Trees of the desert

The effects of global warming due to rising concentrations of greenhouse gases (GHGs) may not all be bad. Xiahong Feng of Dartmouth College in Hanover, New Hampshire, USA, says that rising levels of GHGs have led to faster tree growth in arid regions. This would mean that planting trees in dry areas might help combat global warming as plants combine water with carbon dioxide (CO 2 ), the main GHG, to create complex chemicals. Feng has shown that the rise in atmospheric CO 2 over the past 200 years has made this process more efficient. Feng measured the changing ratio of different carbon isotopes in the annual growth rings of a range of trees in the US. The researcher found an underlying trend that matched the rise in global CO 2 levels. The findings may help climatologists balance the Earth's carbon budget. Roughly half the CO 2 in the atmosphere that arises due to human activity disappears quickly. While the oceans absorb some of it, it is believed that much of the rest is absorbed by forests in cooler temperate regions ( Geochimica et Cosmochimica Acta , Vol 63, p1891).

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