Saturday, June 14, 2008

Global Warming - A Real Concern

I thought I would post the summary points from the IPCC (Intergovernmental Panel on Climate Change) report (see below), just to highlight items that concern me and apparently many millions of people.

Even though I am skeptical of the future predictions of climate based on global warming science, I believe humans are altering the atmosphere (the numbers indicated below are inescapable), and governments should take steps to reduce greenhouse gas emissions.
  • Eleven of the last twelve years (1995-2006) rank among the 12 warmest years in the instrumental record of global surface temperature (since 1850).
  • Most of the observed increase in globally averaged temperatures since the mid-20th century is very likely (90%+ probability) due to the observed increase in anthropogenic greenhouse gas concentrations.
  • The average temperature of the global ocean has increased to depths of at least 3000 m and that the ocean has been absorbing more than 80% of the heat added to the climate system. Such warming causes seawater to expand, contributing to sea level rise.
  • Mountain glaciers and snow cover have declined on average in both hemispheres. Widespread decreases in glaciers and ice caps have contributed to sea level rise
  • Global average sea level rose at an average rate of 1.8 mm per year over 1961 to 2003. The rate was faster over 1993 to 2003, about 3.1 mm per year.
  • Average Arctic temperatures increased at almost twice the global average rate in the past 100 years.
  • More intense and longer droughts have been observed over wider areas since the 1970s, particularly in the tropics and subtropics.
  • Widespread changes in extreme temperatures have been observed over the last 50 years. Cold days, cold nights and frost have become less frequent, while hot days, hot nights, and heat waves have become more frequent
  • The global atmospheric concentration of carbon dioxide has increased from a pre-industrial value of about 280 ppm to 379 ppm in 2005. The atmospheric concentration of carbon dioxide in 2005 exceeds by far the natural range over the last 650,000 years (180 to 300 ppm) as determined from ice cores.
  • The primary source of the increased 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. Annual fossil carbon dioxide emissions increased from an average of 23.5 Gt CO2 per year in the 1990s, to 26.4 Gt CO2 per year in 2000-2005.
  • The global atmospheric concentration of methane has increased from a pre-industrial value of about 715 ppb to 1732 ppb in the early 1990s, and is 1774 ppb in 2005.
  • The combined radiative forcing due to increases in carbon dioxide, methane, and nitrous oxide is +2.30 W/m2, and its rate of increase during the industrial era is very likely to have been unprecedented in more than 10,000 years.

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