Amid the current UN climate talks and massive march for action on climate change in New York City, the New York Times runs an oh-so-naughty op-ed by Nadine Unger, an assistant professor of atmospheric chemistry at Yale, entitled "To Save the Planet, Don't Plant Trees." Now, if she had reversed the title as "Don’t Plant Trees To Save the Planet," she might have had a bit of a case. We ourselves reject the "carbon trading" scam that gives corporations a license to pollute if they plant trees—despite the fact that they often don't even plant the trees, but just grab forested lands from indigenous peoples, and (worse) the burninng of fossil fuels releases carbon that had been more thoroughly "locked" than that in trees, which do eventually die and rot. This is indeed a point that "carbon trading" and "biofuels" boosters seek to obfuscate. But this is not Unger's point. Instead, she is literally loaning legitimacy to Reaganoid nonsense that "trees cause pollution." To wit:
Climate scientists have calculated the effect of increasing forest cover on surface temperature. Their conclusion is that planting trees in the tropics would lead to cooling, but in colder regions, it would cause warming…
Worse, trees emit reactive volatile gases that contribute to air pollution and are hazardous to human health. These emissions are crucial to trees — to protect themselves from environmental stresses like sweltering heat and bug infestations. In summer, the eastern United States is the world's major hot spot for volatile organic compounds (V.O.C.s) from trees.
As these compounds mix with fossil-fuel pollution from cars and industry, an even more harmful cocktail of airborne toxic chemicals is created. President Ronald Reagan was widely ridiculed in 1981 when he said, "Trees cause more pollution than automobiles do." He was wrong on the science — but less wrong than many assumed.
So what do the "climate scientists," who Unger ingenuously invokes without actually naming any, have to say about this? Some 30 of them—actually named, and with better bona fides than Unger—respond in an an open letter on the rainforest news site Mongabay:
1) Forests have a cooling effect on our climate because they store vast amounts of carbon in tree trunks, branches, leaves and soil. They keep this carbon out of the atmosphere for as long as they remain healthy, intact forests. If they are cleared or degraded, there is a net flow of carbon to the atmosphere, contributing to climate change. Slowing forest clearing and degradation is precisely the focus of the UN's mechanism for encouraging tropical nations to reduce emissions from deforestation and forest degradation. Unger’s statement confuses this fundamental aspect of forest carbon dynamics.
2) Forests also cool the atmosphere because they convert solar energy to water vapor, which increases sky albedo (or reflectivity) via cloud formation. This effect is particularly strong in the tropics, where the UN mechanism is focused. Unger neglects to mention this effect. She correctly points out that forests often reflect less solar energy than snow, rock, grassland or soil, but ignores the effect of forests on increasing the albedo of the sky above the land, which is the stronger effect in the tropics.
3) Unger's recent global study of deforestation suggests that the removal of trees reduces emissions of naturally-occurring chemicals called biogenic volatile organic compounds (BVOC). Although Unger opined that BVOCs cause global warming, her science indicates that BVOCs have anywhere from a cooling to a warming effect. Her study also found that any potential cooling effect generated by reducing BVOC emissions through tree removal is outpaced by the larger warming effect of carbon emissions from deforestation.
So is Unger distorting her own research in order to get a sexy headline in the Times op-ed page? She herself calls her findings "counterintuitive." That's putting it rather mildly.
Meanwhile, the authors of the repudiation letter, alas, buy into some of the carbon-utopianism, boasting: "Brazil has reduced deforestation rates in the Amazon region by 70%, for example, keeping 3.2 billion tons of carbon dioxide out of the atmosphere since 2005 and elevating this nation to global leadership in climate change solutions." Yes, except that the rate of deforestation in the Brazilian Amazon increased by 28% between August 2012 and July 2013, after years of decline. What nobody, either the carbon-utopians or the carbon-skeptics, can admit is that any strategy against climate change is a mere holding action at best as long as we live under an economic system predicated on endless growth. Better to keep us arguing about whether trees cause pollution than demanding a public expropriation of the hydrocarbon and automotive industries.