Published by On Line Opinion, 8 Dec.
The triumph of climate delialists in the Liberal Party and the recent unauthorised release of allegedly damaging emails from a British climate research group are being portrayed by some as the end of the global warming conspiracy.
However the so-called scandal of the emails is a manufactured storm in a teacup. Anyway the evidence for human-caused global warming is far more diverse and robust than denialists make out. In fact the latest evidence is even clearer, and more ominous. Denialist politicians are on the wrong side of history.
The hacking of the Climate Research Unit of the University of East Anglia and the selective release of allegedly damaging emails has generated a crescendo of outrage and righteousness among those who believe human-caused global warming to be a scientific conspiracy. The truth seems to be rather different. The scientists became suspicious they were being set up in a political sting operation. They were receiving seemingly excessive requests, from people they werent familiar with, not only for publicly-available data but for details of intermediate calculations, for computer code, even for computer code that would run on any platform. The full record of the emails is one of conscientious, very hard-working scientists trying to ensure the science wasnt distorted by political interests.
Is the idea of a sting operation just another crazy conspiracy theory? Well no, it is well documented that ExxonMobil and other interests have been funding a systematic and sophisticated effort to create public doubt and confusion about the climate science. What is striking is how readily many people who call themselves sceptics have been willing to swallow without question the denialist interpretation spun from highly selected, out-of-context emails that were obtained illegally. And many people who claim scientists are conspiring on global warming just to obtain research money overlook the trillion-dollar incentives of fossil fuel companies to conspire to deny global warming.
The evidence for global warming does not depend on just one group, or just one kind of evidence. There are at least four groups in the world estimating global temperatures, two in the US, one in Britain and one in Japan. Their estimates are combined in the image below, and they are consistent in their main features, and even consistent in many of their details. If the British group fudged their data, as alleged, it could not have been by much because they still got the same answer as the other groups. Temperatures rose strongly from 1900 to 1940. They fell a bit from 1940 to 1970, mainly because of an increase in human particulate pollution. Since 1970 temperatures have been rising more strongly.
[Michael Schlesinger / University of Illinois. Trends in global temperature estimated by the National Oceanic and Atmospheric Administration, NASA, Britains Hadley Center and Climatic Research Unit (Univ. of East Anglia) and Japans meteorological agency.]
The current rising trend cannot be explained without taking account of the effect of human emissions of greenhouse gases. Those who attack the computer models that demonstrate this overlook the fact that the general trend of global warming was predicted in the 1970s on the basis of much simpler models, and the world has been pretty much following those predictions, except things have recently begun to run much faster than previously projected.
There are fluctuations around these long-term trends because of various other effects. For example, the El Niño La Niña cycle causes fluctuations over periods of a few years. This accounts for the slowing of the upward trend since about 2000, and even a brief recent reversal. Such brief reversals are not new or unexpected. They occurred in the early 1980s and early 1990s. As last years La Niña fades the warming resumes, and estimates for the 2009 mean are that it will indeed be warmer.
Senator Stephen Fielding has paraded a graph in front of Parliament House showing atmospheric carbon dioxide rising steadily since 1995 while the global temperature has fluctuated without rising steadily. The graph is also on his web site, and is shown below. He claims this proves human emissions of greenhouse gases cannot be the cause of global warming. Senator Fielding is foolish to believe this simplistic interpretation, which comes from a noisy minority of scientists. Presumably the many other sceptics in the Parliament are guilty of the same folly.
This graph is misleading, because it begins only at 1995, when the temperature was relatively high, and because it excludes from view the earlier temporary pauses that make it obvious that the current pause in nothing unusual, and no reason to doubt the longer-term warming trend. The scientists who feed such misinformation to politicians are guilty of an elementary misinterpretation of a data series, and an elementary misunderstanding of the nature of climate. Climate is about long-term trends, not short-term fluctuations.
There are many other kinds of evidence for human-caused global warming. The evidence is becoming ever clearer, as is demonstrated in a recent report by a group of prominent scientists (The Copenhagen Diagnosis). Glaciers are melting, the Arctic is melting, the Antarctic ice sheet seems now to be losing mass, sea level rise has accelerated, the oceans are warming and becoming more acid, drought and other extreme weather events are increasing, pest infestations are killing forests, and so on. Geological records show there was much less polar ice when last the Earth had this much carbon dioxide in the atmosphere. If we dont soon slow the increase in carbon dioxide, it will within a few decades reach levels at which the Earth was completely ice free in the past.
Sceptics and denialists misunderstand or misrepresent the scientific process. Even when there is broad agreement on the main features of a topic, scientific debates still continue about details and underlying mechanisms. This is true, for example, of evolution as well as climate science. The Intergovernmental Panel on Climate Change is charged specifically with finding those things that most climate scientists can agree on, despite continuing debates. Its 2007 statement was relatively conservative, yet still quite clear: it is at least 90% probable that humans are causing global warming. Many scientists consider the evidence has strengthened significantly since then.
When the collective professional judgement of climate scientists is stated so clearly, politicians can have no reason to delay action. The imperative to action is actually even stronger, because we have known all along that the full effects of greenhouse gas emissions are delayed by decades. By the time the full effects of current emissions become apparent it will be far too late for effective action.
The denial of global warming by the Liberal Party is now exposed to the bright sunlight. Denialism lurks also in the other major parties, courtesy of the coal lobby. Hopefully it will soon melt away. Perhaps Kevin Rudd will even start acting as though he believes his own rhetoric. The Greens are waiting to cooperate on sensible, cost-effective and urgent measures that can actually reduce Australias emissions.
There are lots of things wrong with the second graph. 10-15 years is not lengthy enough a series to be able to analyze that sort of thing. Temperatures lag CO2 by about 10 years. From time to time, you do have significant deviations from the long term trend like the 1998 blip.