Global temperatures continued their alarming rise in May 2025, confirming it as the second warmest May on record, according to the European Copernicus Climate Observatory. While global temperatures briefly dipped below the critical 1.5°C threshold above pre-industrial levels, the month still followed a concerning trend of extreme heat that has persisted for over two years.
The average global temperature for May 2025 reached 15.79°C, just 0.12°C below the record set in May 2024, and marginally above that of May 2020, which now ranks third.
Sea surface temperatures also reflected this trend. May 2025 recorded a global ocean surface temperature of 20.79°C, the second highest in modern history after May 2024. Marine heat anomalies were particularly intense in regions such as the northeastern North Atlantic, where record temperatures for the month were documented. Much of the Mediterranean Sea was also significantly warmer than the historical average.
These persistent marine heatwaves are having a profound ecological impact. Experts warn they can lead to widespread species migration or die-offs, degraded marine ecosystems, and disruption of ocean nutrient cycles, which are crucial for sustaining marine life.
Covering 70% of the planet, oceans play a critical role in climate regulation. Rising sea temperatures are linked to stronger and more frequent hurricanes and storms, increasing the risk of coastal devastation and flooding.
These findings come as global leaders gather at the Third United Nations Ocean Conference (UNOC) in Nice, where ocean safety and sustainability are among the top priorities amid rising concern over climate impacts.
