Failure to meet the Paris Agreement target of limiting global warming to 1.5°C could trigger several dangerous “tipping points” where changes in climate systems become self-sustaining, according to a major new study published in Science.

Even current rates of warming have already put the world at risk of five major turning points – including the collapse of the Antarctic and Greenland ice sheets – but it’s not too late to change course, the authors point out.

“The way I think about it, it will change the face of the world – literally if you look at it from space,” given long-term sea-level rise, rainforest dieback and more, senior author Tim Lenton of the University of Exeter told AFP.

Lenton authored the first major study of tipping points in 2008.

These points are defined as the amplifying feedback in a climate system so strong that it is self-propelling at a certain threshold—that is, even if warming stopped, an ice sheet, ocean, or rainforest would always transition to a new state .

While early estimates said these would be in the range of 3-5°C warming, advances in climate observations, modeling, and paleoclimate reconstructions of warming periods in the distant past have found the thresholds to be much lower.

The new paper synthesizes more than 200 studies to produce new estimates of when common turning points might occur.

It identifies nine global “core” tipping points that contribute significantly to the functioning of the planetary system and seven regional tipping points that contribute significantly to the well-being of humanity, for a total of 16.

Five of the 16 can be triggered at today’s temperatures: the collapse of the Greenland and West Antarctic ice sheets; widespread abrupt thawing of permafrost; convection collapse in the Labrador Sea; and massive die-offs of tropical coral reefs.

Four of these move from “possible” events to “probable” events at 1.5°C global warming, with five more becoming possible around that level of warming.

Passing the tipping points for the Greenland and West Antarctic ice sheets is “a commitment to an additional 10 meters of global sea level,” Lenton said, although that particular change may take hundreds of years.

Coral reefs are already dying from warming-induced bleaching, but can partially recover at current temperatures.

At a certain level of warming, recovery would be impossible, devastating equatorial coral reefs and the 500 million people worldwide who depend on them.

Labrador Sea convection is responsible for warming Europe, and changes could result in much harsher winters, comparable to the “Little Ice Age” of the early 14th century to the mid-19th century.

Abrupt thawing of permafrost – affecting Russia, Scandinavia and Canada – would further amplify carbon emissions in addition to drastic landscape changes.

Systems that could come into play at around 1.5°C also include the Atlantic Meridional Overturning Circulation, which is closely linked to sea level on the US East Coast.

From 2°C, monsoon rains could be seriously disrupted in West Africa and the Sahel, and the Amazon rainforest could face widespread ‘dieback’ and turn into savannah.

First author David Armstrong McKay stressed that even if the planet did reach 1.5C of warming, much would depend on how long it stays there, with the worst effects occurring if the temperature stayed that way for five or six decades stay hot.

Next: “These inflection points, which occur at 1.5 degrees, don’t add a huge amount of global warming as a feedback — and that’s pretty important because it means we’re not in a runaway train situation at 1.5 degrees condition.”

That means humanity can still control further warming, and it “still pays to reduce emissions as soon as possible,” he added.

Lenton said what gave him hope is the idea that human society might have its own “positive” turning points, where years of incremental change are followed by urgent, widespread action.

“This is how I get out of bed in the morning… Can we change ourselves and our way of life?” he said.