Instead of an existential crisis for species worldwide, or threatening to submerge entire Pacific nations and coastal cities where hundreds of millions of people live, or a phenomenon driving unprecedented heatwaves and wildfires, the climate crisis was characterised somewhat differently on the major US cable show Real Time with Bill Maher.
Climate change was “a problem”, the Danish political scientist Bjorn Lomborg told the comedian, but would only shave a few percentage points off global GDP by the end of the century and in any case, he said, by then people would be much richer anyway.
Was climate change a problem for the Great Barrier Reef? Lomborg pushed that aside too, saying pollution or overfishing were the reef’s real challenges. (They’re not.)
Great Barrier Reef suffering ‘most severe’ coral bleaching on record – video
While these are not new statements from Lomborg, longtime contrarian of the risks of the climate crisis, the audience’s applause suggested they went down well.
But what’s missing from his soundbites?
Three degrees
About 700,000 people watch Maher’s show on HBO each week.
A clip of Lomborg’s appearance on YouTube, shared by the conservative commentator Dave Rubin, has been viewed more than 1.7m times (Rubin incorrectly described Lomborg as a climatologist – he is actually a political scientist and a director of a thinktank).
In the clip, Lomborg said two climate economists, including the Nobel-winner William Nordhaus, had come to similar conclusions this year: that if the planet warmed by 3C by the end of the century, the effect on global GDP would be just two or three percentage points.
Nordhaus and others use what are known as Integrated Assessment Models. Peter Howard, a leading climate economist at New York University who researches IAMs, says “the devil is really in the details”.
Howard says the models don’t account for some effects, including so-called “tipping points”, and have large uncertainties associated with them.
“Some well-respected economists question if we can even accurately estimate climate damage,” he said in an email, pointing to one commentary branding IAMs as “close to useless”.
He said Lomborg’s framing as presented in the clip was “incorrect and misleading” because it “ignores significant potential risks of climate change due to uncertainty in the physical and social sciences”.
Given that Lomborg cites Nordhaus, it is worth asking what the Yale University professor thinks about the climate emergency.
In an article published in 2019, the year after he won the Nobel, Nordhaus wrote that global heating “menaces our planet and looms over our future like a Colossus” and was “a major threat to humans and the natural world”.
‘A different perspective’
This year Nordhaus released results from an update to his model.
He wrote that the “most important single economic concept in the economics of climate change is the social cost of carbon” – the amount that each tonne of CO2 costs the economy now, and in the future.
Howard said the SCC calculations from Nordhaus’s modelling could “give a different perspective” on the costs of emitting greenhouse gases than a reference to GDP.
For example, Howard said Nordhaus’s results suggested greenhouse gas emissions from 2020 would cause between US$4tn and US$5tn of damage over the course of their lifetime.
“It is unsurprising given these dollar totals that a standard finding in economics is that it makes economic sense to decrease greenhouse gas emissions in order to reduce these costs of climate change,” Howard added.
The Great Barrier Reef
Lomborg regaled Maher with data he said showed the amount of coral on the Great Barrier Reef “has been at the highest level” since records started in 1986, and had recovered from low levels seen five years ago.
He did not mention the reef had just been through probably its worst mass coral bleaching event on record.
The data cited by Lomborg was taken from underwater surveys carried out by the Australian Institute of Marine Science.
But the latest data from those surveys, Aims said this week, was “conducted before and during the recent mass bleaching event, one of the most serious and extensive on record”.
Mass coral bleaching is caused by rising ocean heat, driven mostly by the burning of fossil fuels.
Bleached coral was still counted as alive, Aims said, and “as such, the most recent coral cover result did not capture how many corals survived or died following the 2024 bleaching”.
The increase in coral cover over the reef has been driven by fast-growing corals that are the most susceptible to heat stress.
Aims said the high levels of coral cover was “due in part to a period between 2018 and 2022 that was relatively free of disturbance events that cause widespread coral mortality on the reef”.
The greatest threat to coral?
Lomborg claimed most of the challenge for the reef “comes from overfishing, from industrial pollution from sea runoff”, saying: “Those are the kinds of things that we should fix, but we’re not being well informed if we’re being told this is because of climate change.”
His view, that the climate crisis is not the biggest threat to coral reefs everywhere, is shared by almost nobody actually researching the issue.
Aims said: “Climate change remains the biggest threat by some margin. The challenge facing the Great Barrier Reef and coral reefs globally is existential because of climate change.”
Reefs not ‘doing better’
Maher asked Lomborg why coral reefs “are doing better in the last three years … it’s not like we did anything”.
“I don’t know,” Lomborg responded.
The Great Barrier Reef off Cairns in far north Queensland. Photograph: Max Shen/Getty Images
Perhaps the answer is that coral reefs are not “doing better” in the last three years.
Not mentioned by Lomborg or Maher was that the world’s coral reefs have just experienced the most widespread heat stress event on record, driven by record ocean temperatures around the world – with more than 70% hit by bleaching.
What would 3C actually mean?
In the clip, Lomborg didn’t talk about the risks of allowing the planet to warm by 3C. Considering global heating of just over 1C has likely pushed the planet to its hottest levels for at least 100,000 years, getting to 3C would push human civilisation well past anything it had experienced before.
Prof Mark Howden, director of the Institute for Climate, Energy & Disaster Solutions at the Australian National University, has been involved in several UN climate change assessments. He said at 3C, heat stress would be “many times worse” affecting human physical and mental health, increasing the risks of food insecurity and malnutrition, threatening many species with extinction, pushing up rainfall intensity and flood risk, and increasing sea levels that could result in the displacement of 400 million people.
“The world at 3C would be a poorer and riskier place, with inhabitants having diminished lives and livelihoods,” Howden said.
“The list could go on and on. More and more economic analyses show the net costs of climate change and associated impacts are far higher than the costs of reducing greenhouse gas emissions. In other words, the most rational and just pathway ahead is to reduce our emissions rapidly, substantially and persistently.”
Graham Readfearn is Guardian Australia’s environment and climate correspondent