‘Halve emissions or else’

Climate

Global carbon dioxide emissions must almost halve within 12 years to avoid a catastrophic loss of coral reefs and Arctic ice, intense floods and droughts, according to a UN report.

Preventing the worst effects of climate change will require ‘‘unprecedented changes in all aspects of society’’ costing pounds 1.8 trillion a year. The changes include a rapid switch to electric vehicles, huge expansion of renewable energy and closing hundreds of coal-fired power stations.

The Intergovernmental Panel on Climate Change (IPCC) said that the global average temperature should be limited to 0.5C in addition to the 1C increase that has already occurred since preindustrial times.

The UN body said that there were ‘‘clear benefits to people and natural ecosystems’’ from restricting total global warming to 1.5C compared with 2C. The panel was tasked with considering the impact of 1.5C of warming after the 2015 Paris Agreement, in which 195 countries pledged to keep the temperature increase ‘‘well below’’ 2C and to ‘‘pursue efforts’’ to limit it to 1.5C.

Its report, written by 91 scientists from 40 countries and based on 6000 scientific papers, will inform key decisions at a climate change meeting in Poland in December about implementing the Paris Agreement.

A 2C rise would result in the loss of 99 per cent of coral reefs, the disappearance of Arctic ice one summer in 10 and the sea level rising an extra 10cm, inundating many coastal communities, the report said. It would also leave twice as many species facing a loss of habitat compared with a rise of 1.5C.

Hundreds of millions of people would be at greater risk of poverty, particularly in Africa, southeast Asia and Central and South America where yields of maize, rice and wheat would decline. It said that global warming was already causing more extreme weather, rising sea levels and loss of Arctic ice.

It calculated that CO2 emissions must fall by 45 per cent on 2010 levels by 2030 and be at ‘‘net zero’’ by 2050 to have ‘‘no or limited overshoot of 1.5C’’. That means balancing the amount of carbon released by humans by sucking CO2 from the atmosphere.

Limiting the increase to 2C would require emissions to fall 20 per cent by 2030. This would still be extremely challenging because global emissions rose by 1.6 per cent last year.

The IPCC said the proportion of global electricity generated by burning coal would have to have fall from about 38 per cent to ‘‘close to 0 per cent’’ by 2050 to limit warming to 1.5C. Gas-fired power would have to fall from 23 per cent to 8 per cent.

Claire Perry, a UK energy minister, said: ‘‘This report should act as a rallying cry for governments around the world to innovate, invest, and raise ambition to avert catastrophic climate change.’’

Jim Skea, professor of sustainable energy at Imperial College London and one of the report’s main authors, said: ‘‘Limiting warming to 1.5C is possible within the laws of chemistry and physics but doing so would require unprecedented changes.’’ – The Times

‘‘Limiting warming to 1.5C is possible within the laws of chemistry and physics but doing so would require unprecedented changes.’’ Jim Skea, professor of sustainable energy at Imperial College London