Every year, understanding of climate science grows stronger.

With each new research project and published paper, scientists learn more about how the Earth system responds to continuing greenhouse gas emissions.

But with many thousands of new studies on climate change being published every year, it can be hard to keep up with the latest developments.

Our annual “10 new insights in climate science” report offers a snapshot of key advances in the scientific understanding of the climate system.

Produced by a team of scientists from around the world, the report summarises influential, novel and policy-relevant climate research published over the previous 18 months.

The insights presented in the latest edition, published in the journal Global Sustainability, are as follows:

1. Questions remain about the record warmth in 2023-24
2. Unprecedented ocean surface warming and intensifying marine heatwaves are driving severe ecological losses
3. The global land carbon sink is under strain
4. Climate change and biodiversity loss amplify each other
5. Climate change is accelerating groundwater depletion
6. Climate change is driving an increase in dengue fever
7. Climate change diminishes labour productivity
8. Safe scale-up of carbon dioxide removal is needed
9. Carbon credit markets come with serious integrity challenges
10. Policy mixes outperform stand-alone measures in advancing emissions reductions

In this article, we unpack some of the key findings.

A strained climate system

The first three insights highlight how strains are growing across the climate system, from indications of an accelerating warming and record-breaking marine heatwaves, to faltering carbon sinks.

Between April 2023 and March 2024, global temperatures reached unprecedented levels – a surge that cannot be fully explained by the long-term warming trend and typical year-to-year fluctuations of the Earth’s climate. This suggests other factors are at play, such as declining sulphur emissions and shifting cloud cover.

(For more, Carbon Brief’s in-depth explainer of the drivers of recent exceptional warmth.)

Ocean heat uptake has climbed as well. This has intensified marine heatwaves, further stressing ecosystems and livelihoods that rely on fisheries and coastal resources.

The exceptional warming of the ocean has driven widespread impacts, including massive coral bleaching, fish and shellfish mortality and disruptions to marine food chains.

The map below illustrates some of the impacts of marine heatwaves from 2023-24, highlighting damage inflicted on coral reefs, fishing stocks and coastal communities.

Land “sinks” that absorb carbon – and buffer the emissions from human activity – are under increasing stress, too. Recent research shows a reduction in carbon stored in boreal forests and permafrost ecosystems.

The weakening carbon sinks means that more human-caused carbon emissions remain in the atmosphere, further driving up global temperatures and increasing the chances that warming will surpass the Paris Agreement’s 1.5C limit.

This links to the fourth insight, which shows how climate change and biodiversity loss can amplify each other by leading to a decrease in the accumulation of biomass and reduced carbon storage, creating a destabilising feedback loop that accelerates warming.

New evidence demonstrates that climate change could threaten more than 3-6 million species and, as a result, could undermine critical ecosystem functions.

For example, recent projections indicate that the loss of plant species could reduce carbon sequestration capacity in the range of 7-145bn tonnes of carbon over the coming decades. Similarly, studies show that, in tropical systems, the extinction of animals could reduce carbon storage capacity by up to 26%.

Human health and livelihoods

Growing pressure on the climate system is having cascading consequences for human societies and natural systems.

Our fifth insight highlights how groundwater supplies are increasingly at risk.

More than half the global population depends on groundwater – the second largest source of freshwater after polar ice – for survival.

But groundwater levels are in decline around the world. A 2025 Nature paper found that rapid groundwater declines, exceeding 50cm each year, have occurred in many regions in the 21st century, especially in arid areas dominated by cropland. The analysis also showed that groundwater losses accelerated over the past four decades in about 30% of regional aquifers.  

Changes in rainfall patterns due to climate change, combined with increased irrigation demand for agriculture, are depleting groundwater reserves at alarming rates.

The figure below illustrates how climate-driven reductions in rainfall, combined with increased evapotranspiration, are projected to significantly reduce groundwater recharge in many arid regions – contributing to widespread groundwater-level declines.

These losses threaten food security, amplifying competition for scarce resources and undermining the resilience of entire communities.

Human health and livelihoods are also being affected by changes to the climate.

Our sixth insight spotlights the ongoing and projected expansion of the mosquito-borne disease dengue fever.

Dengue surged to the largest global outbreak on record in 2024, with the World Health Organization reporting 14.2m cases, which is an underestimate because not all cases are counted.

Rising temperatures are creating more favourable conditions for the mosquitoes that carry dengue, driving the disease’s spread and increasing its intensity.

The chart below shows the regions climatically suitable for Aedes albopictus (blue line) and Aedes aegypti (green line) – the primary mosquitoes species that carry the virus – increased by 46.3% and 10.7%, respectively, between 1951-60 and 2014-23.

The maps on the right reveal how dengue could spread by 2030 and 2050 under an emissions scenario broadly consistent with current climate policies. It shows that the climate suitable for the mosquito that spreads dengue could expand northwards in Canada, central Europe and the West Siberian Plain by 2050.

The ongoing proliferation of these mosquito species is particularly alarming given their ability to transmit the zika, chikungunya and yellow fever viruses.

Heat stress is also a growing threat to labour productivity and economic growth, which is the seventh insight in our list.

For example, an additional 1C of warming is projected to expose more than 800 million people in tropical regions to unsafe heat levels – potentially reducing working hours by up to 50%.

At 3C warming, sectors such as agriculture, where workers are outdoors and exposed to the sun, could see reductions in effective labour of 25-33% across Africa and Asia, according to a recent Nature Reviews Earth & Environment paper.

Meanwhile, sectors where workers operate in shaded or indoor settings could also face meaningful losses. This drain on productivity compounds socioeconomic issues and places a strain on households, businesses and governments.

Low-income, low-emitting regions are set to shoulder a greater relative share of the impacts of extreme heat on economic growth, exacerbating existing inequalities.

Action and policy

Our report illustrates not only the scale of the challenges facing humanity, but also some of the pathways toward solutions.

The eighth insight emphasises the critical role of carbon dioxide removal (CDR) in stabilising the climate, especially in “overshoot” scenarios where warming temporarily surpasses 1.5C and is then brought back down.

Scaling these CDR solutions responsibly presents technical, ecological, justice, equity and governance challenges.

Nature-based approaches for pulling carbon out of the air – such as afforestation, peatland rewetting and agroforestry – could have negative consequences for food security, biodiversity conservation and resource provision if deployed at scale.

Yet, research has suggested that substantially more CDR may be needed than estimated in the scenarios used in the Intergovernmental Panel on Climate Change (IPCC’s) last assessment report.

Recent findings showed that a pathway where temperatures remain below 1.5C with no overshoot would require up to 400Gt of cumulative CDR by 2100 in order to buffer against the effect of complex geophysical processes that can accelerate climate change. This figure is roughly twice the amount of CDR assessed by the IPCC.

This underscores the need for robust international coordination on the responsible scaling of CDR technologies, as a complement to ambitious efforts to reduce emissions. Transparent carbon accounting frameworks that include CDR will be required to align national pledges with international goals.

Similarly, voluntary carbon markets – where carbon “offsets” are traded by corporations, individuals and organisations that are under no legal obligation to make emission cuts – face challenges.

Our ninth insight shows how low-quality carbon credits have undermined the credibility of these largely unregulated carbon markets, limiting their effectiveness in supporting emission reductions.

However, emerging standards and integrity initiatives, such as governance and quality benchmarks developed by the Integrity Council for Voluntary Carbon Markets, could address some of the concerns and criticism associated with carbon credit projects.

High-quality carbon credits that are verified and rigorously monitored can complement direct emission reductions.

Finally, our 10th insight highlights how a mix of climate policies typically have greater success than standalone measures.

Research published in Science in 2024 shows how carefully tailored policy packages – including carbon pricing, regulations, and incentives – could consistently achieve larger and more durable emission reductions than isolated interventions.

For example, in the buildings sector, regulations that ban or phase out products or activities achieve an average effect size of 32% when included in a policy package, compared with 13% when implemented on their own.

Importantly, policy mixes that are tailored to the country context and with attention to distributional equity are more likely to gain public support.

These 10 insights in our latest edition highlight the urgent need for an integrated approach to tackling climate change.

The science is clear, the risks are escalating – but the tools to act are available.

Analysis: What are the causes of recent record-high global temperatures?

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The post Guest post: 10 key climate science ‘insights’ from 2025 appeared first on Carbon Brief.

Guest post: 10 key climate science ‘insights’ from 2025