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“The world’’s nations cannot play dice with the climate of our planet”

Critics who have dismissed the recent report commissioned by the Pentagon, An Abrupt Climate Change Scenario and Its Implications for United States National Security, should instead view it as a clarion call. Small risks that can result in catastrophic consequences—even if they cannot be precisely quantified—should not be ignored. Neither should the government use it as an excuse to postpone effective action.

Peter Schwartz, one of the authors of the provocative report, encouraged the Department of Defense to “imagine the unthinkable” by exploring the consequences of abrupt climate change for US national security. As he told us at a symposium at the World Resources Institute, his report has largely been buried in the Pentagon bureaucracy.

Schwartz reminded us that climatologists and the international policy community have mainly focused on gradual climate change scenarios. These scenarios rest on mathematical models that fail to capture the discontinuous and extreme events that characterize the earth’s climate history. By investigating planetary history recorded in tree rings, ice cores, and sediments, scientists have discovered several instances of significant, abrupt climate changes over the last 100,000 years. Temperature changes in some regions of up to 16 degrees Celsius (28 degrees Fahrenheit) have been observed, sometimes in the span of a decade. Altered climate patterns could last for many decades, as they did when the heat conveyor of the ocean (like the Gulf Stream) collapsed about 8,200 years ago.

The report provides an alternative to the commonly accepted scenarios of gradual climate change. In one scenario, patterned after the event that occurred 8,200 years ago, polar glaciers continue to melt, the waters of the North Atlantic lose their salinity, and the flow of the Gulf Stream ceases. Average annual temperatures drop by up to 5°F over Asia and North America, and 6°F in Northern Europe. The Southern Hemisphere experiences an increase of up to 4°F, all in a single decade. The report explores the destabilization of the geo-political environment brought about in such a scenario. It points out that wars could break out among old and new adversaries over access to water, food sources, and energy supplies. Millions of refugees would cross national borders.

The National Academy of Sciences has examined the earth’s climate archives to provide the scientific evidence for abrupt climate change. Many scientists see the need for a new generation of mathematical models that accurately represent the behavior of complex, non-linear systems like the earth’s climate. With such systems, smooth, predictable behavior is the exception rather than the norm. Even if current models cannot reproduce past discontinuities or predict the future, climate science points to an uncertain but non-zero risk of sudden and cataclysmic change.

The ratification of the Kyoto Protocol is a first step toward reducing the risk of climate instability by cutting greenhouse gas emissions in the developed world. After conflicting statements by his bureaucrats, Prime Minister Vladimir Putin recently signaled that Russia will ratify the Protocol, thus ensuring that it will come into force. That leaves the US, the largest contributor to greenhouse gas emissions, isolated from the rest of the world.

While the US Administration is in denial of the science and blocks effective action, Hollywood has taken artistic liberties with the science, and latched on to abrupt climate change in this summer’s blockbuster, The Day After Tomorrow. Moviegoers should realize that the world will not end in a weekend, and should not confuse cinematic special effects with the science and mathematics of complex, non-linear systems. However, the movie’s underlying message is clear: the world’s nations, led by the US, cannot play dice with the climate of our planet.

Dr. David Jhirad is vice president for science and research at the World Resources Institute.


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