Article
BAMOS 2021 / 2022
Summer 13
The world has warmed and will continue to warm in the coming decades but the Paris Agreement targets a stabilised future climate with low global warming . Graphic of recent climate and future climate scenarios provided by the authors .
Even after the global temperature stabilises at the levels set out in the Paris Agreement , many ocean areas would likely warm by at least a further 0.5oC . Meanwhile some land areas would cool by
at least 0.5oC .
The ocean takes time to catch up — and as it does , land temperatures have to fall to maintain the same global average temperature .
In addition , if global temperature remained near-constant , rainfall patterns would likely
change . In some subtropical regions , such as southern Australia , this might mean a reversal of the drying trends we ’ ve seen over the past few decades .
New models are needed
Clearly , we need new experiments to model Earth ’ s climate if warming is stabilised at 1.5oC . Our
recently published paper proposes a framework for designing these experiments .
Our framework differs from the approach taken by various climate modelling groups around the world in recent decades .
These groups have all used the same projection of greenhouse gas concentrations in the atmosphere , and how they change through time . This
approach allows for comparison of climate projections between models for the same greenhouse gas scenarios .
But because each group fed this projection into their own climate model — each with their own characteristics — each produced different predictions for how much global warming would occur . Also , these model simulations are mostly run only to 2100 , and so represent a world that ’ s continuing to warm and hasn ’ t had time to stabilise .
Instead , our framework involves reaching the same level of global warming across a range of climate models . This would be achieved by “ turning off ” the carbon emissions used in various climate models at different times .
So , a climate model that warms more strongly in response to greenhouse gas emissions would have its carbon emissions “ turned off ” earlier , relative to a slower warming model . This would provide a group of climate model simulations at around the same level of global warming .
Stopping carbon emissions will
cause global warming to slow and , eventually , stop . Running these simulations for up to 1,000 years after carbon emissions stop will allow us to investigate and understand the effects of climate stabilisation in line with the Paris Agreement .
A few global modelling centres have started running simulations following similar frameworks , including Australia ’ s CSIRO . We invite other climate modelling centres to join us in our experiments , and help policymakers and societies better prepare for a warmer world .
This article was orginally published at
The Conversation and is reproduced here under Creative Commons .