Experts admit global warming predictions wrong
The worst impacts of climate change can still be avoided, senior scientists have said after revising their previous predictions.
The world has warmed more slowly than had been forecast by computer models, which were “on the hot side” and overstated the impact of emissions, a new study has found. Its projections suggest that the world has a better chance than previously claimed of meeting the goal set by the Paris agreement on climate change to limit warming to 1.5C above pre-industrial levels.
The study, published in the journal Nature Geoscience, makes clear that rapid reductions in emissions will still be required but suggests that the world has more time to make the changes.
Michael Grubb, professor of international energy and climate change at University College London and one of the study’s authors, admitted that his past prediction had been wrong.
He stated during the climate summit in Paris in December 2015: “All the evidence from the past 15 years leads me to conclude that actually delivering 1.5C is simply incompatible with democracy.” He told The Times yesterday: “When the facts change, I change my mind, as [John Maynard] Keynes said. It’s still likely to be very difficult to achieve these kind of changes quickly enough but we are in a better place than I thought.”
The latest study found that a group of computer models used by the Intergovernmental Panel on Climate Change had predicted a more rapid temperature increase than had taken place. Global average temperature has risen by about 0.9C since pre-industrial times but there was a slowdown in the rate of warming for 15 years before 2014.
Myles Allen, professor of geosystem science at the University of Oxford and another author, said: “We haven’t seen that rapid acceleration in warming after 2000 that we see in the models. We haven’t seen that in the observations.” He added that the group of about a dozen computer models, produced by government institutes and universities around the world, had been assembled a decade ago “so it’s not that surprising that it’s starting to divert a little bit from observations”. Too many of the models used “were on the hot side”, meaning they forecast too much warming.
According to the models, keeping the average temperature increase below 1.5C would mean that the world could emit only about 70 billion tonnes of carbon after 2015. At the present rate of emissions, this “carbon budget” would be used up in three to five years. Under the new assessment, the world can emit another 240 billion tonnes and still have a reasonable chance of keeping the temperature increase below 1.5C.
“That’s about 20 years of emissions before temperatures are likely to cross 1.5C,” Professor Allen said. “It’s the difference between being not doable and being just doable.”
Professor Grubb said that the fresh assessment was good news for island states in the Pacific, such as the Marshall Islands and Tuvalu, which could be inundated by rising seas if the average temperature rose by more than 1.5C.
Other factors pointed to more optimism on climate change, including China reducing its growth in emissions much faster than predicted and the cost of offshore wind farms falling steeply in Britain. Professor Grubb called on governments to commit themselves to steeper cuts in emissions than they had pledged under the Paris agreement to keep warming below 1.5C. He added: “We’re in the midst of an energy revolution and it’s happening faster than we thought, which makes it much more credible for governments to tighten the offer they put on the table at Paris.”
The Met Office acknowledged yesterday a 15-year slowdown in the rise in average temperature but said that this pause had ended in 2014, the first of three record warm years. The slowing had been caused by the Pacific Decadal Oscillation, a pattern of warm and cool phases in Pacific sea-surface temperature, it said.
