BAMOS May 2026
14 Article
Scientists have scrapped the worst‐case climate scenario – because action is making a difference
Andrew King, ARC Centre of Excellence for 21st Century Weather, University of Melbourne( andrew. king @ unimelb. edu. au)
When major new climate change scenarios are released, there’ s always strong interest. These scenarios lay out what our future climate will look like, depending on how fast we act to cut emissions.
But what was surprising about the seven new scenarios announced last week was that United States President Donald Trump took an interest.
Why? Because a high-emissions scenario – known as RCP8.5 and its successor SSP5-8.5 – had been removed. Under these worstcase scenarios, nations would make no effort to cut emissions and expand fossil fuel use. By 2100, carbon dioxide levels would almost triple, to 1,135 parts per million and the world would be around 4.5 ° C hotter than the pre-industrial period.
The climate scientists responsible for laying out the range of possible futures removed the RCP8.5 scenarios for a very good reason. Although often slow and incomplete, our efforts to tackle climate change have made a tangible difference. We have averted the worst climate future once thought possible.
The job is far from done. Emissions are at record highs and global warming is speeding up.
But the removal of this high-emissions scenario isn’ t, as Trump and other climate sceptics have claimed, a sign of failed modelling, or that climate change was a hoax. It’ s a sign the expansion of solar, wind, electric vehicles and batteries have slowed emissions growth.
How are these scenarios made?
Many climate impacts are becoming evident after about 1.4 ° C of warming – the level we’ re roughly at now.
Because this period of extremely rapid climate change is due to human activities, it means we also have the opportunity to shape the future.
What will this look like? Will the world keep heating up, or will rapid action cut emissions and bring warming to a halt? The answer will make a big difference to the future humanity faces.
Predicting anything is difficult. But a group of scientists has created scenarios representing a range of possible climate futures.
Because the future is not set, scientists lay out a range of possible pathways for our future greenhouse gas emissions. They base them on what’ s happened so far and what might happen in politics and technology over coming decades.
Then they select the emissions pathways deemed most plausible and then sample a range of different futures which are more or less optimistic about our fossil fuel use.
Scientific groups around the world then model these scenarios in depth using different climate models to ensure there’ s a large amount of data available at global, regional and local levels.
These scenarios aren’ t ranked by how likely they are. All are considered to be plausible futures. The huge range of
Under the previous worst-case climate scenario of SSP5-8.5, the world would have warmed about 4.5 ° C by 2100. IPCC, CC BY-NC-ND