2025 was the third warmest year on record, following a long-term trend of unusually high temperatures that has increased the frequency and severity of extreme weather events around the world.

Last year’s global average temperature of 14.97C was only 0.01C lower than 2023 and 0.13C lower than 2024, the warmest year on record, according to data from several dataset providers, including the European Center for Medium Range Weather Forecasts Copernicus Climate Change Service (ERA5) and Berkley Earth.

According to the ERA5 dataset, worldwide surface air temperature was 1.47 degrees Celsius greater than it was before the industrial revolution. While the average for 2023-2025 exceeded 1.5C for the first time in three years, the current long-term global warming level is approximately 1.4C over pre-industrial levels. Only in 2024 did the temperature exceed the key global warming limit set by nearly all countries in 2015 under the Paris Agreement.

Experts warn that if global warming exceeds 1.5 degrees Celsius, critical tipping points will be breached, resulting in devastating and potentially irreversible consequences for several vital Earth systems that keep the planet hospitable, such as rising sea levels, more intense heatwaves, stronger storms, and disruptions to ecosystems and biodiversity.

The burning of coal, natural gas, and oil for electricity and heat is the single-largest source of global greenhouse gas emissions, which are the principal cause of global warming because they trap heat in the atmosphere and raise the Earth’s surface temperature. While global fossil fuel usage has more than doubled over the last 50 years, experts have long warned that limiting fossil fuel extraction and consumption is the only way to slow global warming and ensure a livable future.

Unmistakable Trend

In 2025, much of the world experienced above-average temperatures. This includes the Arctic and Antarctic regions, which had their second-highest and highest values on record. The northwestern and southwestern Pacific, the northeastern Atlantic, far eastern and north-western Europe, and central Asia all saw record-high yearly temperatures.

The last 11 years have been the warmest on record. This “provides further evidence of the unmistakable trend towards a hotter climate,” according to Carlo Buontempo, Director of the Copernicus Climate Change Service. “The globe is fast approaching the long-term temperature limit established by the Paris Agreement. We are obligated to pass it; the decision now is how to effectively manage the unavoidable overshoot and its ramifications for communities and natural systems.”

Ocean Heat

According to a study released last week in Advances in Atmospheric Sciences, ocean temperatures in 2025 were among the highest ever recorded.

“Regionally, about 33% of the global ocean area ranked among its historical (1958-2025) top three warmest conditions, while about 57% fell within the top five, including the tropical and South Atlantic Ocean, Mediterranean Sea, North Indian Ocean, and Southern Oceans, underscoring the broad ocean warming across basins,” the World Meteorological Organization stated in its annual bulletin, also published on Wednesday.

Oceans serve as the Earth’s major heat sink, absorbing more than 90% of the excess heat produced by human-caused greenhouse gas emissions. As a result, ocean heat content is an important indication of climate change.

Extreme Weather Events on the Rise

Last year, extreme weather events impacted all continents, with record heatwaves and storms affecting Europe, Asia, and North America, as well as devastating wildfires damaging infrastructure and killing scores in Spain, Canada, and southern California. 2025 was one of the most expensive years for climatic catastrophes worldwide, and the third-highest year for billion-dollar disasters in the United States, behind 2023 and 2024.

Global warming, mostly caused by human-generated greenhouse gas emissions, has increased the frequency and intensity of several extreme weather occurrences since pre-industrial periods, such as flooding, heavy rainfall and storms, and droughts. Emissions of all three major greenhouse gases increased in 2025.