Small climate changes may have large impact

“It’s important for people to understand that the risks of climate change are very significant and that they’re already starting to manifest themselves in various corners of the world,” said geosciences professor Michael Oppenheimer, one of the study’s co-authors. The results of the study, which appeared in this week’s online edition of Proceedings of the National Academy of Science, “found that since the previous assessments in 2001 and 2007, those risks have increased,” he explained. “Those risks will continue to increase as long as the emissions of the gases continue to increase.”

An increase of just 1.8 degrees Fahrenheit above 1990 levels in the average global temperature could significantly affect endangered species and increase the risk of adverse weather. Data from the National Climatic Data Center suggest that the planet is more than one-tenth of the way there: Average temperatures have risen by .22 degrees since 1990.

“These findings develop from several year’s worth of evaluation, so by the time you get to the end, in a way they’re not so surprising,” Oppenheimer said. “But I think all of us were a bit surprised that the risks seemed to have gotten so much worse in all areas.”

The authors identified several major areas of concern in their report. First, they warned of irreversible damage to unique structures like coral reefs and tropical glaciers, noting that they have recently found stronger evidence of the hazardous impact of temperature increases on those systems.

These small increases could also affect the impact of bad weather, increasing the intensity or frequency of heat waves, wildfires or droughts.

Researchers told the Associated Press (AP) that other climate change scientists have suggested that “the likelihood of the 2003 heat wave in Europe, which led to the death of tens of thousands of people, was substantially increased by increased greenhouse gas concentrations.”

In the future, the researchers noted, even small temperature changes could negatively affect several million people. The risk of crossing a “tipping point” — the threshold beyond which sudden, large-scale catastrophes, like the melting of a large part of Antarctica, are likely to occur — will also increase dramatically.

The scientists also expressed concern for low-lying developing nations, which would be hit much harder than more developed countries or those at higher altitudes. Even within each country, the scientists noted, financial inequality could create disparities in the impact of global warming by rendering some people unable to deal with its consequences.

“Today, we have to assume that the risks of negative impacts of climate change on humans and nature are larger than just a few years ago,” Hans-Martin Fussel, one of the c0-authors, said to the Agence France-Presse.

Despite the study, global warming and greenhouse gases remain contentious issues on Princeton’s campus. In January, physics professor William Happer GS ’64 labeled the idea that carbon dioxide, a gas exhaled by humans, could cause global warming “propaganda.”

“To say that that’s a pollutant just boggles my mind,” Happer said. “What used to be science has turned into a cult.”

Happer explained that he based his conclusions on his physics research on fluid flow and the absorption and emission of radiation, topics that he says are related to the greenhouse effect.

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Ecology and evolutionary biology professor Stephen Pacala and mechanical and aerospace engineering professor Robert Socolow, on the other hand, have developed “stabilization wedges,” which seek to limit carbon emission levels in different ways, from expanding nuclear energy to reducing vehicle use.

These wedges may be more necessary than scientists had previously thought, the new study suggests.

According to the AP, the researchers concluded that “[i]t is now more likely than not that human activity has contributed to observed increases in heat waves, intense precipitation events, and the intensity of tropical cyclones.”

Despite the important role humans have played in worsening the climate situation, many people are not aware of how serious the current risks are, Oppenheimer said.

“There’s a finite pool of worry, in some ways: a limited amount of stuff [people] can worry about at once,” he explained. “If something’s not happening right in front of them, they tend not to worry about it because the tendency is to worry about the stuff they can see immediately, like the economy going bad.”