[Marxism] Use of U.S. Croplands for Biofuels Increases Greenhouse Gases

[Les Schaffer]

Science 29 February 2008:  Vol. 319. no. 5867, pp. 1238 - 1240  DOI: 
10.1126/science.1151861


Use of U.S. Croplands for Biofuels Increases Greenhouse Gases Through 
Emissions from Land-Use Change

Timothy Searchinger, Ralph Heimlich, R. A. Houghton, Fengxia Dong, Amani 
Elobeid, Jacinto Fabiosa, Simla Tokgoz, Dermot Hayes, Tun-Hsiang Yu

Most prior studies have found that substituting biofuels for gasoline 
will reduce greenhouse gases because biofuels sequester carbon through 
the growth of the feedstock. These analyses have failed to count the 
carbon emissions that occur as farmers worldwide respond to higher 
prices and convert forest and grassland to new cropland to replace the 
grain (or cropland) diverted to biofuels. By using a worldwide 
agricultural model to estimate emissions from land-use change, we found 
that corn-based ethanol, instead of producing a 20% savings, nearly 
doubles greenhouse emissions over 30 years and increases greenhouse 
gases for 167 years. Biofuels from switchgrass, if grown on U.S. corn 
lands, increase emissions by 50%. This result raises concerns about 
large biofuel mandates and highlights the value of using waste products.

[snip to end]


Because emissions from land-use change are likely to occur indirectly, 
proposed environmental criteria that focus only on direct land-use 
change (7) would have little effect. Barring biofuels produced directly 
on forest or grassland would encourage biofuel processors to rely on 
existing croplands, but farmers would replace crops by plowing up new 
lands. An effective system would have to guarantee that biofuels use a 
feedstock, such as a waste product, or carbon-poor lands that will not 
trigger large emissions from land-use change.

Counteracting increases in biofuels with controls or disincentives 
against land conversion would not only face great practical challenges 
but also have harsh social consequences. In our analysis, a diversion of 
12.8 million ha, otherwise generating 10% of the world's feed grain by 
weight, would reduce world consumption of meat 0.9% by weight and dairy 
products 0.6% (fluid milk equivalents) (1). This effect, of which around 
half reflects poorer diets in developing countries, depresses emissions 
and has a GHG "benefit" but probably not a desirable one. Effective 
controls on land conversion would constrain the major source of new 
supply to meet increased biofuel demands, resulting in less additional 
cropland and higher prices as markets seek equilibrium. In that event, 
more greenhouse benefits would stem in reality from reduced food 
consumption.

Use of good cropland to expand biofuels will probably exacerbate global 
warming in a manner similar to directly converting forest and grasslands 
(29). As a corollary, when farmers use today's good cropland to produce 
food, they help to avert GHGs from land-use change.


full ($$$$): http://www.sciencemag.org/cgi/content/full/319/5867/1238