The Earth’s climate is getting too close to a hot tipping point

livemint.com:

Between this summer’s biblical floods, apocalyptic fires and life-threatening heat domes, people are wondering whether we’ve lurched over a climate tipping point. Climate scientists and ecologists who study tipping points say that these are merely extreme events amplified by global warming. They’ve been warning about climate tipping points for years.

Now people are listening. Research published last year in Science suggests the risk of a global tipping point that triggers accelerated climate warming starts to become significant when average worldwide temperatures rise 1.5° Celsius above pre-industrial levels, which is likely to happen in the 2030s. In science, a tipping point refers to a straw-that-broke-the-camel’s-back phenomenon, where a small change in input makes a big difference in outcome.

When climate scientists talk about tipping points, they’re looking at a shift in feedback loops—the disruption of stabilizing feedback loops and the start of new ones that amplify change. Physicists call this a positive feedback loop, but from our standpoint it won’t be beneficial. Scientists have documented dozens of regional and local climate tipping points.

Long ago, the Earth experienced planet-wide tipping points when the climate whiplashed from an ice-free hot-house to a snowball and back again. Looking at its history for an Earth Day column a few years ago, I talked to scientists who marvelled at the habitability of Earth for nearly 4 billion years, thanks to stabilizing feedback loops. For most of that history, there was only bacteria.