Current climate path will lead to collapse of life on Earth, say climate scientists

The state of peril facing the Earth is so serious that on current trends life the Earth will soon be incapable of supporting human life, according to two climate scientists speaking at the inaugural Innovation Zero Congress in London.

Professors Johan Rockstrom, director of the Potsdam Institute for Climate Impact Research, and Sir David King, founder and chair at Cambridge’s Centre for Climate Repair, said that failing to limit the global temperature to 1.5C above pre-industrial levels is likely to trigger tipping points, destroying rainforests and marine life while making vast areas around the tropics uninhabitable for human life.

Opening the Innovation Zero Congress in London, Prof Rockstrom and Prof Sir David King, put the current trends into the starkest imaginable perspective.

The Intergovernmental Panel on Climate Change (IPCC) has said that the Earth has already warmed by 1.2C, with the World Meteorological Organisation warning there is a two-thirds chance of scientists recording a 1.5C temperature sometime in the next five years – though some assessments say it could happen later this year.

Prof Rockstrom told delegates at the inaugural two-day conference in London: “1.5C is not a target. I call it a physical limit.

“There’s one conclusion without any uncertainty whatsoever, and that is that 2.5C global mean surface temperature rise is a disaster. It’s something that humanity has absolutely no evidence that we can cope with. It would actually exceed the warmest temperature on Earth over the past four million years.

“Push ourselves to 2.5C – we’re in unknown terrain. It would lead to a complete melting of the big ice sheets, which would be a 10 metre sea level rise.

“There would be a collapse of all the big biomes on planet Earth – the rainforest, many of the temperate forests – abrupt thawing of permafrost, we will have complete collapse of marine biology, we will have a shift of large parts of the habitability on Earth.

“Over one-third of the planet around the equatorial regions will be uninhabitable because you will pass the threshold of health, which is around 30C. It’s only in some parts of the Sahara Desert today that has that kind of average temperature.

“So in summary, it’s a place we do not want to go to. The problem is, we’re following that path today.”

He added that how the Earth’s natural systems behave after 1.5C is unknown and that it will likely trigger five tipping points which would see the Earth heat uncontrollably towards disaster. Three of these tipping points are in the Arctic, which is heating up four to five times faster than the rest of the Earth, Prof King said.

The five tipping points identified are: melting of the West Antarctic and Greenland ice sheets, melting of permafrost in the far north, mass die-off of tropic coral reefs and melting sea ice in the Bering Sea.

Prof Rockstrom said: “The big fear that we have in science is when you cause tipping points, when the system goes from self-cooling to self-warming.

“Today we’re the ones causing the warming but the nightmare is of course, the moment the planet itself starts causing the warming and that’s what we under all circumstances have to avoid.”

Asked if he had a magic wand to summon whatever change he would like to see, Prof King said he wished the Earth’s natural systems were treated as importantly as human ones and that we learn to remove greenhouse gases from the atmosphere at scale, while refreezing the polar regions and Himalayas.

He added: “That 1.5C target is a must. If we don’t stay below that, frankly, the talk about going up to 2C then bringing the temperature down by removing greenhouse gases, that is not good enough. Too many people will die in that period when we allow the temperatures to go up.”

The IPCC states that current climate policies will leave the Earth between 2.5C and 2.7C hotter by 2100 compared with pre-industrial levels UN member states pledged in the Paris Agreement in 2015 to limit temperature rise to below 2C and to strive for 1.5C. At the time, the 1.5C goal seemed achievable – but now appears to be hopelessly unrealistic.