In the past couple of days a pernicious little meme has appeared in two leading North American newspapers. I refer to the notion that there is such a thing as “settled science.” First, on a column about climatology Monday the Globe and Mail‘s Margaret Wente asked not-so-rhetorically “So much for the science being settled. Now what?” The following day the Wall Street Journal‘s editorial page weighed in with a review of “what used to be called the ‘settled science’ of global warming.”
Both offerings betrayed a solid lack of understanding, not only of recent events involving recent allegations of errors in IPCC reports, but also of how science works, further reinforcing the thesis that journalists who write about science really should take a few courses in the subject first.
The Wall Street Journal editorial, it will come as no surprise, is the most egregious of the two when it comes to misrepresenting matters climatological. Citing Jonathan Leake of London’s Sunday Times demonstrates just how little respect the WSJ editorialist has for responsible journalism. But Wente does more or less the same thing; she just doesn’t bother to source her statements back to the discredited journalists who first came up with some of the more outlandish allegations.
More troubling, though, is the fact that both writers just don’t seem to get the nature of the scientific process. Science is never completely “settled.” Of course, much our understanding of the way the universe works has long been nailed down to the point where there’s little to no controversy among scientists. But even on the most fundamental matters generally taught to students as an established fact, there are always scientists poking around the edges, looking for flaws in the ointment. Nothing is ever settled. Indeed, almost every scientist makes his or her living challenging what others have already agreed.
Read through the archives of magazines like New Scientist, for example, and you’ll find plenty of features investigating such things as modified Newtonian dynamics (maybe F doesn’t always equal ma), or theories that suggest the speed of light might actually change over time, or that Darwinian natural selection might be in need of some rethinking. Papers are being written every day that remind us that our understanding of nature is an evolving and neverending process. We’re forever refining and reforming our model of reality. Anyone who suggests that the science is “settled” is missing the point.
So if ever there was a straw man in climatology circles, it would be that the science of anthropogenic global warming is “settled.” It isn’t and never will be.
That doesn’t mean that there isn’t widespread agreement on the basics as currently understood. We’ve known since the early 19th century that carbon dioxide is a greenhouse gas. We’ve known since the middle of the 19th century that CO2 could be warming the planet. The first estimates of how much warmer a doubling of atmospheric CO2 levels would make the planet are more than a hundred years old (and surprisingly similar to current calculations).
The precise details of the physics and chemistry are always changing, of course, as technology and techniques and theories improve. But we don’t wait for the science to be settled before taking action based on scientific understanding, because that would mean never doing anything. If the Wall Street Journal and Margaret Wente believe otherwise, perhaps they should restrain their pontificating to less serious subjects.
Their failure to grasp this fundamental concept is important because it affects their ability to interpret the details. Both writers invoke British climatologist Phil Jones — the man at the centre of the University of East Anglia email drama — who in an odd little interview with the BBC, agreed with the meaningless question “Do you agree that from 1995 to the present there has been no statistically-significant global warming.”
Here’s his response (which suggests Jones is in need of some media training, but that’s another matter):
Yes, but only just. I also calculated the trend for the period 1995 to 2009. This trend (0.12C per decade) is positive, but not significant at the 95% significance level. The positive trend is quite close to the significance level. Achieving statistical significance in scientific terms is much more likely for longer periods, and much less likely for shorter periods.
Which the WSJ and Wente (and countless others) have interpreted as definitive proof that global warming has stopped.
… The science isn’t settled.
You don’t have to be a trained climatologist or statistician to know just why the question was meaningless. It helps, but isn’t necessary (I’m talking to you, BBC). Here’s the bottom line: Climate is all about long-term trends. Fifteen years is a short period. So you wouldn’t expect to to extract a statistically significant trend for such a period. And it’s an arbitrary time period. Change the start and end times and you get different results. The only thing that matters is the long term.
And when you look at the long term, the only signal that emerges is a gradual warming of the planet, one that tracks global emissions of fossil fuels. Again, that doesn’t mean the science of global warming is “settled,” but it does mean that arguments based on short, arbitrary time periods do not challenge our current understanding.