Three UN-backed climate reports in one week: what they say before COP31

Within two days, three reports have landed with the same message: the climate is changing faster than plans to deal with it. They arrive just before the UN's COP31 climate conference in Antalya, Türkiye, which runs from 9 to 20 November. This explainer is written in our own words from UN News coverage, which can be reused with attribution. Each section links to the original report.

1. Heat killed a record 710,000 people in 2023

The Lancet Countdown report, produced with the World Health Organization and led by University College London, estimates that heat caused 710,000 deaths worldwide in 2023, a record. For the first time, more than seven in ten of those deaths were attributed to human-caused climate change. Heat-related deaths rose by nearly 36 per cent in the years after the 2015 Paris Agreement compared with the decade before.

Other findings include:

• Extreme drought affected 51.8 per cent of the world's land for at least one month in 2025.
• Conditions suitable for dengue spread by Aedes albopictus mosquitoes were 24 per cent more common in 2016 to 2025 than in 1981 to 1990.
• The world's 100 largest oil and gas companies plan to produce 150 per cent more fossil fuels by 2040 than is compatible with limiting warming to 1.5°C.

There was some good news. Clean energy investment reached a record $2.1 trillion last year, and about one in four countries now has a national plan to adapt health services to climate change.

2. Greenhouse gases hit another record

The World Meteorological Organization's Greenhouse Gas Bulletin says carbon dioxide averaged 426.8 parts per million in 2025, which is 153 per cent of the pre-industrial level in 1750. Methane and nitrous oxide, the next two most important long-lived greenhouse gases, also reached new highs. WMO's Ko Barrett said the past 11 years have been the warmest on record, and that because CO2 lasts so long it will affect the climate for decades and even centuries.

3. The ocean is soaking up less carbon

A report from the UN Environment Programme and the UN climate secretariat says the ocean absorbs about 30 per cent of human-caused CO2 and 90 per cent of the excess heat, but climate change has already cut its capacity to absorb carbon by about six per cent. The authors say the process could accelerate. They call for better monitoring, since there is little reliable data for the Southern and Indian Oceans, the Arctic and many coasts, and for protecting mangroves, seagrasses and salt marshes, which already store around 407 million tonnes of CO2 a year. They caution that technologies to remove carbon from the sea are uncertain and should not be treated as a shortcut around cutting emissions.

What happens next

COP31 begins on 9 November. The Lancet Countdown authors want climate change formally recognised as a global health emergency, and the UN reports all point to the same priorities: cutting emissions faster, funding adaptation and investing in resilient health systems. Small island states, which contribute less than one per cent of global emissions, are among those most exposed to ocean and climate impacts.

Sources

• Record heat-related deaths in 2023, WHO-partnered report finds (UN News)
• Record carbon dioxide levels will impact us for centuries, says UN weather agency (UN News)
• Ocean's ability to absorb carbon is weakening as climate change intensifies, UN warns (UN News)