New climate model predicts 2 degrees warming within 41 years

A new international study has designed a new and simpler climate model that gives a more precise picture of prospects for global warming this century, predicting a global rise of two degrees within 41 years.

The new model, developed by researchers at ANU in collaboration with the University of Southampton and the University of Liverpool in the United Kingdom, finds that at current emission rates, the Paris Agreement's 1.5 degree warming target is reached in 17 or 18 years and the two degree target in 35 to 41 years, leaving a limited window to develop a low carbon future.

Co-researcher Professor Eelco Rohling from ANU said the uncertainties in climate models used currently by scientists were too large to develop future carbon budgets that meet specific warming targets.

"There is significant uncertainty in projecting the amount of carbon that can be emitted, in part due to the limited number of Earth system model simulations and their discrepancies with present-day observations," said Professor Rohling from the ANU Research School of Earth Sciences.

The study used theory and geological evidence to generate a very large ensemble (3 × 104) of projections that closely match records for nine key climate metrics, which include warming and ocean heat content.

"Our model narrows the uncertainty in global warming projections and reduces the range in equilibrium sensitivity of global temperatures to emissions."

Professor Rohling said a warming target of 1.5 degrees above the pre-industrial level would require the total emitted carbon from the start of last year to be less than 195-205 petagrams of carbon. A petagram is one billion metric tonnes.

"The two degree target is only likely if the emitted carbon remains less than 395 to 455 petagrams of carbon," Professor Rohling said.

"Immediate action on climate change is essential, to develop strategies towards zero carbon emissions, options to take carbon out of the atmosphere and ways to adapt to the effects of a much warmer climate."

ANU conducted the study in collaboration with the University of Southampton and the University of Liverpool in the United Kingdom.

The study is published in Nature Geoscience.

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