[ The first part of this post is an article I’ll peddle around the traps. After that I provide some more detail, which is quite illuminating, especially a changing gif and a video. I was alerted to all this by Grist. ]
Perhaps in this season of heat and fire we might finally stop listening to climate denialists, the vast majority of whom are not scientists. Their only remaining argument is a grand conspiracy theory. Despite what you hear in mainstream discussion, the evidence supporting the conclusions of climate scientists is very strong, and just gets stronger.
Take, for example, the claim that global warming has stopped. This claim has been around for quite a few years now, but it got a bit of a boost recently when that well-known bastion of sober scientific analysis, Britain’s Daily Mail, interrupted its usual fare of tits, celebrity scandal and tits to misconstrue a UK Met Office report, claiming the report showed there has been no warming for 16 years. The claim is bunk, and a debunking is provided by the website The Carbon Brief, among others.
Meanwhile a careful analysis of the recent record of global warming that came out a year ago has made little or no impression on public discussion. It shows very simply and clearly that global warming has proceeded steadily for the past thirty years.
Climate scientists Grant Foster and Stefan Rahmstorf, writing in Environmental Research Letters in December 2011, carefully subtracted several known natural effects from global temperatures between 1979 and 2010. The subtracted effects are from volcanic eruptions, the el Niño – la Niña cycle and a very small effect of the sunspot cycle. The result is the following graph.
There is not the slightest hint of slower warming after 1996. The mistaken impression of slower warming in the original data is because of a very strong el Niño in 1998, which raises the global average, and several la Niña episodes in recent years, which lower temperatures. Scientists have been pointing this out all along: the recent analysis just makes the point with unmistakable clarity.
Thus the claim that warming has slowed or stopped is a manufactured myth.
Unfortunately there is so much confusion created by conflicting claims that many people will not know whether to believe this graph.
The main reason to believe climate scientists is that climate science, like all science, has a well-developed bulldust filter. It is not perfect, but it removes much of the bulldust.
In contrast, climate denialism is promoted mainly by non-scientists, some of whom, like The Daily Mail, The Australian and Andrew Bolt, are adept bulldusters. Behind them is a well-organised, well-funded and well-documented little industry that generates climate bulldust and feeds it to the gullible front-line outlets.
The main technique of the denial industry is to cherry-pick the data. They pick out any bits that can be construed, out of context, as casting doubt on global warming, ignore the abundant counter-evidence, and scrupulously avoid giving a balanced portrayal of the evidence.
Scientists, on the other hand, strive for a balanced evaluation of the evidence. They know that if they do not, the bulldust filter will come into play and, sooner or later, their bias will be revealed by their colleagues and discounted.
The number of papers in the scientific literature that argue global warming is not caused by human activities is now miniscule. A recent survey found just 24 dissenting papers out of nearly 14,000 published over the past twenty years. The scientific balance of opinion is thus 99.83% for, 0.17% against.
In contrast, public opinion is fairly evenly balanced. The difference is because of the cloud of confusion deliberately created by the denial industry. The people who run that industry are some of the same ones who ran a deliberate campaign to generate confusion about the effects of smoking on health. Their slogan is “Doubt is our product”.
There is one last resort for those who do not want to believe the science. It is claimed the scientists are conspiring to fudge the data to keep everyone alarmed so they can get more funding for their research. Claims the “climategate” emails proved such fudging were more nonsense, one of the biggest beat-ups ever. Some even claim there is a conspiracy of scientists and greenies to establish a global socialist dictatorship.
Scientists are, of course, professional sceptics themselves. They know they can become famous if they can disprove a prevailing scientific view. So they look, all the time, at all the things the denialists claim are being ignored. But they have not been able to find anything that will knock over the conclusion that humans are causing global warming. And the evidence just keeps getting stronger.
Take your pick. Either the scientists are conspiring, against all their instincts and training, so they can get thousands of dollars to support their research for another year, or some fossil fuel companies are conspiring to protect an industry that turns over hundreds of billions of dollars annually.
The separate data sets, with the three effects removed, are shown here.
The original data sets and the corrected versions are shown in this gif (click on it if the animation is not working):
The signals subtracted for each natural effect are shown here for two of the data sets. (They differ because the statistical technique looks for the amplitude that best correlates with the source of the effect.)
Finally here is a nice video that shows the whole story in concise form:
Another point I have mentioned recently but didn’t have a good illustration of, most of the extra heat being trapped by Earth goes into the oceans, not into the atmosphere: 93.4%. Therefore small variations in the amount taken up by oceans will make a bigger percentage difference to atmospheric temperatures. This may be part of the reason la Niña years are cooler. Here are the proportions: