Commodities, Conservation and Policy
The Intergovernmental Panel on Climate Change issued the "Synthesis Report" of its Fourth Assessment Report on Sat., Nov. 17, 2007 in Valencia, Spain.
This 24-page synthesis is intended to be a summary for policy makers, many of whom will meet in Indonesia in December to discuss a follow-up to the Kyoto Treaty.
Sources:Main points of the climate change panel synthesis report
The synthesis gives margins of variability and uncertainty intervals.
Average global temperature has risen 1 ° Celsius since 1850, but the trend is accelerating. Of that increase, average temperature has risen 0.74 ° Celsius since 1905.
The sea level has risen 200 millimeters (7.8 inches) since 1850. The rate sea level rise is quickening; since 1961 it is rising 1.8 mm per year, but since 2003 it has been rising 3.1 mm (0.12 inches) per year.
Concentrations of carbon dioxide (CO2) and methane (CH4) far exceed the natural ranges of the last 650,000 years. In 2005 there were 389 parts per million of carbon dioxide in the atmosphere and 1774 parts per million of methane.
The Greenland ice sheet is unlikely to experience widespread surface melting and is likely to gain mass from snowfall. However, ice discharge could create a net loss of ice; also, the ice sheet could disappear (and cause a 21 foot increase in sea levels) if average temperatures remain 1.9 ° C - 4.6 ° C above pre-industrial levels for the next several thousand years.
About 30% of the species on the planet are at risk at current levels of global warming. If warming continues, there could be significant extinctions around the world.
Addressing greenhouse gas emissions will require a shift in investment that would result in a net investment increase of 5% and 10% by 2050. The impact on the GDP would be between a 1% gain (in improved natural resource services and human health, for example) and a 5% decrease (which would be a 0.12% drop per year until 2050).