Here’s a remarkable thing. Neither Mitt Romney nor Barack Obama – with the exception of one throwaway line each – have mentioned climate change in the wake of hurricane Sandy.

They are struck dumb. During a Romney rally in Virginia on Thursday, a protester held up a banner and shouted “What about climate? That’s what caused this monster storm”. The candidate stood grinning and nodding as the crowd drowned out the heckler by chanting “USA! USA!”. Romney paused, then resumed his speech as if nothing had happened. The poster the man held up? It said “End climate silence”.

While other Democrats expound the urgent need to act, the man they support will not take up the call. Barack Obama, responding to his endorsement by the mayor of New York, mentioned climate change last week as “a threat to our children’s future”. Otherwise, I have been able to find nothing; nor have the many people I have asked on Twitter. Something has gone horribly wrong.

There are several ways in which the impact of hurricane Sandy is likely to have been exacerbated by climate breakdown. Warmer oceans make hurricanes more likely and more severe. A warmer atmosphere holds more moisture, increasing the maximum rainfall. Higher sea levels aggravate storm surges. Sandy might not have hit the United States at all, had it not been for a blocking ridge of high pressure over Greenland, which diverted the storm westwards. The blocking high – rare there at this time of year – could be the result of the record ice melt in the Arctic this autumn.

This might sound like the wisdom of hindsight. But in February the journal Nature Climate Change published an article warning that global warming is likely to “increase the surge risk for New York City”. As storms intensify and the sea level rises, it predicted that storm surges previously described as 100-year events would become between five and 30 times as frequent.

Four years ago, Obama pledged that “my presidency will mark a new chapter in America’s leadership on climate change”. He promised a federal cap and trade system and “strong annual targets” to reduce carbon pollution. But he ran into a ridge of high pressure. His cap and trade bill was killed in the Senate in 2010.

At a meeting in the White House in 2009, his strategists decided that climate change was a banned topic: it caused too much trouble. From then onwards, Obama would talk about clean energy and green jobs and improvements in fuel economy, but would seldom explain why these shifts were necessary. The problem with this approach is that you cannot engineer a sustained reduction of greenhouse gas emissions only by getting into clean energy: you also have to get out of dirty energy. And that requires statesmanship: active and persuasive engagement with the public.

In April, Obama said that global warming “will become part of the campaign” and that he would be “very clear” about how he would deal with it. It hasn’t happened. There were a couple of noncommittal paragraphs in his speech to the national convention, during which he also boasted that “we’ve opened millions of new acres for oil and gas exploration in the last three years, and we’ll open more.” There was more of the same in the Democratic platform (the party’s manifesto). Otherwise, this remains the issue that dare not speak its name. For the first time since 1988, climate change wasn’t mentioned in any of the presidential debates.

This, remember, is after a year of climate disasters: the droughts and wildfires that devastated much of the continental interior of the United States, the Arctic meltdown, the superstorm that ripped through the Caribbean before piercing the financial and spiritual heart of the nation. You wonder what it takes.

As for Romney, his contribution has been confined to mockery. Even as hurricane Isaac cut short the Republican national convention, he ridiculed Obama, to the delight of the delegates, for wanting to stop the sea level from rising. It was a revolting spectacle, which, in the aftermath of Sandy, would have become a major liability, had climate change not been taboo.

In the Republican party platform, “climate change” – yes, in quotes – is mentioned only once, to attack Obama for taking it seriously. The platform commits the party to blocking all effective measures to curb it, and to developing new coal (which Romney now professes to “love”), the Keystone XL tar sands pipeline and oil drilling on the outer continental shelf and in the Arctic National Wildlife Refuge. Planetary ruin, for the Republicans, seems no longer to be an unfortunate side-effect of development: now it looks almost like a desirable end in itself; a test of manhood and corporate muscle.

Successive polls show that an effective response to climate breakdown will not lose votes. Votes are not the problem: the problem is money and traction. Anyone who tries to address this subject encounters a storm surge of attack ads, obstruction and manufactured fury.

During the crucial year – 2009 – in which the cap and trade bill was struggling through Congress and governments were preparing for the summit in Copenhagen, environmental groups threw everything they had at climate change. After massive fundraising efforts, a coalition of green NGOs managed to find $22m for federal lobbying. But Exxon alone outspent them with a casual flick of the wallet. The $27m it dropped into the counter-campaign represented half of a day’s profits. The other fossil fuel companies threw in a further $150m. Without a major reform of both lobbying and campaign finance, the big money will keep winning. Protecting the planet and its people is impossible in a plutocracy.

The Republicans in Congress have no choice but to keep obstructing or filibustering every means of addressing our foremost global crisis, for to alter their position would be to jeopardise their political funding. As David Roberts of grist.org points out, Obama has little incentive to talk about climate change when he knows that any promise he makes will be thwarted. All he can do is to “fight for gridlock because gridlock is better than the alternative”.

So the two candidates remain struck dumb. Speech fails them, action is abominable, they will not even raise their hands in self-defence. The world’s most pressing crisis, now breaking down the doors of the world’s most powerful nation, cannot be discussed.

• Read a fully referenced version of this article at www.monbiot.com