Actually, this is pretty easy to believe

Al Gore's people apparently believe that higher carbon dioxide levels are making people dumber. No, really:

First, United Nations officials label bacon and deli meats as carcinogens, and now scientists are claiming that higher concentrations of carbon dioxide are not only heating the planet, they’re making people dumber.
A new study by the Harvard School of Public Health claims “carbon dioxide (CO2) has a direct and negative impact on human cognition and decision-making,” according to ThinkProgress, a left-wing advocacy website.
Former Vice President Al Gore wasted no time tweeting out ThinkProgress’ in-depth article, trying to link higher carbon dioxide levels to lower cognition in humans.

Looking at Al Gore, I know that something is making people dumber -- at least, something is making Al Gore dumber -- so maybe he's finally onto something.

Actually, as anyone who has watched the movie "Apollo 13" knows, high concentrations of CO2 do, in fact, interfere with cognitive functions. However, the atmospheric concentrations of CO2 are nowhere near those levels. Al Gore thinking that they are is proof that something, at least, is making Al Gore dumber. Or maybe he started out that dumb. Hmmm.