In 2025, greenhouse gas emissions produced by human activities turned what should have been a cooler year into one of the hottest ever, fuelling more dangerous and frequent heatwaves, droughts, storms and wildfires, climate scientists said in an annual report.
Planet-heating emissions primarily caused by burning fossil fuels pushed temperatures this year to “extremely high” levels, worsening extreme weather with devastating consequences – especially for the world’s most vulnerable, concluded scientists working with the World Weather Attribution (WWA) group.
Despite the return of La Niña – a climate pattern linked to large-scale cooling of the Pacific Ocean, which can temporarily bring milder global temperatures – the EU monitoring service Copernicus has said 2025 is “virtually certain” to end as the second- or third-warmest year on record.
In its report released on Tuesday, the WWA research group found that climate change made 17 of the 22 extreme weather events it assessed this year more severe or more likely, while its remaining studies were inconclusive, mostly due to a lack of weather data from remote areas.
Ranging from heatwaves in South Sudan and Western Europe to extreme rainfall in Southeast Asia and wildfires in Los Angeles, those disasters killed thousands of people and displaced millions from their homes.
11 extra hot days since Paris Agreement
Theodore Keeping, a researcher at Imperial College London, said the catastrophic wildfires, record-breaking rainfall, unprecedented temperatures and devastating hurricanes seen in the last 12 months provide “undeniable evidence” of a rapidly changing global environment.
“We are living in the climate that scientists warned about a decade ago, when the Paris Agreement was signed,” he added.
Since the landmark accord was adopted in 2015, global average temperatures have risen by about 0.3C, and the world now experiences an average of 11 additional hot days each year, according to WWA’s research.
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UN accepts overshooting 1.5C warming limit – at least temporarily – is “inevitable”
UN chief António Guterres says the world’s temperature will rise by more than 1.5C over pre-industrial levels but can be brought down
For the first time, global average temperatures over the last three years are on track to exceed 1.5C, the most ambitious goal governments agreed in Paris, according to the EU’s Copernicus service. The UK’s Met Office expects 2026 to be between 1.34C and 1.58C hotter than preindustrial levels.
“The continuous rise in greenhouse gas emissions has pushed our climate into a new, more extreme state, where even small increases in global temperatures now trigger disproportionately severe impacts,” said Sjoukje Philip, a researcher at the Royal Netherlands Meteorological Institute (KNMI). “We are entering a new era of climate extremes, where what was once an anomaly is quickly becoming the norm,” she added.
Silent-killer heatwaves
While heatwaves don’t leave a visible trail of destruction and often go underreported, the research group found they were the deadliest extreme weather event of 2025. One study estimated that climate change more than tripled the number of deaths caused by searing temperatures recorded across Europe this summer.
In South Sudan, extreme heat forced schools to close for two weeks in February 2025 after dozens of children collapsed with heatstroke. Human-made climate change made that heatwave 4C hotter and transformed an exceptionally rare event into a common one, now expected to happen every other year in South Sudan, a WWA assessment found.
Keeping of Imperial said the impacts are disproportionately shouldered by women and girls who predominantly work in sectors with high heat exposure such as agriculture and street-vending.
Flood risks rise as adaptation limits near
Floods were the disasters most studied by the WWA team in 2025, with devastating downpours made worse by climate change hitting Pakistan, Sri Lanka and Indonesia, the Mississippi River Valley in the US and Botswana.
In the Southern African nation, spells of extreme rainfall are becoming more frequent within a single year, while the rapid expansion of urban centres without adequate infrastructure upgrades makes them more susceptible to severe flooding, according to WWA.
The research group said this underscores the urgency of investing in measures to adapt to a warming world which can prevent many deaths and widespread destruction but remain critically underfunded.
However, the scientists also warned that even strong efforts to prepare for disasters cannot prevent all impacts, as climate change is already pushing millions close to the “limits of adaptation”.
“Jamaica was in a state of preparedness for Hurricane Melissa five days before landfall,” noted Keeping, “but when such an intense storm hits a small island nation in the Caribbean, even high levels of preparedness cannot prevent extreme losses and damages”.
Fossil fuel dependency is “costing lives”
Hurricane Melissa caused an estimated $8.8 billion in physical damage in Jamaica, equal to 41% of the country’s 2024 GDP, with only a small share of the losses expected to be covered by innovative insurance schemes.
In their report, WWA researchers said that drastically reducing fossil fuel emissions remains the key policy to prevent the worst climate impacts.
“Decision-makers must face the reality that their continued reliance on fossil fuels is costing lives, billions in economic losses, and causing irreversible damage to communities worldwide,” said Friederike Otto, WWA’s co-founder.
The post “New era of climate extremes” as global warming fuels devastating impacts in 2025 appeared first on Climate Home News.
“New era of climate extremes” as global warming fuels devastating impacts in 2025
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The planet is heating up more quickly than ever before.
For decades, greenhouse gas emissions caused by human activity have been building up in the atmosphere and trapping ever-higher levels of heat.
The resulting asymmetry between incoming solar energy and energy radiated back out into space – known as “Earth’s energy imbalance” – provides a direct measure of the extent to which humans are disrupting the Earth’s climate system.
This imbalance is growing and in 2025 its 10-year average reached a record high, indicating that global temperatures could increase at even higher rates in the future.
This is among the headline findings of the latest “indicators of global climate change” (IGCC) report, published in the journal Earth System Science Data, which tracks changes in the climate system on an annual basis.
The report, now in its fourth iteration, has been produced by dozens of scientists from around the world.
Its findings are designed to fill the gap between Intergovernmental Panel on Climate Change (IPCC) science reports, which are published every 5-7 years.
In this article, we unpack the IGCC report, which explores how human activity is driving a growing energy imbalance and why monitoring systems to track global climate are so crucial.
(For more on previous IGCC reports, see Carbon Brief’s coverage in 2023, 2024 and 2025.)
Greenhouse gas emissions remain at an all-time high
Global greenhouse gas emissions are continuing to increase, mostly as a result of the use of fossil fuels. However, deforestation, agriculture and industrial processes also play an important role.
Over the most recent decade (2015-24), emissions stood at the equivalent of 54.6bn tonnes of carbon dioxide equivalent (GtCO2e) per year. In 2024, the most recent year for which we have complete data, emissions reached 56.8GtCO2e.
As the chart below shows, these emissions have pushed up atmospheric levels of CO2, methane and nitrous oxide. In 2025, concentrations of these gases reached 425.6 parts per million (ppm), 1936.3 parts per billion (ppb) and 339.4ppb, respectively.
This represents a rise of 3.8%, 3.8% and 2.2%, respectively, since the 2019 levels reported in the IPCC’s sixth assessment report (AR6).
At the same time, declines in emissions of aerosols such as sulphur dioxide, partly as a result of efforts to tackle air pollution, are increasing the Earth’s energy imbalance. This is because aerosols have a cooling effect on the Earth’s climate, counteracting warming from CO2 and other greenhouse gas emissions.
(Tackling sulphur dioxide, alongside other particulate emissions, remains critical because the immediate health and environmental damage they cause far outweighs their short-term cooling effect on the climate.)
The Earth’s energy imbalance is rising rapidly
The Earth’s energy imbalance has long been recognised as a key indicator of how the climate is being affected by human activities.
However, it is only in the last few decades that scientists have been able to record temperature changes deep enough in the ocean to accurately quantify it.
Earth’s energy imbalance measures how quickly excess heat is accumulating in every part of the Earth system, primarily in the ocean, but also in land, ice and atmosphere.
Through this accumulation of heat, the energy imbalance influences the rate of sea level rise and ice melt across the world, as well as increasing the frequency and intensity of extreme weather events, such as storms, floods and droughts.
Without human influence, the Earth’s energy imbalance would be close to zero.
But, as greenhouse gas emissions have built up in the atmosphere, the imbalance has been growing since the 1970s. Recent increases to Earth’s energy imbalance have outpaced those projections made by climate models — indicating the planet could see more warming than expected in the future.
As the right-hand chart below shows, the imbalance is now at a record high, having more than doubled over the past two decades.
It has increased by around 40% since 2019, from an average 0.79 watts per square metre (Wm2) over 2006-18, according to IPCC AR6, to 1.12Wm2 over 2013-25.
The left-hand chart shows how heat is accumulating in the ocean (blues), ice (grey), land (orange) and atmosphere (purple).
Global temperature rise
The excess heat building up in the climate system from the energy imbalance is pushing up global temperatures at a record rate of 0.27C per decade.
We estimate that human-induced warming – the amount of observed global surface
temperature increase attributable to both the direct and indirect effects of human activities – reached 1.37C in 2025. This has risen from 1.0C in 2017, as reported in IPCC AR6.
While natural variability in the climate system – such as El Niño or La Niña events – can also influence temperatures year-to-year, the upward temperature trend we are seeing is being driven by the persistent imbalance in energy.
We now expect global temperatures to exceed the Paris Agreement limit of 1.5C above pre-industrial levels around the year 2030.
This is significant because 1.5C has been identified as the critical dividing line between manageable climate risks and catastrophic, potentially irreversible damage to global ecosystems and human societies.
Heat accumulating throughout the Earth system
While heat is accumulating throughout the Earth system, it is not being distributed evenly around the globe.
Since the 1970s, around 90% of this heat has been taken up by the ocean, affecting marine ecosystems, ocean circulation patterns, sea level rise and climate extremes.
For example, the number of marine heatwave days – periods of unusually high sea surface temperatures – has more than tripled globally since the early 1990s. The year 2025 alone saw 65 days of marine heatwaves – meaning they occurred, on average, more than one day a week.
Meanwhile, the cryosphere – the portion of the Earth made up of frozen water, including glaciers, ice sheets and permafrost – is experiencing widespread ice loss and thawing in response to the growing energy imbalance. This affects ecosystems, sea level rise and infrastructure in polar and high-latitude regions.
Rapid warming has also resulted in record extreme temperatures over land, with average maximum temperatures for any single day over 2016-25 around 1.92C above pre-industrial levels). This is an increase of almost half a degree compared to the previous decade (2006-15).
Sea level rise and the energy imbalance
Sea level rise provides one of the clearest long-term signals of a changing planet.
It is closely linked to Earth’s energy imbalance. As heat accumulates in the ocean, water expands, raising sea levels. Meanwhile, a warming land and atmosphere means addition of water to the oceans through melting of glaciers and ice sheets, also adding to sea level rise.
Over the long-term, sea levels have been rising, on average, at a rate of around 1.8mm per year since 1901, totalling a record 23cm in 2025. This is increasing the risk of coastal flooding, erosion and habitat loss in many low-lying areas around the world.
This rise can be seen in the left-hand chart below, which shows observed global sea level changes from tide gauges (grey and blue dashed lines) and satellites (red dashed lines) since 1901. The solid lines indicate the average across multiple datasets.
Sea level rise is accelerating consistent with the observed increase in Earth’s energy imbalance. Over 2006-25, sea levels have risen at a rate of 3.67mm per year – more than double the rate of 1.69mm per year seen over 1976-95.
This increasing rate is shown in the right-hand figure below, which shows four successive overlapping 20-year periods and the most-recent decade.
(Last year’s transition from El Niño to weak La Niña conditions affected global rainfall patterns and led to a small and temporary fall in global average sea level in 2025. This explains the slight decrease in rate of sea level rise for the most recent decade, which is affected more than the 20-year period 2006-25.)
The bigger picture
Despite greenhouse gas emissions not increasing as rapidly as in the 2000s, this year’s IGCC findings continue to show how far and how fast the climate is changing due to human activity.
A significant increase in decarbonisation efforts in the second half of this decade is required to slow down the rate of human-caused warming and limit the escalation of climate risks and impacts.
These findings, like many others produced by scientists across the globe, rely on international expertise, partnership and the maintenance and availability of global climate datasets and the global observing programmes that underpin them.
This year’s edition of IGCC used more than 40 global datasets produced by research teams around the world, including the NASA satellite record of the Earth’s energy imbalance and the ARGO deep ocean float network.
However, a number of long-term monitoring programmes could be threatened by funding decisions made by governments around the world, most notably the Trump administration in the US.
Local meteorological data and weather balloon measurement programmes in many countries have declined in recent years, especially in Africa, the west Pacific and South America. This reduces scientists’ ability to monitor and understand key indicators of climate change.
This is not just an issue for climate science. Many of these observations are key to weather forecasts and systems that provide early warning for extreme weather. For example, media reports have suggested that recent reductions in weather balloon measurements in Alaska led to a lack of warnings for a recent winter storm.
The continuity and integrity of the climate observations that scientists use to understand how the climate is changing depends on effective and sustained coordination by international organisations, such as the Global Climate Observing System, the World Meteorological Organization and World Climate Research Programme.
Without this data and its coordination, future assessments will be much more difficult at a time when urgent climate action is needed.
The post Guest post: How a record-high ‘energy imbalance’ is driving global warming appeared first on Carbon Brief.
Guest post: How a record-high ‘energy imbalance’ is driving global warming
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