Gore suggests that it would be "quite literally insane" to approve the Keystone pipeline

Al Gore calls on Barack Obama to 'act boldly' on climate change | Environment | guardian.co.uk

The vice-president's intervention for a carbon tax could give critical support to an idea that has gained currency since the election – at least among Washington thinktanks.
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Gore said he supported their campaign. "I do agree with those who are trying to stop the Keystone pipeline. The tar sands are just the dirtiest source of liquid fuel you can imagine," he said. "At a time when we are desperately trying to bend the emissions curve downwards it is quite literally insane to open up a whole new source that is much more carbon intensive and that makes the problem worse."