Global Heating – a Guide to the Arguments
The following is a quick guide to the science of climate change. Climate change deniers tend to repeat the same claims – no global warming since 1998, for instance – so it is useful to have a section which deals concisely and robustly with these claims at the level of the science. The following is indebted to Dr Peter Gleick of CEO Pacific Institute, MacArthur Fellow, National Academy of Sciences. Dr. Gleick received a B.S. from Yale University in Engineering and Applied Science, and an M.S. and Ph.D. from the Energy and Resources Group of the University of California, Berkeley. He is the recipient of the prestigious MacArthur “genius” Fellowship in 2003. He was elected to the U.S. National Academy of Sciences in 2006.
A frequent argument of those who deny that climate change is happening is that since 1998 there has been a global cooling, not a global warming or heating. Since CO2 emissions have continued, so this must mean (they argue) that scientists are wrong to claim that climate change is caused by human activity and that environmental problems must be addressed at the level of government action and public policy. Government intervention is expensive, unnecessary and irrelevant.
There only one thing wrong with this argument – it is false from first to last. Global heating has not stopped and those who continue to make this claim are either ignorant of science, engaged in a politically motivated denial of scientific evidence, or willing dupes, poor men and women who have enlisted in the cause of the rich and the powerful.
There are many variations of this single theme, and it can get tedious having to rebut what is in essence the same assertion. So it needs to be stated clearly from the outset that claims that global heating has stopped since 1998 is a deliberate deception and falsehood. The fact that the Earth is heating is confirmed by the major climate research institutions tracking temperatures on the planet. Time and again the US National Academy of Sciences has confirmed this observation, indeed has firmed up the evidence. So has every other national academy of sciences on the planet, and every professional society in the geosciences. I would challenge climate change deniers to propose one credible scientific body, one not under the thumb of corrupt governments and industrial lobbies, that does not confirm that the planet is getting warmer.
The actual data is available and accessible on public websites around the world. NASA’s Goddard Institute for Space Sciences, NOAA’s National Climate Data Center, and the United Kingdom’s Met Office Hadley Center all make regularly analyzed and updated data on global surface temperatures available for free. There is no excuse for ignorance on the matter. Distortion and cherry picking can only be explained by political motives.
Those who distort the evidence or draw false conclusions do so by exploiting the fact that the average temperature of the planet does vary from year to year for natural reasons. El Niños, La Niñas, cloud variability, volcanic activity, ocean conditions mean that certain years can be warmer or colder than average. And this natural variability makes it possible for data to be selected and used to support claims of cooling. Particular years or groups of years are selected, particular subsets of data are selected, just to get the pre-determined conclusion.
However, when all the data is examined and set in the context of long-term trends, the conclusion is clear - the Earth is heating and human activity is the main cause. And that is the conclusion that the scientific community has drawn as a result of observations and fundamental physics.
We could play around endlessly with different base points to prove warming or cooling. We could take 2011 and prove both warming and cooling. 2011 was slightly cooler than 2007, but warmer than 2008. Global warming? Global cooling? We need to know the long term trend. And this trend continues to show warming, albeit masked by temporary cooling forces. As the British Met Office stated, in dealing with another false claim that warming has stopped: “what is absolutely clear is that we have continued to see a trend of warming, with the decade of 2000-2009 being clearly the warmest in the instrumental record going back to 1850.”
So the claim that global heating has stopped since 1998 is simply false. Warming or heating (as I prefer to call it) has continued.
To properly assess the changes underway in the climate system requires that the full body of evidence is taken into account. Most arguments behind climate change denial select the pieces of data required to support a pre-determined position. The argument that “global warming stopped in 1998” is exemplary in revealing the approach taken by climate change deniers and so should be given prominence.
Physicist John Cook of Skeptical Science shreds the global cooling myth, calling it “3 levels of cherry picking in a single argument.”
Cherry Pick #1: Select one particular temperature record
This argument is based on a temperature record from the Hadley Centre in the UK, often referred to as HadCRUT (Hadley Climatic Research Unit Temperature). This dataset shows unusually warm temperatures, leading to 1998 being the hottest year in the HadCRUT record. These unusually warm conditions were due to the strongest El Nino on record occurring at the time.
Cherry Pick #2: ignore what’s happening to the rest of the climate
The surface temperature record is only a small part of global warming. It tells us only about air temperature at the Earth’s surface. However, as a result of increased greenhouse gases, more energy coming in than going out, the planet is building up heat. The evidence is that this energy imbalance has continued beyond 1998, showing that global warming has not stopped. The evidence also shows that most of global warming is going into the oceans, since the heat capacity of the land and atmosphere is small compared to the ocean. This brings Cook to the third cherry pick.
Cherry Pick #3: Comparing single years rather than statistical trends
Since the ocean holds significantly more heat than the atmosphere, relatively small exchanges of heat between the atmosphere and ocean can cause large changes in surface temperature. The year 1998 was the strongest El Nino on record, moving massive amounts of heat from the Pacific Ocean into the atmosphere, thereby bringing about an abnormally warm year. Conversely, 2007 saw the strongest La Nina for two decades, having a cooling effect on global temperatures. In 2010, the Pacific transitioned back to El Nino conditions, resulting in the warmest 12 months on record from June 2009 to May 2010.
The point is that such internal variability makes it treacherous to draw conclusions by comparing one point of a noisy signal to other years. Those making claims of global cooling do precisely this when they take the extreme El Nino year of 1998 at the base. For a more accurate and more reliable picture, scientists include all data in order to discern long-term trends, thus removing short-term variations.
The claim that “there has been no global warming since 1998” is evidence only of climate change deniers cherrypicking the best year for supporting their claim for global cooling. The deniers should be challenged to pick another year from before 1998. Take 1997, or 1987, or 1977, keep going backwards. Pick any year before the extreme La Nina year of 1998 and the claim for global cooling is falsified. Remove 1998 and the claim is falsified. That’s all the case for global cooling has going for it – the one extreme year, the highest temperature ever recorded, and the fact there has been a slight drop in temperatures since. These temperatures should be cause for alarm. Instead, they are being claimed as evidence for cooling. Some people live in an Alice in Wonderland world.
I’m afraid many of the articles contained below may become repetitive. That’s the nature of climate change denial, I’m afraid. The deniers make the same points over and again. Their arguments play like a psychological stuck record. It soon becomes clear that not only do climate change deniers completely miss the points at issue, they deliberately miss the points. There is a consistent politics behind climate change denial, and that’s what makes for repetition in their arguments. They seek to waste precious resources, especially time, to prevent the action needed to avert eco-catastrophe. They are defending the existing economic system against all comers. Looking on the bright side, the arguments are so feeble that one is inclined to draw the conclusion that we are at the fag end of the capitalist megamachine and there is nothing to stop a global social movement committed to reclaiming social power for the common good.
We should avoid getting bogged down in interminable, tedious debates about temperature increases and climate data. This is to narrow the issue unduly. There is much more evidence pointing to global warming than temperature measurements of the atmosphere and oceans. As Peter Gleick argues, the evidence for warming includes such incontrovertible data as that sea levels are rising, glaciers are melting, arctic sea ice is thinning, snow cover is decreasing, arctic tundra is thawing, relative humidity is rising, plants are blooming earlier, and the habitats of many species of flora and fauna are expanding into cooler areas (higher elevations and north). What other explanation for this data is there but a warming world?
Global warming is not in doubt. The real debate concerns the causes. Here, Gleick comments: the fact that greenhouse gases absorb and reemit thermal energy (heat) has been part of basic science for almost 200 years. Scientists know that the small amount of greenhouse gases in the atmosphere keep Earth’s surface about 33 degrees C warmer than it would be without them. Greenhouse gases have increased about 40 percent since 1800. If they are not causing warming, that would be a deep mystery calling for explanation.
To conclude with a simple rule of thumb I’ve learned through reading countless articles on the climate crisis, whenever you come across someone claiming that the earth isn’t warming, or it hasn’t warmed since the year “xxxx”, or the earth is cooling, check the source of the claim, ask for the evidence, the research behind it, examine the reasoning. It really is very simple, if time consuming. But it’s necessary. The odds are that the person making the claim is a deceiver, a dissembler or a dupe dealing in second hand, cherry-picked data.