We are familiar with Donald Trump’s stance on climate change: it’s a “con job” perpetrated by the Chinese. His views on energy policy are strongly pro-coal, but also contradict themselves. The Republican Party’s 2016 platform also describes coal as a “clean” source of energy.

But the Democratic platform might not be meaningfully better. Although Hillary Clinton has a climate change plan, and it is supportive of President Obama’s Clean Power Plan (which is held up in the courts), and makes broad promises to cut subsidies for the oil and gas industry, it leaves out one big thing: a carbon tax.

Under Obama, America has now made promises to have half of its electricity come from carbon-free sources by 2025—an almost unthinkable goal, even though emissions have ebbed in the last few years. The Clean Power Plan would help, if it is ever implemented: the EPA estimates the plan could cut carbon emissions from the energy sector to 32 percent below 2005 levels by 2030. But it makes almost no attempt to tell states how to cut their emissions, only that they must.

Among the many possible methods states might employ is putting a price on carbon. This can take various forms, such as a cap-and-trade scheme or a straight-up fee for each ton of carbon a power plant emits. Using market forces to reduce pollution from the energy industry works: it has happened before. In fact, it’s the only thing that’s likely to spur the kind of change Obama has promised, and that is needed to curtail global warming. But anything that could be labeled a “tax” is a political third rail.

Until this week, Bernie Sanders was the only presidential candidate who espoused a carbon tax. Now that he has ceded the field to Clinton, the idea is unlikely to come anywhere near conversation for the rest of the 2016 election cycle. And, unfortunately, neither is meaningful action on climate change.

(Read more: Washington Post,"Dear Mr. President: Time to Deal with Climate Change," “Obama’s Ambitious Clean-Energy Goal Will Depend on Nuclear—and the Next President,” “Donald Trump’s “America-First Energy Plan” Shows He Knows Virtually Nothing About the Issue”)