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BAMOS 2021 / 2022 Summer
Article
Even if we halt global warming , local climates will change — and we need new experiments to understand how
Andrew King1 , Andrea Dittus2 , Ed Hawkins2 , Josephine Brown1 , Kale Sniderman1 , Tilo Ziehn3
1 The University of Melbourne 2 University of Reading 3 CSIRO
A new paper outlines a design framework for new experiments to model Earth ' s climate when warming is stablised at 1.5
o C . Photograph of Surfers Paradise ©
Nathan Cowley from Pexels .
There ’ s a big question mark over whether the world will keep global warming below the limits set out in the Paris Agreement . But even if we do , the climate will keep evolving — and society needs to prepare for this .
At the moment , climate models don ’ t tell us much about a future world in which temperatures have stabilised . As our
research argues , new model experiments are needed to close this knowledge gap and better understand the challenges ahead .
For example , in southern Australia , climate change has already caused a
trend towards less rain and more frequent and prolonged drought . If the global climate stabilises , we expect this drying trend to reverse , which could ease future strains on water supply in this region . This would in turn affect urban planning , agriculture and water policy .
The new models we ’ re proposing would enable more useful climate projections aligned with the Paris Agreement targets — and better prepare society for a warmer , but more stable , global temperature .
Targeting a stable climate
Under the landmark Paris Agreement , the world is aiming to keep global warming well below 2oC compared with preindustrial times , and preferably below 1.5oC .
The world is warming at a rate of around 0.25oC per decade and is already about 1.2oC warmer than in pre-industrial times .
This warming won ’ t stop until net greenhouse gas emissions are near zero . If we don ’ t greatly reduce emissions in the next decade , we will warm the planet beyond 1.5oC .
To date , climate simulations used to examine the implications of the Paris Agreement either assume warming continues beyond 1.5oC and 2oC , or only examine a short period after warming has stopped . This is because most of these simulations were not specifically designed to analyse global warming levels linked to the Paris Agreement , and mostly focus only on what will happen this century .
If we manage to stabilise global temperatures , other aspects of Earth ’ s climate would continue to change . Studies based on
long model experiments suggest ocean and land temperatures continue to evolve for centuries after global warming slows . That ’ s because the ocean warms at a slower rate than the land , and warming water can take hundreds , and even thousands , of years to mix into the deep ocean .