James Hansen, director of the NASA Goddard Institute for Space Studies, recently wrote in the New York Times that if Canada continues to pump oil from its tar sands, "it will be game over for the climate." This from the same climate scientist who warned three years ago, "We're toast if we don't get on a very different path."
Hansen may be a scientist, but neither statement is scientific. It's not clear what "game over for the climate" means -- either for the climate or for humans. His statement doesn't take into account that Canada's oil sands are a tiny fraction of the world's supply of fossil fuels. And the ramifications of climate on human life and industry lie well outside Hansen's expertise.
Hyperbolic and emotional as they are, these statements are examples of a scientist speaking not as a scientist, but as an advocate. They address policy, not science. And for these kinds of proclamations, Hansen is embraced by environmentalists and excoriated by climate-change deniers.
But what about all the people in the middle? People who may be willing to accept that the globe is warming, that humans are probably responsible, but still wonder what we might do about it?
Most likely, their bullshit detectors just went on high alert.
First, so you know, I am not a climate-change skeptic. Or a science skeptic. I believe most of what James Hansen says and that science offers a uniquely profound way to understand the world.
But by advocating policy positions -- overtly or by stealth -- scientists may be forfeiting their privileged positions as scientists and becoming just ordinary guys with opinions, and in the process, undercutting the credibility of their scientific work.
"I'm not saying that natural scientists aren't entitled to be people," says Jon A. Krosnick, professor of humanities and social sciences at Stanford University. "They are. Of course they have opinions about what they want government to do. They're entitled to express those opinions, to become activists, pressure government.