Title: Re: The Cost Of Liberal Party's Inaction On CC
Post by Greens_Win on Dec 10th, 2010 at 4:33am
http://rainforests.mongabay.com/0907.htm
ATMOSPHERIC ROLE OF FORESTS
Global Carbon Emissions Breakdown
Gigatons
Global Emissions: 8.7-9.1
Fossil fuels: 6.9-7.0
Land-use change (deforestation): 1.8-2.0
Other: 0.1
Global Absorption: 8.7-9.1
Remains in atmosphere: 4.5
Absorbed by oceans: 2.3
Absorbed by vegetation: 1.9-2.3
Global Carbon Reservoirs
Carbon
Reservoir Size
(Gigatons)
Atmosphere 750
Forests 610
Surface oceans 1,580
Deep ocean 38,100
Fossil fuels 5,000
Coal 4000
Oil 500
Natural gas 500
Natural gas 500
Source: Kasting 1998
Rainforests play the important role of locking up atmospheric carbon in their vegetation via photosynthesis. The vegetation and soils of the world's forests contain about 125 percent of the carbon found in the atmosphere. When forests are burned, degraded, or cleared, the opposite effect occurs: large amounts of carbon are released into the atmosphere as carbon dioxide along with other greenhouse gases (nitrous oxide, methane, and other nitrogen oxides). The burning of forests releases about two billion metric tons of carbon dioxide into the atmosphere each year, or about 22 percent of anthropogenic emissions of carbon dioxide.
The buildup of carbon dioxide and other gases in the atmosphere is known as the "greenhouse effect." The accumulation of these gases is believed to have altered the earth's radiative balance, meaning more of the sun's heat is absorbed and trapped inside the earth's atmosphere, producing global warming. Greenhouse gases like carbon dioxide are transparent to incoming shortwave solar radiation. This radiation reaches the earth's surface, heats it, and re-radiates it as long-wave radiation. Greenhouse gases are opaque to long-wave radiation and therefore, heat is trapped in the atmosphere. As greenhouse gases build up, this opacity is increased and more heat is trapped in the atmosphere.
The largest anthropogenic contributor to the greenhouse effect is carbon dioxide gas emissions, about 77 percent of which comes from the combustion of fossil fuels and 22 percent of which is attributed to deforestation. The final 1 percent comes primarily from energy-costly production activities like the manufacture of concrete, steel, and aluminum. The preindustrial atmospheric concentration of carbon dioxide was 280 ppm, though today levels have risen to 375 ppm, a 30 percent increase. Climatologists estimate that a level pf 450 ppm—as projected for 2050—may result in an eventual 1.8-3 degrees Celsius (3.2-5.4 degrees Fahrenheit) increase in temperature. Some scientists predict that global warming will produce a sharp upswing in global temperatures followed by a deep plunge into a glacial period several thousands years from now. However, there are still a lot of unknowns about the impact of climate change.
The extent and effect of global warming has been long debated by scientists, industries, and politicians. In 1995 leading scientists and the Intergovernmental Panel on Climate Change (IPCC) concluded that global warming had been detected and that "the balance of evidence suggests a discernible human influence on global climate." Their evidence included a 0.5-1F (0.3 to 0.6C) increase in average global temperature since 1960, a 4.5F (2.5C) degree increase at the Earth's poles, the breaking up of the Antarctic ice sheets, the receding of glaciers worldwide, the longest El Niño ever recorded, a record number of hurricanes in 1995, a record number of heat waves, and an increase of epidemics attributed to global climate change, including dengue fever, malaria, hanta virus, and the plague. According to scientists at the National Oceanic and Atmospheric Administration, 1998 was the warmest year on record, although 2005 was a close second. A British study at the University of East Anglia suggested that 1998 may be the warmest year in over 800 years. The 1990s have been the warmest decade of the millennium and the past decade has witnessed nine of the eleven hottest years this century. In the 900 years before the twentieth century, temperatures dropped an average of 0.02 degrees C (0.04 degrees F) per century.
Since 1960 atmospheric carbon-dioxide levels have increased from 313 ppm to 375 ppm (20 percent increase), according to measurements from Mauna Loa observatory, and carbon-dioxide levels are now 27 percent higher than at any point in the last 650,000 years. The Intergovernmental Panel on Climate Change (IPCC) projects that atmospheric carbon-dioxide levels could reach 450-550 ppm by 2050, possibly resulting in higher temperatures and rising sea levels, along with a myriad of potential impacts ranging from increased storm and hurricane intensity; melting of polar ice, Arctic permafrost, and glaciers; changes in ocean currents including the Gulf Stream; a rise in global sea levels which could inundate low-elevation cities like Cairo, Venice, Lagos, New Orleans, and Amsterdam and cause problems for low-lying nations; increased coral bleaching and mortality of reef ecosystems; changes in ecosystems; species migration and mass extinction, especially among cold climate species; heightened danger from human pollutants like ozone; health impacts including the spread of tropical disease into cooler climates and range expansion of other pathogens; and water shortages.
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