Over the past year, there has been a vigorous debate among scientists – and more broadly – about whether global warming is “accelerating”.
This, in turn, has led to questions about whether the world is warming “faster than scientists expected”.
Here, Carbon Brief takes a detailed look at the issue and finds that there is increasing evidence of an acceleration in the rate of warming over the past 15 years.
However, this acceleration is broadly in line with projections from the latest generation of climate models and the recent sixth assessment report (AR6) from the Intergovernmental Panel on Climate Change (IPCC). They all expect the world to warm notably faster in both current and future decades than the rate the world has experienced since 1970.
Carbon Brief’s analysis also reveals that the speed up in warming projected in the latest climate models (known as CMIP6) is similar to the acceleration estimated by prominent climate scientist Dr James Hansen and colleagues in their much-discussed 2023 paper in Oxford Open Climate Change.
The IPCC’s AR6 also produced a set of “assessed warming projections” that incorporate multiple lines of evidence. While these project future warming levels a bit below the average of CMIP6 models, they still expect the rate of warming up to 2050 to be around 26% faster than the world has experienced to date since 1970.
Even with an apparent acceleration in recent warming, there remain major questions regarding drivers of 2023’s record-breaking heat relative to 2022, though annual temperatures still remain well within the range of climate-model projections.
An accelerating debate
Between 1970 and 2008, the world warmed at an approximately linear rate – by 0.18C per decade.
However, in recent years, the rise in global surface temperatures has climbed above this long-term trend, with eight of the past nine years showing warming levels above what would be expected given the historical warming rate.
In December 2022, former NASA scientist Dr James Hansen and colleagues published a preprint (later published as a peer-reviewed paper in 2023) projecting an acceleration in the rate of warming over the next few decades. Hansen and colleagues argued that the rate of warming would increase to between 0.27C and 0.36C per decade – or a 50-to-100% increase in the warming rate since 1970 – over the next 30 years.
These projections – coupled with the exceptional and unusual temperatures in 2023 – has fuelled a debate within the scientific community and among the broader public about a potential acceleration in warming in recent years.
This potential acceleration is illustrated in the figure below, which shows a composite of global surface temperatures from five different groups – NASA GISTEMP, NOAA’s GlobalTemp, the UK Met Office/University of East Anglia’s HadCRUT5, Berkeley Earth and Copernicus’ ERA5 – following an approach used by the World Meteorological Organization.
The circles indicate individual years and the dashed lines show the trend over 1970-2008 (blue) and 2009-23 (red). (The past 15 years are highlighted here as that is the time period that has previously been used to assess potential changes in the underlying trend in the scientific literature.)
Annual global average surface temperatures from a composite of NASA GISTEMP, NOAA’s GlobalTemp, the UK MET Office/UEA’s HadCRUT5, Berkeley Earth, and Copernicus’ ERA5 following an approach used by the World Meteorological Organization, with linear trends between 1970 and 2008 (blue) and 2009 and 2023 (red) shown by the dashed lines. Chart by Carbon Brief.
The chart shows how the warming rate of 0.18C per decade seen since 1970 has almost doubled to roughly 0.3C per decade over the past 15 years.
Researchers have proposed a number of potential contributors to the increased rate of warming seen in recent years.
One is the significant decline in global air pollution over the past few decades, as well as a 2020 phase-out of sulphur in marine fuels, which have reduced the levels of cooling aerosols in the atmosphere.
Other suggested factors include an approaching peak in the 11-year solar cycle, the 2022 eruption of the Hunga Tonga volcano and the continued increases in atmospheric greenhouse gas concentrations.
The fact that the past 15 years ended on a particularly high point due to the current El Niño event might also result in higher warming rates – although the contribution of El Niño to overall 2023 temperatures remains an area of vigorous scientific debate.
It is possible to remove the estimated influence of some of the natural factors – such as El Niño and La Niña events, volcanic eruptions and variations in solar output – from the global temperature record.
The figure below shows a version of the temperature record above where these natural factors are removed. The recent warming (red dashed line) is even more evident in this chart compared to the prior trend (blue).
Composite of five annual global average surface temperature records with the El Niño-Southern Oscillation (ENSO), volcanic eruptions and solar variations removed. Linear trends between 1970 and 2008 (blue) and 2009 and 2023 (red) shown by dashed lines. Data from Tamino following an updated version of the methodology in Foster and Rahmstorf 2011. Chart by Carbon Brief.
However, despite this spate of very warm years, it is challenging to draw firm conclusions on the overall rate of global warming based on a time period as short as 15 years.
Even though recent trends appear to show significant acceleration, the long-term trend remains – just barely – within the full range of uncertainty in climate model projections.
There is a risk of conflating shorter-term climate variability with longer-term changes – a pitfall that the climate science community has encountered before.
Parallels with the warming ‘hiatus’
The debate around a potential acceleration in warming shares similarities with another scientific contretemps – the so-called “hiatus” in warming of the early 21st century.
During the 15-year period from 1998 to 2012, the rate of warming at the surface appeared to nearly “pause” – or at least slow down dramatically compared to climate-model projections.
The debate so consumed the scientific community – and some sections of the media – that there was a running joke among scientists that the journal Nature Climate Change should be renamed “Nature Hiatus” for the number of studies it published trying to explain the apparent slowdown.
In retrospect, the apparent hiatus and associated disagreement between climate models and observations was caused by a number of different factors. Key among them were natural variability (in the form of more heat uptake by the oceans), disparities in surface temperature records associated with a transition from ship engine room to automated buoy-based measurements of sea surface temperatures, and incomplete comparisons between climate models and observations that excluded areas such as the Arctic that had sparser observational coverage.
With the development of the 2015-16 “super” El Niño, any sign of a “pause” in warming quickly vanished and the argument faded away – though it made a brief return in climate-sceptic circles in more recent years. However, it left behind a lasting appreciation among many scientists for the danger of overinterpreting short-term climate variability and is one of the reasons why there has been reticence in some circles about current claims of an acceleration.
Nonetheless, there are a number of reasons to expect that what the world is currently experiencing is not just the influence of natural variability on top of human-caused warming. An acceleration of warming in recent decades also shows up in ocean heat content and in satellite measurements of the Earth’s energy imbalance.
And, perhaps most importantly, an acceleration in the rate of warming in recent years – and over the coming decades – is exactly what is seen in climate models under a scenario in keeping with current global policies (known as SSP2-4.5). Under this scenario, greenhouse gas emissions remain around current levels until the middle of the century, alongside a decline in emissions of planet-cooling aerosols such as sulphur dioxide.
An expected acceleration
The most notable thing about the current apparent acceleration in warming is that it was expected.
Climate models have long shown a faster rate of warming in current and future decades than has been observed to date, though there is some disagreement among modelling estimates.
The table below shows a compilation of both observed rates of warming to date and different model projections out to 2050.
| Projection | Time period | Trend (C/decade) |
|---|---|---|
| Observed trend since 1970 | 1970-2023 | 0.19 (0.17 to 0.21) |
| Observed trend since 2009 | 2009-2023 | 0.30 (0.17 to 0.43) |
| Estimated human contribution (Forster et al, 2023) | 2013-2022 | 0.23 |
| IPCC AR6 assessed warming projections under SSP2-4.5 | 2015-2050 | 0.24 (0.17 to 0.34) |
| Full CMIP6 ensemble under SSP2-4.5 | 2015-2050 | 0.29 (0.2 to 0.4) |
| Hansen et al, 2023 | 2011-2050 | 0.32 (0.27 to 0.36) |
Global surface temperatures have warmed at a rate of 0.19C per decade between 1970 and 2023. They have warmed at a faster rate (~0.3C per decade) over the past 15 years – though with large uncertainties of 0.17C to 0.43C given the shorter time period.
The estimated human contribution to global warming of 0.23C for the past decade (2013 to 2022), as published in Earth System Science Data by Prof Piers Forster and colleagues, is based on a climate model emulator that is driven by an updated estimate of factors including the influence of greenhouse gases and aerosols on the Earth’s climate in recent years.
The IPCC’s AR6 provided “assessed warming projections” based on CMIP6 models – weighted based on their ability to accurately reproduce historical temperatures – and the recent synthesis of climate sensitivity estimates. These assessed warming projections show 0.24C warming per decade between 2015 and 2050 with an uncertainty range of 0.17C to 0.34C in the current-policy-type SSP2-4.5 scenario. This represents approximately 26% faster warming than the world has experienced since 1970.
The full CMIP6 ensemble of models has notably more warming than the IPCC-assessed warming projections. CMIP6 models, on average, warm by 0.29C per decade with a range of 0.2C to 0.4C, or 53% faster than historical warming since 1970.
The recent projections by Dr James Hansen and colleagues has a very similar projection of future warming rates to the CMIP6 ensemble, estimating warming of around 0.32C per decade with an uncertainty of 0.27C to 0.36C.
These estimates are summarised in the charts below, which show the historical warming rate (top left), the AR6 assessed range under SSP2-4.5 (top right), the CMIP6 models under SSP2-4.5 (bottom left) and Hansen et al’s future warming projection (bottom right). The blue dots and red dashed lines show observed data and the long-term trend, while the black lines and yellow shading show the average of model projections and their ranges.
Comparison of historical and future warming projections from a continuation of the 1970-2023 linear trend (top left), the IPCC AR6 assessed warming range for SSP2-4.5 (top right), the CMIP6 multimodal mean and range for SSP2-4.5 (bottom left) and Hansen et al 2023 (bottom right). Blue dots and red dashed lines show observations and trends, while the black lines and yellow shading show model projections and their ranges. Chart by Carbon Brief.
In all three cases, there is an expectation of acceleration of warming both at present and in coming decades compared to the warming the world has experienced since 1970.
However, this does not mean that the world will pass climate limits such as 1.5C sooner than expected. The current best estimates of when these thresholds will be passed are based on climate models that include the near-term warming acceleration.
The apparent acceleration of warming in recent years is well in line with climate model projections, which lends confidence that what the world is experiencing is a result of human activity rather than a result of natural variability.
However, this does not mean that the world will not experience cool years in the future; the next La Niña year – likely in 2025 – will probably end up well below some of the prior record-setting years.
But, as long as global emissions of CO2 and other greenhouse gases fail to decline and the world continues to tackle aerosol pollution, the world will likely warm faster than experienced in the past.
The post Factcheck: Why the recent ‘acceleration’ in global warming is what scientists expect appeared first on Carbon Brief.
Factcheck: Why the recent ‘acceleration’ in global warming is what scientists expect
The launch of the Africa Energy Bank (AEB) has been put back yet again, raising doubts about the institution’s future ability to finance fossil fuel projects – its main objective – as global lenders retreat from such investments over climate concerns, experts told Climate Home News.
The bank, which had been billed to launch in September after a series of delays, is now scheduled to begin operations in November, according to the head of the African Energy Chamber, an advocacy body for the continent’s oil and gas sector.
Even as the world aims to transition away from fossil fuels, many African leaders have made clear they want to continue exploring and extracting the continent’s large oil and gas deposits – estimated at around 125 billion barrels of crude and over 600 trillion cubic feet of gas – to boost economic development.
As a group, Africa sided with a number of powerful oil-and-gas producing nations in blocking progress on negotiations to craft a global roadmap to transition away from fossil fuels at last year’s UN COP30 climate talks, although some countries did individually support the proposal.
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Meanwhile, major projects under development across the continent – including the 1,443-km East African Crude Oil Pipeline (EACOP) and Dangote’s 700,000-barrel-per-day Kenyan refinery – show that African governments see oil and gas as playing a significant role in meeting their energy and economic needs for many years to come.
In 2022, at a gathering of the African Petroleum Producers’ Organization (APPO) in oil-rich Angola, ministers from its member states adopted a resolution to create the Africa Energy Bank to finance projects for the production, use and trade of oil, gas and broader energy sources.
African control over energy resources
An article on the APPO website explains that the bank was conceived as a way to overcome “disenchantment” with fossil fuels among “the international community” which it said had crystallised around the “energy transition” concept.
“If Western countries, after having long taken advantage of the energy sources they now revile to develop, can afford the luxury of abandoning them, this is not the case in Africa,” it adds, noting that many of the continent’s economies are still largely dependent on oil and gas revenues.
A separate web page about the bank, also hosted on APPO’s website, says its objectives include financing the exploration, production and refining of oil and gas, as well as supporting member states in transitioning from fossil fuels to cleaner energy sources “while ensuring energy security”.
Said Addi, a former executive with Shell and energy commodities trading house Gunvor, said the new bank was judged necessary because financing for hydrocarbons from many traditional international lenders has become constrained.
In trying to fill this financing gap, Africa is not simply setting up another fund to support oil and gas, he added. “It is also an attempt to give African countries greater control over how their energy resources and infrastructure are financed,” he explained.
Nigeria to host the AEB
The energy bank – a joint initiative of APPO and the African Export–Import Bank (Afreximbank) – has so far suffered several delays and is almost two years behind schedule. The initial plan was to start operations in January 2025, with Nigeria as the host country, but the bank’s opening was delayed to June of that year to allow Nigeria time to finalise the construction of the bank’s headquarters in Abuja.
After the government announced the completion of the offices in late November 2025, a new launch date was set for January 2026, which was moved back to April, June and then September. Now it has shifted again to November, raising concerns that the institution may be losing momentum.
Former Shell executive Addi said that if the capital is eventually paid in, the bank becomes operational and its first projects are commercially credible, then the delays will be regarded as normal teething troubles in setting up a multilateral institution. But, he added, scepticism will be justified if it continues to stall.
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Baron Lamarré, an oil and gas expert and former Petronas oil trader, said that missing “three deadlines in a row is not normal”, and warned that if the timeline slips again, “the story flips from ‘ambitious institution finding its footing’ to ‘good idea that lost momentum before it found any’.”
The Nigerian government, APPO and Afreximbank did not respond to requests for comment by the time of publication.
The funding challenge
The Africa Energy Bank is targeting base capital of $5 billion, with plans to scale up to $120 billion within five years by mobilising private-sector funds. However, it is expected to start operations with initial seed capital of $500 million.
The funding plan is to have the 18 member countries of the APPO contribute $83 million each to the bank as equity for a combined $1.5 billion. Afreximbank, other non-APPO African countries and investors outside the continent are expected to provide the remaining $3.5 billion.
But even the initial $500 million has not been easy to mobilise. In May, APPO Secretary-General Farid Ghezali called on members to deliver on their pledges towards the startup goal before the end of June. But the delays suggest this may not have been met, with experts saying Africa may be finding it difficult to self-fund its oil and gas projects in the absence of international capital.
Lamarré said every extension of the deadline points to the fact that “raising fossil fuel capital in Africa without the majors and their financing networks is brutally hard”.
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Since 2020, Western lenders, export credit agencies and insurers have been in steady retreat from African hydrocarbons, he said, while oil majors are divesting their African assets, handing over fields to smaller local operators whose credit ratings are not high enough to borrow cheaply.
Even capital from China and the Gulf, which has partially filled the gap, cannot match the volume, tenor or pricing that Western investors once offered, Lamarré argued.
“If mobilising the first $500 million of seed capital [for the AEB] has taken this long, that’s the clearest signal yet of how steep the climb to $120 billion looks,” he said, noting that the continent’s energy financing gap is as large as $30 billion-$45 billion per year.
Africa’s investment landscape, meanwhile, has been shifting. While foreign direct investment dropped from a 2024 peak, inflows remained roughly one-third above the continent’s long-term average in 2025, according to the 2026 World Investment Report from UN Trade and Development (UNCTAD). They are concentrated in a few sectors including critical minerals needed for renewable energy technologies, battery manufacturing and advanced industrial production.
At the same time, data on global energy investment from the International Energy Agency (IEA) shows that fossil fuel investment in Africa has declined over the last decade.
“Trojan horse” for fossil fuels
While the Africa Energy Bank struggles to get off the ground, climate campaigners have criticised its primary aim of financing oil and gas on the continent at a time when the world is starting to move away from high-carbon fuels to cleaner alternatives.
Bhekumuzi Dean Bhebhe, founder of Africa Change Lab, described the bank as a “Trojan horse”, arguing that its focus on fossil fuel financing runs counter to the global energy transition and the African Union’s Agenda 2063 goals of sustainable development and inclusive growth.
The energy bank, he warned, “risks locking Africa into a new cycle of debt, dependency and fossil fuel entrenchment”, adding that its financing blueprint does not pave the way for a climate-resilient future. “In truth, it is to deepen the same extractive, carbon-heavy pathways that the continent should be moving away from,” he added.
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Kenya-based climate and energy expert Joab Okanda said the AEB’s plan to finance oil and gas is “a misplaced priority” and it should instead back clean energy in line with the policies of some of Africa’s major export markets like Europe.
In addition, the new bank could struggle to mobilise enough resources to advance large-scale oil and gas projects, he added, noting that its proposed $5-billion initial capital is equivalent to the cost of the East African Crude Oil Pipeline alone.
The AEB’s aim of backing more fossil fuels should be flipped “to support countries that are oil-dependent to start working on their transition plans”, Okanda said.
The post Launch of Africa Energy Bank delayed again in blow to oil and gas hopes appeared first on Climate Home News.
Launch of Africa Energy Bank delayed again in blow to oil and gas hopes