Meeting current pledges to cut greenhouse gas emissions could prevent an additional 57 deadly hot days per year, compared with a world without the landmark Paris Agreement to curb climate change, according to a new report.
Heat is the deadliest type of extreme weather, yet it is often overshadowed by more dramatic threats such as floods and hurricanes. Even a slight increase in temperature can wreak havoc on plants, animals and humans.
Yet climate change is making heat waves hotter and more likely. Every year, heat kills nearly half a million people, and rising temperatures are pushing vital ecosystems – including coral reefs – to the brink.
But increasing emissions cuts to meet the goals of the Paris Agreement will mean the difference of life or death in the event of a warming climate for many communities around the world. This is according to the report of Scientific Initiative World Weather Attribution and the US research organization Climate Central.
“We are still not looking at the highest possible ambition and that is clearly a big problem,” said Friedrich Otto, a scientist who works with WWA to study the relationship between climate change and extreme weather. “This is a problem that will cost the lives and livelihoods of the poorest people in every country in the world.”
The Paris Agreement makes a difference
Adopted in 2015, the Paris Agreement united 196 countries in pledging to step up efforts to limit global warming to well below 2 °C (3.6 °F) and limit the increase to 1.5 °C. The targets are measured against pre-industrial levels, before widespread fossil fuel use began changing the planet’s climate.
Global warming is currently about 1.4C above that benchmark. And if countries’ current pledges to cut emissions are met, the world will be on track for at least 2.6C of warming by the end of the century. There will be an additional 57 hot days compared to today’s climate.
“We are still headed toward a dangerously hot future,” said Christina Dahl, vice president of science at Climate Central. He said that many countries are not even prepared for today’s temperatures.
Yet, without the historic Paris Agreement, the future will be very grim, with 4C of warming and 114 extra hot days per year by 2100 compared to today – double the number in a warming scenario under current pledges. Hot days are defined as days when the temperature is significantly above normal for a given location.
Such warming would make recent record-breaking events – such as the extreme European temperatures of 2023 and the 2024 heat in South America and Mexico – five to 75 times more likely than today.
Those heat waves caused an estimated more than 47,000 deaths in Europe, while extreme temperatures in the US and Mexico exacerbated existing droughts.
Every degree counts
The world has warmed 0.3C since the Paris Agreement was adopted and now experiences 11 hotter days per year, the report said.
Even that small spike has had a big impact. The likelihood of heat waves – causing wildfires, lower wheat yields and power outages – doubled in 2022 in India and Pakistan. And extreme temperatures, reaching 45C, were nine times more likely to occur in Mali and Burkina Faso in 2024, causing hospitalizations and deaths.
The report highlights the danger of even small amounts of warming in areas such as the Amazon rainforest, which is vital to climate stability due to its potential to store billions of tonnes of carbon.
Theo Keeping, an environmental researcher at Imperial College London who also works with WWA, said, “Over a decade, with 0.3C of warming, six months of extreme heat in the Amazon – such as the 2023 summer that severely exacerbated severe drought – becomes 10 times more likely.”
According to a UN report, the drought has forced an estimated 420,000 children out of school and many have faced shortages of food and water.
Every fraction of a degree for human health “will be the difference between safety and suffering for millions of people,” said Otto, professor of climate science at Imperial College London.
Heat often hits the most vulnerable the hardest, including low-income households, people with pre-existing medical conditions, outdoor workers and older populations. For example, since the 1990s, heat-related deaths among people over the age of 65 have increased by 167%.
“We humans are more vulnerable than we think,” Otto told DW.
Requires more heat acclimatization
Even if the Paris promises are met, two additional months of hot days each year would have “huge implications for human rights and the need for adaptation,” Otto said.
Extreme heat is putting pressure not only on health but also on labour, livelihoods and infrastructure.
The report found that protective measures have improved since 2015, but only half of all countries have early warning systems for heat, and about 47 have national heat action plans.
“People don’t have to die from the heat: There are measures, relatively simple measures, that societies can take to save lives,” Otto told DW.
Measures include strengthening water, energy and health care systems, expanding urban green cover in cold cities and reducing flooding, and implementing labor protections to protect people’s health and ability to work. Yet funding for adaptation remains seriously inadequate.
Emissions still need to decline rapidly
The report found that the Paris Agreement currently keeps the world away from the most dangerous climate scenarios. For example, for the first time, renewable energy has overtaken coal as the world’s dominant source of electricity.
However, 2024 was also the hottest on record, and CO2 levels in the atmosphere reached new highs. World Meteorological Organization.
Countries need to introduce more ambitious emissions cuts if they are to keep temperature rise below 2C. But ahead of the international COP30 summit in Belém, Brazil, next month, many countries have not yet announced their national climate plans.
So far, the world is not doing enough to move away from oil, gas and coal, Otto said. “We have all the knowledge and technology needed to move away from fossil fuels, but strong, fair policies are needed to move faster,” he said.
Edited by: Jennifer Collins