Heatwaves and acidification are growing problems for corals and other marine life. Photograph: Mike Veitch/Alamy
State of the Climate report finds Earth’s energy has moved dangerously out of balance, with oceans absorbing vast majority of trapped heat
Our home planet is struggling with a record energy imbalance, which is warming oceans to unprecedented levels, making weather more extreme and threatening health and food supplies, the World Meteorological Organization has warned.
The United Nations body confirmed 2015 to 2025 were the hottest 11 years ever measured, but a still bleaker message was that the rising temperature experienced by humans on the surface was only 1% of the faster-accumulating heat in the wider Earth system.
More than 90% of that excess is absorbed by the oceans, which experienced the highest heat content in history last year. The rate of ocean warming has more than doubled over the past two decades, compared with the average over the previous 45 years.
The authors of the latest annual State of the Global Climate report say this highlights the increasing vulnerability of a planet that is moving ever further out of balance as a result of human activity. The burning of oil, gas, coal and forests releases heat-trapping greenhouse gases such as carbon dioxide, methane and nitrous oxide, which are all at their highest level in at least 800,000 years.
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At present, humans and other life forms on the surface directly suffer only a small fraction of that energy backup because 91% is absorbed by oceans, 5% by the land, 1% warms the atmosphere, and 3% melts ice at the poles and on high mountains.
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Last autumn, a UK government report warned that climate-driven ecosystem collapse could lead to food shortages, mass migration, political extremism and even nuclear conflict. The report was never officially launched.
Commissioned by Defra – the Department for Environment Food and Rural Affairs – and informed by intelligence agencies including MI5 and MI6, the briefing assessed how environmental degradation could affect UK national security.
At the last minute the launch was cancelled, reportedly blocked by Number 10. Thanks to pressure from campaigners and a freedom of information request, a 14-page version of the report was snuck out (no launch, not even a press release) on January 22.
That report says: “Critical ecosystems that support major food production areas and impact global climate, water and weather cycles” are already under stress and represent a national security risk. If they failed, the consequences would be severe: water insecurity, severely reduced crop yields, loss of arable land, fisheries collapse, changes to global weather patterns, release of trapped carbon exacerbating climate change, novel zoonotic disease and loss of pharmaceutical resources.
In plainer terms: the UK would face hunger, thirst, disease and increasingly violent weather.
An unredacted version of the report, seen by the Times, goes further. It warns that the degradation of the Congo rainforest and the drying up of rivers fed by the Himalayas could drive people to flee to Europe (Britain’s large south Asian diaspora would make it “an attractive destination”), leading to “more polarised and populist politics” and putting more pressure on national infrastructure.
The Times describes a “reasonable worst case scenario” in the report, where many ecosystems were “so stressed that they could soon pass the point where they could be protected”. Declining Himalayan water supplies would “almost certainly escalate tensions” between China, India and Pakistan, potentially leading to nuclear conflict. Britain, which imports 40% of its food, would struggle to feed itself, the unredacted report says.
The report isn’t an outlier, and these concerns are not confined to classified briefings. A 2024 report by the University of Exeter and think-tank IPPR warned that cascading climate impacts and tipping points threaten national security – exactly the risk outlined in the Defra report.
Melting glaciers in remote mountains ultimately pose a security threat for the UK, say intelligence services. Hussain Warraich / shutterstock
The government has not publicly explained why the launch was cancelled. In response to the Times article, a Department for Environment, Food and Rural Affairs spokesperson said: “Nature underpins our security, prosperity and resilience, and understanding the threats we face from biodiversity loss is crucial to meeting them head on. The findings of this report will inform the action we take to prepare for the future.”
Perhaps there are mundane reasons to be cautious about a report linked to the intelligence services that warns of global instability. But the absence of any formal briefing or ministerial comment is itself revealing – climate risks appear to be treated differently from other risks to national security. It’s hard to imagine a report warning of national security risks from AI, China or ocean piracy getting the same treatment.
This episode is not even especially unusual, historically. Governments have been receiving warnings about climate change – and downplaying or delaying responses – for decades.
Decades of warnings
In January 1957, the Otago Daily Times reported a speech by New Zealand scientist Athol Rafter under the headline “Polar Ice Caps May Melt With Industrialisation”. And Rafter was merely repeating concerns already circulating internationally, including by a Canadian physicist whose similar warning went around the world in May 1953. Climate change first went viral more than seven decades ago.
By the early 1960s, scientists were holding meetings explicitly focused on the implications of carbon dioxide build-up. In 1965, a report to the US president’s Science Advisory Council warned that “marked changes in climate, not controllable though local or even national efforts, could occur”.
But the story we see today was the same. Reports are commissioned, urgent warnings are issued – and action is deferred. When climate change gained renewed momentum in the mid-1980s, following the discovery of the ozone hole and the effects of greenhouse gases besides carbon dioxide, the message sharpened: global warming will come quicker and hit harder than expected.
Margaret Thatcher finally acknowledged the threat in a landmark 1988 speech to the Royal Society. But when green groups tried to get her to make specific commitments, they had little success.
Since about 1990, the briefings have barely changed. Act now, or suffer severe consequences later. Those consequences, however, are no longer theoretical.
Why does nothing happen?
Partly, it’s down to inertia. We have built societies in which carbon-intensive systems are locked in. Once you’ve built infrastructure around, say, the private petrol-powered automobile, it’s hard for competitors to offer an alternative. There’s also a mental intertia: it’s hard to let go of assumptions you grew up with in a more stable era.
Secrecy plays a role too. As the Defra report illustrates, uncomfortable assessments are often softened, delayed or buried. Then, if you do accept the need for action, you are then up against the problem of responsibility being fragmented across sectors and institutions, making it hard to know where to aim your efforts. Meanwhile, social movements fighting for climate action find it hard to sustain momentum for more than three years.
Here’s the final irony. Conspiracy theorists and climate deniers insist governments are exaggerating the threat. In reality, the evidence increasingly suggests the opposite. Official assessments tend to lag behind scientific warnings, and the most pessimistic scenarios are often confined to technical or classified documents.
The situation is not better than we are told. It’s actually far worse.
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The year 2025 was in the top-three warmest years on record, with average surface temperatures reaching around 1.44C above pre-industrial levels across eight independent datasets.
The different temperature records confirm that last year was either the second or third warmest since observations began in the mid-1800s, with razor-thin margins between 2025 and 2023.
Last year also set a new record for ocean heat content, with the oceans absorbing more than 90% of the heat trapped by increasing greenhouse gas concentrations in the atmosphere.
Here, Carbon Brief examines the latest data across the Earth’s oceans, atmosphere, cryosphere and surface temperature. (Use the links below to navigate between sections.)
Noteworthy findings from this 2025 review include…
Ocean heat content: It was the warmest year on record for ocean heat content and one of the largest year-over-year increases in ocean heat content. In 2025, the oceans added 39 times more heat than all annual human energy use.
Global surface temperatures:The year 2025 is effectively tied with 2023 as the second-warmest year on record – coming in at between 1.33C and 1.53C above pre-industrial levels across different temperature datasets and 1.44C in the synthesis of all groups.
Second warmest over land: Global temperatures over the world’s land regions – where humans live and primarily experience climate impacts – were 2C above pre-industrial levels, just below the record set in 2024.
Third warmest over oceans: Global sea surface temperatures were 1C above pre-industrial levels, dropping from 2024 record levels due to fading El Niño conditions.
Regional warming: It was the warmest year on record in areas where, collectively, more than 9% of the global population lives.
Unusual warmth: The exceptionally warm, record-setting temperatures over the past three years (2023-25) were driven by continued increases in human emissions of greenhouse gases, reductions in planet-cooling sulphur dioxide aerosols, variability related to a strong El Niño event and a strong peak in the 11-year solar cycle.
Greenhouse gases: Concentrations reached record levels for carbon dioxide (CO2), methane and nitrous oxide.
Sea ice extent: Arctic sea ice saw its lowest winter peak on record as well as its 10th-lowest summer minimum extent, while Antarctic sea ice saw its third-lowest minimum extent.
Looking ahead to 2026: Carbon Brief predicts that global average surface temperatures in 2026 are likely to be between the second and fourth warmest on record, similar to 2023 and 2025, at around 1.4C above pre-industrial levels.
Ocean heat content sets a new record
The year 2025 was the warmest on record for the heat content of the world’s oceans.
Ocean heat content (OHC) increased by around 500 zettajoules – billion trillion joules – since the 1940s.
The heat increase in 2025 alone compared to 2024 – about 23 zettajoules – is around 39 times as much as the total energy produced by all human activities on Earth in 2023 (the latest year in which global primary energy statistics are available). It was also the largest increase in ocean heat content since 2017 (following the strong El Niño event of 2016).
Human-emitted greenhouse gases trap extra heat in the atmosphere. While some of this warms the Earth’s surface, the vast majority – around of 93% – goes into the oceans. About two-thirds of this accumulates in the top 700 metres, but some also ends up in the deep oceans.
The figure below shows annual OHC estimates from the Chinese Institute for Atmospheric Physics (IAP) between 1950 and present for the upper 700 metres (light blue shading) and 700-2,000 metres (dark blue) of the ocean.
Annual global ocean heat content (in zettajoules – billion trillion joules, or 10^21 joules) for the 0-700 metre and 700-2,000 metre layers. Data updated from Cheng et al. (2024). Chart by Carbon Brief.
In a new paper published last week, researchers found that the rate of OHC increase over the past 15 years is unprecedented over the observational record in the IAP dataset. More broadly, there has been a distinct acceleration in OHC after 1991 – and recent OHC growth rates are generally consistent with satellite measurements of Earth energy imbalance (EEI).
(Energy imbalance is a measure of how much surplus heat there is in the Earth’s climate system. It is the difference between how much energy enters Earth’s atmosphere from the sun and how excess heat is radiated back into space as the world warms.)
In many ways, OHC represents a much better measure of climate change than global average surface temperatures, because it is where most of the extra heat ends up and is much less variable on a year-to-year basis than surface temperatures.
The analysis reveals that global surface temperatures were between the second and third warmest since records began in the mid-1800s. Temperatures effectively tied with 2023 within the margin of uncertainty, below the record set last year in 2024.
The figure below shows global surface temperature records from the eight datasets.
Global surface temperature records can be calculated back to 1850, though some groups such as NASA GISTEMP choose to start their records in 1880 when more data was available.
Prior to 1850, records exist for some specific regions, but are not sufficiently widespread to calculate global temperatures with high accuracy (though newly published research has attempted to extend this back to 1781).
These longer surface temperature records are created by combining ship- and buoy-based measurements of ocean sea surface temperatures with temperature readings of the surface air temperature from weather stations on land. (Copernicus ERA5 and JRA-3Q are an exception, as they use weather model-based reanalysis to combine lots of different data sources over time.)
Some differences between temperature records are apparent early in the record, particularly prior to 1900 when observations are more sparse and results are more sensitive to how different groups fill in the gaps between observations. However, there is strong agreement between the different temperature records for the period since 1970, as shown in the figure below.
Annual global average surface temperatures as in the prior chart, but showing the period from 1970-2025. Chart by Carbon Brief.
Global temperatures over the past three years clearly stand out as much warmer than anything that has come before, well above the prior record set in 2016. More broadly, the 11 warmest years on record all happened in the past 11 years.
Two of the eight datasets analysed by Carbon Brief – NASA and DCENT – had 2025 as the second-warmest year behind 2024, while six of the datasets had 2025 as the third-warmest year behind both 2023 and 2024.
However, in nearly all cases the difference between 2023 and 2025 falls within each dataset’s published uncertainty range, making it effectively a tie between the two years.
The table below shows the reported 2025 global temperature anomalies (relative to each group’s 1850-1900 pre-industrial baseline), as well as a 2025 value using a common pre-industrial baseline between the 1850-1900 and 1981-2010 periods across the five groups with data back to 1850 (NOAA, Hadley/UEA, Berkeley Earth, DCENT and China-MST).
Dataset
2025 Reported
2025 With common baseline
Ranking
NASA GISTEMP
1.39
1.45
Second
Hadley/UEA HadCRUT5
1.41
1.39
Third
NOAA GlobalTemp
1.33
1.41
Third
Berkeley Earth
1.44
1.44
Third
Copernicus ERA5
1.47
1.47
Third
JRA-3Q
1.46
1.46
Third
DCENT
1.53
1.44
Second
China-MST
1.39
1.42
Third
Reported temperature anomalies range from as low as 1.33C (NOAA) to as high as 1.53C (DCENT), primarily reflecting differences in the early part of the record. The 2025 values with a common baseline have a much smaller range, from 1.41C (NOAA) to 1.47C (Copernicus).
Separate land and ocean temperatures are not available yet from all of these groups. However, Berkeley Earth reports that global land temperatures in 2025 were the second warmest on record, at 2.03C above pre-industrial levels, while ocean temperatures were the third warmest at 1.03C.
Land and ocean temperature rise since the pre-industrial 1850-1900 period. Figure from Berkeley Earth.
Global land regions – where the global human population lives – has generally been warming around 70% faster than the oceans and 40% faster than the global average since 1970.
The year started off quite hot, with January 2025 setting a new record as the warmest January. All other months of the year ended up being either the second or third warmest on record after 2024 and 2023.
The figure below shows each month of 2025 in dark red, compared to all prior years since 1850. Each year is coloured based on the decade in which it occurred, with the clear warming over time visible, as well as the margin by which both 2023, 2024 and 2025 exceeded past years.
Monthly global surface temperatures for each year since 1850, using the average of the eight different temperature datasets assessed by Carbon Brief. Anomalies are shown relative to the pre-industrial 1850-1900 period.
Extreme regional temperatures
While the globe as a whole was tied as the second warmest on record, many different regions of the planet set new records in 2025.
The figure below shows how global temperature deviated from the average in 2025 across the world. Areas shaded in red were warmer than the baseline period (1951-80) used by Berkeley Earth, whereas the few blue areas experienced cooler temperatures.
Collectively, approximately 770 million people – 9.3% of Earth’s population – live in places that experienced their warmest year on record in 2025. This was mostly concentrated in Asia, including around 450 million people in China.
The figure below highlights regions of the planet that experienced their top-five warmest (red shading) or coldest (blue) temperatures on record in 2025. Overall, around 9% of the planet set a new record, including 11% of the land and 8% of the ocean. No location on the planet experienced record cold temperatures – or even top-five record cold temperatures – for the year as a whole.
Regions of the world among the five warmest (reds) of five coolest (blues) on record for average annual temperatures in 2025. Figure from Berkeley Earth.
Drivers of recent record warmth
Global temperatures over the past three years have been unusually warm, well above what would be expected given the long-term warming trend of around 0.2C per decade since the 1970s.
Recent research has found that global warming has accelerated in recent years to around 0.27C per decade, though this acceleration is largely in-line with climate model projections under scenarios where greenhouse gas emissions continue to rise while emissions of planet cooling aerosols are reduced.
According to analysis from Berkeley Earth, the odds of global temperatures over 2023-25 occurring as a result of greenhouse gas emissions and natural variations in the Earth’s climate alone “is less than one-in-100” and “likely indicates that recent years have been impacted by additional warming factor(s)”.
The figure below shows how the exceptional warming spike of 2023-25 compares to the longer-term warming trend and historical climate variability.
Global surface temperatures between 1965 and 2025 (blue) along with the linear trend (black) and range (grey) from 1970-2019. The red line shows a locally linear regression that captures recent acceleration. Figure from Berkeley Earth.
Carbon Brief recently explored the drivers of recent warmth in more detail, finding that it is likely to have been driven by a combination of:
A strong El Niño event that developed in the latter part of 2023.
An unusual volcanic eruption in Tonga in 2022 that put a large amount of aerosols and water vapor into the upper atmosphere.
A stronger-than-expected solar cycle.
This is illustrated in the figure below, which provides an estimate of the impact of each of these different factors on 2023 and 2024 temperatures, along with their respective uncertainties.
The sum of all the factors is shown in the “combined” bar, while the actual warming compared to expectations is shown in red. The upper chart shows 2023, while the lower one shows 2024.
Attribution of 2023 and 2024 unusual warmth. Light blue bars show individual factors and their uncertainties, the dark blue bar shows the combined effects and combination of uncertainties and the red bar shows the actual warming compared with expectations. HTHH refers to the Hunga Tonga-Hunga Ha’apai volcano. Adapted from Figure 12 in WMO’s state of the global climate 2024 report.
The first bar includes both El Niño and natural year-to-year climate variability; the height of the bar reflects the best estimate of El Niño’s effects, while the uncertainty range encompasses year-to-year variability in global temperatures that may be – at least in part – unrelated to El Niño.
While a similar analysis has yet to be undertaken for 2025, the end of El Nino conditions and the development of a modest La Nina would have driven temperatures down, while the warming impact of shipping, Chinese aerosol declines would have slightly increased. The warming effect of the solar cycle would likely have remained flat or slightly declined as solar cycle 25 passed its peak.
Finally, a World Meteorological Organization (WMO) assessment of the Hunga Tonga-Hunga Ha’apai volcano found that “the record-high global surface temperatures in 2023-24 were not due to the Hunga eruption”.
The report suggested that the volcano had a small cooling effect (-0.03C) globally in 2023 and 2024. This might switch to a small warming effect (+0.03C) in 2025 and 2026 as the planet-cooling aerosols from the volcano fall back down to the surface but some of the stratospheric water vapour remains, it noted.
However, it added, these effects are “indistinguishable from background variability in the current climate”.
El Niño and La Niña are generally the largest drivers of year-to-year variability in global temperatures. The figure below shows the El Niño (red shading) and La Niña (blue) conditions over the past 40 years (collectively referred to as the El Niño-Southern Oscillation, or “ENSO”).
Carbon Brief has used the historical relationship between ENSO conditions and temperature to effectively remove the effects of El Niño and La Niña events from global temperatures, as shown in the figure below.
This analysis indicates that El Niño cooled global temperatures in 2025 around -0.05C, following a boost to global temperatures of around 0.12C in 2024, compared to the estimate of global temperatures with both El Niño and La Niña events removed.
Annual global average surface temperatures from the average of the eight datasets, as well as Carbon Brief’s estimate of global temperatures with the effect of El Niño and La Niña (ENSO) events removed using the Foster and Rahmstorf (2011) approach. Chart by Carbon Brief.
This suggests that the shift from El Nino to La Nina conditions can fully explain the decline in global temperatures between 2024 and 2025 and that 2025 would have likely been the warmest year in the observational record if it had not been for the effects of ENSO.
Scientists provided estimates of where they expected 2025 temperatures to end up at the start of the year.
The figure below shows estimates by four different groups that provided temperature predictions for the year prior to any data being collected – the Met Office, NASA’s Dr Gavin Schmidt, Berkeley Earth and Carbon Brief’s own estimate — compared to what actually transpired.
Temperature predictions for 2025 from UK Met Office, NASA’s Dr Gavin Schmidt, Berkeley Earth and Carbon Brief’s estimate relative to pre-industrial (1850-1900) temperatures and compared to the historical average of the eight observational datasets. Chart by Carbon Brief.
Unlike in 2023 –and, to a lesser extent, 2024 –when start-of-year predictions were notably low, 2025 fell reasonably in-line with what was expected. The Met Office estimate was nearly exactly on target, with Berkeley Earth’s being close as well. Carbon Brief and Schmidt’s estimates were a little on the low side, but actual temperatures were well within the estimated error bars.
Observations in-line with climate model projections
Climate models provide physics-based estimates of future warming given different assumptions about future emissions, greenhouse gas concentrations and other climate-influencing factors.
Here, Carbon Brief examines a collection of climate models – known as CMIP6 – used in the 2021 science report of the IPCC’s sixth assessment.
In CMIP6, model estimates of temperatures prior to 2015 are a “hindcast” using known past climate influences, while temperatures projected from 2015 onward are a “forecast” based on an estimate of how things might change.
The figure below shows how observations compare to the full ensemble of 37 CMIP6 models under the middle-of-the-road SSP2-4.5 emissions scenario for future projections. The red line represents the average of all the models and the red areas showing the 5th to 95th percentile range. The average of the eight observational temperature datasets are plotted as dots on top of the climate model data.
The chart illustrates how observations have generally been a bit below the model average over the past two decades, were slightly above model average in 2024 and are more or less dead on in 2025.
Annual global average surface temperatures from CMIP6 models and observations between 1950 and 2030 (through 2025 for observations). Models use the SSP2-4.5 scenario after 2015. Anomalies plotted with respect to a 1850-1900 baseline. Chart by Carbon Brief.
However, the ensemble of CMIP6 models differs from the main projection of future warming in the recent IPCC AR6 report. A subset of CMIP6 models have unrealistically high climate sensitivity and they reproduce historical observations poorly.
To account for this, rather than simply averaging all the models – as had been done in prior assessments – the IPCC employed an approach that effectively weights models by their performance. As a result, the models align better with the range of climate sensitivity derived from multiple different lines of evidence.
The chart below shows the assessed warming projections from the IPCC AR6 report in red, with historical observations since 1850 as black dots.
Annual global average surface temperatures from the average of eight datasets (black dots) along the 30-year LOWESS fit (red line), combined the AR6 assessed warming projection for SSP2-4.5 as published and without any baseline alignment. Chart by Carbon Brief.
The chart reveals that observed global surface temperatures (black dots) are further above the modeled central estimate 2023-25, but generally remain within the IPCC assessed range.
Climate models broadly expect an acceleration of warming in the current period in a scenario like SSP2-4.5 where emissions of CO2 and other greenhouse gases continue to modestly increase, but emissions of planet-cooling aerosols like sulphur dioxide are rapidly reduced.
Second-warmest atmospheric temperatures
In addition to surface measurements over the world’s land and oceans, satellite microwave sounding units have been providing estimates of temperatures at various layers of the atmosphere since 1979.
The lowest layer of the atmosphere that satellite microwave units provide temperature estimates for is the lower troposphere. This data reflects temperatures a few kilometres above the Earth’s surface. It reveals a pattern of warming in the lowest troposphere that is similar – though not identical – to surface temperature changes.
The records produced by Remote Sensing Systems (RSS), the University of Alabama, Huntsville (UAH) and NOAA show 2025 as the second warmest year on record in the lower troposphere, after 2024. The chart below shows the three records for the lower troposphere, using a more recent baseline period (1981-2010) given the absence of satellite data before 1979.
Global average lower-troposphere temperatures from RSS version 4 (dark blue), UAH version 6 (mid-blue) and NOAA STAR version 5 (light blue) for the period from 1979-2025, relative to a 1981-2010 baseline. Chart by Carbon Brief.
The lower troposphere tends to be influenced more strongly by El Niño and La Niña events than the surface. Therefore, satellite records show correspondingly larger warming or cooling spikes during these events. This explains why there was both a bigger increase between 2023 and 2024 and a bigger decline between 2024 and 2025 in the satellite record than in surface records.
The lower-tropospheric temperature records show large differences after the early 2000s. RSS shows an overall rate of warming quite similar to surface temperature records, while UAH and NOAA show considerably slower warming in recent years than has been observed on the surface.
Greenhouse gas concentrations reach new highs
Greenhouse gas concentrations reached a new high in 2025, driven by human-caused emissions from fossil fuels, land use and agriculture.
Three greenhouse gases – CO2, methane (CH4) and nitrous oxide (N2O) – are responsible for the bulk of additional heat trapped by human activities. CO2 is by far the largest factor, accounting for roughly 42% of the increase in global surface temperatures since the pre-industrial era (1850-1900).
Methane accounts for 28%, while nitrous oxide accounts for around 5%. The remaining 25% comes from other factors including carbon monoxide, black carbon and halocarbons, such as chlorofluorocarbons (CFCs).
Human emissions of greenhouse gases have increased atmospheric concentrations of CO2, methane and nitrous oxide to their highest levels in at least a few million years – if not longer.
The figure below shows concentrations of these greenhouse gases – in parts per million (ppm) for CO2 and parts per billion (ppb) for methane and nitrous oxide – from the early 1980s through to October 2025 for CO2 and September 2025 for CH4 and N2O (the most recent data currently available).
Global concentrations of CO2, methane (CH4) and nitrous oxide (N2O). Based on data from NOAA’s Earth Systems Research Laboratory. Note that the y-axes do not start at zero. Chart by Carbon Brief.
Sea level is rising rapidly
Modern-day sea levels have risen to a new high, due to a combination of melting land ice (such as glaciers and ice sheets), the thermal expansion of water as it warms and changes in land water storage.
In recent years, there have been larger contributions to sea level rise from melting ice sheets and glaciers, as warmer temperatures accelerate ice sheet losses in Greenland and Antarctica.
Since the early 1990s, the increase in global sea level has been estimated using altimeter data from satellites. Earlier global sea levels have been reconstructed from a network of global tide gauge measurements. This allows researchers to estimate how sea level has changed since the late 1800s.
The chart below shows five different modern sea level rise datasets (blue lines), along with satellite altimeter measurements as assessed by AVISO (in black) after 1993. (As sea level rise data has not yet been released for the whole year, the 2025 value is estimated based on data through to November.)
Global average sea level rise reconstructed from tide gauge data between 1880 and 2025 from Frederikse et al. (2020), Dangendorf et al. (2019), Hay et al. (2015), Church and White (2011), and Palmer et al. (2021). Satellite altimeter data from 1993 (black) to present is taken from AVISO. Chart by Carbon Brief.
Sea levels have risen by over 0.2 metres (200mm) since 1900. While sea level rise estimates mostly agree in recent decades, larger divergences are evident before 1980. There is also evidence of accelerating sea level rise over the post-1993 period when high-quality satellite altimetry data is available.
(To understand more on how climate change is accelerating sea level rise, read Carbon Brief’s explainer.)
Shrinking glaciers and ice sheets
A significant portion of global sea level rise is being driven by melting glaciers on land.
Scientists measure the mass of glaciers around the world using a variety of remote-sensing techniques, as well as through GRACE measurements of the Earth’s gravitational field. The balance between snow falling on a glacier and ice loss through melting and the breaking off – or “calving” – of icebergs determines if glaciers grow or shrink over time.
The World Glacier Monitoring Service is an international consortium that tracks more than 130 different glaciers in 19 different regions around the world. The figure below shows the change in global average glacier mass from 1950 through to the end of 2024. (2025 values are not yet available.) Note that glacier melt is reported in metres of water equivalent, which is a measure of how much mass has been lost on average.
Global average glacier melt over the 1950-2024 period from the World Glacier Monitoring Service, in metres of water equivalent. Carbon Brief.
Greenland ice sheets have become a larger contributor to sea level rise in recent years due to accelerating loss of mass. The year 2025 was the 29th in a row where Greenland lost ice overall, with 105bn tonnes of ice lost over the 12 months from September 2024 to August 2025. Greenland last saw an annual net gain of ice in 1996.
The figure below shows the cumulative mass balance change – that is, the net ice loss – from Greenland between 1970 and 2025. The authors find that Greenland has lost around 6tn tonnes of ice over the past 50 years – more than 700 tonnes lost per person for every person on the planet.
Cumulative ice loss from Greenland in billion metric tonnes (gigatonnes) between 1970 and 2025 from Mankoff et al 2021. Chart by Carbon Brief.
Lowest winter Arctic sea ice extent
Arctic sea ice saw its lowest winter peak on record as well as its 10th-lowest summer minimum extent, while Antarctic sea ice saw its third-lowest minimum extent.
Both the Arctic and Antarctic were at the low end of the historical (1979-2010) range for most of 2025, with new daily lows recorded for Arctic sea ice extent in January, February, March, June and December.
The figure below shows both Arctic (red line) and Antarctic (blue line) sea ice extent for each day of the year, along with how it compares to the historical range (corresponding shading).
Arctic and Antarctic daily sea ice extent from the US National Snow and Ice Data Center. The bold lines show daily 2025 values, the shaded area indicates the two standard deviation range in historical values between 1979 and 2010. The dotted black lines show the record lows for each pole. Chart by Carbon Brief.
Looking ahead to 2026
There is reason for caution when estimating likely temperatures for 2026.
In 2023, temperatures were significantly higher than predictions made at the start of the year, while 2024 temperatures were towards the high end of annual predictions. Temperatures in 2025 were more in-line with predictions, albeit still on the higher side for three out of the four predictions included above.
There are currently weak La Niña conditions currently present in the tropical Pacific, which are expected to extend through February. This would somewhat suppress temperatures in the first half of the year. However, the latest forecasts suggest a growing likelihood of El Niño conditions developing by June, which may lead to warmer temperatures in late 2026 – and potentially much warmer temperatures in 2027.
Carbon Brief predicts that global average surface temperatures in 2026 are likely to be between the second and fourth warmest on record, similar to 2023 and 2025, at around 1.4C above pre-industrial levels.
The figure below shows the four different 2026 predictions compared to the average of eight different temperature records explored in this article. (These have been “normalised” to show 2026 warming relative to the 2023-25 average to allow a clear comparison, given that each of the predictions was originally presented for a different temperature record.)
Carbon Brief’s prediction of likely 2026 temperatures is based on a statistical model using the average temperature of the past year, the latest monthly temperature and projections of ENSO conditions over the first three months of 2026.
Temperature projections for 2026 from the Met Office, NASA’s Dr Gavin Schmidt, Berkeley Earth and Carbon Brief, relative to pre-industrial (1850-1900) temperatures and compared to the historical average of eight different surface temperature datasets. Chart by Carbon Brief.
The Met Office, Dr Schmidt, Berkeley Earth and Carbon Brief estimates all have 2026 ending up as somewhere between the second- and fourth-warmest year on record, with the best estimate as being more or less tied with 2023 and 2025.
There is a very small chance that 2026 could end up beating 2024 as the warmest year on record, or end up below 2016 as the fifth or sixth warmest year.
However, with the growing likelihood of El Niño conditions developing in the second half of 2026, it is increasingly likely that 2027 will challenge 2024 for the title of the warmest year on record. The rate of warming has notably accelerated over the past 15 years and the period of exceptionally warm years that started in 2023 shows no signs of abating.
Experienced climbers scale a rock face near the historic Dumbarton castle in Glasgow, releasing a banner that reads “Climate on a Cliff Edge.” One activist, dressed as a globe, symbolically looms near the edge, while another plays the bagpipes on the shores below. | Photo courtesy of Extinction Rebellion and Mark Richards
Donald Trump urges you to be a Climate Science denier like him. He says that he makes millions and millions for destroying the planet, Burn, Baby, Burn and Flood, Baby, Flood.Nigel Farage urges you to ignore facts and reality and be a climate science denier like him and his Deputy Richard Tice. He says that Reform UK has received £Millions and £Millions from the fossil fuel industry to promote climate denial and destroy the planet.
Campaigners from Oceana UK protest outside the Royal Courts of Justice in London, where the environmental group is taking the government to court over 31 licences for oil and gas exploration, March 26, 2025
NOT a single exploration well was drilled in North Sea waters in 2025 – the first year since oil and gas was discovered there in the 1960s, analysis finds.
Energy consultants Wood Mackenzie found oil and gas investment on the UK continental shelf, which stood at £4 billion this year, is set to plunge by more than 40 per cent in the next to £2.5bn, its lowest level for more than 50 years.
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Greenpeace UK’s Paul Morozzo said: “This isn’t a temporary blip.
“The North Sea’s days as an oil and gas basin are coming to an end. Investment is falling because of physical constraints and decreased profitability.
“The real risk now is chasing a declining industry instead of preparing for what comes next.
“Doubling down on oil and gas won’t protect jobs, energy security or household bills.
“It’s time the government took action on the cost of living crisis, as well as to protect us all against the worst impacts of climate change.
“The way to do that is by investing in the industries of the future, not clinging to one that’s in terminal decline.”
Experienced climbers scale a rock face near the historic Dumbarton castle in Glasgow, releasing a banner that reads “Climate on a Cliff Edge.” One activist, dressed as a globe, symbolically looms near the edge, while another plays the bagpipes on the shores below. | Photo courtesy of Extinction Rebellion and Mark RichardsImage of InBedWithBigOil by Not Here To Be Liked + Hex Prints from Just Stop Oil’s You May Find Yourself… art auction. Featuring Rishi Sunak, Fossil Fuels and Rupert Murdoch.
Siân Berry has a long history in politics and success was sweet when she took the Brighton seat. Photograph: Ian West/PA
Since Zack Polanski took over as leader, the party has doubled its membership and its four MPs want to take on Reform’s anger and build community spirit
“Someone has to be out there making the narrative for social security. Someone has to fight the corrosive attitudes to people on benefits,” says Siân Berry, who has just finished her first year as a Green MP in the House of Commons.
She is speaking to the Guardian in her Brighton constituency office, formerly occupied by the legendary Caroline Lucas who flew a lone flag as the only member of parliament for the Green party for 14 years.
Now, however, there are four MPs including Berry, battling together, she says, to hold the space for the left at a moment when it feels the far right has hypnotised the entire political body. “Often Adrian [Ramsay, MP for Waveney Valley] is the only one bringing up animal welfare in Defra questions, or Carla [Denyer, MP for Bristol Central] will be the only person arguing for a refugee’s right to work to the Home Office.” They have all, at different times, been the only party to raise the need for taxes on extreme wealth.
“Caroline was a lone voice in parliament,” she says. ‘But there are four of us so we can share responsibilities. We each shadow six government departments.” Berry’s portfolio covers crime and policing, justice, transport, work and pensions, culture, media and sport and democratic standards. “We absolutely have to be ready if an issue comes up. There are some issues where if a Green isn’t in the chamber asking a question, that question won’t be asked.
‘There are four of us so we can share responsibilities’: from left, Siân Berry, Carla Denyer, Adrian Ramsay and Ellie Chowns. Photograph: Ian West/PA
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Most of all, Berry longs to see strong action on climate. “The climate situation is awful. A two degree rise is within sight. We are on a knife-edge of whether we can protect this ecosystem. It’s our only home.”
Nigel Farage urges you to ignore facts and reality and be a climate science denier like him and his Deputy Richard Tice. He says that Reform UK has received £Millions and £Millions from the fossil fuel industry to promote climate denial and destroy the planet.Neo-Fascist Climate Science Denier Donald Trump says Burn, Baby, Burn.
Campaigners from Oceana UK protest outside the Royal Courts of Justice in London, where the environmental group is taking the government to court over 31 licences for oil and gas exploration, March 26, 2025
