Is the 1.5°C climate target out of reach? Scientists warn as human-driven warming reaches record levels

Even as wars, economic uncertainty and political upheaval dominate global headlines, a major international climate assessment has delivered a stark conclusion: human activity is driving more global warming than ever before.

The latest Indicators of Global Climate Change (IGCC) report, published in the journal Earth System Science Data, found that nearly all of the warming observed in 2025 was caused by human activities, primarily the burning of fossil fuels and the release of greenhouse gases.

According to the assessment, global temperatures in 2025 were about 1.39 degrees Celsius above pre-industrial levels, with 1.37 degrees Celsius of that increase directly attributable to human influence.

Compiled by more than 70 climate scientists, including contributors to the Intergovernmental Panel on Climate Change (IPCC), the report serves as an annual update on the state of the climate between the IPCC’s larger assessment cycles.

The findings reinforce earlier estimates from the World Meteorological Organization (WMO), which ranked 2025 as the third-warmest year on record, behind only 2024 and 2023.

Why 2025 wasn’t the hottest year — but still set a record

Scientists say the apparent contradiction is explained by the difference between long-term climate change and short-term natural climate variability.

While human-caused warming reached a record level in 2025, global temperatures were moderated by La Niña conditions in the Pacific Ocean. La Niña typically exerts a temporary cooling effect, offsetting some of the heat trapped by greenhouse gases.

As a result, overall temperatures were slightly lower than those recorded during recent El Niño-driven years, even though the long-term warming trend continued to intensify.

The report estimates that human-induced warming is now increasing at approximately 0.27 degrees Celsius per decade. Meanwhile, global greenhouse gas emissions reached a record 56.8 billion tonnes of carbon dioxide equivalent in 2025.

Carbon budget running out fast

One of the report’s most significant warnings concerns the world’s remaining carbon budget — the amount of carbon dioxide humanity can still emit while maintaining a reasonable chance of limiting warming to 1.5 degrees Celsius above pre-industrial levels, the central goal of the Paris Agreement.

Scientists estimate that only about 130 billion tonnes of additional carbon dioxide can be emitted from the start of 2026 before that budget is exhausted.

At current emission rates, the remaining budget could be depleted in less than three years.

Researchers warned that while a single year above the 1.5-degree threshold does not mean the Paris target has formally been breached, the rapidly shrinking carbon budget indicates that the world is moving steadily toward that outcome.

Earth’s energy imbalance hits record levels

The report also found that Earth’s energy imbalance — the gap between incoming solar energy and the energy radiated back into space — has reached a record high.

Under stable climatic conditions, that balance remains close to zero. Today, however, excess heat is accumulating in the climate system at an accelerating pace due to rising greenhouse gas concentrations.

Scientists also noted that declining aerosol pollution, while beneficial for human health, has reduced the amount of sunlight reflected back into space, removing part of the atmosphere’s temporary cooling effect.

Much of the excess heat is being absorbed by the oceans. Global sea levels have risen by about 23 centimetres since 1901, while the rate of rise has accelerated to nearly 3.84 millimetres annually.

For the first time, the report included marine heatwaves as a core climate indicator. It found that the average number of marine heatwave days has more than tripled since 1991, reaching roughly 65 days in 2025.

Concerns over climate monitoring systems

The scientists also raised concerns about the future of climate observation networks, which rely on satellites, weather stations, ships, aircraft, ocean buoys and weather balloons to monitor changes across the planet.

According to the report, several monitoring programmes face growing financial and operational pressures. Researchers pointed to budget constraints affecting international observation efforts and warned that reductions in ocean-monitoring systems could weaken scientific understanding of climate change.

The report also highlighted declining ground-based observations in parts of Africa, South America and the Pacific, raising concerns about emerging data gaps in regions already vulnerable to climate impacts.

A warning as climate talks continue

The assessment comes as governments gather for mid-year UN climate negotiations in Bonn, Germany, where countries are preparing updated emissions-reduction commitments.

Despite fluctuations caused by natural climate cycles, the report’s central message is clear: human activity remains the overwhelming driver of global warming, and greenhouse gas emissions continue to push the planet toward higher temperatures.

For scientists, the latest findings underline a narrowing window to meet the most ambitious climate goals, with each year of continued emissions making the challenge more difficult.