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| View of rising Earth about five degrees above the Lunar horizon, taken on December 22, 1968 - - This is one of the more famous images of the Earth from the Apollo program, taken by the Apollo 8 astronauts as they became the first humans to circumnavigate the Moon. The rising Earth is about five degrees above the lunar horizon in this telephoto view taken from the Apollo 8 spacecraft near 110 degrees east longitude. The horizon, about 570 kilometers (250 statute miles) from the spacecraft, is near the eastern limb of the Moon as viewed from the Earth. On the earth, the sunset terminator crosses Africa. The south pole is in the white area near the left end of the terminator. North and South America are under the clouds. The lunar surface probably has less pronounced colour than indicated by this print. Photo: NASA - US National Aeronautics and Space Administration |
A panel of UN climate change scientists and national delegations agreed on a guide for policymakers Friday, warning of the rising risk of global warming affecting the planet.
Delegates of the UN Intergovernmental Panel on Climate Change (IPCC) from more than 140 countries met this week in Valencia, Spain to agree on a fourth "synthesis report" report summarising key scientific research on climate change from scientists across the globe .
The five-day meeting concluded Friday with the approval of a 20-page summary of countless data pages and computer projections, compiled since 2001 by the 2007 Nobel Peace Prize-winning IPCC.
The summary report provides a common scientific baseline for future political discussion on climate change, as it was adopted by consensus, meaning that all participating governments accept it and cannot disavow its conclusions.
The document, which summarizes the scientific consensus on climate change caused by human beings, will be distributed to delegates due to attend a key UN meeting in Indonesia next month that is intended to launch a process on international cooperation to control global warming and to produce a successor agreement to the Kyoto Protocol, which is due to expire in 2012.
The fourth report describes how climate systems are changing and why, the impact this is having on mankind and ecosystems, and many of its possible future impacts if due action is not taken to slow the trend.
The summary and a longer "synthesis report" of about 70 pages, which is due for release Saturday at a news conference attended by UN Secretary-General Ban Ki-moon. See IPCC website.
The forthcoming climate change meeting in the Indonesian resort of Bali, starting on Dec. 3, will focus on the next step in combating climate change after the measures adopted in the Kyoto Protocol expire in five years.
The IPCC was set up in 1988 by the UN Environment Program and the World Meteorological Organization to give governments scientific advice about climate change.
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 report says that eleven of the last twelve years (1995-2006) rank among the twelve warmest years in the instrumental record of global surface temperature (since 1850). The 100-year linear trend (1906-2005) of 0.74 [0.56 to 0.92]°C is larger than the corresponding trend of 0.6 [0.4 to 0.8]◦C (1901-2000) given in the Third Assessment Report (TAR).
The temperature increase is widespread over the globe, and is greater at higher northern latitudes. Land regions have warmed faster than the oceans.
Rising sea level is consistent with warming. Global average sea level has risen since 1961 at an average rate of 1.8 [1.3 to 2.3]mm/yr and since 1993 at 3.1 [2.4 to 3.8]mm/yr, with contributions from thermal expansion, melting glaciers and ice caps, and the polar ice sheets. Whether the faster rate for 1993 to 2003 reflects decadal variation or an increase in the longer-term trend is unclear.
Observed decreases in snow and ice extent are also consistent with warming. Satellite data since 1978 show that annual average Arctic sea ice extent has shrunk by 2.7 [2.1 to 3.3]% per decade, with larger decreases in summer of 7.4 [5.0 to 9.8]% per decade. Mountain glaciers and snow cover on average have declined in both hemispheres.
From 1900 to 2005, precipitation increased significantly in eastern parts of North and South America, northern Europe and northern and central Asia but declined in the Sahel, the Mediterranean, southern Africa and parts of southern Asia. Globally, the area affected by drought has likely increased since the 1970s.
It is very likely that over the past 50 years: cold days, cold nights and frosts have become less frequent over most land areas, and hot days and hot nights have become more frequent. It is likely that: heat waves have become more frequent over most land areas, the frequency of heavy precipitation events has increased over most areas, and since 1975 the incidence of extreme high sea level has increased worldwide.
There is observational evidence of an increase in intense tropical cyclone activity in the North Atlantic since about 1970, with limited evidence of increases elsewhere. There is no clear trend in the annual numbers of tropical cyclones. It is difficult to ascertain longer term trends in cyclone activity, particularly prior to 1970.
Average Northern Hemisphere temperatures during the second half of the 20th century were very likely higher than during any other 50-year period in the last 500 years and likely the highest in at least the past 1300 years.
Numbers in square brackets indicate a 90% uncertainty interval around a best estimate, i.e., there is an estimated 5% likelihood that the value could be above the range given in square brackets and 5% likelihood that the value could be below that range. Uncertainty intervals are not necessarily symmetric around the corresponding best estimate.
