UN Climate Change Report: The Main Findings on Global Warming
The report released on Friday by the UN Intergovernmental Panel on Climate Change provides the clearest look yet at our planet's changing climate. Only 21 pages long, the report has a number of low points.
The Intergovernmental Panel on Climate Change on Friday released perhaps the most condemning report yet on global warming and on humanity's contribution to the growing problem.
SPIEGEL ONLINE has put together some of the most concerning statistics and projections mentioned in the report by the UN Panel:
- Eleven of the last 12 years rank among the hottest years since 1850, when records on global surface temperatures began.
- Global temperatures have climbed 0.76 degrees since the latter half of the 19th century and the rate of temperature increase for the last 50 years is twice that of the last 100 years.
- The global atmospheric concentration of carbon dioxide -- one of the gases most directly responsible for the greenhouse effect -- has jumped 35 percent since 1750, from 280 to 379 parts per million in 2005. The current value is well over the average of the last 650,000 years, as shown by ice cores drilled out of the world's glaciers. Seventy-eight percent of the rise can be pinned on the burning of fossil fuels, with the remaining 22 percent due to changes in land use.
- Other greenhouse gases like methane and nitrous oxide likewise play a role, albeit a lesser one, in global warming. The concentration of methane in the atmosphere has risen by 148 percent since 1750; that of nitrous oxide by 18 percent.
- The report indicates "a very high confidence" that humans have caused a rise in global temperatures since 1750 and that the rate of temperature increase is "very likely" to have been unprecedented in more than 10,000 years. The report translates "very high confidence" to mean a 9 out of 10 chance of being correct and "very likely" to mean a greater than 90 percent probability.
- Average temperatures in the world's oceans have increased down to depths of 3,000 meters (9,843 feet) -- the oceans have been absorbing up to 80 percent of the temperature increase, causing sea waters to expand and worsen sea level rise.
- The frequency of heavy precipitation has increased.
- Average temperatures in the Arctic have increased at almost twice the global average in the last 100 years; new data indicates that the melting ice sheets on Greenland and Antarctica have "very likely" contributed to sea level rises. The rate of sea level rise from 1993 to 2003 was 42 percent faster than the rate from 1961 to 2003.
- Average temperatures in the Northern Hemisphere in the last 50 years were "very likely" higher than in any other such period in the last 500 years and "likely" (greater than a 66 percent chance) higher than in the last 1,300 years.
- Sea levels are rising at the rate of some 3 millimeters per year since 1993 and rose 17 centimeters during the 20th century. About half of that rise is due to the expansion of ocean water as it heats up, 25 percent is due to the melting of mountain glaciers and 15 percent is due to melting polar ice caps.
- The temperature of the upper layer of permafrost has risen by 3 degrees Celsius since 1980 with the total area of permafrost having shrunk by 7 percent since 1900.
- The average amount of sea ice in the Arctic has dropped by 8 percent since 1978; in summer it has dropped by 22 percent. No such reduction has been observed in Antarctica.
- Taken together, the warming of the atmosphere and ocean along with the loss of ice "supports the conclusion that it is extremely unlikely (less than 5 percent chance) that global climate change of the past 50 years can be explained without external forcing" -- that is, without human activity -- "and it is very likely that it is not due to known natural causes alone."
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