Scientists say we’re seeing how global warming will drive forest ecosystems beyond a point of no return as devastating wildfires spread through large swaths of Australia.
Under today’s warmer climate some of those forests won’t recover, scientists say. They expect the same in other regions that have been scarred by flames in recent years; some post-fire forest landscapes will shift to brush or grassland in semi-arid areas like parts of the American West, the Mediterranean Basin and Australia.
Over the last three months, more than 17 million acres have been burning in Australia despite record heat that has dried up vegetation and stripped moisture from the ground. Hundreds of millions of animals are thought to have died in the infernos, including a large number of koalas. The survivors face drastically altered habitats. Water flows and vegetation will change, and carbon emissions will rise as burning trees release carbon, leaving fewer living trees to extract and store CO2 out of the air.
It’s a tipping point in many ways, as habitats turn from one kind into another.
Over the past few years, the emergence of massive, devastating forest fires from the Arctic to the tropics has surprised even researchers who have been focusing on forests and fires for years and warning of such tipping points.
The predictions were seen as distant, “something that would happen farther in the future,” said David Breashers, a climate scientist at the University of Arizona. “But it’s happening now. Nobody saw it coming this early, even though it was like a freight train.” The trees certainly won’t return as we know them.
The link between global warming, forests and wildfires is complex but very obvious, said Nerilie Abram, a climate researcher at Australian National University.
“Rising temperatures are drying fuel out and contributing to more days of extreme fire conditions,” she said. “The poleward movement of the western winds of the Southern Hemisphere draws winter rainfall away from southern Australia, triggering a long-term drying pattern that makes the landscape more susceptible to burning.” The process feeds itself, she explained: forest drought and loss cause higher temperatures across the land and lower humidity, which in turn worsens wildfire conditions.
“Each degree of warming has a greater effect on forest fire than the previous degree of warming,” wrote on Twitter the lead author of that report, Park Williams of Lamont-Doherty Earth Observatory at Columbia University when the study was published.
The time for humanity to act is now. Before it’s far too late.