Duke expert in hot debate

Climate change consensus may turn on her statistical explanation of warming

Gabriele Hegerl is in the middle of what may be the hottest moment so far in global warming science.

In Paris this week, the Duke University climate researcher is among hundreds of scientists helping government representatives from more than 100 countries craft a consensus statement on how and why Earth is heating up. They are placing blame strongly on humans.

The statement is built, word-by-word, on research Hegerl and many others assembled and synthesized over the past three years. Her chapter, "Understanding and Attributing Climate Change," could be pivotal.

Reached via e-mail, Hegerl said she could not discuss what was happening behind closed doors in the French capital. But as delegates pushed to meet a deadline to release the statement early today, pressure was mounting.

"We are sitting at it now at 10:30 p.m. Paris time, and there is little hope that tomorrow's day will be shorter," Hegerl wrote Wednesday.

German-born Hegerl, 45, has worked with the panel for years. She is one of two lead authors of a chapter in the larger report focused on attributing root causes for climate change. The full report is expected later this year.

Hegerl, an expert in using statistics to explain warming, is not an extreme voice. Last April, in a study published in Nature, she concluded that warming caused by greenhouse gases in the northern hemisphere will fall short of the most dire predictions.

The most extreme estimates have said the Earth's average temperature could rise more than 9 degrees Celsius this century. Hegerl's report said the increase would more likely be between 1.5 degrees and 6.2 degrees.

Still, she is convinced that warming is happening and could have dire consequences. When conservative radio host Rush Limbaugh mentioned her Nature report as evidence that global warming isn't likely, Hegerl was dismayed, said Tim Lucas of Duke's Nicholas School of the Environment, where Hegerl is based. When the Washington Times published a story saying the findings deflated warnings, she got "boiling" mad and requested a correction, he said.

Hegerl, a mother of two, has been involved in her chapter for at least three years, devoting half her professional work to the task, said her husband, Thomas Crowley, also a Duke climate scientist.

"She'd be hammering away at the computer every night for two and three hours," Crowley said.

In written statements released by Duke, Hegerl said scientists are getting a more precise grasp on global warming. "We are now seeing, not merely predicting, effects of greenhouse warming on a scale and in ways that were not observable before," Hegerl said.