As they survey the charred wreckage of the world economy, some global leaders appear to believe they've found a shortcut back to business as usual. On the 10th of March, China announced it was "adjusting" its environmental rules to aid its post-coronavirus recovery. In the US, the Trump administration has decided to suspend environmental laws indefinitely – and as the country opens back up, they're reportedly planning further regulatory bonfires in a bid to boost growth.
Governments everywhere like to claim that they're being guided by "the science" when it comes to their coronavirus response. Yet the science suggests that, far from aiding economic recovery, the slashing and burning of environmental regulations is likely to make things worse. There's no proof of a direct link between global warming and the current outbreak, but according to a slew of recently-published papers, the climate crisis makes similar pandemics far more likely in the future.
Professor Arturo Casadevall is chair of the department of molecular microbiology and immunology at John Hopkins University, the Baltimore institution that's been spearheading global efforts to monitor the spread of coronavirus. He's currently working flat-out on a project that uses blood plasma from people who've recovered from the virus to treat COVID-19. Back in January, he published an article in the Journal of Clinical Investigation, warning of the ways in which climate change will make outbreaks of new infectious diseases more likely.
It's long been known that changes in atmospheric temperature can affect the range of disease-carrying "vectors", such as mosquitos, Dr Casadevall explains, allowing them to thrive in areas where the cold might once have killed them. But less attention has been paid to the evolution of pathogens themselves. "There is concern that global warming will select for microbes with higher heat tolerance," he writes. This would allow new diseases to emerge that can beat our "endothermic defences" and infect warm-blooded human bodies more easily.
"You have the viruses of, let's say, a lizard," he tells me over a Zoom call from Maryland. "Lizards are cold-blooded. Their temperature is different in different environments. If lizards get used to living in a warmer world, the viruses will have to adapt to a warmer host, and when that happens, our high temperature will not protect us."
Professor Casadevall says that although it's unlikely a virus could ever jump directly from a lizard to a human host, there is ever-increasing danger that viruses from other species will. "We know that viruses can jump from animals to humans," he says. "Just look what's happened with coronavirus."
Dr Christine Kreuder Johnson – a Professor of Epidemiology in the school of Veterinary Medicine at the University of California, Davis – has spent years looking at the underlying causes of these so-called "host shift" events. In early April she published a research paper examining the factors that increase the risk of "virus spillover" from mammals to humans. Unsurprisingly, given the source of the current outbreak, it's generated a lot of media attention.
The study revealed that bats and primates are the most dangerous mammals when it comes to passing on "high-consequence pathogens" to humans. "Some species just shouldn't be hunted," she tells me. Her main finding, however, was that certain human activities – namely hunting, the trading of live wild animals and the conversion of "wild" landscapes for agricultural use – dramatically increase the risk of new disease transmission.
Underlying all of this, she says, is the climate crisis: "Climate change puts additional pressure on people for food security, and I think that oftentimes results in people resorting to what's called bushmeat – which is hunting." Food insecurity can also cause farmers to push further into biodiverse areas, destroying wildlife habitats. This in turn drives mammals to move around and swap germs in ways they might not have done otherwise.
A colony of bats, for example, might "move to a mango tree next to a pig farm, or just to a new location where the bats haven't seen their diseases before", says Professor Johnson. "That creates epidemics, and it's at the peak of these epidemics, usually, that the probability is highest for spillover [between species]."
The idea that the warming world makes viruses more likely to jump between hosts is backed up by other studies. In 2018, a team from the University of Exeter found that hotter temperatures themselves make host shifts between "susceptible species" more likely.
There's another, even more alarming way in which the climate crisis might expose humans to new viral infections. In 2014, a team of French scientists led by Dr Jean-Michel Claverie found a "new" virus, completely unknown to human science, in a 32,000-year-old sample of Siberian permafrost. It had been perfectly preserved, and when it was exposed to a suitable host it re-activated, rapidly becoming infectious again.
"Siberian permafrost is the optimum medium for conservation," Professor Claverie says. "It is dark, there is no oxygen, it's pH neutral, and it's cold, of course. If you put a yoghurt in the Siberian permafrost and came back 30 years later, it would still be good to eat, I think."
So far, Jean-Michel Claverie and his colleagues have only reactivated pathogens that infect amoebas. "Of course, we are not crazy enough to try to revive viruses of human diseases from the past," he says. But he believes that they may well be out there. "There is no reason viruses affecting plants, animals or humans couldn't also survive. And I will say, if it's alive, the only thing a virus needs to restart its life – and business as usual – is to encounter its host."
The idea of a long-dead disease emerging from the permafrost and infecting people might sound like something out of a Stephen King novel. But in 2016, a 12-year-old boy was killed by an outbreak of anthrax poisoning in Siberia. The source was believed to be a reindeer carcass that had melted out of the permafrost, contaminating the water supply. Although anthrax, a bacteria, is known to science, there's every chance that other pathogens preserved in the permafrost would be ones we've never encountered, for which we have no immunity.
The thawing of the Arctic tundra presents less direct, but perhaps more dangerous, risks too. "Climate change has allowed industrial exploitation to start in these regions," says Professor Claverie. "It's especially dangerous because the technology is not very sophisticated. There are a lot of open cast mines. They dig out a diameter of one or two kilometres, about 500 metres deep, and all at once you are moving things that have not been moved for a couple of hundred-thousand years."
Set against these scientific studies, the idea that we should put the fight against the climate crisis on hold in the name of short-term economic recovery looks, at best, self-defeating. As well as the floods, the wildfires, the hurricanes, the droughts and the crop failures, it appears we can now add plagues to the list of Biblical evils exacerbated by climate change.
Of course, that won't stop lobbyists' voices growing louder as the crisis drags on. The CEOs of those poor, set-upon oil companies who've had to cut shareholder dividends; the airline bosses who've been forced to cancel plane orders; the mining executives who've had to scale down coal production – all will begin clamouring for the lifting of "onerous" environmental regulations so they can speed up their return to profitability, regardless of the cost to the planet.
If governments were really listening to scientists like Dr Casadevall or Professor Johnson, they’d be strengthening environmental protections, not weakening them. "We need to take a more holistic approach," says Dr Casadevall. "Our health, the climate, we need to realise that everything on this planet is interconnected. We need to give more thought to how small changes can have an enormous effect.
"Just look at what's happened to our world from an event that's almost certainly unintentional, from somebody getting infected by an animal. The tremendous disruption that's had on people's lives, the people it's killed, the damage it's done to our society. It's a big warning."