These are stirring sentiments, to be sure, and once in a great while they may even be true. But for most human endeavors, moderation is a virtue and extremism is a vice. The reason is clear: all extremists think they are defending liberty and pursuing justice, from Timothy McVeigh and the 9/11 terrorists to Torquemada and abortion clinic bombers. One country’s terrorist is another country’s freedom fighter.

Extreme environmentalists are a case in point. Members of environmentalist groups who vandalize Hummer dealerships, destroy logging equipment, or torch scientific laboratories see themselves not as the terrorists that they are, but as environmental freedom fighters. And environmental groups who paint doom and gloom scenarios and exaggerate, distort, or even fabricate claims in order to keep the donations flowing only hurt their cause in the long run when doomsday comes and goes without incident or the claims turn out to be baseless.

As an undergraduate in the early 1970s, we were told that overpopulation would lead to worldwide hunger and starvation, oil depletion, precious mineral exhaustion, and rainforest extinction by the 1990s, predictions that have all failed utterly. Scientists like Bjorn Lomborg in The Skeptical Environmentalist have, in my opinion, properly nailed environmental extremists for these exaggerated scenarios. And his book is where I entered the debate.

In 2001, Cambridge University Press published Lomborg’s book which, given the similarity between its title (The Skeptical Environmentalist) and that of the magazine that I publish (Skeptic), his publicist thought it would be a perfect topic for the Skeptics Society’s public science lecture series at the California Institute of Technology, which I host. Given the highly debatable nature of many of Lomborg’s claims, however, I only agreed to host him if it could be a debate. Lomborg agreed at once to debate anyone, and this is where the trouble began — I could not find anyone to debate Lomborg. I contacted all of the top environmental organizations, and to a one they all refused to participate. “There is no debate,” one told me. “We don’t want to dignify that book,” said another. One leading environmentalist warned me that my reputation would be irreparably harmed if I went through with it. So of course I did. My own Senior Editor, Frank Miele, who is an expert on evolutionary biology and biodiversity (and is one of the fastest and most facile researchers I’ve ever known), challenged Lomborg on several of the chapters in his book, and we had a lively and successful debate.

My experience is symptomatic of deep problems that have long plagued the environmental movement, and for a time the political pollution of the science turned me into an environmental skeptic. That alone would be meaningless, given that I have only ever written one article on the subject, but I believe that the extremists had a similar effect on millions of others who remain skeptical in the teeth of what I now believe to be overwhelming evidence for anthropogenic global warming. The tragedy of this inappropriate conflation of politics and science is that world-class scientists and science communicators like David Suzuki have been warning us about this problem for decades, and doing so in a systematic and reasonable manner that so many of us failed to hear because of the extremists’ claims.

What turned me around on the global warming issue was a convergence of evidence from numerous sources. My attention was piqued on February 8, 2006, when 86 leading evangelical Christians — the last cohort I expected to get on the environmental bandwagon — issued the Evangelical Climate Initiative calling for “national legislation requiring economy-wide reductions” in carbon emissions. After attending a 2002 Oxford conference on the science of global warming, the chief lobbyist for the National Association of Evangelicals, the Reverend Richard Cizik, described his experience as “a conversion … not unlike my conversion to Christ.”

Later that month I attended the TED (Technology, Entertainment, Design) conference in Monterey, California, where former Vice President Al Gore delivered the single finest summation of the evidence for global warming I have ever heard, based on the 2006 documentary film about his work in this area, An Inconvenient Truth. Because we are primates with such visually dominant sensory systems, we need to see the evidence to believe it, and the striking visuals of countless graphs and charts, and especially the before-and-after photographs showing the disappearance of glaciers around the world, shocked me viscerally and knocked me out my skepticism.

Four recent books on the subject then took me to the flipping point. Archaeologist Brian Fagan’s The Long Summer (Basic, 2004) documents how civilization is the gift of a temporary period of mild climate. Geographer Jared Diamond’s Collapse (Viking, 2005) demonstrates how natural and human-caused environmental catastrophes led to the collapse of civilizations. Journalist Elizabeth Kolbert’s Field Notes From a Catastrophe (Simon and Schuster, 2006) is a page-turning account of her journeys around the world with environmental scientists who are documenting species extinction and climate change that are unmistakably linked to human action. And biologist Tim Flannery’s The Weather Makers (Atlantic Monthly Press, 2006) reveals how he went from being a skeptical environmentalist to a believing activist as incontrovertible data linking the increase of carbon dioxide, CO₂, to global warming accumulated the last decade.

It is a matter of CO₂ Goldilocks. In the last ice age CO₂ levels were 180 parts per million (ppm) — too cold. Between the Agricultural Revolution and the Industrial Revolution CO₂ levels rose to 280 ppm — just right. Today CO₂ levels are at 380 ppm and are projected to reach 450 to 550 ppm by the end of the century — too warm. Like a kettle of water that transforms from liquid to steam when it changes from 211 to 212 degrees F, the environment itself is about to make a CO₂–driven flip.

According to Flannery, even if we reduce our CO₂ emissions by 70 percent by 2050 average global temperatures will increase between 2 to 9 degrees C by 2100. This rise could lead to the melting of the Greenland Ice Sheet, which the March 24 issue of Science reports is already shrinking at a rate of 224 ±41 cubic kilometers per year, double the rate measured in 1996 (Los Angeles uses 1 cubic kilometer of water per year). If it and the West Antarctic Ice Sheet melt, sea levels will rise 5 to 10 meters, displacing half a billion inhabitants of coastal communities.

I mentioned above that I have only ever published one article about the environment, and that was recounting my conversion from global warming skeptic to believer in my monthly column in Scientific American. In that column I closed with this sentence: “Because of the complexity of the problem environmental skepticism was once tenable. No longer. It is time to flip from skepticism to activism.”

What I meant by that final clause is that it is time to do something about the problem. I did not specify what we should do, but in my opinion we have time to fix the problem without drastic and draconian governmental intervention. For example, I believe that if we start the transition now, we can make the shift from burning fossil fuels to alternative fuels through normal market channels. The market for hybrid automobiles, for example, will continue growing at a breakneck pace such that within two decades the vast majority of cars will be hybrids and the transition to purely electric cars (or cars that run on some other combination of electricity and a cleaner alternative fuel), will be successful. In other words, I would much prefer to see governments establishing pollution standards and carbon dioxide levels that the marketplace is then free to work around in its usually efficient manner (more efficient, in any case, than most government programs are capable of achieving).

In response to my Scientific American column, I received thousands of letters and emails. A few were surprised that it took me so long to come around. For example:

Michael Shermer announces that “it is time to flip from skepticism to activism” with respect to anthropogenic global warming. Well, gosh, Shermer, welcome to the party. Where the heck have you been? No offense, but most of your readers realized it was “time to flip” years ago. Maybe the shocked and horrified response (“there is no debate”) that you got when trying to promote skepticism about global warming was not, as you assume, “symptomatic of deep problems that have long plagued the environmental movement,” but was, rather, indicative of how far off the rails of rationality you had gone. After all, as you observe, even the evangelical Christians abandoned the skeptical position before you did! It might be worthwhile to devote a little time and introspection to exactly why you stuck to a dangerously irrational point of view for so long; because the sand you buried your head in is exactly the same sand that we need to get the average American’s head out of. If it took four books and a lecture by Al Gore to change your mind, I despair that we will ever change the minds of the people who really matter: the voters.

— Ben Haller, Menlo Park, CA

Indeed, my correspondent is right, the vast majority of letters that I received were skeptical of my loss of skepticism. That is, in spite of what I now see as overwhelming evidence for anthropogenic global warming, there are still plenty of skeptics out there, and I believe that they are primarily motivated for the same reason that I was — they got burned by environmental extremists. Here is a small sampling.

Michael Shermer sure has ‘flipped’! He quotes Flannery as saying that “even if we reduce our carbon dioxide emissions by 70% by 2050, average global temperatures will increase between two and nine degrees by 2050.” Could it be that global warming is caused, in the main, by forces beyond our control?

— Robert Schnepp, Port Hueneme, CA

I was disappointed to see that Mr. Shermer has surrendered his skepticism on anthropogenic global warming in the June 2006 issue of “Scientific American.” His “flipping point” seems to be the demonstrated reduction in some of the world’s glaciers. I suggest he enroll in a freshman course in historical geology. There he will learn that glaciers have come and gone many times in the recent history of the earth (geologically speaking). The most recent episodes of glaciation are referred to as the Pleistocene era. I think his change of heart will turn out to be as wrong as his stated belief in the 1970s that starvation and depletion of resources would plague the earth by the 1990s.

—Howard Sahl, Longmont, CO

Very appropriate Michael. I have always looked somewhat askance at Scientific American’s views on environmental matters. Shame on you for following their editorial dictates. I will never again read my Skeptic magazine (I am a subscriber) in the same open minded way that I have previously. You have joined the philistines. The blunt, highlighted in red, comment: “Reducing our CO₂ emissions by 70% by 2050 will not be enough.” shows a ‘grab’ at a statement that would put even the most rabid environmental group to shame. Prove it!

—Ivor Davies, Oakville, Ontario, Canada

Before you jump on the idiotic bandwagon and irreparably destroy your reputation, you ought to talk to John Brignell of www.numberwatch.co.uk and Michael Fumento of www.fumento.com and most importantly Steve Milloy at www.junkscience.com. Keep in mind:

1. Climate changes no matter what we do.
2. The single greatest heat source is … THE SUN, variations in its output will cause variations in our temperature.
3. The trouble with people presenting evidence is that they like to present the stuff the supports their premise, but ignore all the rest. You can show 50 glaciers that are receding and ignore the 50 that are growing. You can show the ice shelf breaking off but ignore the fact that it is getting colder in antarctica.

The greatest danger we face on this planet is the Eco Freaks. The climate will change no matter what we do. If the Freaks have their way, we will not be able to combat it, because we will have squandered resources trying to stop a hurricane instead of getting out of the way. I like your work, but you are scaring me now.

—Brad Tittle, Senior Systems Analyst, Trainnow.net

I too, am a skeptic. I am particularly skeptical of conventional wisdom that reeks of left wing politics and uses none other than Al Gore as a reference. Look up Malthusian economic theory so that you understand what it means when I accuse you of having a Malthusian mind. Several months ago there was an excellent greenhouse gas article printed in your publication using thousands of years of ice core data as its basis. This data showed quite convincingly that the glacial cycles, most probably brought on by the precession of the earth in its orbit around the sun, are accompanied by increases and decreases in greenhouse gases. It also showed that the most recent interglacial warm period should have begun to cool off and green house gases should have begun declining about 6000 years ago. They have not. They have, instead, increased. The scientist who did this study pointed out that about the only possible variable to explain this change in these cycles would be the rapid expansion of human population accompanied by farming, irrigation and raising of domestic live stock. Greenhouse gases have been going up when they should have been going down for 6000 years. There were no SUV’s back then. The answer to the dilemma you fear was also in the data from that article. The two largest plagues of the last two thousand years actually showed up in the ice core data as reductions in greenhouse gases. You want a 70% reduction in greenhouse gases you’d better plan a plague, a big one. The fact is that if anything can be proven as cause and effect, the only thing one might be able to say with some certainty is that the mere existence and growth of the human population has delayed a glaciation, which the aforementioned data indicated should have begun about 2000 years ago. Probably this is a GOOD thing!

—Jim Gampetro, Buffalo, WY

It seems the primary reason for the Skeptic’s “flipping” is the change in carbon dioxide levels from 180ppm (ice age), 280ppm (industrial revolution), 380ppm (today), and then the projections. So what about the previous 4.5 million years? What were carbon dioxide levels BEFORE the last ice age? The time frame for which we have data is so small compared to the history of the earth (which has endured numerous hot and cold periods), that forecasts based on that data are unscientific. Kinda like calling an elephant long and skinny based on a feel of it’s tail. I’m not ready to “flip” yet.

—John Guimont

I well remember watching television programs about the environment hosted by David Suzuki. They were visually stunning and brilliantly presented. But my mind had already been hardened by the failed predictions of the extremists, and so I watched and listened, but I did not see or hear. But you were right, David, and for many decades of tireless work on behalf of this pale blue dot and its inhabitants, we all owe you a debt of gratitude.

This article was first published in an edited volume as a Festschrift
for David Suzuki by Greystone Books, Canada.

In 2001 Cambridge University Press published Bjorn Lomborg’s book The Skeptical Environmentalist, which I thought was a perfect debate topic for the Skeptics Society public lecture series at the California Institute of Technology. The problem was that all the top environmental organizations refused to participate. “There is no debate,” one spokesperson told me. “We don’t want to dignify that book,” another said. One leading environmentalist warned me that my reputation would be irreparably harmed if I went through with it. So of course I did.

My experience is symptomatic of deep problems that have long plagued the environmental movement. Activists who vandalize Hummer dealerships and destroy logging equipment are criminal ecoterrorists. Environmental groups who cry doom and gloom to keep donations flowing only hurt their credibility. As an undergraduate in the 1970s, I learned (and believed) that by the 1990s overpopulation would lead to worldwide starvation and the exhaustion of key minerals, metals and oil, predictions that failed utterly. Politics polluted the science and made me an environmental skeptic.

Nevertheless, data trump politics, and a convergence of evidence from numerous sources has led me to make a cognitive switch on the subject of anthropogenic global warming. My attention was piqued on February 8 when 86 leading evangelical Christians — the last cohort I expected to get on the environmental bandwagon — issued the Evangelical Climate Initiative calling for “national legislation requiring sufficient economy-wide reductions” in carbon emissions.

Then I attended the TED (Technology, Entertainment, Design) conference in Monterey, Calif., where former vice president Al Gore delivered the single finest summation of the evidence for global warming I have ever heard, based on the recent documentary film about his work in this area, An Inconvenient Truth. The striking before-and-after photographs showing the disappearance of glaciers around the world shocked me out of my doubting stance. Four books eventually brought me to the flipping point.

Archaeologist Brian Fagan’s The Long Summer (Basic, 2004) explicates how civilization is the gift of a temporary period of mild climate. Geographer Jared Diamond’s Collapse (Penguin Group, 2005) demonstrates how natural and human-caused environmental catastrophes led to the collapse of civilizations. Journalist Elizabeth Kolbert’s Field Notes from a Catastrophe (Bloomsbury Publishing, 2006) is a page-turning account of her journeys around the world with environmental scientists who are documenting species extinction and climate change unmistakably linked to human action. And biologist Tim Flannery’s The Weather Makers (Atlantic Monthly Press, 2006) reveals how he went from being a skeptical environmentalist to a believing activist as incontrovertible data linking the increase of carbon dioxide to global warming accumulated in the past decade.

It is a matter of the Goldilocks phenomenon. In the last ice age, CO₂ levels were 180 parts per million (ppm) — too cold. Between the agricultural revolution and the industrial revolution, levels rose to 280 ppm — just right. Today levels are at 380 ppm and are projected to reach 450 to 550 by the end of the century — too warm. Like a kettle of water that transforms from liquid to steam when it changes from 99 to 100 degrees Celsius, the environment itself is about to make a CO₂–driven flip.

According to Flannery, even if we reduce our carbon dioxide emissions by 70 percent by 2050, average global temperatures will increase between two and nine degrees by 2100. This rise could lead to the melting of the Greenland Ice Sheet, which the March 24 issue of Science reports is already shrinking at a rate of 224 ±41 cubic kilometers a year, double the rate measured in 1996 (Los Angeles uses one cubic kilometer of water a year). If it and the West Antarctic Ice Sheet melt, sea levels will rise five to 10 meters, displacing half a billion inhabitants.

Because of the complexity of the problem, environmental skepticism was once tenable. No longer. It is time to flip from skepticism to activism.