Record warmth only possible due to human-caused emissions
30 October 2025
Record global warmth may be causing the planet’s natural carbon sinks to absorb fewer emissions than expected, a new report warns.
Launching today (Thursday, 30 October) ahead of COP30, the study distils the latest advances in climate science from the past 18 months into ten concise insights.
Produced by 70 globally renowned scientists from 21 countries, including experts from the University of Reading, the annual 10 New Insights in Climate Science (10 New Insights) report reveals that weaker land sinks, especially forests and soils in the Northern Hemisphere, threaten to derail today’s emissions projections while accelerating global warming.
Professor Richard Allan, University of Reading, worked on Insight 1, which examined the record warmth in 2023 and 2024. He said: " The record global warmth in 2023 and 2024 was made possible by rising greenhouse gases and declining aerosol particle pollution. While cleaning up our air is important for health, it is causing clouds to lose an artificially boosted “shiny mirror” effect, adding to the heat trapped by rising greenhouse gases. Rapid and massive cuts in greenhouse gas emissions are essential for limiting further warming and the growing impacts of climate change on societies and ecosystems."
Professor Chris Merchant, University of Reading, collaborated on Insight 2, which looked at recent upticks in sea surface warming and intensifying marine heatwaves. He said: "The ocean has been breaking temperature records month after month, and marine heatwaves are lasting longer and hitting harder than ever before. This isn't just bad news for fish and coral reefs—it affects all of us. Warmer oceans fuel fiercer storms, disrupt fishing industries worth billions, and reduce the ocean's ability to absorb the carbon dioxide we emit."
The report also:
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Finds the large-scale deployment of nature-based removals could come at a cost to food security and biodiversity, as these projects compete with both for land space.
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Examines the factors contributing to the record warmth of 2023 and 2024, with extreme heat placing unprecedented pressure on freshwater resources, human health and livelihoods.
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Explains how heat stress is driving a sharp decline in labour productivity, impacting incomes and leading to wider economic instability. For example, just 1°C of warming is expected to expose more than 800 million people in tropical regions to unsafe levels of heat stress, potentially reducing their working hours by as much as 50%.
The study comes as negotiators prepare for COP30, taking place ten years after the Paris Agreement and amid a new wave of updated climate targets from countries worldwide. The report concludes that nearly every major climate risk stems from one root cause – the failure to cut emissions at the speed and scale required. Relying on nature and markets alone will not solve the crisis. Record-breaking temperatures in 2023 and 2024, faster recent ocean warming, and the growing strain on ecosystems and societies are all symptoms of delayed action.
Full list of 10 insights:
1. Record warming 2023/24: Evidence on the drivers behind recent global temperature
jumps suggests a possible acceleration of global warming.
2. Accelerated ocean warming: Rapid ocean warming and intensifying marine heatwaves
are harming ecosystems and increasing extreme weather risks.
3. Strain on land carbon sinks: Global land carbon sinks are showing signs of stress as the
planet continues to warm.
4. Climate–biodiversity feedback: Biodiversity loss and climate change reinforce each
other in a destabilising loop.
5. Declining groundwater levels: Climate change is accelerating groundwater depletion,
increasing risks to agriculture and urban settlements.
6. Climate-driven dengue outbreaks: Rising temperatures are creating more favourable
conditions for the mosquitoes that spread dengue, driving the disease’s geographical
spread and intensity.
7. Impacts on labour productivity: Increasing heat stress is projected to reduce working
hours and economic output.
8. Scaling carbon dioxide removal (CDR): Scaling CDR responsibly is essential, but with a
focus on hard-to-abate emissions and limiting climate overshoot.
9. Carbon market integrity challenges: Strengthening standards and transparency in
voluntary carbon markets is needed to ensure real mitigation benefits.
10. Effective policy mixes: Carefully designed policy mixes are more effective than single
measures in achieving deep and lasting emission cuts.
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