At Bonn Conference, Scientists Warn 1.5°C Threshold Could Be Breached in Four Years
The report says that at the current emissions rate, the carbon budget will be exhausted slightly over the next three years
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A new Indicators of Global Climate Change (IGCC) report found that human activities have pushed warming to 1.37˚C in 2025, with global temperatures projected to surpass 1.5°C in about four years.
The report that was unveiled at the Bonn Conference highlighted that global greenhouse gas (GHG) emissions are at an all-time high, reaching 56.8 billion tonnes of carbon dioxide equivalent emissions (CO2e) in 2024, mainly from the burning of fossil fuels.
The annual report assessment was prepared by more than 70 climate scientists from 56 institutions across 17 countries. Scientists said that one of the most alarming findings of the report was the rapid increase in the Earth’s Energy Imbalance (EEI) which is a measure of how much more energy the planet absorbs than it emits back into space.
Professor Piers Forster, Director of the Priestley Centre for Climate Futures at the University of Leeds and lead author, said, “A key indicator is the Earth's energy imbalance, which measures how fast heat is accumulating in the climate system, and provides a crucial measure of the pace of climate change. Without human influence, it should be close to zero, but it has been growing since the 1970s and is now at a record high, doubling in recent decades.”
The report noted that Earth's energy imbalance has more than doubled in recent decades, indicating that excess heat is accumulating across the oceans, land, and cryosphere at an accelerating pace.Forster at the report launch said, “It potentially points to higher climate sensitivity and potentially to very strong temperature increases to come."
The study estimated that the remaining carbon budget for limiting warnings to 1.5°C has fallen to just 130 billion tonnes of CO2 in the beginning of 2026. At the current emissions rate, the carbon budget will be exhausted slightly over the next three years. Scientists also estimated that at the current emissions level, global temperatures will likely cross 1.5°C around 2030.
“Human-induced global warming has now reached 1.37°C and continues to rise rapidly, coming ever closer to 1.5°C of global warming. Given th by hat greenhouse gas emissions are still on the rise, keeping global warming below this threshold now seems unachievable,” said Dr. Aurélien Ribes, Climate scientist at Météo-France, France.
Greenhouse Gas Emission at All Time High
Global greenhouse gas emissions reached 56.8 billion tonnes of carbon dioxide equivalent in 2024, the highest level recorded so far. The report noted that fossil fuel combustion remained the dominant source of emissions, although the rate of growth has slowed compared with the 2000s.
Scientists described this as one of the few encouraging signals emerging from the data "We're not yet at peak greenhouse gas emissions, but the rate of increase has been slowing down," Chris Smith, senior research scholar at the International Institute for Applied Systems Analysis (IIASA), said during the launch.
Experts stressed that slowing emissions growth is not the same as reducing emissions.
"The concentration in the atmosphere continues to rise," Smith said. "These indicators are not just a scientific scorecard; they are a real-time feedback system on global climate policy."
Oceans are Absorbing Excess Heat Generated by Greenhouse Gases
The report highlighted growing evidence that oceans are absorbing much of the excess heat generated by greenhouse gases. For the first time, the assessment included marine heatwave days as a climate indicator. It found that the number of marine heatwave days has more than tripled globally since 1991.
The planet experienced 65 marine heatwave days in 2025 alone, following a record 82 days in 2024. Scientists said prolonged marine heatwaves threaten fisheries, marine biodiversity, coastal economies and natural coastal protection systems.
At the same time, global sea levels reached a record 23 centimetres above 1901 levels, with the rate of rise continuing to accelerate due to ocean warming and melting land ice.
Climate Monitoring is Under Threat
Researchers warned that the scientific infrastructure underpinning climate monitoring is increasingly vulnerable. The report relied on more than 40 global datasets sourced from satellites, ships, buoys, and weather stations. Scientists cautioned that funding cuts, geopolitical instability and weakening observation networks could undermine future climate assessments.
"Just when we need to monitor the Earth system the most, the observations and the global programmes that coordinate them are imperilled," said Peter Thorne, professor at Maynooth University and deputy chair of the Global Climate Observing System.