In mid-November, the UN’s Intergovernmental Panel on Climate Change published a special report on extreme weather events, such as hurricanes, floods and heat waves. But its emphasis on the uncertainty of its predictions has enraged scientists and activists alike, just days before the UN Climage Change Conference in Durban.
Storms — and especially hurricanes, typhoons and cyclones — are the most interesting weather systems for people dedicated to preventing climate change. Satellite photographs of these swirling storms are seen as a symbol of a world growing progressively warmer — and of the considerable dangers that lurk in such a world.
The storm of the century, Hurricane Katrina, was seen as a warning sign, a harbinger of disasters to come. But six hurricane seasons have passed since then, and not a single massive, high-category storm has arrived to devastate the coasts of the United States. “Meteorologists last recorded such a calm phase between 1911 and 1914,” explains Roger Pielke, Jr., a professor of environmental studies at the University of Colorado, in Boulder, who is working to reconstruct the climate history of the United States.
After years of combing through the data related to climate catastrophes, Pielke has concluded that: “Science cannot detect a clear trend. Some indicators even suggest that the number of hurricanes is more likely to decrease.” Indeed, Pielke admits he’s given up wondering why environments have ironically chosen hurricanes as their icons for climate change.
But, he adds, the public perceives something quite different. “Most of them say: ‘Of course there are going to be more hurricanes; that’s what you climate researchers told us,'” he says.
The IPCC Report
Weather-created disasters are once again in the spotlight. On Friday, Nov. 18, the UN’s Intergovernmental Panel on Climate Change (IPCC) published a special report on extreme weather events, providing environmental activists a welcome opportunity to remind the public of past natural disasters and to call for increased climate-protection efforts. “But such events don’t make good indicators of climate change,” Pielke says.
Indeed, the fact is that researchers still can’t really attribute such individual, extreme events to human influence. And, as frustrating as it might be for some people, closer inspection of the IPCC’s new report reveals that such is its message, as well.
The report says that one “very likely” trend is that heat waves will occur more frequently and last longer around the world and that an increase in the frequency and magnitude of warm days and nights around the globe is “virtually certain.” By the end of the century, the report predicts, temperatures on days with extreme heat will be between 2 and 5 degrees Celsius (3.5 and 9 degrees Fahrenheit) higher than they are today.
The report is more cautious in what is says about heavy rainfalls. “There is medium confidence,” it says, “that, in some regions, increases in heavy precipitation will occur despite projected decreases of total precipitation in those regions.” Recent studies even conclude that flooding has not become more frequent. There has also been a decrease in damage caused by rivers overflowing their banks, as sometimes occurs at the Oder River on the border between Germany and Poland, for example.
The IPCC report offers a picture of the future that is far from uniform. It is “likely” that heavy precipitation as a proportion of total rainfall will grow more frequent in many areas of the world in the 21st century, especially at high latitudes and in tropical regions. But, in other areas, the opposite is likely to be true.
In the United States, although the eastern and northeastern coastlines will receive more rain, the Midwest will grow drier. Monsoons in Asia could shift westward, bringing more precipitation to Pakistan, while southern China will have to contend with increased aridity.
Confusing, ‘Watered Down’ and Poorly Timed
One thing is certain: The IPCC’s climatologists aren’t offering politicians any simple truths to work with. Indeed, it might sound logical enough to assume that more heat means more water evaporating and thus more rain, but this assumption unfortunately bears no relation to real-life weather patterns. Temperatures have risen just under 1 degree Celsius over the last century, but “our measurements show no increase in precipitation,” says Andreas Becker, the director of the Global Precipitation Climatology Centre (GPCC), operated by the German National Meteorological Service (DWD), based in Offenbach, near Frankfurt.
When asked whether this means that the IPCC climatologists have made a mistake in their measurements or whether their equations are wrong, Becker admits that it’s “a major conundrum” for researchers.
Indeed, the new IPCC report has triggered sharp attacks from some climate activists for the way in which it underlines the very uncertainty of its predictions. For example, Climate Progress, a blog of the US-based think tank Think Progress, has criticized the report as being “watered down” and representing yet “another blown chance to explain the catastrophes coming if we keep doing nothing.”
Fear of Exaggerating the Threats
Pielke, whose work has focused on the intersection between science and policy, sees the matter precisely the other way around and warns against allowing science to be roped into the service of climate-related politics. “The world is getting warmer, and we urgently need to do something about it,” he says. “But we shouldn’t use natural disasters as our argument for doing so.” As an expert on such disasters, Pielke considers it a mistake to have released the report on the eve of the 2011 United Nations Climate Change Conference, which kicks off in Durban, South Africa, on Nov. 28. As he sees it, doing so “gives off the impression that we’re trying to say something political.”
All this leaves those hoping to save the climate facing a dilemma. On the one hand, there is a decreasing level of interest in the issue of climate change. Achim Steiner, the executive director of the United Nations Environment Program (UNEP), particularly blames the financial crisis for this decrease. “The financial crisis forces the political actors to take an unhealthy short-term view,” he told SPIEGEL in a recent interview.
On the other hand, researchers such as Pielke fear that exaggerating the threats posed could backfire. “In doing so,” he warns, “we risk losing our credibility.” But that still leaves one question unanswered: How much uncertainty can his field afford to express before the public and politicians turn away?