Reducing Global Warming
It's pretty well known that the way to deal with global warming is with a carbon tax. People who should know better, like Paul Krugman, advocate for a slightly hidden carbon tax called cap and trade, but it has proven completely unworkable. Its slightly hidden character doesn't fool anybody but the most naive rubes, creating a vast space for those who do know better to manipulate and jimmy the tax.
Of course the problem with the carbon tax is that it's immensely unpopular. People really really don't want to pay more for gasoline, electricity, or heating oil. It's also a highly regressive tax, so that it would be devastating to lower income people without an aggressive rebate program, and such transfer programs are anathema to the right.
The human race may not be collectively smart enough to survive.