This month, we learned that the melting of permafrost in Arctic regions is giving a new lease of life to hitherto unknown viruses. These have been buried in the ice for thousands of years but rising global temperatures are now thawing some of them out. As the melting continues, who knows what dangerous pathogens might be released?
The response from virologists was generally along the lines of: “Don’t panic.” That’s not quite the right reaction. There is something to worry about here.
The big discovery was the pithovirus, now confirmed as the world’s largest virus. It was last active 30,000 years ago and the French team that reactivated it managed to get the virus to infect amoebae. The researchers claim to have ruled out the possibility of human beings becoming infected with pithovirus but there are reasons to be sceptical.
A few years ago, the same French biologists said they were confident that a previous virus discovery, the mimivirus, could not infect people. But it also infected amoebae – and blood samples taken from one of their lab technicians, who had come down with mild pneumonia, were found to contain mimivirus antibodies. In other words, it seems they were wrong. Just because the researchers haven’t managed to infect human cells with the new virus, that doesn’t mean it couldn’t happen.
However, that’s not what we should be worried about. Neither should we be too concerned that the receding permafrost could bring us into contact with other potentially dangerous viruses. It is possible that the tundra contains deep-frozen organisms that could be harmful to people; plans to drill for oil and gas in those regions could create new threats. Yet you could say the same of exploring the oceans. Every litre of seawater contains roughly ten billion microbes and 100 billion viruses. Most are not in our catalogues.
It is even possible that this is a good thing. We are learning how to harness the peculiar abilities of viruses to deliver gene therapy and even fight cancer. Something called a reovirus, for instance, is being tested against tumours; it attacks cancerous cells but leaves normal cells untouched.
Other viruses are proving effective at smuggling healthy human DNA into diseased organs, enabling us to cure some cases of partial blindness, for example. Having a new set of viruses to play with might prove useful.
What we should be concerned about is far more straightforward. The threat from a newly released virus is nothing compared to the threat from newly released molecules of methane. Atmospheric methane accelerates warming about 25 times faster than carbon dioxide. There is roughly 400 billion tonnes of methane trapped in permafrost. As global temperatures rise, the ground melts and the gas is released.
There have been very few studies into the risks posed by melting permafrost (pdf). Last summer, however, a team of economists and polar science researchers warned that it is an “economic time bomb”. If there is a sudden release of methane – and no one knows if it will be a slow leak or an enormous belch – the effects will include flooding, extreme weather events and, consequently, a huge downturn in agricultural production. Researchers estimate that the economic impact of the tundra melting could be as much as $60trn.
Resurrected monster viruses make great headlines but the creep of unmitigated climate change is far more likely to do the serious damage.