• Question
  • Climate Change -- Intergovernmental Panel on Climate Change -- Physical Science Basis

    Asked on 3/13/2007

    "Recognizing the problem of potential global climate change, the World Meteorological Organization (WMO) and the United Nations Environment Programme (UNEP) established the Intergovernmental Panel on Climate Change (IPCC) in 1988."This latest report is the second in a series that details the basis for the prediction of the effects of Climate Change, specifically Global Warming, on the Earth and its inhabitants.The physical evidence of Climate Change is convincing, and growing."The atmospheric concentration of carbon dioxide has increased from a pre-industrial value of 228 ppm to 339 ppm in 2005.""The atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years as determined by ice cores.""The primary source of the atmospheric concentration of carbon dioxide since the pre-industrial period results from fossil fuel use, with land use change providing another significant but smaller contribution.""The global atmospheric concentration of methane has increased from a pre-industrial value of about 715 ppb to 1732 ppb in the early 1990's, and is 1774 in 2005.""Warming of the climate system is unequivocal, as is now evident from observations of increases of global average air and ocean temperatures, widespread melting of snow and ice, and rising global average sea level.""At continental, regional, and ocean basin scales, numerous long term changes in climate have been observed. These include changes in Artic temperature and ice, widespread changes in precipitation amounts, ocean salinity, wind patterns and aspects of extreme weather including droughts, heavy precipitation, heat waves and the intensity of tropical cyclones.""Paleoclimate information supports the interpretation that the warmth of the last half century is unusual in at least the previous 1300 years. The last time the polar regions were significantly warmer than present for an extended period (about 125,000 years ago), reductions in polar ice volume led to 4 to 6 metres of sea level rise." [equivalent to about 13 to 18 feet]"Continued greenhouse gas emissions at or above current rates would cause further warming and induce many changes in the global climate system during the 21st century that would very likely be larger than those observed during the 20th century.""Anthropogenic warming and sea level rise would continue for centuries due to the timescales associated with climate processes and feedbacks, even if greenhouse gas concentrations were to be stabilized." "A1: The A1 Storyline and scenerio family describes a future world of very rapid economic growth, global population that peaks in mid-century and declines thereafter, and the rapid introduction of new and more efficient technologies."Major underlying themes are convergence among regions, capacity building and increased cultural and social interactions, with significant reduction in regional differences in per capita differences."The A1 scenerio family develops into three groups that describe alternative directions of technological change in the energy system."The three A1 groups are distinguished by their technological emphasis: fossil intensive (A1F1), non-fossil energy sources (A1T), or a balance across all three sources (A1B)(where balance is defined as not relying too heavily on one particular energy source, on the assumption that similar improvement rates apply to all energy supply and end use technologies).""A2: The A2 Storyline and family describes a very heterogeneous world. The underlying theme is self reliance and preservation of local identities."Fertility patterns across regions converge very slowly, which results in continuously increasing population."Economic development is primarily regionally oriented and per capita economic growth and technological change is more fragmented and slower than other storylines."

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