An acceleration in human-caused global warming could see the Paris Agreement’s 1.5C limit breached before 2030, a new study suggests.
The paper, published in Geophysical Research Letters, finds that, over the past decade, the planet has been warming at its fastest rate on record.
The authors isolate the trend of human-driven warming in the long-term global temperature record, removing the influence of natural factors, such as El Niño, volcanic eruptions and solar variation.
They find that the world had been warming at a rate of around 0.2C per decade since the 1970s, but has “accelerated” since 2015 to a rate of 0.35C per decade.
The study warns that if the current rate of warming persists, the 1.5C Paris threshold will be breached in the next few years.
“The essential result of this paper isn’t how fast we’re warming, but that warming is now happening faster than before and that the difference isn’t negligible,” an author on the study tells Carbon Brief.
Warming signal
The year 2024 was the hottest on record, with global average temperatures at the surface exceeding 1.5C above pre-industrial levels for the first time.
Crossing the 1.5C threshold in a single year is not equivalent to a breach of the Paris Agreement, which refers to long-term warming – typically interpreted as over a 20-year period.
However, rapidly rising global temperatures are prompting scientists to ask when this internationally recognised threshold might be broken.
Human activity has been the primary driver of rising global temperature in the long term, through greenhouse gas emissions and land-use change. However, natural factors also have warming and cooling effects from year to year.
The study authors identified three main sources of this natural variability.
El Niño and La Niña – collectively referred to as the El Niño-Southern Oscillation (ENSO) – are generally the largest drivers of year-to-year fluctuations in global temperatures. The study authors identify volcanic activity and changes in solar variation as the other two main natural influences on global temperature trends.
Study author Dr Grant Foster, formerly from the consulting firm Tempo Analytics and now retired, describes these sources of natural variability as “random noise” that sits on top of the long-term warming signal. He explains that “the larger the noise, the harder it is to see the real trend”.
To isolate the warming trend, the authors used a statistical technique that they first employed in a 2011 paper to remove the contributions of ENSO, volcanic activity and solar variation from the global temperature record.
The authors carried out this analysis on five separate datasets of global average surface temperature – NASA, NOAA, the Met Office Hadley Centre and University of East Anglia’s HadCRUT5, Berkeley Earth and Copernicus ERA5.
The plots below show the global temperature between 1880 and 2024, relative to pre-industrial temperatures, from the five datasets.
Each plot shows the original warming record (light blue), in which all drivers of warming are included, as well as the adjusted record (dark blue) which excludes the effects of ENSO, volcanoes and solar activity.
Removing the effects of natural variability makes the years 2023 and 2024 slightly cooler, the study notes, but they remain the two warmest years since the beginning of instrumental record.
Acceleration
Record-high temperatures in recent years have led scientists to ask whether global warming is accelerating.
The authors of the new study decided to use two different statistical approaches to test whether they can identify a “statistically significant” acceleration in global warming from the long-term temperature record.
The “noise” from natural drivers of temperature change, such as ENSO, can make it tricky to spot underlying trends. However, Foster tells Carbon Brief that after removing the influence of natural variability, “acceleration is easy to prove statistically – some might even say it becomes obvious”.
Both tests find that warming is accelerating with more than 98% confidence for each of the five datasets. When the same tests were run on the unadjusted data, they failed to reach even 95% confidence, showing the importance of removing natural variability from the warming signal, according to the study authors.
Under the first statistical approach, called a quadratic analysis, the authors applied a single curved trend line to the warming signal.
For the second approach, the authors used a technique to identify the month when the rate of global warming changed noticeably. The different datasets estimated this date to range from February 2013 to February 2014. They then calculated the speed of global warming both before and after these dates.
Global temperatures increased at an average rate of around 0.2C per decade over 1970-2015, according to the study.
In contrast, the authors find that warming rates have increased to 0.34-0.42C per decade, across the five different datasets, since the February 2013-February 2014 period.
The study reveals that the rate of warming observed over the past decade has been higher than any previous decade in the instrumental record.
Foster tells Carbon Brief that “the essential result of this paper isn’t how fast we’re warming, but that warming is now happening faster than before and that the difference isn’t negligible”.
If this warming rate remains constant, the Paris Agreement 1.5C threshold would be breached between 2026 and 2029, the authors find.
(Their approach estimates the 20-year period where the average exceeds 1.5C of warming, and the breach of the limit is taken as the halfway point in this period.)
The table below shows key results for the five different datasets, including estimates for the date that warming started accelerating, the rate of warming and the year that the Paris Agreement will be breached in each.
| Data source | Date of acceleration | Warming rate (C per decade) | Year to cross 1.5C |
|---|---|---|---|
| NASA | April 2013 | 0.36 | 2028 |
| NOAA | February 2013 | 0.36 | 2028 |
| HadCRUT | January 2014 | 0.34 | 2029 |
| Berkley | February 2014 | 0.36 | 2028 |
| ERA5 | February 2014 | 0.42 | 2026 |
Results for the five different datasets, including estimates for the date that warming started accelerating, the rate of warming and the year that the Paris Agreement will be breached in each. Source: Foster and Rahmstorf (2026).
‘Statistical significance’
There are “many opinions” among climate scientists about how fast the planet is currently warming, Foster tells Carbon Brief.
For example, a study from Dr James Hansen calculates a warming rate of 0.27C per decade after 2010. Similarly, the latest Indicators of Global Climate Change report estimates warming of 0.27C per decade over 2015-24.
Foster continues:
“But we all agree it’s higher than before. [The] thing is, we couldn’t prove that statistically.”
Foster tells Carbon Brief that in 2024, Dr Claudie Beaulieu – an assistant professor at the University of California – led a study which concluded that “a recent surge in global warming is not detectable yet”.
Beaulieu used the same statistical method as Foster to investigate whether global temperature data shows an acceleration in warming. However, she did not first remove the natural drivers of temperature change, such as ENSO.
(Carbon Brief wrote about Beaulieu’s work in more detail when it was published.)
Foster tells Carbon Brief that the study was “excellent”, adding:
“They found that confirming acceleration was a close call – the data are very suggestive – but not quite ‘statistically significant.’”
Foster explains that after removing the natural influence, the warming trend is clearer, making it easier to find statistically significant warming levels.
Beaulieu praises the new study, explaining that “the fact that the acceleration signal appears consistently across all five independent datasets is reassuring”.
However, she stresses that “the acceleration may prove temporary”.
She says that “continued monitoring over the next several years will be essential to determine whether the accelerated warming rate identified here represents a lasting shift”.
The study authors say that the main limitation of their work is that the method of removing natural variability is “empirically based, but approximate and imperfect”.
Foster says:
“We estimate the impact of things like El Niño by comparing past values of the El Niño index to past temperature changes, hence we don’t need to know the physics behind it, just the numbers. Statistical results like this are only approximate.”
Meanwhile, an acceleration in warming is supported by many other observations of the Earth’s climate.
For example, ocean heat content – the measure of the amount of energy stored in the ocean – is rising year on year. There is also evidence of acceleration in recent years, with the period from 2020 onward seeing the largest year-to-year increases in ocean heat content on record.
In addition, the Earth’s energy imbalance, which measures the difference between incoming solar radiation and outgoing radiation, has also increased in recent years.
The post Pace of global warming has nearly doubled since 2015, reveals study appeared first on Carbon Brief.
Pace of global warming has nearly doubled since 2015, reveals study
Claver Gatete is Executive Secretary of the UN Economic Commission for Africa. Jason Veysey is Energy Modeling Program Director and Senior Scientist at the Stockholm Environment Institute. Lisa Sachs is Director of the Columbia Center on Sustainable Investment at Columbia University.
The case for global energy transition has rarely been clearer. The closure of the Strait of Hormuz earlier this year exposed the cost of unplanned, fossil-dependent systems, while the falling cost of renewables, the rising penetration of electric vehicles, and the growing value of demand flexibility have made the direction of travel obvious. The benefits of a clean, secure, integrated system are no longer in dispute. What remains unclear is how to build it.
Countries around the world have called for faster renewable energy deployment and alternative energy arrangements. A secure, affordable, resilient, decarbonised system requires specific investments in specific places in a specific sequence, optimised across sectors and borders. But very few governments have the analytical foundation to translate those imperatives into investment.
The two instruments that are supposed to determine investment priorities for decarbonisation – Nationally Determined Contributions (NDCs) and country platforms – cannot answer the most basic question facing any country undertaking an energy transition: what should the energy system look like?
-
New coal mine openings slow as East Asian demand plateaus
China and Australia drove global decline in new capacity additions in 2025, but planned production kept growing
To close this gap, every country needs a bankable, economy-wide optimisation model for its energy system. A model is not a plan, but it can help answer the critical question of what the future energy system should look like. It shows how optimal scenarios vary as assumptions and policies are adjusted, calculates investment requirements and sequencing, and quantifies how system costs are affected by assumptions, policies, and exogenous variables like trade policy and financing terms.
Tool for efficient investment
Optimisation is a simplified way of simulating an energy system, but it can be an extremely powerful tool for moving energy planning from reactive (how do we manage the disparate actions in the energy system?) to intentional (what energy system underpins our national objectives?). A model can show how optimal scenarios vary as assumptions and policies are adjusted, and how investment requirements are quantified and sequenced.
Optimisation models can treat the energy system and the sectors it serves as an integrated whole, optimising across sectors and projects in ways that can be mutually reinforcing. If considered independently, growth in industrial demand, transport electrification, and digital infrastructure can add stress to the energy system. But an optimised plan can arrange these and other changes in an efficient, synergistic way.
Two to tango: How governments can unlock private investment for national climate goals
New load can be added where low-cost power is available; industrial customers can ensure the viability of investments in energy supply; electric vehicle charging policy can smooth load curves and reduce costs for all consumers.
Additionally, optimisation modeling can also change the financeability of investments. Taken alone, each project faces uncertainty about the rest of the system, which raises the cost of capital and causes projects to stall or unwind after contracts are signed. A coherent, optimised plan makes visible the coordination that private capital would otherwise have to bet on: identified offtake, sequenced and committed transmission, contracted power supply, and so on.
What COP31 and COP32 should do
The upcoming COPs in Turkey and Ethiopia can shift the center of gravity of international climate cooperation from fragmented commitments to planning. Three moves are urgently needed.
First, optimised, economy-wide, long-term energy system planning must be the foundation on which any meaningful NDC, country platform, or finance commitment rests. NDCs are typically drafted by environment or single-line ministries, with limited cross-sectoral input from ministries of energy, finance, and planning. They contain targets, derived from sectoral strategies or national commitments, not from an analytically grounded picture of what the energy system should look like and what investments would make it work. Country platforms are generally a portfolio of investments assembled from existing project pipelines, rather than derived from a system-level analysis of what an optimised, decarbonised energy system would require.
Second, recognise regions as a key planning unit. Modern integrated energy systems are inherently regional. Renewable endowments are unevenly distributed; balancing variable supply across borders lowers aggregate cost, reduces redundant backup capacity, and unlocks economies of scale no individual nation can achieve. Many energy investments in Southeast Asia, East Africa, Southern Africa and Central Asia may only be financeable in a regional context. Assessing domestic infrastructure without regional optimisation perpetuates the perception that decarbonisation is more expensive than it is.
COP31 leaders unveil global targets, with spotlight on electrification
Third, finance the planning capacity. A coordinated commitment by multilateral development banks, bilateral donors, and philanthropic partners to help every region and its constituent countries develop and maintain their own modelling capability, with open-source tools and regional analytical hubs, would close the most consequential gap in the current architecture. The cost is small relative to current spending on country platforms, failed project preparation, and misallocated infrastructure investment.
This includes supporting regional institutions such as the ASEAN Centre for Energy, the African Energy Commission, regional power pools, and the Latin American and Caribbean Energy Organization to determine what optimised regional systems require. Country-by-country pledging, repeated at every COP, will not deliver what meaningfully integrated systems can.
The 2026 energy crisis made the cost of unplanned, fossil-dependent systems newly visible. That window of clarity will close. The international community should seize the moment to build the planning foundation that has been missing for thirty years, rather than commissioning another round of NDCs or pledges, striving for outcomes neither was designed to deliver.
The post Every country needs a model to help optimise its energy transition appeared first on Climate Home News.
Every country needs a model to help optimise its energy transition
The world is currently experiencing what is expected to become the strongest El Niño on record – dubbed a “super El Niño” by many.
El Niño is the warm phase of a recurring climate pattern in the tropical Pacific that releases heat from the ocean into the atmosphere.
This temporarily raises global temperatures and reshapes rainfall and extreme weather around the world – impacting the lives of billions of people.
The current El Niño event began in June and is expected to last into 2027.
El Niño is part of a wider climate pattern called the El Niño-Southern Oscillation (ENSO) cycle.
The ENSO cycle also has a cool phase, known as La Niña, as well as a “neutral” phase. El Niño and La Niña events typically last between nine and 12 months, but can go on longer.
Below, Carbon Brief explains how the ENSO cycle works, its impacts on extreme weather and global temperatures and why this El Niño event is projected to be the most intense since records began.
The post Explainer: How the ‘super El Niño’ will reshape the world’s weather appeared first on Carbon Brief.
https://interactive.carbonbrief.org/el-nino-explainer/index.html
The second-largest reservoir in the US reached a record-low water height on Saturday – just days after the country’s largest reservoir broke its own record.
Both Lake Mead and Lake Powell are located on the Colorado River.
They provide water for populations across seven US states in the south-western US, with around 40 million people getting some or all of their municipal water from the Colorado River.
The river also provides water for around 5.5m acres (22,258 square kilometres) of farmland across Colorado, Arizona, California and the other states in the river basin.
Experts tell Carbon Brief that climate change, population growth and over-consumption are all contributing to the current record-low levels of the reservoirs.
Record lows
At full capacity, Lakes Mead and Powell can hold a combined 68 cubic kilometres of water – enough to supply all household consumption in the contiguous US for nearly 1.5 years. However, the water level in both reservoirs has been declining for decades.
The chart below shows the water level of Lake Mead, in metres above mean sea level. The reservoir, which began to fill in 1935 following the construction of the Hoover Dam, has a “full pool” maximum capacity of 347.60 metres. The water level in Lake Mead reached a record low of 317.11 metres on 7 August.
The following chart shows the water level of Lake Powell, in metres above mean sea level. Lake Powell’s full-pool level is 1,127.76 metres.
While the reservoir reached its maximum capacity several times in the 1980s, it has not done so since. On 15 August, the water level in Lake Powell was recorded at a new record-low of 1,072.87 metres.
Both reservoirs have continued to decline in the days since breaking their respective records. The downward trend will largely continue in both lakes until next spring, when the snowpack in the mountains of the Upper Colorado River Basin begins to melt, says Dr Jack Schmidt, a senior research scientist at Utah State University’s Center for Colorado River Studies. He tells Carbon Brief:
“The big dilemma of the moment is that we’re only in the middle of August, and we have no assurance of what the coming winter will be. The only thing we can be sure of is that we will be depleting overall total basin reservoir storage from now until, roughly, early April.”
Compounding factors
The record lows across the two reservoirs are the result of several compounding factors, experts tell Carbon Brief.
Since the turn of the 20th century, the amount of water flowing along the Upper Colorado River has declined by about 20%. Research suggests that half of this decline can be attributed to human-induced climate change.
Most of the river’s streamflow comes from the snowpack of the Upper Colorado River Basin, which stretches across five western US states but is primarily located in Colorado and Utah.
This region has been gripped by a historic “megadrought” for more than a quarter of a century. Nearly half of the megadrought’s intensity over 2000-18 is attributable to climate change, according to a 2020 study.
At the same time, the increasing population in the US south-west has put added pressure on the Colorado River’s water supply. The number of people obtaining some or all of their water from the Colorado system has grown by 15 million (around 60%) since 1992.
Schmidt tells Carbon Brief:
“There’s an ultimate cause of the present water crisis, and there’s a proximate cause. The ultimate cause is a warming climate, a warming planet and a pretty clear correlation between warming conditions and decreased runoff in the Colorado River Basin.
“The proximate cause is that in this messy democratic republic of ours, big policy decisions that match the variability of the climate occur painfully slowly – with intense political negotiations – and only incrementally.”
On 31 July, the US Bureau of Reclamation, which manages water resources in the western US, released an environmental impact statement on its proposed post-2026 strategy for managing Lakes Powell and Mead. The strategy itself has not been released yet.
Schmidt notes that the statement does appear to give the Bureau flexibility to “respond to crisis” by reducing the delivery of water to several states. However, he adds:
“They acknowledge it won’t work if we just stay critically dry, and of course every climate model for the 21st century, especially with a continually warming planet, says that that’s exactly what’s going to happen.”
The post Analysis: The two largest reservoirs in the US have hit record-low levels appeared first on Carbon Brief.
Analysis: The two largest reservoirs in the US have hit record-low levels
-
Climate Change1 year ago
Guest post: Why China is still building new coal – and when it might stop
-
Greenhouse Gases1 year ago
Guest post: Why China is still building new coal – and when it might stop
-
Greenhouse Gases2 years ago嘉宾来稿：满足中国增长的用电需求 光伏加储能“比新建煤电更实惠”
-
Climate Change2 years ago嘉宾来稿：满足中国增长的用电需求 光伏加储能“比新建煤电更实惠”
-
Climate Change2 years ago
Bill Discounting Climate Change in Florida’s Energy Policy Awaits DeSantis’ Approval
-
Renewable Energy10 months agoSending Progressive Philanthropist George Soros to Prison?
-
Greenhouse Gases1 year ago
嘉宾来稿：探究火山喷发如何影响气候预测
-
Carbon Footprint2 years agoUS SEC’s Climate Disclosure Rules Spur Renewed Interest in Carbon Credits