CO2 to hit record in 2025, key temperature limit could be reached in 4 years: Study

(Photo credit: AFP)

Source: The Straits Times

For the UN’s top climate science body, 2025 is a key year. This is the year global greenhouse gas emissions must start to fall and then decline rapidly to limit the severity of climate change.

Instead, global carbon dioxide (CO2) emissions from burning planet-warming fossil fuels are predicted to reach another record in 2025, a study released on Nov 13 found.

Humanity is hurtling towards the key Paris Agreement temperature limit of 1.5 deg C above pre-industrial levels. And it will do so with just four more years of CO2 emissions at current levels, the authors said in their report, which was released during the ongoing COP30 UN climate talks in Belem, Brazil.

The study by the Global Carbon Project (GCP), an international scientific consortium, predicts CO2 emissions from burning coal, oil and gas will hit 38.1 billion tonnes in 2025, up 1.1 per cent from 2024. Emissions also increased 1.1 per cent in 2024 versus 2023.

Emissions are projected to grow in the US and the European Union, reversing their long-term declining trends. But emissions growth is expected to slow in China and India on lower demand for polluting coal, the world’s top source of CO2.

“Global fossil fuel CO2 emissions have been persistently hovering around 1 per cent (growth) per year for the last few years,” said GCP executive director Pep Canadell.

The GCP analysis, in its 20th year, is produced by more than 100 scientists from dozens of scientific institutes across the globe.

“However, we do find clear signs of slower growth from some of the major emitters, including China, and real declines in many other medium to small emitters. It is now very possible that over the next few years (three to five years), we will reach global peak emissions,” Dr Canadell told The Straits Times.

But that is too slow, especially as the impacts of climate change are worsening and being felt across the globe, from more deadly hurricanes and typhoons to severe floods and heatwaves. Each year of adding large amounts of CO2 to the atmosphere is literally fanning the flames of global warming, scientists say.

The UN’s top science body, the Intergovernmental Panel on Climate Change, has said that greenhouse gas emissions need to halve by 2030 from 2019 levels. “Without immediate and deep emissions reductions across all sectors, limiting global warming to 1.5 deg C is beyond reach,” it said.

But the reverse is happening.

The authors project CO2 emissions growth in 2025 will be driven by increased consumption of coal, oil and gas. Emissions from gas will rise the most, by 1.3 per cent above 2024 levels, returning to the persistent growth trend before the Russian invasion of Ukraine.

Despite rapid expansion of renewable energy such as wind, solar and battery storage, this still cannot meet all of the rising energy demand and explains why emissions continue to increase, Dr Canadell said. Add to this growing populations and increasing demand for electricity in many countries where demand has been stable for the past one to two decades.

This includes the rapid expansion of power-hungry data centres, electrification of transport and household appliances.

Investment in data centres is expected to reach US$580 billion (S$754 billion) in 2025, surpassing the US$540 billion invested in global oil supply in 2025, the International Energy Agency said on Nov 12.

The US, the world’s second top CO2 emitter, is projected to see carbon pollution increase by 1.9 per cent, due partly to colder weather, a switch to cheaper coal, and rising demand for electricity, for instance, to supply data centres. EU emissions are predicted to rise 0.4 per cent on higher demand for gas.

“The most significant positive news of this year’s carbon budget is the slower emissions growth in China and India, given their first and third positions in the ranking of top global emitters,” said Dr Canadell. China accounts for 32 per cent of all fossil fuel CO2 emissions and India, 8 per cent.

In 2025, China’s emissions are expected to rise 0.4 per cent compared with 0.7 per cent in 2024, due to moderate growth in energy consumption and rapid expansion in renewable energy investment and electric vehicle sales. This means coal consumption is stagnant.

China is by far the largest investor in renewable energy, and it added 231 gigawatts (GW) of solar and 58GW of wind capacity between January and August 2025. Zero-emission power is now 41 per cent of generation, according to Sydney-based think-tank Climate Energy Finance. But China is also still building coal-fired power plants.

India’s CO2 emissions are projected to rise 1.4 per cent versus 4 per cent in 2024, on lower demand for coal. This is due in part to an early monsoon and high rainfall substantially reducing cooling requirements in May and June, the hottest months of the year, as well as strong growth in renewables.

The study also shows that 35 economies (representing 27 per cent of global fossil fuel emissions) have decreased their fossil fuel CO2 emissions significantly while growing their economies during the 2015 to 2024 decade. These include Australia, France, New Zealand, South Korea, Taiwan and Thailand.

This is double the number of economies compared with the previous decade of 2005 to 2014.

Land “sinks”, such as forests, soils and grasslands, are also expected to soak up more CO2 from the atmosphere in 2025 after recovering from the disruptions caused by the 2023 to 2024 El Nino event that pushed up global temperatures and helped fuel more extreme wildfires.

The planet has natural pathways that absorb CO2 from the atmosphere. Plants, for example, need CO2 to photosynthesise and grow, locking the carbon in their trunks, roots and shoots. In total, the land and ocean have absorbed 21 per cent and 29 per cent of humanity’s CO2 emissions, respectively, over the past decade, the analysis says.

But land use change and degradation, such as deforestation and fires, will still add a further 4.1 billion tonnes to humankind’s CO2 tally, bringing the total for 2025 to 42.2 billion tonnes.

And that is a huge problem because it means humanity is rapidly running out of time to limit more extreme climate change.

“The remaining carbon budget to limit global warming to 1.5 deg C is virtually exhausted,” the authors said. “With a warming of the planet attributed to human activities of 1.36 deg C in 2024, the remaining budget for 1.5 deg C is 170 billion tonnes of CO2, equivalent to four years at the 2025 emissions levels.”

“The breaching of the 1.5 deg C stabilisation target is no longer a risk. It is now unavoidable and coming at full speed,” Dr Canadell said.