🌡️ Human-caused global warming reached 1.37°C in 2025

For the fourth consecutive year, an international consortium of 73 researchers has updated key indicators of climate change and human influence on a global scale. Their findings, published in the scientific journal Earth System Science Data, indicate that the planet is accumulating heat at an accelerating rate, and that the level of global warming due to human activities now stands at 1.37°C.

Global greenhouse gas (GHG) emissions reached a record high, amounting to 56.8 billion metric tons (62.6 billion short tons) of carbon dioxide equivalent (CO₂e) emissions in 2024, three-quarters of which are directly attributable to fossil fuel use. However, GHG emissions are no longer increasing as rapidly as they did during the 2000s.

Human-caused warming reaches 1.37°C, rising rapidly

Human-induced global warming reached 1.37°C in 2025, and is expected to exceed 1.5°C around 2030. The remaining carbon budget — the total amount of carbon dioxide that can still be emitted if we are to have a one-in-two chance of keeping global warming below 1.5°C — is estimated at 130 billion metric tons (143.3 billion short tons) of CO₂ from the beginning of 2026. This carbon budget will be exhausted before 2030 at current CO₂ emission levels. It is now inevitable that human-caused global warming will reach and then exceed 1.5°C.

The year 2025 was the third warmest on record, with an observed temperature for the year of 1.39°C above the 1850-1900 average. This level is almost identical to the long-term human-caused warming level of 1.37°C for 2025. This shows that natural variability in the climate system had only a limited effect on global average temperatures last year.

The rate of human-caused warming remains at its highest historical level, about 0.27°C per decade. This high rate is primarily due to record levels of greenhouse gas emissions in the atmosphere and, to a lesser extent, the continued decline in aerosols, particularly sulfur-containing ones, whose cooling effect masked part of the GHG-induced warming. The decline in aerosols is partly a result of air pollution control measures.

Heat accumulates at an unprecedented rate

The Earth's energy imbalance, the difference between the solar radiation received by the Earth and the outgoing radiation emitted by the Earth into space, measures the accumulation of heat in the climate system. It results from both human-induced disturbances and the climate's response, with its feedback loops.

This imbalance is a key indicator of the rate of climate change. It has been increasing since the 1970s, doubling over recent decades to reach a record high. This heat accumulation is at the heart of the consequences of global warming and affects every component of the climate system: warming of air over continents; warming of the ocean, both at the surface and at depth; melting of continental ice and sea ice.

Sea level rise is accelerating

The intensification of the Earth's energy imbalance has the direct consequence of accelerating sea level rise, which results from ocean warming and the melting of continental ice. Global mean sea level reached a new record high of 23 cm (9 inches) in 2025 since 1901. The rate of sea level rise now stands at 3.7 mm per year (0.15 inches per year) (average over 2006-2025).

3 times more marine heatwaves

Changes in the frequency and intensity of extreme climate and weather events provide tangible evidence of widespread changes in the climate system. The number of marine heatwave days, a new indicator in the study, has more than tripled (x3.3) from 1991 to 2025. The year 2025 alone experienced 65 marine heatwave days.

This update of key climate indicators shows the continuation at a record pace of climate change due to human activities. It underscores the need to massively intensify decarbonization efforts during this critical decade to slow global warming and limit the risks and impacts of climate change (health, food security, socio-economic impacts, biodiversity), which increase very sharply with global warming.

Maintaining the ability to observe the global climate, preserving and updating global datasets, are essential to provide the most recent, accurate, and comprehensive information, enabling evidence-based decision-making and monitoring of future climate evolution.