Human contribution to global warming highest ever in 2025, says study
Here's a climate report you should file away carefully. The Indicators of Global Climate Change study, the IGCC, found that 2025 was the third warmest year on record, about 1.39 degrees Celsius above the 1850 to 1900 baseline. Now the striking part, 1.37 degrees of that warming came from human activity, mainly greenhouse gas emissions, the highest human contribution ever recorded. The study backs the World Meteorological Organisation's earlier estimate, and many of its authors also contribute to the IPCC. So for your CLAT prep, just remember IGCC, 1.39 degrees total, 1.37 degrees human-caused, and 2024 still standing as the warmest year ever.
At a time when global political attention toclimate changeappears to be receding, a new assessment has confirmed earlier estimates that 2025 was the third warmest year on record. Importantly, this annual study, called the Indicators of Global Climate Change or IGCC, found that the contribution of human activities to the overall warmingobserved in 2025 was possibly the highest ever.
The IGCC study, first published in 2023, is the work of an independent international group of climate scientists which includes several contributors to the Intergovernmental Panel on Climate Change (IPCC) that produces periodic reports on the state of climate change, which are considered the most authoritative word on the subject.
The latest IGCC study said average global temperatures in 2025 were about 1.39 degree Celsius higher than the average of 1850-1900 baseline. Of the total increase, it said 1.37 degree Celsius was due to human activities, primarily greenhouse gas emissions, while the rest could be the result of natural variations in climate systems.
The IGCC study, published in the peer-reviewed open access journal called Earth System Science Data, confirms the earlier estimate of the World Meteorological Organisation (WMO) which, in January this year, had said that 2025 was likely to emerge as the third warmest year, after 2024 and 2023. WMO had said the average global temperatures in 2025 were likely to be 1.44 degree Celsius above the 1850-1900 baseline.
The warmest-ever year, 2024, was about 1.55 degree Celsius hotter than the 1850-1900 baseline. That year, human activities had contributed about 1.36 degree Celsius of warming, according to the IGCC study for 2024, the rest being attributed to natural variations. The year 2023 was about 1.45 degree Celsius warmer than 1850-1900 baseline. Human contribution that year was assessed to be about 1.31 degree Celsius.
For 2025, the contribution of human activities to global warming is possibly the highest ever, but the scale of natural variations in climate differ from year to year. 2025 happened to be a La Nina year, a year in which the equatorial Pacific Ocean, off the western coast of South America, was cooler than normal. La Nina is known to have a general cooling effect on the planet. This could have been the reason why the year, despite the potentially record-breaking contribution of human-induced warming, was slightly cooler than 2024 and 2023.
The ongoing climate meet in Germany has proposed a global commitment to ensure that electricity accounts for at least 35% of final energy consumption by 2035. Currently, it accounts for 20% of global energy consumption. This is a key step towards the transition from fossil fuels.
The IGCC study said human-induced warming had been increasing at the rate of about 0.27 degree Celsius per decade, as a result of record levels of greenhouse gas emissions. It found that greenhouse gas emissions had reached 56.8 billion tonnes of carbon dioxide equivalent in 2025, an all-time high.
It said the world could emit no more than 130 billion tonnes of additional carbon dioxide from the start of 2026, if it entertained any hopes of restricting global rise in temperatures to within 1.5 degree Celsius from the 1850-1900 baseline. At current rate of emissions, this ‘carbonbudget’ would be exhausted in less than three years.
The IGCC study is being released in a week when countries are assembled in Bonn, Germany, for the annual mid-year climate talks. The discussions are centred mainly around ways to increase the ambition of climate action which has suffered a major blow due to the withdrawal of the United States from the 2015 Paris Agreement last year. Global climate action has been unable to keep pace with the requirement to significantly cut greenhouse gas emissions in the near term.
The findings of the IGCC study are a further reminder to the rapidly rising global temperatures. Just last month, a WMO study said there was a 91 per cent chance that at least one of the next five years, between 2026 and 2030, would break the 1.5 degree Celsius threshold, just like 2024 did. It further said that there was a 75 per cent possibility that the average temperature of this five-year period also exceeded 1.5 degree Celsius level from the 1850-1900 baseline.
This year, a strong El Nino is predicted to develop in the equatorial Pacific Ocean. El Ninos have the opposite effect of La Nina, and generally have a warming impact over the planet. This year’s El Nino is expected to persist not just through the end of the year, but possibly also continue into early next year.