Meeting Paris Agreement goals that have put the world on track for warming of 2.6C this century would halve the average number of hot days globally each year in comparison with a scenario of unchecked rising emissions, new research has found.
Before the 2015 treaty, the world was headed for heating of 4C by 2100, which would have caused about 114 hot days annually compared with the 57 recorded today, said scientists at the World Weather Attribution (WWA) partnership and research organisation Climate Central.
“The Paris Agreement is a powerful, legally binding framework that can help us avoid the most severe impacts of climate change,” said Friederike Otto, climate science professor at the Centre for Environmental Policy, Imperial College London.
However, she said countries need to do more to shift away from oil, natural gas and coal, calling on political leaders to “take the reason for the Paris Agreement much more seriously … because every fraction of a degree of warming – whether it is 1.4, 1.5, or 1.7C – will mean the difference between safety and suffering for millions of people”.
The Paris climate pact commits countries to try to limit global warming to 1.5C above pre-industrial times, but the UN Environment Programme’s 2024 Emissions Gap Report said countries’ current national targets meant the world was on track for a 2.6C increase.
Curbing future heat
The group of 18 researchers drawn from the WWA and Climate Central mapped 207 countries, analysing weather data and climate models to track the frequency of heat-related events since cooler pre-industrial times.
They found the reduction in projected warming from 4C to 2.6C by 2100 would result in at least 100 fewer hot days per year on average in nearly 30 countries and 57 fewer days globally. In Kenya, that could mean 82 fewer hot days, a reduction of 30 in India and the US and a drop of 29 hot days in China and Britain.
They also applied their analysis to six heatwaves, including a deadly heatwave that swept Mexico and part of the southwestern United States last year, killing scores of people.
Since the Paris Agreement was signed, the research found that the Mexican heatwave had become 86% more likely and about 0.3C hotter.
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Under the 2.6C warming scenario expected this century, similar heatwaves are expected to become an additional 1.7C hotter. But under the 4C outlook, such events would have been 3.5C hotter than what was observed in 2024, the researchers said.
But while the global treaty has helped avoid the worst possible outcomes, Kristina Dahl, vice president for science at Climate Central, said the world was still headed for “a dangerously hot future”.
“The impacts of recent heatwaves show that many countries are not well prepared to deal with 1.3C of warming, let alone the 2.6C of warming projected if – and it’s a big if – countries meet their current emissions reduction pledges.”
Dahl said “faster, deeper, and more ambitious emissions cuts are crucial to ensure future generations live in a safe climate”.
CO2 levels soar to record
On Wednesday, the World Meteorological Organization (WMO) said carbon dioxide (CO2) levels in the atmosphere soared by a record amount to new highs in 2024, putting the planet on a course for greater long-term temperature increases.
In its Greenhouse Gas Bulletin, the UN agency traced the increase to human activities, wildfires and a decline in absorption by so-called carbon sinks such as forests and the ocean.
WMO Deputy Secretary-General Ko Barrett said the heat trapped by greenhouse gases was “turbo-charging our climate and leading to more extreme weather”.
“Reducing emissions is therefore essential not just for our climate but also for our economic security and community well-being,” Barrett said.
Following a series of intense heatwaves across the world in 2024 – the hottest year on record, UN Secretary-General António Guterres warned that extreme heat has become the “new normal” and appealed to countries to reduce the devastating consequences.
Despite 500,000 heat-related deaths recorded annually, access to early-warning systems is limited in some regions and heat adaptation continues to lag, particularly when it comes to finance, governance and long-term measures, the WWA and Climate Central researchers said.
They called for improved early-warning systems, heat action plans and monitoring mechanisms, especially in Africa, Latin America and parts of Asia, and said such policies should extend beyond the health sphere to be integrated into urban planning, labor protection, infrastructure and social policy.
They emphasised the importance of heat warnings by national weather services, currently only issued in about half of all countries, adding that long-term solutions such as increasing shaded areas and trees in cities and strengthening health systems could prevent about 100,000 deaths each year.
“The danger of heat will only increase this century, so it is crucial that every country implements measures that help keep people safe,” said Roop Singh, head of urban and attribution at the Red Cross Red Crescent Climate Centre.
