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Monday, June 11, 2007


Global Warming Skepticism

I followed a link from Tim Blair to a "Denialism" blog which purports to debunk criticisms of Global Warming (mostly by labeling critics as "denialists" whose arguments therefore need not actually be refuted). The Denialism blog posting soon accumulated a couple of hundred very heated pro and con comments. So I decided to throw in my two cents worth, but inflation hit me hard. After my comment grew to over two thousand words, I decided to post it here as well:

After scanning through these many comments, it appears that there are at least a few intelligent and reasonable posters on both sides to leaven the numerous vitriolic attackers and counter-attackers. I’m therefore moved to lay out my own reasons for being a global warming skeptic. I’m certainly not an expert on climatology, but I’ve read a number of articles and I consider myself an educated layman (I’m an electronic engineer with a Bachelor’s degree from M.I.T. and a Master’s degree from U.S.C.). So here goes:

1. Extracting information from noisy data. Temperatures differ widely geographically and over short periods of time. Daily, weekly, and yearly variations dwarf the one or several degree changes which global warming models predict over a period of decades or a century. There are also much longer-term variations in the earth’s temperature, with periodicities of centuries or tens of thousands of years, as demonstrated by various proxy evidence and obvious macro events such as past ice ages.

It is difficult to extract information which proves the existence of recent anthropogenic temperature changes from all those short- and long-term variations, particularly when reasonably high-quality temperature measurements covering most of the globe have only become available in the last few decades. And it is only anthropogenic changes which matter in this discussion. If we were in the midst of a purely natural trend which would add perhaps 1 to 5 degrees to average global temperatures over the next century, my reaction would be “so what”? Life on this planet, and human life in particular, has survived such changes in the past, and we easily handle much greater variations on a scale of months and years, so we’ll deal with similar natural variations in the future.

Medium- and long-term natural temperature variations will always exist, so at most there might be an anthropogenic component which makes up some portion of future trends. Only if that anthropogenic component is significant and growing will it matter. In my profession I specifically deal with the problem of extracting meaningful data from noisy measurements, albeit on time-scales which are at least ten orders of magnitude faster than climate change. (For what it’s worth, I also deal with the obverse problem of creating better random noise. I have a patent, 6130755, which reduces the low-frequency components of pseudo random number generators so as to limit excursions from the ideal random behavior.) Based purely on past temperature variations and the relatively short span of high-quality measurements, it is not possible to prove that a significant anthropogenic component exists, at least up to the present time.

Of course Anthropogenic Global Warming (AGW) theorists do not rely merely on extrapolating from past data. They postulate a physical mechanism, a greenhouse effect caused by elevated CO2 levels, which will result in significant future anthropogenic temperature increases. But the earth’s climate is an enormously complex, non-linear system with lots of feedback loops. Our climate models (and the computing power to run them) are still rather limited. The proof that elevated CO2 will indeed result in significant global warming involves specific predictions and verification derived from future data collected over the next several decades or centuries. It cannot come merely from the data collected to date.

Some AGW theorists may object that we can’t afford to wait that long. But that is a political objection, not a scientific objection. It may be unfortunate if irreversible ill effects occur before enough data can be collected to confirm the theory, but that doesn’t alter the fact that that amount of time is still necessary. Climate changes happen over relatively long time scales; that’s just reality.

2. Slow AGW isn’t a big danger. It’s not enough to prove that medium- or long-term temperature rises contain a significant anthropogenic component if the effect is limited to one or several degrees over a century. The big danger, if there really is one, would come from a runaway effect in which temperatures would suddenly and rapidly rise following some irreversible tipping point, leading to the destruction of civilization or even human life. This requires extrapolating an exponential temperature increase from past data even though we are currently below the knee of the curve. But the data is way too sparse and noisy to reliably do that; it could just as easily fit any number of other lines or curves.

Alternately one could argue that the physical mechanism is so well established and understood that (even absent past corroborating evidence) rising CO2 levels will produce an exponential increase with high probability. But that would be a very strong claim, and not one which I hear coming even from scientists who are strong advocates of AGW. They may sometimes speculate on that possibility, and worry about the consequences, but they do not formally assert it as part of their theories. Instead they confine themselves to the much milder temperature predictions emanating from their global warming models.

Without an imminent irreversible tipping point, the debate over AGW loses its urgency. We have time to make predictions, collect data, improve our models, and ponder the best corrective actions to take (if any).

Still, some AGW advocates resort to a form of Pascal’s Wager: Even if the chance of catastrophe is only one in (fill in the blank), isn’t it better to take action now rather than wait till it’s too late? Well, no, that depends very heavily on the (fill in the blank) value. Maybe, if the chance of thermal runaway is 1 in 10, it is necessary to take precautionary action now. Maybe not, if the chance is 1 in 1,000 or 1 in 1,000,000. After all, human resources are limited and there are all kinds of low-probability risks. We can’t protect against everything.

A good example is the threat of a civilization-destroying meteor strike. The generic odds of it occurring in any given year are perhaps one in ten million or less, based on what we now deduce about the history of our planet. So do we spend trillions of dollars on a crash project to construct meteor defenses? Failure to do so could lead to our destruction if we get really unlucky during the next few years. But we have to assess that risk and weight it against other dangers and opportunities in deciding how to prioritize and allocate resources. The same applies to the risk of runaway global warming.

3. Many AGW advocates try to tailor the evidence to fit a preconceived political agenda. The alarmist rhetoric coming from the Al Gore types and a lot of environmentalists appears fixated on enacting a specific policy prescription (reduction in CO2 levels through massive government controls and restrictions on economic activities) and then work backwards to justify that policy by agglomerating every possible argument they can think of no matter how nebulous. Perhaps that’s not your impression, but it certainly is my impression and the impression of many others. It makes me very suspicious of the conclusion when I see the extreme efforts being made to promote it.

Unfortunately, web sites such as the Denialism blog contribute to the perception, as they appear to be efforts to shut off open debate by applying derogatory labels to those who question the evidence and reasoning leading to the preconceived policy goal. Perhaps that’s not entirely fair to the authors of this site, or other respectable scientists who consider the evidence for AGW to be conclusive. But the science is being tarnished by the demagoguery of those who are using AGW to advance their own agendas.

My advice would be to stick to the evidence and stick to the science. Labeling doubters as “denialists” is not going to convince anyone of the validity of the theory, and will more likely have the perverse effect of raising additional doubts about the robustness of the theory when subjected to criticism.

If the science is good, it will win out in the end. Evolution wins out over creationism because evolution works; its explanatory power informs all modern biological advancements. Similarly, the HIV virus theory works; it results in cocktails of anti-viral drugs which keep people alive. The same attitude should apply to AGW; if correct, it will result in accurate and testable predictions and explanations of climate changes. Why get bent out of shape over the doubters? Let them be wrong or remain ignorant. Who cares, unless of course the real objective is political policy rather than achieving scientific validity.

4. The policy proposals are at variance with the purported problem. If I was convinced that AGW was a serious problem, my normal reaction as an engineer would be to look for the most innovative and cost-effective geoengineering methods of solving the problem. Placing restrictions on the release of CO2 into the atmosphere would be way down on my list, since the sources of CO2 are so pervasive and diffuse and often result from processes which carry many other benefits. Possible solutions to global warming include seeding the oceans with iron dust to stimulate CO2-absorbing plankton; modifying surface albedo to reduce light absorption; putting parasols in orbit; adjusting the exhaust of jet airliners to leave dust or sulfur in the upper atmosphere to increase cloud formation, etc.

Perhaps none of these ideas will work, or else they might have drawbacks which make them unsuitable. The best solutions may still be waiting to be invented. But they all offer greater hope than the solution du jour of adopting the Kyoto treaty so as to ever-so-slightly reduce CO2 emissions (or just reduce the rate of growth of emissions). Anyone who is seriously concerned about AGW should be urgently searching for a technological solution. Anyone who is frightened about the prospect of a near-term thermal runaway effect should be desperately searching for a technological solution, since that would be the only realistic route to preventing it.

Carbon offsets are actually a good idea, despite the hypocrisy of some of the politicians who utilize them and despite the sleazy similarity to the selling of religious indulgences to expiate sins. Carbon offsets provide a competitive market mechanism whereby various approaches to ameliorating CO2 levels can be financed and tested. The comparative lack of interest in technological solutions compared to government controls on CO2 emissions reinforces my opinion that the issue is being driven by a political agenda rather than by science.

5. If AGW is a serious problem, economic growth and exponential technological advancement is the best solution. Not only do I doubt the urgency of the problem (see point # 2 above), if it even is a problem (see point # 1 above), but I doubt the need to find an immediate solution. Science and technology are advancing at exponential rates, as is most evident by the improvements in computer processing power but is also showing up in many other fields. If we are not facing an irreversible disaster within the next thirty years, why not just wait fifteen or twenty years to try to solve the problem? By that time computer power will have advanced a thousand-fold, and our engineering capabilities and resources will be vastly greater than they are at present. What today constitutes an enormous technological challenge or an impossibly expensive engineering task might be simple and relatively inexpensive two decades from now.

Our civilization will also be far wealthier then, making even expensive engineering tasks easier to bear, if economic growth is not artificially constricted by short-sighted limits on CO2 emissions and other regulatory restrictions.

Going back to the analogy of a civilization-destroying meteor strike, suppose we detected a sizable comet which was projected to directly impact the earth in five years and wipe out life on our planet. Surely it would be worth spending trillions of dollars in an emergency program to deflect the comet. We have the technology, albeit crude and incredibly expensive (especially on a highly-compressed schedule) to achieve that goal.

Now suppose we detected that same comet and projected that it would impact the earth in thirty years. Would it make sense to spend the same trillions of dollars on the same emergency compressed-schedule? Surely not. It would make much more sense to leisurely study the problem, use improved computer modeling over the next couple of decades to determine the simplest and most cost-effective method of perturbing the comet, and develop the space infrastructure and advanced propulsion technologies which would allow us to achieve the goal.

Putting it another way, advances in technology are already rounding the knee of the exponential growth curve, thereby far exceeding even the most pessimistic forecasts for exponential thermal runaway. For anyone who doubts that exponential advances in technology will continue, I recommend Ray Kurzweil’s book The Singularity Is Near. If we do nothing now, and Anthropogenic Global Warming turns out to be a real danger, we’ll still have the time and ability to fix it before it can manifest itself as a disaster.

I think I’ve written enough for now. I originally intended this to be a fairly short comment. Somewhere along the line I totally lost control, and it exploded into a two thousand-plus word monster. I’ll be posting a version of it on my rarely-updated blog ( simply because I hate to waste all this writing.

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