PeopleSystems and Sustainability: This Week in the Global Environment

Maybe It IS Easy Being Green

Early debates (going back more than a decade now) regarding the potential impacts of global warming were backed up by ecological simulation models of primary production and plant biomass that ignored a key factor—carbon dioxide limitation of much of the vegetation in the biosphere. Recently, more sophisticated models have incorporated this parameter in one form or another, providing what are likely to be seen in retrospect as more accurate, precise, and well-calibrated projections of climate change effects.

This week, Science Daily (http://www.sciencedaily.com/releases/2013/05/130531105415.htm) presented a synopsis of work conducted by Randall Donahue and colleagues at the Australian Commonwealth Scientific and Industrial Research Organization (CSIRO) and published in the Geophysical Research Letters in which the authors attempted to sort out a signal of carbon dioxide increase from the “noise” of the many parameters, such as temperature and moisture affecting plant growth. 

The exercise was far from straightforward. Donahue and his people concentrated on arid areas where increased “green” could be quantified by contrast to the dry substrate (as opposed, say, to tropical or temperate forests where leaf cover already exceeds 100%, making remotely-sensed increases in leaf area impossible to ascertain). They established site-specific indices of maximum “green” attainable via a three-year moving average of moisture changes. Then they quantified green exceedances of the index, likely indicating the effect of carbon dioxide fertilization on the landscape. 

One thing the authors did not comment on is the fortuitous high value of forcing their work into arid regions. Desertification is one of the greatest environmental problems we face today. If carbon dioxide fertilization can, even incrementally, slow or reverse desertification in key areas of the Sahel, central Asia, the Americas, and even Australia, it will be an enormous boost to the ecological quality of the biosphere. At the same time, it will feedback on human quality-of-life, offering reduced hardships in regions traditionally among the most challenging places for people to live.

I suggest we all take a deep breath and re-read the cover of our copy of The Hitchhiker’s Guide to the Galaxy, where it reads, in soothing green letters, “DON’T PANIC”. As scientists and environmental managers, it is critically important for us to be objective, to sort the good and bad effects of global climate change, and incorporate those in our communications to politicians and the public. In this case, CSIRO scores one for the good guys. Climate change may help truncate desertification. Time to tackle other items on the impact assessment list. But those are subjects for subsequent columns.