We’ve had four and a half hours of presidential and vice-presidential debates. We’ve covered a lot of ground. There’s been a lot of substance. Yet it is unconscionable that the biggest crisis the world faces has not yet warranted a mention: global warming.

Will it be mentioned in the last presidential debate on Monday?

It’s not promising. Moderator Bob Schieffer released his planned topics for the debate designed to solely cover foreign policy, and climate was not on the list.

And the media in general seem incapable of bringing up the subject. The broadcast network Sunday talk shows literally spent a total on 9 minutes on climate in 2011 and that include Fox News Sunday’s coverage of the bogus scandal dubbed “ClimateGate.” Not even an msnbc.com piece on the “Five key issues omitted from first two [presidential] debates” could be bothered to mention it.

But climate perfectly fits within two of Schieffer’s broadly worded topics, “America’s Role in the World” and “The Rise of China and Tomorrow’s World.”

Which speaks to the larger point: the foreign policy debate is where the issue of global warming belongs. It is, after all, global. Even Mitt Romney — who, as usual, is all over the map on the subject — has said, “The reality is that the problem is called Global Warming, not America Warming.”

Mr Schieffer, that Romney quote could be your entry point in the debate. You can easily ask: “Both of you agree that the climate is a global problem. What global solution do you believe American should pursue? Does it need to be a formal treaty? Should we build on European, Chinese and American regional ‘cap-and-trade’ systems? Should we instead pursue a carbon tax? Or do you think the private sector will solve this on its own?”

Or there is the national security impact. The American military and intelligence establishment sees climate change as destabilizing, “raising the prospect of military intervention to deal with the effects of violent storms, drought, mass migration and pandemics” per the New York Times.

Of course, the Republican Party deems this issue the one where we shouldn’t listen to our military leadership. One senator said this year, “The Department of Defense should focus on continuing to do what it was created for — to protect the security of our country … It would be a terrible mistake to allow the debate over climate change to distract our military…”

Mr. Schieffer, you could ask the candidates if they agree with the military, or Washington Republicans, whether climate change poses a national security risk that must be addressed.

And there are thorny questions involving our relationship with China. Should we place tariffs on China so they will stop lowballing the price of solar panels and hurting domestic green energy jobs, as President Obama has done? Or should we be embracing cheap green energy wherever it comes from because solving the climate crisis is a higher priority?

Solving the climate crisis is one of the greatest challenges America faces, and it will incredibly difficult to do without a mandate from the public. For the issue to receive zero attention at any of the debates is simply an abdication of journalistic duty.

Yet despite my pessimism, there is one very good reason to believe that Mr. Schieffer will not shirk from this responsibility.

Because when he moderated the last presidential debate in 2008, he made sure to ask a question about climate.