COP31 is underway in Turkiye, where world leaders and climate experts are discussing ways to tackle climate change. One of the major concerns is the amount of carbon dioxide the world can still release into the atmosphere without making global warming worse.
Scientists have warned that the world has very little time left to meet the 1.5 degrees Celsius global warming target. According to a study published in June 2025, the remaining carbon budget could run out in just two years if countries continue releasing carbon dioxide at the same rate, The Guardian reported.
The study, prepared by 60 climate scientists, found that the world had only 80 billion tonnes of carbon dioxide left to emit from 2025 onwards. This amount would give the world a 66% chance of keeping global warming below 1.5 degrees Celsius.
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The warning comes as global carbon dioxide emissions reached a record high in 2024. Scientists say countries need to cut emissions much faster to limit the damage caused by climate change.
What is a carbon budget?
A carbon budget is the amount of carbon dioxide the world can still release into the atmosphere while trying to keep global warming within a set limit. Once the budget is used up, keeping global warming within the target becomes much harder.
How much carbon budget is left?
For the 1.5 degrees Celsius target: Only 80 billion tonnes of carbon dioxide were left from 2025 onwards. At the 2024 emission rate, this amount would last around two years.
According to the IPCC report, the world could release only 400 billion tonnes (Gt) of carbon dioxide from the beginning of 2020 if it wanted to have a 66% chance of keeping global warming below 1.5 degrees Celsius.
For the 1.7 degrees Celsius target: The remaining budget was 390 billion tonnes of carbon dioxide, which would last around nine years at the same emission rate.
Why is the 1.5 degrees Celsius target important?
The 1.5 degrees Celsius target is part of the Paris Climate Agreement. It aims to limit the rise in the Earth’s average temperature to 1.5 degrees Celsius above pre-industrial levels. This limit matters because even a small rise in global temperatures can make weather conditions more dangerous.
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Going beyond 1.5 degrees Celsius could increase the risk of heatwaves, floods, droughts and storms. It could also affect farming, water supplies, wildlife and people living in vulnerable areas.
What happens if the carbon budget runs out?
If the remaining carbon budget is used up, it will become much harder to stop global temperatures from rising further. Scientists warn that higher temperatures could lead to more extreme weather, faster melting of glaciers and rising sea levels.
The June 2025 study found that sea levels were rising at around 4mm every year. This was almost twice the average rate recorded between 1971 and 2018. The study also found that the amount of extra heat trapped by the Earth had increased by 25% compared with the previous decade.
The biggest reason for the budget shrinking is the continued use of fossil fuels such as coal, oil and gas. These fuels release carbon dioxide when used to generate electricity, run vehicles and power industries. The year 2024 was the hottest year on record. For the first time, the annual global average temperature reached around 1.5 degrees Celsius above pre-industrial levels.
Carbon budgets explained: How much more carbon dioxide can world emit before climate risks intensify
