Experts Fear Climate Tipping Points


“With Speed and Violence — Why Scientists Fear Tipping Points in Climate Change,” by Fred Pearce, Beacon Press, 2007, xxvi + 278 pgs., $24.95

By David L. Brown

Climate scientists are afraid. That is the underlying message in this new book by Fred Pearce, long-time editor and environmental consultant to New Scientist magazine. As a leading environmental journalist Pearce has covered the subject of climate change for nearly two decades and has interviewed and observed the work of most of the top figures in climate research and modeling.

His conclusions are ominous, for as he says:

“Often in environmental science it is the young, idealistic researchers who become impassioned advocates. Here I find it is the people who have been in the field the longest—the researchers with the best reputations for doing good science, and the professors with the best CVs and longest lists of published papers—who are the most fearful, often talking in the most dramatic language.”

Pearce focuses his attention on the growing mass of evidence that climate change does not occur slowly, but in sudden spurts. Cores from ice sheets and the ocean bottom reveal that the planet “flickers” between temporary states of equilibrium. It does not slowly morph from one state to the other, but behaves as if an on-off switch had been clicked back and forth. For example, the 1300 year reversion to the last Ice Age called the Younger Dryas era, which occurred about 12,000 years ago after the warming period of the Holocene had seen the glaciers retreat, may have set in as suddenly as within a single year. The end came almost as abruptly with a sudden return to warmer conditions.

Climate scientists are constantly seeing their assumptions challenged. For example, Pearce describes how those who study glaciers and ice sheets have until quite recently posited the idea that massive bodies of ice could only melt slowly and steadily. For example, they predicted that the two-mile thick Greenland ice sheet would take 10,000 years before thawing could reach its bottom.

But recent discoveries reveal that the ice sheet has developed cracks, and rivers of warm meltwater are pouring down those cracks to the bottom of the sheet. As Pearce points out, instead of 10,000 years, the thawing reaches the bottom of the ice sheet in ten seconds. It has been realized that the Greenland ice sheet could break up much faster than ever believed possible.

Similar events are changing ideas about the stability of the Antarctic ice, where the Larson B ice sheet—larger than the nation of Luxembourg and 650 feet thick—broke up entirely over three days in March, 2002. The Larson B had been stable for thousands of years and the only reasonable explanation for its breakup is global warming.

These are only examples of the kind of “inevitable surprises” that are popping up all over the Earth. Pearce discusses a long list of environmental events, trends, and possibilities, each of them with the potential to represent a tipping point beyond which sudden climate change is likely to occur. Besides the melting Arctic and Antarctic ice, these include thawing permafrost that could be releasing vast amounts of methane, the effects of human-engendered aerosols, the possible feedback and tipping point events that could be triggered by changes in ocean currents and the El Nino and La Nina cycles in the Pacific Ocean, and much more. Everywhere he turns his attention, it seems, new dangers are being found and the threats appear to be ever more dire.

We have touched on many of these subjects on Star Phoenix Base before, and will continue to do so. Thus, I will not cover that ground again but proceed to Pearce’s interesting discussion in the book’s Appendix, which he titles “The Trillion-ton Challenge.” Here he sets the maximum level to which we can allow carbon dioxide to build up in the atmosphere at one trillion tons, beyond which there is general agreement that runaway heating would quite likely push the planet into a new state. He adds a safety margin and sets the target at 935 billion tons of CO2, which equates to 400 parts per million.

There is no time to waste. At present there already is 880 billion tons of CO2 in the atmosphere, up from 660 billion tons at the start of the Industrial Revolution. Unless we are to exceed the safety margin of 935 billion tons, we can add no more than 55 billion additional tons. We are adding a net 4.4 billion tons per year to the atmospheric load, so at present rates we will reach that 935 billion ton point before 2020, a mere heartbeat in geological time and only a little more than three presidential terms away. Efforts to date have been thin on the ground, with the Kyoto efforts more a sham and source of political cover than any real effort to mitigate climate change.

What would it take to achieve the reduction in greenhouse gas emissions required to keep from going over the limit? Here is where the opinions vary all over the map, with estimates posed to the International Panel on Climate Change ranging from a mere $200 billion to $17 trillion. Pearce points out that the assumptions underlying these estimates differ considerably. For example, the higher numbers assume that the world is going in a completely different direction and that it will take a vast economic turnaround to reverse it. Lower projections assume the world economy is beginning to turn in a different direction anyway and that all that will be required is to accelerate the effect.

There is also a wide range of opinions on what “social cost” to place on the emission of carbon into the air. Again, there is a wide disparity, with proposals examined in a recent review ranging from $1700 per ton down to zero. The British government, which commissioned the study, decided to set the price at $70 per ton, which strikes me as low enough to place zero within the margin of error.

There is also the question of what return can be expected on the “investment” needed to restore the planet to a balanced state. Accountants, Pearce reminds us, discount anything that will not occur until some time in the future, noting that “some economists say that very long-term impacts—such as the rise of sea levels as ice caps melt—should be discounted to zero.” He adds, “these are perhaps questions best not answered by accountants.”

Climate change does have its costs, and Pearce quotes one fact that paints this in stark colors. Discussing the rising costs of cleaning up after hurricanes such as Katrina and other economic losses resulting from worsening weather, he notes:

“Incidentally, a simple extrapolation of trends in insurance claims stemming from extreme weather in recent years suggests that they will exceed total global economic activity by 2060. That may be slightly wacky math, but it is sobering nonetheless.”

Pearce’s book is a wake-up call to warn that the danger of rapid and violent climate change could be imminent, and without fast and aggressive responses the future could be in grave doubt. Against the costs of mitigating climate change there is the question of what will be the ultimate cost of failing to do so. If some of the worst scenarios unfold, it could mean the complete destruction of human civilization, and perhaps even extinction of all advanced life forms.

I will close with the quotation Pearce places at the very beginning of his book. It is from a statement made in December, 2005 by the eminent expert on climate change, James Hanson, director of the NASA Goddard Institute for Space Studies, who said: “We are on the precipice of climate system tipping points beyond which there is no redemption.”

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