SCIENCE

A woman in the eye of the political storm over climate change

Judith Curry thinks climate scientists view her as their "biggest threat."

"I do not pay obeisance to the consensus and I think for myself, and they don't like that," said Curry, a professor at the School of Earth and Atmospheric Sciences at the Georgia Institute of Technology.

"Biggest threat" might be hyperbole, but she certainly is a persistent thorn in the side of the climate community. Google her name, and the descriptors that come up are climate skeptic, climate heretic, climate misinformer, climate change denier.

She hates those labels -- "I object to anybody using that term [climate skeptic] about anybody" -- but they are a result of Curry's views on human-caused global warming. Global temperatures have risen since the 1950s, a fact Curry does not dispute. But she believes the warming was caused predominantly by natural factors, with a smaller contribution from human activity.

This is somewhat in line with views held by climate skeptics and contradicts the Intergovernmental Panel on Climate Change, the global body that publishes a scientific consensus report on climate change every four years. The IPCC states in its latest report that humans have certainly caused at least half and most likely all of the warming.

But why does it even matter what Judith Curry thinks? Because she is a tenured professor at a highly respected university and she has co-authored some prestigious scientific papers. And because she falls squarely within the climate skeptic camp but has some suggestions on climate action that are similar to the ideas floating around Washington, D.C.

If climate skeptics ever arrive at the table to break the city's time-honored gridlock on climate change action, Curry might have something to do with it.

Selective appearances at think tanks

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Lately, she has been making a circuit of the conservative think tank world, with the Marshall Institute as her latest stop. The Marshall Institute is a Washington, D.C., institution that has had scientific programs supporting the tobacco and fossil fuel industries.

Curry's audience of about 50 included experts from the World Bank and the State Department, scientists, representatives of conservative think tanks, and even a medical doctor who had recently traveled to a retreating Greenland glacier to see the impacts of climate change firsthand. They ate a three-course meal, heavy cutlery clinking, as Curry presented on climate change science.

She talked about factors affecting global climate that scientists are uncertain of, and factors no one has yet found that may exist. Her words were reminiscent of a more famous Pentagon message on the known unknowns and unknown unknowns, although in that case, unlike the climate change case, the nation took action and began a war.

Her affiliation with conservative think tanks may affect how people perceive her, said Michael MacCracken, chief scientist of climate programs at the Climate Institute in Washington, D.C., who attended the afternoon lecture.

"I mean, lots of people have presented at the Marshall Institute; I think I've done it sometime long ago," MacCracken explained later in an interview, "and so they [the institute] generally do get a range of views."

"But I think it'd be nice sometimes," he continued, referring to Curry, "if you were presenting with some other sponsors over time."

Curry explained in an interview that she would be happy to speak at greener venues, but that she doesn't get invited. "I'm demonized by green groups," she said. "I don't invite myself to give these talks; people call me up and invite me."

She was not always so reviled by the greens. Back in 2006, in the wake of Hurricane Katrina, she and her colleagues penned a study in Science that found global warming would lead to more intense hurricanes. The study received much media play, and Curry and her colleagues emerged as leaders on hurricane science who endorsed the scientific consensus on global warming. She presented her research at the World Wildlife Fund and other places, she said.

She was uneasy about the IPCC's treatment of uncertainties even then, but "we felt that that was the responsible thing to do," she said at the Marshall Institute.

Burned and branded by the media

The same year, she got burned in the media, she said. In an article in the Wall Street Journal, Curry is quoted as saying one of world's prominent hurricane scientists and a climate skeptic, William Gray, has "brain fossilization."

"I got badly burned by a misquote by a reporter, and I backed away from interacting with the media," she said.

She published a paper that August in which she challenged attacks on her hurricane work by both media and by "green-house warming deniers."

That year, she also launched with her husband, Peter Webster, also a professor at Georgia Tech, a company called the Climate Forecast Applications Network. The company provides climate and weather forecasting for the energy industry, according to its website.

Curry said she uses income from her company to fund her research, which has liberated her from having to agree fully with the IPCC on global warming. But it also opens her up to criticisms of conflict of interest, given that her company gets business from the fossil fuel industry.

Curry's shift to outspoken critic of mainstream climate science was precipitated by the blog Climate Audit, run by Steve McIntyre, a statistician who has attacked climate scientists with great perseverance and has ties to the energy industry. In her early posts, she defended the basis for human-caused global warming -- that pumping carbon dioxide into the atmosphere was raising global temperatures -- while discussing some deficiencies in the science. She also routinely uploaded her scientific data for people to analyze.

In 2009, the emails of some prominent climate scientists were stolen and their words twisted to imply they had engaged in scientific misconduct. As the scandal, called Climategate, played out, Curry criticized climate scientists for a lack of transparency. Her preferred choice of venue was Climate Audit, and later, her own blog, Climate Etc., and her posts began attracting primarily global warming deniers.

Her words were met with silence from her colleagues, she said at the Marshall Institute.

Quibbling with her colleagues

That is certainly no longer the case. Curry's challenges are vehemently refuted online by scientists like Gavin Schmidt, director of the NASA Goddard Institute for Space Studies; Dana Nuccitelli, an environmental scientist; and Michael Mann, a climatologist at Pennsylvania State University and author of the book "The Hockey Stick and the Climate Wars." The back-and-forth can be arcane and detailed.

And yet, for all the hostility, Curry and the other scientists agree on the basics of the science. They are quibbling over the uncertainties.

The problem with explaining or defending climate change science to a lay audience is that the topic gets complex very quickly, and like in all scientific endeavors, scientists are certain of their results only to a certain degree, often 95 percent. Communicating the science of climate change can quickly devolve into an exercise in communicating uncertainty and statistics.

"It gets very challenging because you are trying to explain earth history plus project into the future a few hundred years," said MacCracken of the Climate Institute. "So there is always going to be uncertainties and questions, and [Curry] picked out some."

Since 1951, global temperatures have been rising due to human activities -- greenhouse gas emissions, aerosol emissions, land-use changes. This much is known and acknowledged by Curry and all scientists.

But Curry thinks natural factors could be causing the warming. These factors could include aboveground volcanoes, underwater volcanoes, solar system gravitational and magnetic interactions, long-term ocean oscillations, and other "unknown unknowns."

Some of these factors are not known to exist, but that does not bother Curry. Her point is that they could very well exist, but no one's looking for them. And Curry thinks these factors are causing most of the warming and human emissions are a much smaller problem.

"Sure, that's conceivable," said Seth Darling, a scientist at the Argonne National Laboratory and author of the book "How to Change Minds About Our Changing Climate." "But despite a whole lot of researchers trying to identify such a thing, no one has found a single explanation, other than anthropogenic greenhouse warming, that explains all the observations."

There is another way to refute Curry, Darling said. All scientists (including Curry) acknowledge that humans have emitted CO2 in prodigious amounts since the Industrial Revolution. The greenhouse gas traps heat very well in the atmosphere and raises temperatures.

"So what is happening to all that heat if it isn't warming the oceans and atmosphere?" Darling asked via email. "How could our greenhouse emissions NOT be causing warming?"

Dueling over uncertainty with IPCC

Curry has a response to this. She thinks that warming due to CO2 is happening, just not by as much as laid out in the IPCC. The IPCC currently estimates that a doubling of CO2 concentrations would likely warm the planet by between 2 and 4.5 degrees Celsius.

"I'm basically saying the uncertainty is much greater than the IPCC has portrayed it," she said. "And the IPCC is overconfident in some of its conclusions."

When asked after the Marshall Institute lecture to explain why she disbelieves in the IPCC, Curry looked irritated. She said she does not believe in the computer models used by the IPCC. She thinks scientists should gather better historical climate data, called paleoclimate data, which extend back millennia before the first temperature measurements, to better understand global climate.

Such data are derived from proxies like trees, which add a ring to their bark each year. By analyzing the rings, scientists can reconstruct local weather conditions. They calibrate their measurements using other climate proxies such as ice cores.

Curry thinks paleoclimate proxies "are garbage. Not all of them, most of them."

She referred to the writings of McIntyre of Climate Audit for a better explanation and then snapped, "I don't know why we are talking about tree rings; I'm bored with tree rings."

Thousands of scientists -- the majority in the community -- would disagree with her. Paleoclimate reconstructions may not be as accurate as thermometry, but they are more reliable than Curry implies, Darling of Argonne National Laboratory said.

Scientists charge her with being overconfident in her own ideas and studies while being quick to criticize those of others. She washes over fundamental points in climate science that were established decades ago, said MacCracken of the Climate Institute.

The IPCC's "conclusions are not based on belief; it is based on the best representation of the evidence that we have," he said.

So why does it matter what Judith Curry thinks? Because her ideas align her with the skeptical community, and yet she supports a policy framework where climate science could be used in decisionmaking (ClimateWire, Aug. 8).

"Climate varies all the time, and it can be caused by natural and/or humans," she said. "At one level, it doesn't matter what is causing it; it is changing, and we want to reduce our vulnerability to it."

Curry used to drive a Prius, but she replaced it with a Honda CRV. She still walks a mile to work and recycles. She supports research into alternate energy and energy efficiency because she thinks people will soon run out of fossil fuels. Her life is as green as most people's, and her lifestyle choices are based on practicality.

Similarly, she thinks policy decisions have to be practical, "climate-informed decision analysis." That is, policy should be decided by practical considerations including climate, cost-effectiveness and political viability.

The thinking is similar to a push among the government and green groups to focus on "resilience," or adaptation, to climate change. The difference is that these groups are guided by the IPCC. Curry is not. She thinks that climate changes all the time, so policymakers should plan for all eventualities, not just the possibilities laid out in the IPCC report.

"There is so much we don't understand; there are so many things," explained Curry in an interview. "Why do we need to know what the temperature is going to be in a hundred years? We can pretend we know, but we don't know."

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