Last week, the New York Times delivered the worrisome news that a team of scientists has concluded that maximum hurricane winds will increase 6 percent by the 2080's, thanks to global warming. I was very upset to read that news, but not because I'm afraid my great-grandchildren will get blown away. My concern is what those scientists' work says about the state of climate science.
The researchers reached their conclusions using a series of climate models called General Circulation Models. They assumed that the concentration of atmospheric carbon dioxide--the main global warming gas--will increase by 1 percent per year, compounded yearly. That would warm the ocean, which would create slightly stronger storms.
But there's a problem: Any atmospheric scientist who is worth his or her salt knows that atmospheric carbon dioxide is not increasing at that rate and has not been doing so for decades. And that makes a real difference in the modeling results.
The increase has been about four-tenths of a percent per year, averaged over the last 30 years--not 1 percent. Charitably, throw in another tenth of a percent because of other human "greenhouse" emissions (though the two major ones, chlorofluorocarbons and methane, are declining or holding steady). That means that the researchers' models are envisioning twice the actual increase in carbon dioxide as has been occurring for decades.
The reason that carbon dioxide is growing so slowly is because the world is gradually becoming more energy-efficient as its people become more affluent. That results in both a reduction in per-capita emissions and a reduction in the number of "capits" that are born, as rich folks have fewer kids. Among big countries, this trend started in the United States. It is now spreading globally as the enriching world buys more-efficient cars and power plants.
This trend isn't going to change anytime soon. That means the growth rate in carbon dioxide over the next few decades is likely to be the same as the rate for the last few. Using the more realistic rate delays the time that hurricane winds will increase by 6 percent from the 2080's to the 2180's--175 years from now.
And it's pretty hard to speculate what impact humanity will have on nature over nearly two centuries in time. To understand that, let's go backwards in time 175 years, to 1830, and think about the changes in energy and technology that have occurred since then.
The fact is that, just as folks in 1830 could not possibly imagine the many technological changes we have today (cars, planes, rockets, nuclear bombs, computers and Viagra come to mind), so can we have absolutely no vision of 2185. The only reasonable bet is that it will be dramatically different than today, and our fossil fuel-powered society will seem as remote in the future as one driven by horses and slavery seems remote to us today. So why would anyone make a prediction of what effects humanity will have on the environment some two centuries from now, based on what we're doing today?
Or, in the case of the researchers' exaggerated percentage increase in carbon dioxide, what we're not doing today? That leads to an interesting question: Because carbon dioxide increases have been bouncing around four-tenths of a percent per year for three decades, why do climate modelers insist on using the wrong number? It seems peculiar that people who have the equivalent of doctorates in applied physics (which is what climate science is) would somehow be perfectly happy to do something they know is wrong.
I began asking that question at scientific meetings a decade ago. At that time, I asked Kevin Trenberth, a highly visible atmospheric scientist from the U.S. National Center for Atmospheric Research, who often testifies to Congress on climate issues. He told me it was done because it was "convention."
That answer doesn't set well with me, because it's awfully easy to program a computer to increase a variable by half a percent instead of 1 percent per year.
That leads to the final, nagging question. There are literally hundreds of scientific papers out there in which climate models use this wrong number. Each of those papers gets sent to three outside peer-reviewers. The fact that 1 percent continues to be used only means one thing: when it comes to global warming, hundreds of scientists must prefer convention to truth.
But why? Is it because, when the real numbers are put in, there's no story for the New York Times to report?