Climate change: the 9 points of no return that endanger humanity

The authors of the article in the journal Nature affirm that "there is enough scientific evidence to declare a state of planetary emergency".

Climate change: the 9 points of no return 2019.
Climate change: the 9 points of no return 2019.

The IPCC pointed out that these points of no return could be reached if the temperature of the planet increased five degrees in relation to pre-industrial levels (year 1780).

The risk of irreversible and cascading changes due to climate change is greater than previously thought, according to an article recently published in the journal Nature.

Climate change 2019.
Climate change 2019.

Two decades ago, the Intergovernmental Panel on Climate Change (IPCC) warned of critical points or "points of no return" that could be devastating.

These tipping points, such as the destruction of the Amazon or the loss of ice in Greenland, are thresholds that once crossed would trigger irreversible changes, with a destructive dynamic of their own that can no longer be stopped.

They are also interconnected phenomena, so that one of them can generate a cascade of events that follow one another like dominoes.

But the new article, written by seven experts on the interactions of the climate system, warns about a much closer danger.

Climate change: points of no return

Not only do scientists say that nine of the points of no return identified by the IPCC can be passed with only a temperature increase of between 1 and 2 degrees Celsius. They also point out that these nine critical points are already "active".

"It's not just that human pressures continue to increase at an unprecedented rate," said Johan Rockstrom, director of the German-based Potsdam Institute on Climate Impact and one of the authors of the article.

"The other factor is that as science advances, we must admit that we have underestimated the risks of unleashing irreversible changes with which the planet amplifies global warming.

"Although the Earth's temperatures have fluctuated for millions of years, humans are forcing the system with the concentration of carbon dioxide and temperature increases not seen since the end of the last ice age," the article adds.

Tim Lenton, director of the Institute of Global Systems at Exeter University in England and lead author of the article, said that "the growing threat of rapid and irreversible changes means that it is irresponsible to take a 'wait and see' attitude. The situation is urgent and we need an emergency response.

What are the 9 Climate change active points of no return?

The nine critical points or risk zones are considered active because they are showing evidence of change, in many cases accelerated, in the wrong direction.

The list includes: Arctic sea ice, permanently frozen permafrost, the Atlantic current circulation system, the Amazon rainforest, warm water corals, ice in western Antarctica and parts of eastern Antarctica.

As for the Amazon, the authors point out that deforestation and climate change are destabilizing the forest, the largest on the planet that is home to one of every 10 species.

Climate change amazon 2019.
Climate change amazon 2019.

"Estimates of where the point of no return is vary from 40% to 20% of forest destruction. Seventeen percent of the Amazon rain forest has already been lost since 1970," the article states.

"Forest loss is accelerating, both due to human-induced deforestation and to droughts and fires. And this is sending the Amazon to a point of no return where forests that recycle their own rain can no longer sustain themselves.

The Arctic, on the other hand, is warming twice as fast as the planet's average.

And permafrost in the Arctic has already begun to melt irreversibly and release CO2 and methane, a gas that is about 30 times more potent than CO2 over a 100-year period.

On Antarctica, the authors state that the bay of the Amundsen Sea, in the west of the continent, could have already crossed the tipping point where "the place where the ice, the ocean and the rock meet is irreversibly retreating".

Climate change ice 2019.
Climate change ice 2019.

The article points out that, according to a computer model, if the ice sheet collapses completely, it could destabilize the rest of western Antarctica like a domino.

If western Antarctica, part of the ice sheet in the east of the continent, and the ice in Greenland collapses, we will be forcing future generations "to live with a 10-meter rise in sea level for thousands of years.

Climate change, an existential threat.

On Thursday the European Parliament declared a "climate emergency" in the European Union, making it the first continent to do so, just a few days before the start of next week's annual COP25 climate change summit in Madrid.

The authors of the article in Nature magazine urge even more action.

"There is enough scientific evidence to declare a planetary state of emergency," say the scientists.

Lenton and his colleagues point out that it is unlikely that dependence on fossil fuels can be eliminated before 2050, and say the Earth could exceed 1.5 degrees of temperature increase, the limit considered safest by the IPPC, by 2040.

Even if countries met their commitments under the Paris Accord, there would be a three-degree increase.

Scientists admit that tipping points are complex and difficult to predict, but argue that "the fact that cascades of critical points may occur and a global tipping point cannot be ruled out means that we are facing an existential threat to our civilization.

The Climate change controversy

If we come to a situation of cascades of points of no return, "no cost-benefit analysis is going to help us. We have to change how we deal with the climate problem," the authors say.

"We could already have crossed the threshold for a cascade of interrelated tipping points. But the rate at which they progress, and the risk they pose, can be reduced if we cut our emissions.

Not all scientists agree with the article.

Mike Hulme, from the Department of Geography at Cambridge University. He explained " the authors' position is speculative, and there is no new data presented in the article.

Lenton replied to the criticisms: "We are highlighting the risks and evidence of irreversible events, this always carries some uncertainty but is based on science. It's not speculation but risk assessment.

"On the other hand, the article is not intended to be new evidence, but is a commentary summarizing the last decade of evidence on points of no return.

For his part, Richard Betts, of the UK Meteorological Office, stated that "even if we cross a point of no return, or if we have already done so, which may or may not be the case, we have an opportunity to limit the damage.

"Even if a point of no return is already active in areas of ice, we can do a lot to limit the speed of sea level rise.

Climate change: the 9 points of no return that endanger humanity article was published in Nature magazine.