Climate Analytics warns that exceeding 1.5°C is now inevitable, but halving global emissions by 2035, phasing out fossil fuels and cutting methane could bring warming back below the threshold by 2100.
-By Laura Contemori
Climate overshoot: How global temperatures could fall below 1.5°C by 2100
Halving global emissions by 2035, accelerating the phase-out of fossil fuels and reducing methane emissions could still limit peak global warming to 1.7°C around 2040 and bring temperatures down to 1.2°C to 1.3°C by the end of the century, according to Climate Analytics.
Exceeding the 1.5°C global warming threshold above pre-industrial levels is now inevitable, but there is still time to limit the extent and duration of the overshoot.
That is the central finding of a new report, Climate overshoot: The way back below 1.5°C, published by research institute Climate Analytics during COP31.
“The overshoot ahead of us is now inevitable. It is not a question of physics, but of political choice,” warns Bill Hare, CEO of Climate Analytics.
“How long we remain above 1.5°C, and how quickly and how far temperatures subsequently decline, will depend on the measures governments take now and in the coming years,” he adds.
Climate overshoot and the impacts of exceeding 1.5°C
Every additional tenth of a degree increases climate risks, from exposure to extreme heat and rising sea levels to the possibility of triggering irreversible changes in ecosystems.
According to the report, warming of 1.7°C rather than 1.5°C by 2050 could increase the number of people exposed to heatwaves worldwide by approximately one-third. If temperatures reach 1.8°C by 2050, that figure could rise by a further 10%.
Among the most significant risks are the loss of coral reefs, the melting of the Greenland and West Antarctic ice sheets, and the degradation of the Amazon rainforest.
Limiting both the peak temperature and the duration of the climate overshoot would therefore help contain these impacts.
Halving emissions by 2035 and phasing out fossil fuels
The central priority is to phase out fossil fuels, which account for more than 70% of global greenhouse gas emissions.
According to the analysis, coal consumption must fall by approximately 70% by 2035, gas consumption by 50% and oil consumption by more than a quarter.
Renewable energy sources should progressively replace fossil fuels in electricity generation, while clean electricity should be used to decarbonise transport, buildings and industry.
These measures must be accompanied by improvements in energy efficiency, reductions in methane emissions and the restoration of natural ecosystems.
Methane emissions represent one of the most urgent areas for action. Responsible for approximately one-third of the warming recorded so far, methane emissions should fall by as much as one-third by 2030.
“Given its short atmospheric lifetime, cutting methane emissions is the fastest way to slow warming immediately,” explains Zarrar Khan, Senior Expert in Integrated Assessment Models at Climate Analytics.
Electrification and renewable energy must advance together
Accelerating electrification is another key measure identified in the report.
The issue is central to the COP31 agenda through the “35-by-35” initiative, which aims to increase the global electrification rate by 35% by 2035.
For Climate Analytics, however, this target should be considered a starting point.
Under the institute’s most ambitious scenario, the electrification rate would need to reach approximately 39%.
The growing share of electricity in final energy consumption must be accompanied by the decarbonisation of electricity generation.
“You can have strong electrification, but you have to ask whether it is meeting new demand or replacing fossil fuels,” Khan points out.
If electricity continues to be generated from fossil fuels, electrification may fail to deliver meaningful emissions reductions.
The transition therefore requires “electrification on the one hand, but also decarbonisation of the energy sector on the other. […] Electricity must therefore come from clean sources.”
Carbon removal and the pathway back below 1.5°C
The pathway also requires an increase in the removal of CO₂ from the atmosphere.
Under the most ambitious scenario, which would bring global temperatures back to 1.2°C to 1.3°C by 2100, cumulative carbon removal would need to reach approximately 500 billion tonnes over the course of the century.
The report stresses that carbon removal must complement, rather than replace, emissions reductions and the phase-out of fossil fuels.
This distinction is central to the strategy for reversing climate overshoot. Removing carbon dioxide from the atmosphere cannot substitute for immediate action to reduce emissions at their source.
Hare’s appeal at COP31 is to “act to keep the overshoot as low as possible, make it last as little time as possible and return below 1.5°C as quickly as possible.”
