corn.bmpTortilla prices are going up, causing hardship for the poor in Mexico, apparently because of all the use of ethanol in the U.S.

The U.S. is making lots of ethanol out of corn, to use as an alternative to gasoline — creating a shortage of corn for people wanting to make tortillas. Indeed, there some 100 more ethanol plants being planned, which will eat up even more corn — and this comes despite doubts about whether using corn ethanol for environmental reasons is really worth it. It has marginal benefits.

Besides, UC Berkeley’s Tad Patzek has long warned there isn’t enough land to grow all the needed corn, and that continued production could lead to grotesque and obscene environmental destruction.

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At the same time, as we’ve discussed before, the infrastructure corn ethanol production creates may be helpful, because it paves the way for the efficient distribution of the different cellulosic ethanol, which can be made from waste, residue and plant parts other than the corn kernel itself — and is much more beneficial to the environment. In other words, the corn ethanol boom is a stop-gap measure which, while costly in the short-run, could lead to huge paybacks in a few years. (See the argument of Vinod Khosla here). Although, even here, Patzek appears to disagree; there’s not enough land to produce these alternative plant sources, either, he says.

Other notes on the “global warming” front:

–Oil and gas industries are still getting subsidized, too, which helps make those fuels cheaper, and so provides less incentive to find alternatives. House Democrats are locked in a fight to change that.

–Meanwhile, a promising bipartisan climate change bill has just been introduced by Senators John McCain (Rep.) and Barack Obama (Dem.). This is significant because they’re both strong candidates for the U.S. presidential elections next year. It calls for mandatory caps on greenhouse gas emissions from power plants, industry and oil refineries.

The legislation would require that US greenhouse gas emissions be cut by 2% every year. The senators say that as a result of these cuts, emissions would drop back to 2004 levels by 2012, and to 1990 levels by 2020.

By 2050, the equivalent of 2100 metric tonnes of carbon dioxide would be emitted each year, down from 6100 metric tonnes in 2004, they say. In contrast, the United Nations’ Kyoto Protocol, which the US has not ratified, requires that parties return their emissions to 5% below 1990 levels. Whether or not this Kyoto target will be sufficient to avoid a global temperature rise of 2°C • often used as a threshold beyond which the world would face “dangerous climate change” • is cause for debate.