As Milton barrelled towards the coast on Thursday, Trump repeated the lies at a rally in Pennsylvania and his running mate JD Vance echoed them in Arizona.

According to FEMA, the lies were having a material impact. On Tuesday, the agency’s chief, Deanne Criswell, said disinformation was dissuading needy people from seeking help and it was also buffeting the morale of emergency workers.

“It is absolutely the worst I have ever seen,” Criswell told reporters during a press briefing. “It’s creating distrust in the federal government, but also the state government, and we have so many first responders that have been working to go out and help these communities.”

Indeed, even as FEMA struggled to address the compounding storm crises, it was forced to dedicate resources to countering misinformation, establishing a fact-checking web page.

A typical entry read:

• Myth: If survivors apply for assistance, FEMA may confiscate their property or land.
• Fact: Applying for disaster assistance does not grant FEMA or the federal government authority or ownership of your property or land

Soon threats of violence against FEMA staff and even meteorologists began appearing alongside the conspiracy theories.

The White House pushed back. “Over the last few weeks, there’s been reckless and irresponsible and relentless promotion of disinformation and outright lies about what’s going on,” President Joe Biden said. “It’s undermining confidence in the people in Florida and the incredible rescue and recovery work that has been undertaken.”

Eventually, even elected Republicans in the disaster zone began calling for restraint.

Chuck Edwards, a Republican member of Congress from North Carolina, issued a long statement to rebuff the falsehoods. “Hurricane Helene was NOT geoengineered by the government to seize and access lithium deposits in Chimney Rock,” began the first point.

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Florida Governor Ron DeSantis, no friend of climate scientists, weighed in. His press secretary issued a statement urging residents in evacuation areas to ignore reports that FEMA was hiring private security firms to help them seize the homes of evacuees.

“Spreading LIES like this could have serious consequences. If people in an evacuation zone see this and decide NOT to evacuate, despite warnings from state & local emergency management, they are unnecessarily putting their own lives (& lives of first responders) at grave risk,” she posted.

The Institute for Strategic Dialogue, a London-based anti-extremist non-government organisation issued a report on Wednesday saying its analysis showed FEMA and government workers had been subjected to a wave mis- and disinformation, including antisemitic hate and threats, in the wake of Helene.

“The situation exemplifies a wider trend: increasingly, a broad collection of conspiracy groups, extremist movements, political and commercial interests, and at times hostile states, coalesce around crises to further their agendas through online falsehoods, division and hate,” it said. “They exploit social media moderation failures, gaming their algorithmic systems, and often produce dangerous real-world effects.”

On October 7 and 8, Musk’s site X spread 33 posts containing debunked claims, 30 per cent of which contained “overt antisemitic hate”. They have been viewed 60 million times.

“There is clear crossover between networks primarily engaged in climate denialism and delayism (as covered in prior ISD research), and other extremist groups, conspiracy movements, and spreaders of hate speech online,” it said.

Imran Ahmed, chief executive of the Centre for Countering Digital Hate, another NGO, with offices in London and Washington, DC, said that as the incidence of extreme weather events increased public acceptance of climate science, climate deniers were becoming more aggressive in pushing false material online. “They are making up rumours that this is not caused by carbon dioxide, but that they are ‘government-engineered weather events’,” he said.

“Then there is a political strand seeking to undermine the government, saying that the government is not doing enough to deal with this.

“There are cynical politicians who are exploiting those narratives right now to try and eke out some electoral gain in the upcoming US elections. And then you’ve just got the normal sort of, like the background murmur, which you always get on social media.”

He said that as desperate people in disaster zones were turning to social media for crucial information, they were “being preyed on by a series of bad actors and algorithms that promote disinformation over good information because it gets high engagement”.

He said Musk had become a “superspreader” of misinformation since purchasing X, and that he had both a financial interest in increasing engagement on the platform, and a political interest in undermining the US administration since he had endorsed Trump’s bid for a return to the White House.

“That’s led him to try to undermine [Vice President Kamala] Harris with increasingly unhinged conspiracy theories and lies,” said Ahmed.

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A recent report by the centre said tweets by Musk containing false or misleading information about the election had been viewed 1.2 billion times.

Ahmed said social media users and proprietors alike had a financial interest in spreading lies during events like this, and that autocrats were thriving as the fact-base democracies depend upon was being undermined.

“This is a systematic problem. The lack of guardrails, the algorithmic amplification of disinformation, and the monetisation of disinformation creates a market for it.

“It is a career choice for some people: produce bullshit, make bank.”

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