An Inconvenient Truth, the new movie centered on former vice-president Al Gore's famous global warming slide show, will open in select theaters on May 24th. The movie trailer warns: "If you live on this planet: If you love your children: You have to see this film." Gore declares that man-made global warming "is really not a political issue so much as it is a moral issue." At the conclusion the words "Nothing is scarier than the truth" appear on screen and then Gore portentously intones: "Our ability to live is what is at stake."
Gore is correct that the scientific consensus is that humanity is causing global warming. Earlier this month, a report from the National Oceanic and Atmospheric Administration concluded: Global-average temperature increased at a rate of about 0.12 degrees C per decade since 1958, and about 0.16 degrees C per decade since 1979. In the tropics, temperature increased at about 0.11 degrees C per decade since 1958, and about 0.13 degrees C per decade since 1979.
Gore warns that melting ice sheets in Greenland and Antarctica could lead to a sea level rise of twenty feet inundating Florida, Bangladesh, Shanghai, and New York City. But there is a lot less certainty than he implies in such scenarios. For example, a 2005 computer modeling study in Geophysical Research Letters found that Greenland is losing ice which is contributing annually about 15 millimeter to the rise in global sea levels. However, another 2005 study published in Science found that Greenland's ice sheet was growing in the interior while melting along the edges, perhaps resulting in some net accumulation of ice. And then in February 2006, yet another study in Science finds that glaciers in southern Greenland are flowing faster into the sea.
And scientific knowledge about what is going on with Antarctica's ice sheets is similarly uncertain. For example, a perspective article in the June 25, 2005 issue of Science found that on balance Antarctica's ice cap is thickening and thus reducing sea level rise. A new study based on satellite measurements that detect minute differences in gravity found that Antarctica is losing ice. But others conclude from those measurements that melting ice from Antarctica may not be contributing to sea level rise.
Researchers generally project that the complete melting away of the Greenland ice sheet caused by global warming would take between 500 and 1000 years. A new modeling study suggests that if the average temperature increases by 4 degrees centigrade, we could see a rise in sea level of 20 feet by 2100. Keep in mind that 4 degrees centigrade is at the high end of projected average increases in global temperatures. The trends in the NOAA study cited above suggest that temperature increases over the next century will be at the low end of the projections.
In any case, while there is wide agreement that man-made global warming is happening, what to do about it is very much contested. Having seen only the movie trailer at this point, I don't know exactly what Gore's latest plan is, but I suspect that he favors schemes for reducing greenhouse gases emitted by humanity, given his support for the Kyoto Protocol. If the goal is to stabilize concentrations of greenhouse gases in the atmosphere, then emissions will have to be cut by 70 percent. What will be cut? The use of fossil fuels which have powered a 20-fold increase in world gross domestic product from $2 trillion in 1900 to over $40 trillion today. It may well be possible to shift to other energy sources to fuel humanity's future, but some argue that global warming is not the main problem that faces the bulk of humanity -- poverty is.
In an attempt to counter the media blitz that will accompany the release of An Inconvenient Truth, the free-market Competitive Enterprise Institute, based in Washington, DC, is launching a campaign today featuring two television spots proclaiming that the chief greenhouse gas "CO2 Is Life." The first ad, titled "Energy," properly reminds viewers that fossil fuels "freed us from a world of back-breaking labor" and are used "to create and move the things we need." The ending voiceover declares, "Carbon dioxide. They call it pollution; we call it life." The second spot entitled "Glaciers" points out the scientific uncertainties about how global warming is affecting glaciers in Antarctica and Greenland. The "Glaciers" spot also makes the point that the media tend to headline findings that portend doom, while overlooking less alarming scientific results.
Neither of CEI's TV spots denies the existence of man-made global warming, but they do call attention to the enormous benefits that people have gained from fossil fuels and point to significant scientific uncertainties. CEI's spots are not subtle (hard to do in 60 seconds of video), but neither is the trailer for the movie about Gore's crusade. In both media presentations, CEI and Gore are ignoring scientific evidence that cuts against their views.
In the end, the debate over global warming and its obverse, humanity's energy future, is a moral issue. Global warming may well harm humanity by disturbing the environment, but forcing the world's poorest people (2 billion of whom have never even turned on a light bulb) to use more expensive and technically challenging fuels would also cause great harm. In a sense, Gore is right: What is at stake is our ability to live.
Disclosure: I was the 1993 Warren Brookes Fellow in Environmental Journalism at the Competitive Enterprise Institute and I have been the editor of three CEI volumes on environmental policy and science. I also dine and go drinking with CEI staff members from time to time and we usually split the check.