UN warns 2025 could be among hottest years on record

The United Nations weather agency warned that 2025 is poised to be among the warmest years on record, reinforcing a pattern of unprecedented heat as global leaders gathered in Brazil ahead of the COP30 summit.

The World Meteorological Organization (WMO) said global temperatures for January–August averaged about 1.42°C above pre‑industrial levels (1850–1900), with every month this year ranking among the top three warmest for that month on record. Record-high concentrations of greenhouse gases and rising ocean heat content—both already at historic levels in 2024—continued to climb in 2025, driving a near‑continuous sequence of extreme heat events despite a neutral or weak La Niña. The WMO’s Global Annual to Decadal Climate Update gives an 80% chance that at least one year between 2025 and 2029 will exceed the current warmest year on record (2024), and projects that 2025 will finish in the top three, likely second or third. Scientists warned that the world is on track to cross the 1.5°C warming threshold around 2030, with potentially irreversible consequences for ecosystems, food security and human lives.

UN officials and scientists framed the trend as both symbolic and substantive: higher average temperatures are linked to more frequent and intense heatwaves, wildfires, floods, storms and sea‑level rise, amplifying risks to livelihoods and infrastructure globally. WMO officials stressed that the duration and severity of overshoot above 1.5°C will depend on immediate policy choices, making the coming years and COP30 pivotal.

The agency highlighted numerous climate extremes in the first eight months of 2025, from devastating floods to record Arctic and below‑average Antarctic sea ice extents, and noted that rising greenhouse‑gas emissions—up 2.3% in the previous year per the UN Environment Programme, driven largely by India, China, Russia and Indonesia—are locking in additional warming. Amid the dire warnings, experts pointed to gains in early‑warning systems: the number of countries reporting such systems more than doubled since 2015, from 56 to 119, with improved access in least developed countries and small island states.

Yet the WMO cautioned that about 40% of nations still lack early warnings. The report urged rapid, coordinated emission cuts, strengthened resilience and expanded early‑warning coverage to prevent further record temperatures and to limit the long‑term impacts of the accelerating climate crisis.