By Carla Wise
In December, a number of climate science papers were published on topics including melting sea ice, phytoplankton dynamics, and underwater deposits of frozen methane. It is difficult to choose which to highlight, so I just picked two that I found interesting.
Prairie grass mixture holds great promise for biofuel production
A key element to reducing the threat of very large, destructive climate change is developing alternative fuels for transportation. Until now, biofuels have been produced primarily from monocultures of corn or soybeans grown on fertile soils. These biofuels are “carbon-positive” because their production and combustion increases atmospheric CO2, although not as much as do fossil fuels. In addition, the use of good farmland to grow crops for biofuels sets up potential conflict between land use for fuel and food.
A new study led by David Tilman shows that growing diverse mixtures of prairie plants has the potential to provide more usable energy per acre than corn grain ethanol or soybean biodiesel and is far better for the environment. Tilman’s work shows that the use of 16-species mixtures of native prairie plants grown and used for biofuel could be “carbon negative,” meaning that they would actually subtract carbon dioxide from the atmosphere. His team also demonstrated that the polycultures can be grown successfully with low inputs, without fertilizer and on degraded, infertile soils.
Biofuel production has gained attention in recent years as a potential solution to climate change, diminishing oil reserves, and energy security. However, using food-based biofuels creates many problems. Tilman et al. state: “Current biofuel production competes for fertile land with food production, increases pollution from fertilizers and pesticides, and threatens biodiversity when natural lands are converted to biofuel production.” This work is a real breakthrough, because it demonstrates that biofuels produced by polycultures of prairie species can be “carbon negative” and may provide a substantial portion of global energy needs in a sustainable and environmentally beneficial manner without competing with food production for fertile lands.
The findings are published in the Dec. 8, 2006 issue of the journal Science and featured on the cover. (http://www.sciencemag.org/cgi/content/short/314/5805/1598)
Subscribers can read the full article at:
http://www.sciencemag.org/cgi/reprint/314/5805/1598.pdf
Monsoon intensity increases with climate change
The monsoon is the great life-giver and the great destroyer of the Indian subcontinent. Crops, animals, and food for half of the world’s population depend on rain from these annual storms. But when the storms are too intense, crops are inundated, animals drown, and floods and diseases cause great human suffering. As global climate change has been occurring, the stability of the Indian monsoon rainfall has been a puzzle.
The overall level of rainfall has changed little over the past century. But researchers have discovered a trend within the annual measurements of fewer but more extreme monsoon rains with warming global temperatures. B.N. Goswami and colleagues studied rain gauge data from stations throughout India from 1951 to 2000. They found that with warming temperatures, there has been a trend of fewer but more extreme monsoon rains. Light rain events have declined significantly while heavy and very heavy rain events have increased, keeping the annual mean rainfall essentially unchanged. This study suggests that the impact of continued warming will be to increase flooding and related hazards in central India in the coming decades. The implications of these findings are quite serious and potentially devastating for the many people of the Indian subcontinent.
The findings are published in the Dec.1, 2006 issue of Science:
http://www.sciencemag.org/cgi/content/abstract/314/5804/1442
Subscribers can read the full article at:
http://www.sciencemag.org/cgi/reprint/314/5804/1442.pdf
