For over a decade, many industry groups have maintained that putting carbon dioxide in the air would produce a general "greening" of the planet. In fact, that's the thesis of a famous 1992 video, "The Greening of Planet Earth," which riled the environmental community more than just about anything else that business has done in its own defense on this issue.
"Greening" was put out by energy-industry activists (you can get your own copy by contacting http://www.greeningearthsociety.org), who discovered that several big-name scientists were willing to appear and argue that carbon dioxide will enhance global plant growth by directly stimulating plants and by warming the coldest air of winter. These scientists were confident because the growth stimulation had been observed in literally thousands of controlled lab experiments and reported in the scientific literature. At the same time, the climate data were pouring in showing that "global" warming was much more "winter" warming, and in the coldest air, which was sure to lengthen the growing season for plants.
On September 16, industry will be vindicated with a vengeance in the Journal of Geophysical Research, when Liming Zhou and five co-authors publish their paper demonstrating a profound greening of the planet poleward of latitude 40º, or north of a circle passing through New York City.
Using a satellite designed to measure changes in vegetation, they found that the time of active growth has advanced as much as 18 days per year in Eurasia. (The freeze-free period averages around 170 days at latitude 40º.) In North America the results are more spotty, with a few areas increasing by up to 12 days. On our continent, the results are confounded by the well-known (to scientists, not to newspaper-readers) cooling trend in northeastern North America that has been going on for about 70 years.
Zhou et al. attribute this "greening" (their word) to "global warming," because it matches areas that show maximum warming since 1980 in land-based climate records. In fact, the winter warming in the dead of Siberia has been quite striking for decades, and, everything else being equal, this will lengthen the growing season. (Last year's record cold merely proves that climate is a very variable thing.) Summer warming in Siberia has been less profound, a fact not generally disseminated because it doesn't support the popular global-warming-as-disaster paradigm.
What isn't noted in the paper or the brief flurry of news reports -- there would probably be a bit more coverage if Zhou had written "global warming is killing the North Woods" -- is that the beginning of their satellite record, in 1981, corresponds in the Northern Hemisphere to the end of the coolest era of the last 70 years. The fact is that all analyses show a cooling of our hemisphere from roughly the mid-1940s to the late 1970s. During this climate spasm "global cooling" became popular. So this paper starts at an unusual point, but, unfortunately, that is when the satellite went up. If the satellite went up in, say, 1950, the changes it would have found in the growing season would have been much smaller.
The contra is also true: According to Zhou's findings, if we had continued down that cooling spiral, the world north of 40º would now be much more barren than it was 20 years ago. It's quite reasonable to ask if human-induced global warming has saved the world from a food crisis.
What really ticked off the greens about "The Greening of Planet Earth" were the many sound bites from prominent agricultural scientists about how the future atmosphere would be much more conducive for food production. But look at what NASA, which funded this study, now says about Zhou's work: "The pattern of high growth is especially noteworthy in boreal [northern] Eurasia...This includes the grasslands and croplands of south central Russia....[emphases added]."
In other words, dreaded global warming will produce more food for Russia.
Russians rightfully fear the cold. In 1972, near the bottom of the mid-century cooling (and around the height of global cooling fear) they were so short of food that they purchased just about every kernel of American grain. This sent grocery store prices here to alarming levels. By the end of the crop year 1972, world grain reserves stood at a stunningly low 19 days. Since we warmed up, those fears have become a thing of the past. Now food shortages are largely local and political, and commodity prices have been in the tank for years, reflecting vast supply compared to demand.
So is this what global warming has wrought? It appears to have created a more comfortable planet with more food. The video was right. The greens were wrong. The world is greener.