Con: Earth is never in equilibrium
To a significant extent, the issue of climate change revolves around the elevation of the commonplace to the ancient level of ominous omen. In a world where climate change has always been the norm, climate change is now taken as punishment for sinful levels of consumption. In a world where we experience temperature changes of tens of degrees in a single day, we treat changes of a few tenths of a degree in some statistical residue, known as the global mean temperature anomaly (GATA), as portents of disaster.
Earth has had ice ages and warmer periods when alligators were found in Spitzbergen. Ice ages have occurred in a 100,000-year cycle for the last 700,000 years, and there have been previous interglacials that appear to have been warmer than the present despite lower carbon-dioxide levels. More recently, we have had the medieval warm period and the little ice age. During the latter, alpine glaciers advanced to the chagrin of overrun villages. Since the beginning of the 19th century, these glaciers have been retreating. Frankly, we donít fully understand either the advance or the retreat, and, indeed, some alpine glaciers are advancing again.
For small changes in GATA, there is no need for any external cause. Earth is never exactly in equilibrium. The motions of the massive oceans where heat is moved between deep layers and the surface provides variability on time scales from years to centuries. Examples include El Nino, the Pacific Decadal Oscillation, the Atlantic Multi-decadal Oscillation, etc. Recent work suggests that this variability is enough to account for all change in the globally averaged temperature anomaly since the 19th century. To be sure, manís emissions of carbon dioxide must have some impact. The question of importance, however, is how much.
A generally accepted answer is that a doubling of carbon dioxide in the atmosphere (it turns out that one gets the same value for a doubling regardless of what value one starts from) would perturb the energy balance of Earth about 2 percent, and this would produce about 2 degrees Fahrenheit warming in the absence of feedbacks. The observed warming over the past century, even if it were all due to increases in carbon dioxide, would not imply any greater warming.
However, current climate models do predict that a doubling of carbon dioxide might produce more warming: from 3.6 degrees F to 9 degrees F or more. They do so because within these models the far more important radiative substances, water vapor and clouds, act to greatly amplify whatever an increase in carbon dioxide might do. This is known as positive feedback. Thus, if adding carbon dioxide reduces the ability of the earth system to cool by emitting thermal radiation to space, the positive feedbacks will further reduce this ability.
It is again acknowledged that such processes are poorly handled in current models, and there is substantial evidence that the feedbacks may actually be negative rather than positive. Citing but one example, 2.5 billion years ago the sunís brightness was 20 percent to 30 percent less than it is today (compared to the 2 percent change in energy balance associated with a doubling of carbon-dioxide levels) yet the oceans were unfrozen and the temperatures appear to have been similar to todayís.
This was referred to by Carl Sagan as the Early Faint Sun Paradox. For 30 years, there has been an unsuccessful search for a greenhouse gas resolution of the paradox, but it turns out that a modest negative feedback from clouds is entirely adequate. With the positive feedback in current models, the resolution would be essentially impossible.
Interestingly, according to the U.N.ís Intergovernmental Panel on Climate Change, the greenhouse forcing from manmade gases is already about 86 percent of what one expects from a doubling of carbon dioxide (with about half coming from methane, nitrous oxide, freons, and ozone). Thus, these models should show much more warming than has been observed. The reason they donít is that they have arbitrarily removed the difference and attributed this to essentially unknown aerosols.
The IPCC claim that most of the recent warming (since the 1950s) is due to man assumed that current models adequately accounted for natural internal variability. The failure of these models to anticipate the fact that there has been no statistically significant warming for the past 14 years or so contradicts this assumption. This has been acknowledged by major modeling groups in England and Germany.
However, the modelers chose not to stress this. Rather they suggested that the models could be further corrected, and that warming would resume by 2009, 2013, or even 2030.
Global warming enthusiasts have responded to the absence of warming in recent years by arguing that the past decade has been the warmest on record. We are still speaking of tenths of a degree, and the records themselves have come into question. Since we are, according to these records, in a relatively warm period, it is not surprising that the past decade was the warmest on record. This in no way contradicts the absence of increasing temperatures for over a decade.
Given that the evidence (and I have noted only a few of many pieces of evidence) suggests that anthropogenic warming has been greatly exaggerated, so too is the basis for alarm. However, the case for alarm would still be weak even if anthropogenic global warming were significant. Polar bears, arctic summer sea ice, regional droughts and floods, coral bleaching, hurricanes, alpine glaciers, malaria, etc., all depend not on GATA but on a huge number of regional variables including temperature, humidity, cloud cover, precipitation, and direction and magnitude of wind and the state of the ocean.
The fact that some models suggest changes in alarming phenomena will accompany global warming does not logically imply that changes in these phenomena imply global warming. This is not to say that disasters will not occur; they always have occurred, and this will not change in the future. Fighting global warming with symbolic gestures will certainly not change this. However, history tells us that greater wealth and development can profoundly increase our resilience.
One may ask why there has been the astounding upsurge in alarmism in the past four years. When an issue like global warming is around for more than 20 years, numerous agendas are developed to exploit the issue. The interests of the environmental movement in acquiring more power, influence and donations are reasonably clear. So, too, are the interests of bureaucrats for whom control of carbon dioxide is a dream come true. After all, carbon dioxide is a product of breathing itself.
Politicians can see the possibility of taxation that will be cheerfully accepted to save Earth. Nations see how to exploit this issue in order to gain competitive advantages. So do private firms. The case of Enron (a now bankrupt Texas energy firm) is illustrative. Before disintegrating in a pyrotechnic display of unscrupulous manipulation, Enron was one of the most intense lobbyists for Kyoto. It had hoped to become a trading firm dealing in carbon-emission rights. This was no small hope. These rights are likely to amount to trillions of dollars, and the commissions will run into many billions.
It is probably no accident that Al Gore himself is associated with such activities. The sale of indulgences is already in full swing with organizations selling offsets to oneís carbon footprint while sometimes acknowledging that the offsets are irrelevant. The possibilities for corruption are immense.
Finally, there are the well-meaning individuals who believe that in accepting the alarmist view of climate change, they are displaying intelligence and virtue. For them, psychic welfare is at stake.
Clearly, the possibility that warming may have ceased could provoke a sense of urgency. For those committed to the more venal agendas, the need to act soon, before the public appreciates the situation, is real indeed. However, the need to courageously resist hysteria is equally clear. Wasting resources on symbolically fighting ever-present climate change is no substitute for prudence.
Richard S. Lindzen is the Alfred P. Sloan professor of atmospheric science at MIT. Readers may send him e-mail at rlindzenmit.edu. He wrote this for The Free Lance-Star in Fredericksburg, Va.