Fallible Forecasts

February 26, 2010 Current Commentary Comments Off
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In 2007, the U.N. Intergovernmental Panel on Climate Change surprised scientists when it declared in its seminal report on global warming that certain huge Himalayan glaciers might melt away completely by 2035.

“It’s physically impossible to kill the ice that fast,” Jeffrey Kargel, a professor at the University of Arizona who studies glaciers, told The Washington Post.

A recent letter to the editor in the journal Science noted that the glaciers actually are expected to last about 300 years longer, until 2350. When the U.N. panel reported the incorrect figure, it cited a report by an activist group, rather than the original research in which the number had appeared. The contributors to the U.N. report dutifully copied what the activists had mistyped.

The unearthing of this mistake, along with several others, has raised doubts about the overall quality of the IPCC report.

The report won the panel a Nobel Peace Prize, which it shared with Al Gore, and delivered the message that the “warming of the climate system is unequivocal.” The document helped bring about a shift in public opinion as people began to see global warming as an established fact rather than a subject of debate.

But this definitive report was also something of a patchwork, stitched together with plenty of opportunities for errors to work their way in through the seams. Thousands of scientists across the globe volunteered to work on the report, evaluating tens of thousands of academic documents and translating them into plain English for policymakers and the public. It is not surprising that a few facts got distorted along the way.

Over the past year, several e-mails have also surfaced showing that some prominent climate scientists may have tried to prevent skeptics from publishing data and conclusions contrary to the general consensus on global warming.

Together, the errors and the e-mails remind us that scientific research is produced by human beings, and, as such, can never be perfect. The studies that shape our understanding of the world can be marred by carelessness, by personal rivalries and agendas, and by our limited ability to predict the future, especially the distant future.

As computer simulations become more advanced, we are tempted to believe that we can use science and mathematics to make accurate predictions of the world’s condition decades or even hundreds of years from now. But we are not clairvoyant. Our models are the products of hundreds of assumptions, any of which could be flawed, and many of which undoubtedly are.

We need to remember this margin of error when we consider how to respond to threats like climate change. We have no choice but to make important decisions based on imperfect and incomplete information, but we should not bet our children’s and grandchildren’s future on predictions that are much more error-prone than most people think.

There is no doubt the world’s climate is changing. It has always been changing, which is why the middle latitudes have repeatedly swung from glacial cold to tropical warmth and back. It is very likely that human activity has had some impact on climate change in recent decades and that it will continue to influence the climate system in the future. We cannot change the chemical and physical composition of the atmosphere, such as by altering the concentrations of particles and gases, without changing the way the atmosphere responds to its daily dose of solar energy. That is assured by the laws of physics.

But it is a leap — a big leap — to go from these statements of fact, to an assumption that we can predict future climate changes with precision and certainty. It is an even bigger leap to try to anticipate the physical, economic and human consequences of those future climate changes. Yet we are being asked to make enormous financial and social investments that only make sense if we believe the most dire of the global warming predictions.

Last week, with fanfare, President Obama endorsed the construction of two new nuclear power reactors in Georgia, to be supported by more than $8 billion in federal loan guarantees. This put him on the same page as congressional Republicans who support construction of dozens of new reactors across the country. One of the key selling points is that the plants will produce electricity without adding to the atmosphere’s greenhouse gas burden.

But 65 years into the nuclear age, the United States still has no place to permanently store radioactive waste that can remain highly toxic for thousands of years. The Obama administration has rejected the longstanding plan to bury the waste deep underground at Yucca Mountain, Nev., but has offered no substitute. The instant the proposed new reactors are loaded with atomic fuel, they will become part of the nation’s unsolved, unbudgeted, very-long-term waste problem.

Unless we know how we are going to store atomic waste and what it will cost, we cannot make a rational trade-off between those costs and the anticipated benefits of fighting global warming. Yet the president argues that we know enough about global warming to warrant immediate action, and that we have enough time to deal with nuclear waste to justify forging ahead. This approach is scientifically arrogant, economically reckless and grossly indifferent to the health and safety of many generations that will follow ours.

We accomplish nothing by shouting at one another over whether the global climate is changing, whether humans are responsible and what we ought to do about it. Today’s predictions are likely to prove to be neither as accurate as their backers claim nor as unfounded as critics think. For now, they are the best forecasts we have. The sensible approach is to consider them carefully, understand their limitations, and make decisions that are least likely to come back to haunt us. An unnecessary wind farm is not going to kill anyone in the next 1,000 years, but the waste from an unnecessary nuclear plant just might.

We owe it to ourselves, to our children and to our descendants many generations from now to get the hubris out of the climate debate.


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