It is a scenario climate scientists have feared since first identifying “tipping points” – delicate thresholds where a slight rise in the Earth’s temperature can cause a dramatic change in the environment that itself triggers a far greater increase in global temperatures.
“When you start messing around with these natural systems, you can end up in situations where it’s unstoppable. There are no brakes you can apply,” said David Viner, a senior scientist at the Climatic Research Unit at the University of East Anglia.
“This is a big deal because you can’t put the permafrost back once it’s gone. The causal effect is human activity and it will ramp up temperatures even more than our emissions are doing.”
But calculations by Dr Sitch and his colleagues show that even if methane seeped from the permafrost over the next 100 years, it would add around 700m tonnes of carbon into the atmosphere each year, roughly the same amount that is released annually from the world’s wetlands and agriculture.
It would effectively double atmospheric levels of the gas, leading to a 10% to 25% increase in global warming, he said.
“If we don’t take action very soon, we could unleash runaway global warming that will be beyond our control and it will lead to social, economic and environmental devastation worldwide,” he said. “There’s still time to take action, but not much.
“The assumption has been that we wouldn’t see these kinds of changes until the world is a little warmer, but this suggests we’re running out of time.”
[Excerpts from the linked article]