How hard are we pushing the land?

NASA: We may be becoming an ever more technologically advanced society, but we remain as dependent as ever -- if not more and more so -- on the natural world that surrounds us. That is one takeaway from new NASA research that has found humans are using an increasing amount of the Earth's total land plant production each year for food, fiber, building and packaging materials and biofuels.

This remains a young data record, as one of the first global measurements tied to satellite data was published in 2004. That baseline-setting measurement was for the year 1995, when humans needed 20 percent of all plant growth for our various products. But the early returns are in, and despite uncertainties in the measurement, the signal is headed in a clear direction: up. From 1995 to 2005, global annual plant consumption rose from 20 percent to 25 percent of all plant production in those years.

As the human population continues to grow and more societies develop modern economies, this rate of consumption is increasing both as a whole and on a per capita basis globally, a NASA research group led by Marc Imhoff at NASA's Goddard Space Flight Center, Greenbelt, Md., has found.

The group has also used NASA satellite data to produce a multi-decadal record of plant production (from 1982 to 2007) that establishes a baseline of the Earth's productivity. But it is the consumption data, estimated from UN Food and Agriculture Organization country profiles, that reveals a snapshot of how much pressure human consumption is putting on the landscape. These new findings are being presented at the American Geophysical Union's Fall Meeting.

The first data point that jumps out from the research is the increase in demand for plants, from '95 to '05, from 20 percent to 25 percent. Imhoff said that scientists think this is a significant rise for that period of time, but that part of the challenge of this research is determining the limits of ecosystems' production and the impacts of a rising consumption rate.

"The question is, 'How hard are we pushing the land?'" Imhoff said. "People are wary about that percentage creeping up. Most people consider that a high number, although we're still doing research."…

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