The most obvious benefit is yield increase. In 2010, the report estimates, the world’s corn crop was 31 million tons larger and the soybean crop 14 million tons larger than it would have been without the use of biotech crops. The direct effect on farm incomes was an increase of $14 billion, more than half of which went to farmers in developing countries (especially those growing insect-resistant cotton).
[T]he most striking benefits are environmental. The report calculates that a cumulative total of 965 million pounds of pesticide have not been used because of the adoption of GM crops. The biggest impacts are from insect-resistant cotton and herbicide-tolerant maize, both of which need fewer sprayings than their conventional equivalents…The use of less fuel in farming GM crops results in less carbon-dioxide emission…the GM crops grown in 2010 had an effect on carbon-dioxide emissions equivalent to taking 8.6 million cars off the road.
More from Matt Ridley in the WSJ.