Doubts about global warming

The Czech version was published in "Orientace" (Orientation), a section of the "Lidové noviny" (People's Newspapers), on February 24th, 2007.

The theory of man-made global warming hasn't been tested as carefully as the scientific method demands

A recently published report by the United Nations' Intergovernmental Panel for Climate Change (IPCC) considers global warming to be a fact caused by the emissions of greenhouse gases.

However, the situation is not as simple as many mainstream climatologists seem to think.

Our ancestors were unable to comprehend a wide spectrum of natural phenomena.

The fear from thunderstorms or solar eclipses may have helped the first primitive forms of religion and the first anthropomorphic gods to be born. However, during the several recent centuries, people learned how to look at the natural phenomena rationally. The scientific method allowed them to formulate hypotheses and, using a meticulous analysis of experiments, to decide which of them are valid and which of them are not. The insights obtained in this fashion are valuable per se; however, many of them are practically useful for our everyday lives, too.

Nevertheless, very recently, we are hearing increasingly often the paradigm that our paganic ancestors may have been right in one opinion, namely that the main originator of the climatic phenomena may have anthropomorphic features, after all, because it is no one else than Man himself. Moreover, many laymen as well as experts seem to believe that science has proven beyond reasonable doubt that the judgment day is unstoppably approaching. But is it really possible to deduce from the existing body of knowledge that the human activity will lead to a catastrophic global warming? We will first recall some scientific questions that are important for a proper analysis of climate changes. At the end of the essay, I will try to explain why it is exactly climatology that has so serious problems to preserve its objective character and why so many people are led to scientifically unjustifiable, gloomy visions of the future.

The science of climate

The climate and the weather incorporate a huge selection of rather complex phenomena that are being studied by diverse scientific disciplines. Most of the corresponding questions are only interested for researchers - ordinary people and politicians shouldn't be worried about them. On the other hand, Nature is not interested which of Her mysteries will be useful for the mankind. If we want to understand the phenomena in Nature properly, it is necessary to study many phenomena without any political or practical flavor, too. These phenomena may approximately be sorted according to the typical time scale they occupy.

The Universe was born 13.7 billion years ago and the Solar System was created roughly 4.6 billion years ago. In order to accurately describe the events in the Universe that took place billions of years ago, we need nuclear physics and other disciplines that clearly don't belong to climatology. Among the phenomena that take a somewhat shorter period of time than billions of years, the motion of the Solar System through the Milky Way and the continental drift may serve as two familiar examples. The Sun is oscillating around the main plane of our Galaxy and one period of this motion takes tens of millions of years. All these effects have a certain impact on the climate and the average temperatures: more or less periodic and more or less chaotic waves with various periodicities have to be combined if our goal is to have an idea e.g. about the dependence of the average temperature on time.

The climate is changing and it has always been changing, regardless of the time scale at which the climate is observed. The idea that the climate change is something that was born together with homo sapiens is naive. As we approach shorter time scales, we encounter the so-called Milankovitch cycles: the periodicity of oscillations of the eccentricity of Earth's orbit is close to 100,000 years while the precession of the Earth's axis takes about 20,000 years. These cycles and a few similar phenomena are almost certainly responsible for the glaciation cycles - the alternation of the ice ages and interglacials - even though some recent alternative theories are trying to find their explanation inside the Sun.

The circulation of water in the deep ocean takes about 2,000 years. The Sun itself hides ticking clocks, too: long-term solar variations last 100-400 years while the short-term solar cycles, controlling the number of sunspots, take 11 years in average. We have finally reached the seasons, the day-and-night cycles, and the weather - the winds, precipitation, clouds, high-pressure areas, and cyclones. The difference between the weather and the climate is primarily in the time scale: the climate usually refers to time intervals comparable to 30 years or longer but no sharp boundary between the weather and the climate exists.

Man himself began to influence the climate in many ways, even though we remain a "cherry on the pie" in many respects. Deforestation and the construction of roads and buildings have modified the Earth's albedo. People are emitting various chemical compounds, too. Aerosols and the dust are able to reflect the solar radiation and help to cool the planet while the greenhouse gases, especially water vapor but also carbon dioxide or methane, are able to absorb the infrared thermal radiation of the Earth that would otherwise escape the planet - which helps to warm up our planet. This effect has been known since the 1827 work by Joseph Fourier; however, it only became popular at the end of the 20th century.

However, there exist dozens of other natural as well as industrial effects that influence the climate and may be essential for its accurate description. For example, several teams, including a couple of well-funded groups of experimenters, are working on a theory that galactic cosmic rays, whose flux depends on time, influence the cloudiness on Earth and the temperature, too. Experiments are underway in Denmark (SKY experiment) and they are in preparation at CERN (CLOUD experiment). The cosmic rays may become more crucial for our future description of the climate than carbon dioxide.

How the "big conclusions" are created?

Is the contemporary science able to decide which of these effects are decisive and which of them are not? Has carbon dioxide really become the key player? And can we be certain that its expected increase in the atmosphere will lead to a substantial warming? A group of climatologists that can't be overlooked answers in the affirmative. But surely not all of them.

I am convinced that definitive conclusions cannot be drawn at this moment and the man-made global warming theory hasn't been tested as carefully as the scientific method demands. For example, the proposition that the 20th century warming was unprecedented was incorporated into the so-called "hockey stick graph", a key symbol of the IPCC report from 2001. According to this chart, the average temperature on Earth has been nearly constant for 900 years, before it began to skyrocket around 1900 (apparently due to human activities). However, it was shown, primarily due to relative outsiders, Steve McIntyre and Ross McKitrick, that the "hockey stick graph" was based on flawed statistical methods. Newer articles about the same question show that the 20th century changes do not qualitatively differ from the oscillations in the previous centuries - and the medieval period may have been warmer than the present era, just like the historical sources indicate, although we cannot be quite certain about it. In the newer IPCC report published in 2007, the original hockey stick graph has been silently erased (more precisely, hidden in a confusing juxtaposition of dozens of alternative, non-hockey-stick graphs) and everyone pretends that this symbol never existed.

We know that the concentration of carbon dioxide in the atmosphere is approximately 0.038% of the volume and we are helping to increase it by about 0.0002% annually. Is it possible to calculate how much this otherwise innocent gas warms up the atmosphere? The simplest calculation gives roughly 1 Fahrenheit degree per 20th century but this calculation neglects the effect of the gas and of the temperature changes on the cloud creation, their impact on the temperature, as well as all other complex but important phenomena. Can we believe the existing climate models that are oversimplifying the situation in so many respects? I am convinced that the right answer is No. These models include a huge amount of input parameters and unjustified assumptions and they only roughly agree with a few qualitative observations about the 20th century climate. No observed details seem to match the predictions of models correctly and accurately. And sometimes, the predictions are not even in the ballpark of reality.

No one is able to explain why the warming in the last 25 years only affected the Northern Hemisphere but not the Southern Hemisphere. No one knows why the world oceans were cooling down between 2003 and 2005, why Greenland is cooler now than it was in the 1930s, why the global mean temperature was decreasing between the 1940s and 1970s when the mankind was emitting almost as much carbon dioxide as today, why the observed temperatures are more "persistent" than the theoretical ones and why the warming is observed not only on the Earth but also on Mars, Jupiter, Saturn, Enceladus, Triton, and Pluto. No one has a satisfactory explanation why many predictions of a significant warming that were made 10-20 years ago failed so miserably. No one can explain why the Alps were full of forests - and therefore warmer than today - in the era of the Roman Empire. Moreover, a low number of stomata on the fossils of 450 million years old leaves suggests that the carbon dioxide concentration used to be 8 times higher than it is today but no one can explain how the plants could live in such a "hell on Earth". And no one is able to forecast the weather for more than one week. These examples of our ignorance and potential disagreements between the theory and observations - and many others - are usually swept under the rug while other predictions that happen to agree are being celebrated uncritically. However, this asymmetry of reactions doesn't belong to real science.

How is it possible that such a high percentage of scientists claims that all the big questions about the climate have been answered and that the catastrophic global warming is a fact? It is because of a kind of division of labor - someone is creating the "big picture" while other people are assigned more detailed and less important work. It is not unusual that the "big picture" is often drawn by talented scientists with a profoundly conceptual reasoning.

Unfortunately, the "big picture" in climate science is being invented by the people with certain non-scientific, often political interests. They have introduced a multi-level filter to their discipline. Because of this filter, the newspaper articles have almost nothing to do with the scientific reality. Moreover, the climatological community is strongly affected by a groupthink that prevents it from an objective judgment of all new theories, especially theories proposed by researchers from outside their community. How does it work?

While there are many climate skeptics among retired climatologists, a young climate scientist has to offer a sensational result because these results are the primary factors deciding about the funding of the discipline: because climatology swallows billions of dollars a year - a small fraction of the money that is spent for the "fight against climate change" during the same period - we can't be surprised that the money plays an important role. The main sensational result is shared by the whole discipline (a dangerous global warming) but individual scientists are being pushed to invent their own spectacular results, too. Scientists whose research leads to a different explanation of the existing data or different predictions are routinely intimidated. They are often threatened and accused of co-operation with the "evil" oil corporations and they are not allowed to use the grant resources and advance in their careers.

If someone ends up with inconvenient results despite these pressures, his or her articles are not printed. Those articles that are printed are post-selected according to yet another ideological key. The summaries of reports are being written by the most politically active, and therefore the most biased members of the scientific teams: the IPCC is unfortunately no exception. The most dramatic filter is hiding in the media that have a roughly 5-fold probability to report a "story" about research that leads to a "catastrophic" prediction than a paper whose conclusions are "moderate" or "politically inconsequential".

Nowadays, the journalists also seem to be much more eager to write about a warm weather than a cool weather, even though it used to be the other way around 30 years ago. And whenever they talk about a cool weather, it is not linked to the global climate - even though articles about a warm weather or hurricanes mention the global climate in most cases. If we try to understand a system that is as complex as the climate, it is paramount for a scientist to avoid any bias, if he doesn't want to instantly end on a wrong track. In the real world of climatology, however, the degree of bias is enormous. If someone is free to choose convenient "cherries on the pie" from the huge number of assorted data about the atmosphere and the Earth's history that are available, he is able to "prove" almost anything.

So far I was only talking about our knowledge of the true reasons behind the observed climate changes and our ability to predict the climate in the future, without being able to predict the weather for one week. My conclusions were skeptical. However, if we focus on the question whether science is able to estimate the consequences of the hypothetical warming for the mankind, we would be led to an even more skeptical appraisal. Danish statistician Bjorn Lomborg has tested how it feels when one is treated as a heretic. It was enough for him to publish a book called The Skeptical Environmentalist that collected some arguments that a potential mild warming could be beneficial for our civilization. The modern Danish Inquisition, more precisely the Danish Committees on Scientific Dishonesty, began to work on Lomborg's excommunication from the scientific community as soon as some environmentalist activists raised their concerns and it took one year before Lomborg was rehabilitated. It's obvious that a serious discussion of climatologists and economists about these matters is only getting started and it only occurs at a few institutions where the political correctness is not the main criterion that determines what can be said and thought and what can't be said and thought.

Despite all these gloomy observations, I believe that we are not far from a new era when climatologists will be able and allowed to study a greater set of details - including those politically "inconsequential" or even "inconvenient" ones - using a more diverse set of methods and without intimidation. Maybe sometime in the future, their theories will be competing according to the same fair rules that we know from other disciplines, regardless of the fact that climatology has an impact on politics and many people "know" in advance how the right answers should look like. I am primarily talking about the people who want to use the climate as one of the tools to prove that the free markets lead mankind to the Hell - and these people can be found both among the activists but also among the professional scientists themselves - but I would like to emphasize that a direct influence of the "opposite" ideology on science would be equally undesirable. Let me wrap up with the wish of a more creative and more free future for the discipline of climatology.

About the author: Dr Luboš Motl is a physicist, currently (2007) at faculty of Harvard University