Type I climate change is gradual and follows the graphs of most climate modelers; Type II is much more abrupt and results from crossing hidden "tipping points." Pearce explains what some of these tipping points in a credible and balanced manner.
Charles Keeling began collecting CO2 data at the top of Mauna Loa (14,000 feet) in 1958 (315 ppm), 320 in 1965, 331 in 1975, and 380 now - the level is increasing at an accelerating rate. Nineteen of the twenty warmest years have occurred since 1980, and the five warmest years all since 1998. Thus, credible evidence indicates that global problem is real, and getting worse.
Skeptics claim, however, that weather balloon data do not reveal a daytime warming trend. Pearce explains this is most likely because until recently the thermometers used read too high because they were not shielded from UV rays; further, balloon night-time readings have risen during the same period. Others suggest that warming data are due to urban "heat islands" - on the other hand, the greatest increases are in the polar and oceanic areas, and the "heat island" effect are not affected by windy weather. Another possible explanation is sunspots - data from 1850 onward correlates well with temperature increases, UNTIL 1980 when sunspot activity began declining while warming continued. Finally, a review of almost 1,000 peer-reviewed papers on climate change published between 1993 and 2003 found an almost universal consensus that global warming exists.
"With Speed and Violence" then goes on to review potential tipping points. The Amazon rainforest is the largest living reservoir of CO2 on the earth's land surface - its trees contain 17 billion tons of carbon and its soil perhaps as much again. Thus, trees and soil together contain the equivalent of about 20 years' of man-made emissions from burning fossil fuels. However, an experiment found that while the forest could handle two years of drought, after that the trees began dying, falling down to rot and release CO2. After this occurred the exposed land also released about 75% of its CO2. Current climate change already risks bringing drought to a number of areas in the world. Forests have been growing faster in various areas of the world due to increased CO2, but lately this has reversed due to droughts in various areas.
At least half the world's tropical peat swamps (up to 60 feet deep) are on the Indonesian islands of Borneo, Sumatra, and West Papua. They contain perhaps 50 billion tons of carbon. Wildfires there in '97-'98 released up to 40% of all man-made emissions; these fires are not rare as farmers frequently set them to clear land. Some of the fires continue underground in the deep peat deposits.
As warming proceeds to beyond the Arctic tree line, carbon stored in thick layers of permanently frozen soil (permafrost) comprised of thousands of years' accumulation of dead lichen, moss, etc. that never rotted before freezing becomes at risk for release. The Siberian peat bog covers 400 square miles, and as it begins to thaw, the peat decomposes into swamps and lakes devoid of oxygen. The result is methane production - a gas that has a 100X greater global warming impact than CO2.
Our oceans contain about 50X the CO2 residing in the atmosphere. Water's ability to retain CO2, however, decreases with warming. And then there is the possible methane clathrates (thought to have been created by microbes decaying at the bottom of the ocean) - some scientists are concerned that global warming, combined with cracks in the ocean floor, will release enormous amounts of methane from this source.
Pearce's prognosis is that of uncertainty and new surprises. He believes that our aim must be to avoid crossing thresholds where irreversible change occurs (eg. shutting off the Gulf Stream) - especially changes that trigger further warming. He sees the Kyoto targets as small compared with the cuts that eventually will be needed.
Currently the U.S. and Australia emit about 5.5 tons of carbon/year/citizen, Europeans average about 3, China about 1, and India less than 0.5. Our top priority should be energy efficiency, followed by increased use of nuclear, solar, and wind energy. Estimated total cost to stop global warming - about $8 trillion.
