Nations Intergovernmental Panel on Climate Change (IPCC), is the final comprehensive assessment report in a series of four. The main activity of the IPCC is to provide a regular assessment of the state of knowledge on climate change, according to IPCC.
The report describes progress in understanding the human and natural drivers of climate change, observed climate change and estimates of projected future climate change.
Findings in the report include:
- Global concentrations of carbon dioxide, methane and nitrous oxide have increased as a result of human activities since 1750.
- The warmth of the last half century is unusual in at least the previous 1300 years, based on paleoclimate information.
- A warming of about 0.2 C per decade is projected for the next two decades.
- Changes in the global climate system during the 21st century will very likely be larger than those observed during the 20th century if greenhouse gas emissions are at or above current rates.
- Based on global average air and ocean temperatures, widespread melting of snow and ice and rising global mean sea level, warming of the climate system is unequivocal.
A summary of the report can be downloaded on the
IPCC Web site.
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