Another day, yet another report on global warming and climate change, this time a joint one from the Pacific Northwest National Laboratory (PNNL) and the Swiss Federal Institute of Technology, published in Science. The essential point that I take from this (and other, similar, research papers) is that the true position we're in is that we don't really quite know the truth yet, at least not all of it.
The authors are talking about albedo, that is, how much of sunlight falling on the earth gets absorbed and how much gets reflected. It's one of those points that is important to the science of understanding climate change and as this paper shows, one that we don't really know enough about yet (although this paper does get us further down the road to understanding it).
From the press release on it at the PNNL site we get this:
Ever since a report in the late 1980s uncovered a 4 to 6 percent decline of sunlight reaching the planet's surface over 30 years since 1960, atmospheric scientists have been trying out theories about why this would be and how it would relate to the greenhouse effect, the warming caused by the buildup of carbon dioxide and other gasses that trap heat in the atmosphere.
And then this:
Data analysis capabilities developed by ARM research were crucial in the study, which reveals the planet's surface has brightened by about 4 percent the past decade. The brightening trend is corroborated by other data, including satellite analyses that are the subject of another paper in this week's Science.
As I say above, the first thing I take from this is that we do not, in fact, know everything about this subject yet. The IPCC report is, quite clearly, not the last word on the subject, for if it were, no one would be able to find something to publish on the subject, right?
My second observation ties in neatly with my rather economically minded manner of looking at the world, back to that old second thing about the subject, that there are always opportunity costs (or, if you prefer, there is no such thing as a free lunch). While there is a hesitance to ascribe the effect found purely to changes in pollution it is at least considered:
The report's authors stopped short of attributing a cause to the cycle of surface dimming and brightening, but listed such suspects as changes in the number and composition of aerosols-liquid and solid particles suspended in air-and how aerosols affect the character of clouds.
As we know, the air has been getting cleaner these past two decades, we pump less dust, particulate matter, sulfur dioxide and other pollutants into the atmosphere, and while this is in itself a good thing, it is important to remember that there is nothing, absolutely nothing, that does not have side effects. A cleaner atmosphere means more sunlight reaching the ground, thus more heating of the atmosphere and thus more global warming. No, this doesn't mean that we should start pumping out more soot to reverse the process, I mean it as an example of the fact that we must always consider the fact that whatever we do, whenever, there are always going to be both good and bad effects. What matters is that we take decisions in full knowledge and acknowledgment of all of the effects, and work towards those solutions which have positive effects on balance.
A similar thing could be said, for example, about solar variability itself. If it is true that the observed warming is caused by factors outside our control, by the sun's variability itself, this doesn't actually mean that there is no problem. It means that what we do about it might change, but not that we should do nothing.
Commenting on the report, one of the authors states:
"The atmosphere is heated from the bottom up, and more solar energy at the surface means we might finally see the increases in temperature that we expected to see with global greenhouse warming,"
Which is a comment that can be taken two ways. One is that here is a solution to the rather uncomfortable problem that all of our models get the actual amount of warming wrong, which might be unkindly described as clutching at straws; the other is that the paper is a useful reminder that the science is not, contrary to perceived opinion, settled yet.
Before I get swamped by screams of outrage, by those calling me a greenhouse denialist, please, get a grip. It is quite obvious that there is a thing called the greenhouse effect, the differences between Venus, Mars and Earth are the only evidence one needs for that contention. I've said before and will no doubt have to say it again, I'm broadly of the Lomborg persuasion, that there is a general change in the climate going on, that humans are at least partially responsible for it and the important thing is to find out exactly what is going on and then work out how to deal with it. Papers like this add another level of complexity to this process, but do not obviate the need for such a process, rather they reinforce the notion that we should indeed be doing what we are, researching the problem as best we can.
I have no doubt that some will look at this paper and decide that we all died yesterday unless we smash capitalism, others will be less rational. Me? Scientists doing science, using the Ultimate Resource, the human mind, to understand more about the world around us. Something that will, in time, actually lead us to the solution(s) to the problems that face us.
But the most important and obvious lesson to take is that the IPCC report is not, as yet, the final word on the science of what is going on. There are more things for us to find as yet...for if the IPCC report were the done and dusted last word on the subject, why would Science be publishing this paper?
The author is a TCS contributing writer living in Europe. Find more of his writing here.
