During the two-hour debate, moderators questioned candidates on a range of foreign policy topics, including terrorism, immigration and nuclear proliferation, but there were no questions on the Paris climate agreement. The candidates haven't said much about the pact, in which nearly 200 nations pledged to try to reduce their carbon emissions in an effort to stymie the rise of global temperatures. Many commentators have called the deal historic; Senate Majority Leader Mitch McConnell (R-Ky.) has noted the next president could tear it up.
A rare mention of climate change came when front-runner Donald Trump mentioned it briefly in a rambling answer on nuclear weapons.
"The biggest problem this world has is not President Obama with global warming, which is inconceivable -- this is what he's saying," Trump said. "The biggest problem we have today is nuclear proliferation and having some maniac, having some madman go out and get a nuclear weapon."
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