Not what but how

-A A +A
By Roger Snodgrass

The page is turning on the climate debate.

In recent years and decades, the role of climate scientists was to convince policy-makers and the public that climate change was an issue.

That mission has been largely accomplished, according to Guy Brasseur, a renowned modeler of atmospheric chemistry.

He said the question now is about informing the social and political systems on how best to respond and predicting what effects any particular response might mean to the future.

“What should we do in terms of mitigation and adaptation?” Brasseur asked, as he suggested steps that need to be taken toward developing an “earth-system” perspective, an understanding of the whole planet as a complex, dynamic system.

The weather is always remarkable, it seems, but it has grown slightly more predictable for a few days ahead. But the climate remains puzzling, as the stakes grow larger in terms of when climate change might arrive and how disruptive it might be.

The relationships between the many pieces of the earth’s climate system – the atmosphere and the levels of the atmosphere; the oceans and the currents of the oceans, like the Southern Oscillation or the Gulf Stream; the sea ice and its feedbacks; the natural phenomena; and biological and man-made influences, to name only a few – are still filled with large uncertainties.

Each decade, new complexities have been added to the mix, including the dual nature of aerosols in the atmosphere and atmospheric chemistry.

Tackling these pieces, integrating them into a framework that can be understood, will hopefully help the world develop “appropriate methods for introducing human responses into the system,” Brasseur said.

He spoke at a colloquium sponsored by the Earth and Environmental Sciences Division Wednesday in the Physics Auditorium on the campus of Los Alamos National Laboratory.

During a question-and-answer session, Brasseur was asked if the admission that there were large uncertainties remaining in the field didn’t play into the hands of skeptics who oppose the idea of global warming.

“We are scientists, so we have to stick to the facts,” Brasseur said. “We know that carbon dioxide is increasing; it’s really out of bounds. We know it’s a greenhouse gas. We know there are changes associated with that and we have seen changes consistent with the models. Those models have improved.”

Scientists agree, he added, that the planet will warm and the hydrological cycle will be stronger. They don’t necessarily agree on where the climate will be drier. They don’t always have the same answer. There are robust answers and some things that are not well known.

As for prescriptions into the future, he used a medical metaphor: “If you have a disease, you would prefer that the doctors do the best they can to cure you now, not wait five years for better medicine,” he said.

Brasseur is associate director of the National Center for Atmospheric Research’s Earth and Sun System Laboratory. He is a former director at the Max Planck Institute for Meteorology in Hamburg, Germany. A native of Belgium, he is a former member of the Belgian parliament.