Plant consumption rising significantly

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. In addition to as food, plants are consumed for paper, clothing, livestock feed, firewood, biofuels, building and packaging materials, among other uses.

A NASA research group led by Marc Imhoff at NASA’s Goddard Space Flight Centre, Greenbelt, first quantified this global consumption in 2004, when the group found that in 1995 humans consumed 20 per cent of all the land plant material produced that year.
Now the same line of research has produced a multi-decadal record of plant production (from 1982 to 2007) that establishes a baseline of the Earth’s productivity, and a 10-year trend of human consumption.

Some of the most notable findings from the research include:

*From 1995 to 2005, human consumption of land plants rose from 20 per cent to 25 per cent of the total plant production of each year. Imhoff said scientists think this is a significant rise for that period of time, but that part of the challenge of this research is determining the uncertainties in the measurement, the limits of ecosystems’ production and the impacts of a rising consumption rate.

*Both total, global consumption and per capita consumption are rising.

*In comparing the ratio of a region’s production versus consumption, some major urban areas consume more than 30,000 times the amount of regional plant production.

*Great regional discrepancies remain. The average person in North America consumes about 6 tonnes of plant-based carbon each year, while the average person in Southeast Asia consumes just less than 2 tonnes of plant-based carbon each year.

*If every person in the world were to, in the coming decades, achieve current North American requirements of plant material, we would be consuming about 50 per cent of all plants grown each year.

While plant production itself varies from year to year, mostly depending on weather, the demand trends are holding steady on the increase. Depending on region, some of the increase is due simply to population growth — more people consume more food, more paper, more wood for burning.

This has been seen in places like India, where population is booming but individual consumption levels have not dramatically risen, yet. In other places, where economic growth has allowed for more ‘westernised’ consumption, per capita consumption is driving the trend. And in some places, such as North America, both population and per capita consumption are increasing.

The research group’s 1982-2009 plant production data — called ‘net primary production’, or NPP, in the science literature — is provided by NASA satellite instruments, first from Advanced Very High-Resolution Radiometer (AVHRR) sensors and in more recent years from Moderate-Resolution Imaging Spectroradiometer (MODIS).

The scientists analysed the consumption data from the UN Food and Agriculture Organisation’s country profiles.

“The global demand is going up,” Imhoff said.

“We’ve gone from 20 per cent demand to about 25 per cent demand in 10 years. People worry about that percentage. If, in future scenarios, it’s going to go up to something like 50 per cent, we’re looking at a very high demand for land management to maximise productivity at all levels on the landscape and at the expense of all other uses, for example, carbon sequestration, habitat, or water storage. We would be heading toward a place where the planet would be very carefully managed, from end to end,” Imhoff added.

These new findings have been presented at the American Geophysical Union’s Fall Meeting in San Francisco, California.

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