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Global warming should be called global heating, says key scientist

The heatwave that hit the UK this summer was made 30 times more likely by human-caused climate change, according to the Met Office.

“Global heating” is a more accurate term than “global warming” to describe the changes taking place to the world’s climate, according to a key scientist at the UK Met Office.

Prof Richard Betts, who leads the climate research arm of Britain’s meteorological monitoring organisation, made the comments amid growing evidence that rising temperatures have passed the comfort zone and are now bringing increased threats to humanity.

“Global heating is technically more correct because we are talking about changes in the energy balance of the planet,” the scientist said at the UN climate summit in Katowice, Poland. “We should be talking about risk rather than uncertainty.”

Earlier this month, the Met Office produced a new report that showed the searing heatwave that hit the UK this summer – along with other parts of the northern hemisphere – was made 30 times more likely by human-caused climate change.

Betts said the shifting climate was pushing some natural processes – such as the blossoming of trees and laying of eggs – out of sync. “That’s already happening. We are also seeing higher temperatures of heatwaves. The kind of thing we saw this year will happen more often.

“The risks are compounding all the time. It stands to reason that the sooner we can take action, the quicker we can rein them in.”

His views were echoed by Hans Joachim Schellnhuber, a professor of theoretical physics and founder of the Potsdam Institute for Climate Impact Research in Germany. He said his recent Hothouse Earth report , which was one of the most widely quoted and downloaded studies of this year, had helped to change the language used to describe the climate crisis.

“Global warming doesn’t capture the scale of destruction. Speaking of hothouse Earth is legitimate,” he said.

The scientists expressed frustration at the slow pace of action by political leaders. In signing the 2015 Paris agreement, governments around the world aimed to keep global warming to within 1.5C to 2C above pre-industrial levels. But current commitments are far off track.

The Met Office upgraded its forecasts this week to show the planet is on track to warm by between 2.5C and 4.5C. “We have broadened out the range of possibilities,” said Betts, who is conducting a risk assessment based on the new projections. In the UK, he said the trend was towards wetter winters with more floods, hotter summers with more droughts interspersed with increasingly intense rain.

The Paris pact was a firewall, he said. “It’s not helping us to keep the world as it is now. We’ve lost this opportunity already. It’s a firewall against climate chaos.”

Johan Rockström, executive director of the Stockholm Resilience Centre, said “cracks” were starting to appear in the climate system that were pushing nature from being a friend that absorbs carbon dioxide to an enemy that releases carbon dioxide. These concerns are fuelled by the growing intensity of forest fires, the effect of melting ice-sheets on the jet stream, and the rising risk of permafrost thaw, which would release trapped methane.

Although he stressed it might not yet have passed a tipping point, he said the warnings were getting louder. “This shift from friend to foe is no doubt a scientific nightmare. That is the biggest worry that we have,” he said. “It does terrify me. The only reason we sit here without being completely depressed is that we see we have policy measures and technology to move in the right direction.

“We need to have a diagnosis just like a patient who comes to a doctor and gets a really bad diagnosis. But if the science is right, the technology is right, and the policy is right you can cure that very dire situation. There is no scientific suggestion that the door is shut.”

This week’s climate talks have crept forward with only small progress towards a new global rulebook, but emissions continue to rise and the planet continues to heat.

“Things are obviously proceeding very slowly,” said Betts. “As a scientist, it’s frustrating to see we’re still at the point when temperatures are going up and emissions are going up. I’ve been in this for 25 years. I hoped we’d be beyond here by now.”

Schellnhuber concurred. “I’ve worked on this for 30 years and I’ve never been as worried as I am today.”

Global warming increases the risk of an extinction domino effect

The complex network of interdependencies between plants and animals multiplies the species at risk of extinction due to environmental change, according to a JRC study.

In the case of global warming, predictions that fail to take into account this cascading effect might underestimate extinctions by up to 10 times.

As an obvious, direct consequence of climate change, plants and animals living in a given area are driven to extinction when the local environmental conditions become incompatible with their tolerance limits, just like fish in an aquarium with a broken thermostat.

However, there are many elusive drivers of species loss that go beyond the direct effects of environmental change (and human activity) which we still struggle to understand.

In particular, it is becoming clearer that co-extinctions (the disappearance of consumers following the depletion of their resources) could be a major culprit in the ongoing biodiversity crisis.

While the concept of co-extinction is supported by a sound and robust theoretical background, it is often overlooked in empirical research because it's extremely difficult to assess.

New JRC Study on Co-Extinctions

A new study led by the JRC took on this challenge in order to determine the importance of co-extinctions in conditions of environmental change.

JRC scientist Giovanni Strona, in collaboration with Professor Corey Bradshaw from Flinders University in Adelaide, Australia, constructed 2000 "Virtual Earths", which they populated with thousands of plants and animals organized into a global system of inter-connected food-webs.

They then subjected the virtual Earths to extreme trajectories of environmental change, consisting in either a "global warming", i.e. a linear, monotonic increase in temperature, or a "nuclear winter", i.e. a progressive cooling, such as that which could follow multiple nuclear detonations or an asteroid impact.

They then tracked the loss of species diversity within two separate scenarios up to complete life annihilation.

In the first scenario, they only accounted for the extinction of a species when the temperature became too high or too low for that species to tolerate.

In the second scenario, starting from the extinctions triggered by the mismatch between local temperature and species tolerance limits, they also simulated co-extinction cascades.

By comparing the two scenarios, the scientists were able to provide a quantitative estimate of the relative importance of co-extinctions in planetary biodiversity loss.

They found that failing to account for interdependencies between species led to underestimation of the magnitude of mass extinctions triggered by climate change by up to 10 times.

Giovanni reflects that "conservationists and decision makers need to move fast beyond a species-specific approach, and look with increasing attention at species interaction networks as a fundamental conservation target. Whenever a species leaves our planet, we lose much more than a name on a list".

Global Warming: IPCC Special Report on Global Warming of 1.5°C confirms the utmost urgency to act

The study also explored the worst possible scenario of temperature change due to global warming.

According to the simulations, 5-6°C of warming would be enough to wipe out most life on the virtual Earths the scientists created.

Giovanni recognises that "there are obvious limitations in our ambitious model, due to the multiple challenges of building realistic global ecological systems.

On the one hand, our results are consistent with real-world patterns for which we have empirical evidence.

This make us confident that the many assumptions we had to take in order to build a functional model are sound. On the other hand, however, it would be misleading to just focus on raw numbers."

What is clear is that a warming Earth will put increasing pressure on the planet's biodiversity, and co-extinctions will add to that impact.

While it is unlikely that the Earth will become 5-6°C warmer in the near future, it is quite likely that global temperatures will continue to increase.

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