Ten years of Paris Agreement, eleven extra hot days a year: climate action still far behind

A decade after the signing of the Paris Agreement, the planet is living through the hottest years in recorded history — and extreme heat is killing more people than any other climate hazard, according to a new report.

The global assessment by Climate Central and World Weather Attribution found that while the Paris framework has helped bend the global warming curve — lowering projected end-of-century warming from about 4°C in 2015 to 2.6°C today — even that “success” locks in a future of deadly heat. 

The 2015 Paris Agreement could help the world avoid 57 hot days if countries follow through on their emission-cutting plans and limit warming this century to 2.6°C, it said.

“Every fraction of a degree matters,” said Friederike Otto of Imperial College London and World Weather Attribution. “What we’re already seeing at 1.35°C of warming is just a preview. At 2.6°C, we’ll have 57 extra hot days each year on average — and that’s a level of heat few societies can safely cope with.”

The report showed that since 2015, the world is experiencing an average of 11 additional “hot days” per year, with some regions like Southeast Asia and the Pacific Islands seeing 20 to 35 more. In India and Pakistan, spring temperatures that once occurred every 30 years now strike almost every two years.

Three of the six severe heat events analysed — in the Amazon Basin, Southern Europe, and the Sahel — would have been “virtually impossible” without human-induced climate change. The 2024 Sahel heatwave, which left hospitals overwhelmed and grids collapsing, “would not have occurred without global warming,” the report concludes.

“We are living through the decade that determines whether adaptation will keep up or collapse,” said Julie Arrighi, director at the Red Cross Red Crescent Climate Centre. “The Paris Agreement slowed the rise — but it did not stop the suffering. We’ve made progress on heat early warning systems, but the world’s poorest are still unprotected.”

Indeed, adaptation efforts have expanded — 104 countries now issue extreme heat warnings, and 47 have national heat action plans. But gaps remain stark. Africa, Latin America, and parts of Asia still lack localised heat-health systems. Financing remains the biggest barrier: heat adaptation projects receive less than 2 per cent of total global climate finance.

According to Roop Singh, climate risk advisor with the Red Cross, “the costs of inaction are now rising faster than the pace of adaptation. Health, labour, and infrastructure are straining under repeated heat extremes, and local governments simply don’t have the resources to keep up.”

The report calls for “transformative adaptation” — rethinking urban planning, housing, labour laws, and disaster systems for a hotter world. It recommends embedding equity, gender, and disability data into national adaptation plans to ensure protection for the most exposed groups, from outdoor workers to informal settlement residents.

“Cooling centers and warnings are essential, but not enough,” Singh added. “We need to redesign cities for shade and ventilation, protect outdoor workers, and ensure that access to cooling doesn’t depend on income.”

The report also warns that without “deep, rapid, and sustained” cuts to fossil fuel use, adaptation will soon reach its limits. A 4°C world — which was the expected trajectory before Paris — would bring more than 100 extra hot days a year, turning today’s extremes into the new normal.

“Heat is no longer a seasonal issue — it’s a structural one,” said Kristina Dahl of Climate Central. “The Paris Agreement showed that global cooperation can bend the curve, but the next decade must prove we can deliver the highest possible ambition.”

As the world heads to COP30 in Belem, Brazil, next month, the report urged governments to submit strengthened emission pledges that align with the 1.5°C goal — the only path that keeps large parts of the world within “livable” limits.

“The Paris decade has shown us what’s possible,” Otto said. “The next must show us what’s necessary.”