The Green(leaf)ing of the Earth Continues

Liu et al. (2010) write as background for their study that "vegetation covers three-fourths of the earth's land surface, and plays a key role in global hydrological, biochemical cycles and energy balance." In fact, it plays much more than a "key" role; for it is absolutely essential for all terrestrial animal life, as it resides at the very bottom of all terrestrial food chains, including those that lead to us. Without terrestrial vegetation, put very simply, we would not be here.

In the present study, the authors used leaf area index (LAI) data derived from satellite observations made over the period July 1981 through December 2006 to look for, and compute changes in, this important plant growth parameter for six different latitude bands that included all of earth's continents but Antarctica. These bands were 50-90°N, 30-50°N, 10-30°N, 10°N-10°S, 10-30°S and 30-63°S.

Results indicated that over the period of study LAI "prominently increased" throughout Europe, Siberia, the Indian Peninsula, America and south Canada, the south region of the Sahara, the southwest corner of Australia , and the Kgalagadi Basin; while it declined in southeast Asia, southeastern China, central Africa, central and southern South America, and arctic areas in North America. Yet in spite of these latter negative results, they found that all six of the latitudinal bands they analyzed showed positive trends. Consequently, for the globe as a whole (i.e., the conglomerate of the six different latitude bands they analyzed), they determined that "LAI has increased at a rate of 0.0013 per year during July 1981-December 2006," while for the middle and high northern latitudes (north of 30°N), the linear LAI trend was 0.0032 per year.

It is most interesting that over the period of time when the earth experienced a warming that (1) occurred at a rate that the IPCC contends was unprecedented over the past millennium or two, and that (2) took the planet to a level of warmth that the IPCC also considers to have been unprecedented over the past millennium or two, the planet's vegetation suffered no net ill effect, but in fact prospered.