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For the past two decades, low-level cloud cover has been declining, increasing the amount of sunlight absorbed by Earth and amplifying global warming.

As global temperatures have reached record highs in recent years, there has been concern that the decline in cloudiness may be enhancing warming more than previously expected.

In a new study, published in Atmospheric Chemistry and Physics Letters, we investigate how the decline in global cloudiness affects the Earth’s “energy imbalance” – the difference between absorbed solar energy and heat radiated into space that results in global warming.

This imbalance has more than doubled over the past 20 years, as greenhouse gases have trapped more heat in the atmosphere.

We find that, since 2003, the decrease of cloudiness has been responsible for half of the increase of Earth’s energy imbalance.

Analysing the drivers of global changes to cloud cover, we find that the decrease in cloudiness over the past two decades has been primarily driven by humans, rather than being caused by natural variations in Earth’s climate.

Taken together, our findings mean that scientists can even more confidently attribute recent warming to human activities.

Low-level clouds and warming

Low-level clouds are those that have a base below 6,500 feet (2,000 metres) above Earth and include stratus, stratocumulus and cumulus. They are typically found over large areas of the global ocean, where there is a large moisture supply from evaporation.

These clouds have a powerful impact on the Earth’s climate because they reflect a substantial fraction of incoming sunlight back into space.

By acting as the Earth’s “sunscreen”, they keep the climate cooler than it would otherwise be.

Satellite observations reveal a global decline in these low-level clouds since the turn of the millennium. This is shown in the chart below, where the black line represents the average percentage of the Earth covered by low-level clouds and the dashed line the downward trend.

Low-level cloud amount (in percent of the globe) from July 2003 to June 2024, based on the CERES-FBCT satellite product. Adapted from Ceppi et al (2026).

Our research shows that the decline in cloudiness over the past 20 years has played a major role in increasing the Earth’s energy imbalance and, therefore, warming.

The Earth’s energy imbalance is the difference between the amount of energy arriving at the Earth from the sun and what is reflected and radiated back to space.

Rising greenhouse gas emissions from human activity are upsetting this balance by trapping more energy in the atmosphere, leading to warming.

A less cloudy atmosphere also helps supercharge the energy imbalance, because it means more sunlight reaches the Earth.

In our research, we use a simple model to assess how changes in low-level clouds between July 2003 and June 2024 contributed to the Earth’s energy imbalance.

We find that, averaged globally, changes in low-level cloudiness caused an extra 0.22 watts per metre squared (W/m2) per decade of absorbed sunlight. This amounts to exactly half of the concurrent increase in Earth’s energy imbalance over the same time period.

This is shown in the chart below, where the green line represents the increase in the Earth’s energy imbalance over 2003-24 and the black line shows the contribution of low-level clouds to that trend.

Anomalies in global energy imbalance (green, from CERES-EBAF satellite observations) and contribution of low-level cloudiness changes (black, from CERES-FBCT satellite observations) from July 2003 to June 2024. Adapted from Ceppi et al (2026).
Anomalies in global energy imbalance (green, from CERES-EBAF satellite observations) and contribution of low-level cloudiness changes (black, from CERES-FBCT satellite observations) from July 2003 to June 2024. Adapted from Ceppi et al (2026).

Why is cloudiness changing?

Scientists have attributed declining cloud cover in the 21st century to three main causes.

The first is a decrease in human-caused aerosol emissions over recent decades. Aerosols – tiny, light‑scattering particles produced mainly by burning fossil fuels – influence the formation of clouds, by acting as “seeds” for cloud droplets to form.

In recent years, aerosol emissions have been reduced due to efforts to clean up air pollution, such as cleaner shipping fuel regulations. Cleaner air has resulted in a decline in cloudiness.

Second, increasing concentration of greenhouse gases in the atmosphere has led to a warmer and drier atmosphere, which also helps to dissipate clouds.

Although a warmer atmosphere generally holds more water vapour in absolute terms, what matters for clouds is the “relative humidity” of the air, which has been declining in many places. This is a measure of how “saturated” the air is, or how much water vapour the air contains compared to the maximum it could hold.

Finally, cloud cover decreases have also been linked to ocean surface warming, which affects atmospheric humidity and, thus, cloudiness. Reduced cloudiness leads to more sunlight being absorbed at the ocean surface – and more warming. This amplifying loop is known as a “cloud feedback”.

However, the exact strength of these three effects on cloud cover is still unclear.

In fact, cloud feedbacks are among the main uncertainties in climate model projections of global warming.

Attributing low-cloud cover changes

In the next step of our study, we explore how the three human-caused factors mentioned above – aerosols, greenhouse gases and cloud feedback – contributed to recent low-level cloud changes.

We also look at the extent to which cloud changes could be explained by natural climate variability, which causes substantial year-to-year fluctuations in cloudiness and energy imbalance.

To do this, we use a statistical technique known as “cloud-controlling factor analysis”.

This analysis involves calculating the sensitivity of clouds to their “controlling factors”, including meteorological variables, such as temperature, humidity and winds, as well as aerosol concentrations.

To calculate how each factor contributed to the bigger picture of declining cloud cover, we combine sensitivity calculations with observed trends in meteorology and aerosol emissions.

This analysis allows us to attribute trends in cloud cover to known physical drivers: either natural climate variability, or human activities linked to aerosols, greenhouse gases and cloud feedback.

Our research finds that about 40% of the low-level cloud decrease since 2003 was driven by warming of the ocean surface – in other words, the cloud feedback process. This is followed by the effects of greenhouse gases (21%) and aerosols (14%).

Natural climate variability accounts for just 3% of the low-level cloud trend.

(The remaining 23% of the trend cannot be explained by our statistical method. This could be due to the limitations of cloud, temperature, humidity and aerosol concentration observations.)

The chart below shows how human-driven factors – the sum of aerosol effects (red), greenhouse gas emissions (pink) and cloud feedback (burgundy) – were responsible for almost three quarters of the decrease in low-level cloudiness over 2003-24. Natural climate variability (blue), on the other hand, played a minor role.

Contributions to the decrease in global low-level cloudiness between July 2003 and June 2024, in percent of the total observed trend, from: cloud feedback (40%, burgundy), aerosols (14%, red), greenhouse gases (20%, pink), their sum (“human-driven”, 74%), and natural climate variability (blue, 3%). The remaining 23% of the cloud decrease is unexplained by our statistical method. Thin black bars denote 67% confidence ranges. Adapted from Ceppi et al (2026).
Contributions to the decrease in global low-level cloudiness between July 2003 and June 2024, in percent of the total observed trend, from: cloud feedback (40%, burgundy), aerosols (14%, red), greenhouse gases (20%, pink), their sum (“human-driven”, 74%), and natural climate variability (blue, 3%). The remaining 23% of the cloud decrease is unexplained by our statistical method. Thin black bars denote 67% confidence ranges. Adapted from Ceppi et al (2026).

Thus, our analysis indicates that, at global scales, the observed cloud decrease is primarily driven by humans, rather than being caused by natural variations in Earth’s climate.

And, since low-level clouds contribute to half of the energy imbalance increase over the same period, it follows that a significant part of recent rises in energy imbalance can also be attributed to humans.

Clouds in climate models

So, should we be concerned that this cloudiness decrease means the Earth could see more warming than already anticipated?

To answer this, we looked at whether the climate models used by scientists to project future global warming accurately simulate recent declines in low-cloud cover.

While the models produce a wide range of outcomes, we found that, on average, the simulated changes in low-level cloudiness changes are in close agreement with real-world trends.

This is reassuring, as it means the effects of low-cloud cover are already accounted for in existing warming projections.

However, questions still remain around what is driving recent increases to the Earth’s energy imbalance, which have outpaced projections made by climate models.

Our findings rule out declines in low-level clouds as the reason that climate models have been underestimating the Earth’s energy imbalance, and, as a result, warming. But it is still possible that models are underrepresenting future global warming to some extent.

Low-level clouds are just one of several drivers of changes in energy imbalance. Future work will therefore need to assess other observed and simulated drivers of energy imbalance changes: for example, the impact of upper-level clouds, or changes in water vapour or sea ice.

Finally, it is important to stress that, while our findings are reassuring, they should certainly not make us complacent about the current global warming trend. The impacts of climate change are serious enough as they are – even if there is no evidence of a missing amplifying feedback in our projections.

The post Guest post: How declining cloudiness is accelerating global warming appeared first on Carbon Brief.

Guest post: How declining cloudiness is accelerating global warming

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Indigenous groups warn Amazon oil expansion tests fossil fuel phase-out coalition

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Indigenous leaders from across the Amazon have warned that stopping the expansion of oil drilling into their territories will be a crucial test for a growing international coalition committed to transitioning away from fossil fuels.

As 60 countries discussed at a landmark conference in Santa Marta, Colombia, pathways to end the world’s reliance on fossil fuels, Indigenous groups said the process risks losing credibility if governments continue opening new oil frontiers in the Amazon.

Their central demand was the establishment of fossil fuel “exclusion zones” across Indigenous territories and biodiverse areas of the rainforest, permanently barring new oil and gas expansion in one of the world’s most critical ecosystems. Indigenous representatives proposed establishing protected “Life Zones”, which they said would provide legal safeguards against governments and companies seeking to expand extraction into their lands.

But Indigenous delegates left the conference frustrated as the final synthesis report drafted by co-chairs Colombia and the Netherlands failed to include the proposal.

In a statement at the end of the conference, Patricia Suárez, from the Organization of Indigenous Peoples of the Colombian Amazon (OPIAC), said formally declaring Indigenous territories – especially those inhabited by peoples in voluntary isolation – as exclusion zones for extractive industries was “an urgent measure”.

“If the heart of the conference does not begin there, it risks remaining a set of good intentions that fails to respond to either science or our Indigenous knowledge systems,” she added.

Pushing for a new oil frontier

Campaigners say the pressure on the Amazon is intensifying just as scientists warn the rainforest is nearing irreversible collapse. Around 20% of all newly identified global oil reserves between 2022 and 2024 were discovered in the Amazon basin, fuelling renewed interest from governments and companies seeking to develop the region as the world’s next major oil frontier.

Ecuador has moved ahead with the auction of new oil blocks in the rainforest, while the country’s right-wing president Daniel Noboa has promoted the region as a “new oil-producing horizon” and backed efforts to expand fracking with support from Chinese companies.

    In Santa Marta, a coalition of seven Indigenous nations from Ecuador issued a declaration condemning the government, which did not participate in the conference.

    “While the world talks about energy transition, our government is pushing for more oil in the Amazon,” said Marcelo Mayancha, president of the Shiwiar nation. “Throughout history, we have always defended our land. That is our home. We will forever defend our territory.”

    Indigenous groups also warned that Peru – another South American nation absent from the conference – plans to auction new oil blocks in the Yavarí-Tapiche Territorial Corridor, a highly sensitive region along the Brazilian border that contains the world’s largest known concentration of Indigenous peoples living in voluntary isolation.

    COP30 host under scrutiny

    Indigenous leaders also criticised Brazil, arguing that despite its international climate leadership, the country is simultaneously advancing major new oil projects in the Amazon region.

    Luene Karipuna, delegate from Brazil’s coalition of Amazon peoples (COIAB), said the oil push threatens the stability of the rainforest. Not far from her home, in the northern state of Amapá, state-run oil giant Petrobras is currently exploring for new offshore oil reserves off the mouth of the Amazon river.

    Brazil participated in the Santa Marta conference and was among the countries that first pushed for discussions on transitioning away from fossil fuels at COP negotiations. Yet the country is also planning one of the largest expansions in oil production in the world, according to last year’s Production Gap report.

    Veteran Brazilian climate scientist Carlos Nobre told Climate Home that the country’s participation at the Santa Marta conference contrasted with its oil and gas production targets. “It does not make any sense for Brazil to continue with any new oil exploration,” he said, and noted that science is clear that no new fossil fuels should be developed to avoid crossing dangerous climate tipping points.

    He added that the Brazilian government faces pressures from economic sectors, since Petrobras is one of the countries top exporting companies. “They look only at the economic value of exporting fossil fuels. Brazil has to change.”

    The COP30 host also promised to draft a voluntary proposal for a global roadmap away from fossil fuels, which is expected to be published before this year’s COP31 summit.

    “In Brazil, that advance has caused so many problems because it overlaps with Indigenous territories. Companies tell us there won’t be an impact, but we see an impact,” Karipuna said. “We feel the Brazilian government has auctioned our land without dialogue.”

    For Karipuna and other Indigenous leaders, establishing exclusion zones across the Amazon is no longer just a regional demand, but a prerequisite to prevent the collapse of the rainforest.

    “That’s the first step for an energy transition that places Indigenous peoples at the centre,” she added.

    The post Indigenous groups warn Amazon oil expansion tests fossil fuel phase-out coalition appeared first on Climate Home News.

    https://www.climatechangenews.com/2026/05/08/indigenous-amazon-oil-expansion-fossil-fuel-phase-out-coalition-santa-marta/

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    Kenya seeks regional coordination to build African mineral value chains

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    African leaders have intensified calls for governments to stop exporting raw minerals and step up efforts to align their policies, share infrastructure and coordinate investment to add value to their resources and bring economic prosperity to the continent.

    In a speech to the inaugural Kenya Mining Investment Conference & Expo in Nairobi this week, Kenyan President William Ruto became the latest African leader to confirm the country will end exports of raw mineral ore. The East African nation has deposits of gold, iron ore and copper and recently launched a tender for global investors to develop a deposit of rare earths, which are used in EV motors and wind turbines, valued at $62 billion.

    Kenya is among more than a dozen African nations that have either banned or imposed export curbs on their mineral resources as they seek to process minerals domestically to boost revenues, create jobs and capture a slice of the industries that are producing high-value clean tech for the energy transition.

      “For too long we have extracted and exported raw materials at the bottom of the value chain, while others have processed, refined, manufactured and captured the greater share of economic value,” Ruto told African ministers and stakeholders gathered at the mining investment conference in Nairobi.

      As a result, Africa currently captures less than 1% of the value generated from global clean energy technologies, he said. To address this, Kenya, in collaboration with other African nations, “will process our minerals here in the continent, we will refine them here and we will manufacture them here”, he added.

      Mineral export restrictions on the rise

      Africa is a major supplier of minerals needed for the global energy transition. The continent holds an estimated 30% of the world’s critical mineral reserves, including lithium, cobalt and copper. The Democratic Republic of Congo produces roughly 70% of global cobalt, a key ingredient in lithium-ion batteries, while countries such as Guinea dominate bauxite production, and Mozambique and Tanzania hold significant graphite deposits.

      But African governments have struggled to attract the investment needed to turn their vast mineral wealth into a green industrial powerhouse. Recently Burundi, Malawi, Nigeria and Zimbabwe are among those that have resorted to banning the export of unrefined minerals to incentivise foreign companies to invest in value addition locally.

      Outdated geological data limits Africa’s push to benefit from its mineral wealth

      This week, Zimbabwe exported its first shipments of lithium sulphate, an intermediate form of processed lithium that can be further refined into battery-grade material, from a mine and processing plant operated by Chinese company Zhejiang Huayou Cobalt.

      After freezing all exports of lithium concentrate – the first stage of processing – earlier this year, the government introduced export quotas and will ban all exports from January 2027.

      Export restrictions on critical raw materials have grown more than five-fold since 2009, found a report by the Organisation for Economic Co-operation and Development (OECD) published this week. In 2024, a more diverse group of countries, including many resource-rich developing economies in Africa and Asia, introduced restrictions, including Sierra Leone, Nigeria and Angola.

      This is “a structural shift in the wrong direction,” Mathias Cormann, the OECD’s secretary-general, told the organisations’ Critical Minerals Forum in Istanbul, Turkey, this week.

      “We understand the motivations: building local industries, managing environmental impacts, capturing greater value domestically. But our research is quite clear. Export restrictions distort investment, reduce volumes and undermine supply security often while delivering limited gains in value added,” he said.

      In-country barriers to success

      Thomas Scurfield, Africa senior economic analyst at the Natural Resource Governance Institute, told Climate Home News that export restrictions “can look like a promising route to local value addition” for cash-strapped African mineral producers but have “rarely worked” unless countries already have reliable energy, infrastructure and competitive costs for processing.

      “Without those conditions, bans may simply push companies to scale back mining rather than scale up processing,” he said.

      Alaka Lugonzo, partnerships lead for Africa at Global Witness, identified gaps in practical skills and infrastructure as other major barriers. “You need engineers, geologists, marketers,” Lugonzo said, warning that graduates are increasingly unable to match the pace of industry change.

      On infrastructure, she said that plentiful and stable energy supplies are vital and while Kenya has relatively robust road networks, they are insufficient for industrial-scale operations.

      “Meaningful value addition and real industrialisation requires heavy machinery… and you will need better infrastructure,” she said, highlighting persistent last-mile challenges in mining regions where “there’s no railway, there’s no electricity, there’s no water”.

      Export capacity is another concern, she said, particularly whether existing port systems could handle increased volumes of processed minerals.

      Regional approach recommended

      Scurfield said that through regional cooperation – including pooling supplies, specialising across different stages of refining and manufacturing, and building larger regional markets – “African countries could overcome many domestic constraints that make going alone difficult”.

      That’s what close to 20 African governments are working to deliver as part of the Africa Minerals Strategy Group, which was set up by African ministers and is dedicated to foster cooperation among African nations to build mineral value chains and better benefit from the energy transition.

      Africa urged to unite on minerals as US strikes bilateral deals

      Nigerian Minister of Solid Minerals Dele Alake, who chairs the group, said “true collaboration” between countries, including aligning mining policies, sharing infrastructure, coordinating investment strategies and promoting trade across the continent, will create the conditions for long-term investments that could turn Africa into “a formidable and competitive force within the global mineral supply chain”.

      “The time has come for Africa to redefine its place within the global mineral economy and that transformation must begin with regional integration and regional cooperation,” he told the mining investment conference in Nairobi.

      Lugonzo of Global Witness agreed, saying that value-addition would benefit from adopting a continental perspective. “Why should Kenya build another smelter when we can export our gold to Tanzania for smelting, and then we use the pipeline through Uganda to take it to the port and we export it?” she asked.

      To facilitate that, there is a need to operationalise the Africa Free Trade Continental Agreement (AFTCA), she added. “That agreement is the only way Africa is going to move from point A to point B.”

      The post Kenya seeks regional coordination to build African mineral value chains appeared first on Climate Home News.

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      Key green shipping talks to be held in late 2026

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      The future of the global shipping industry – and its 3% share of global emissions – will be decided in three weeks of talks in the third quarter of this year, after a decision taken in London on Friday.

      At the International Maritime Organisation (IMO) headquarters this week, governments largely failed to substantively negotiate a controversial set of measures to penalise polluting ships and reward vessels running on clean fuels known as the Net-Zero Framework. The green shipping plan has been aggressively opposed by fossil fuel-producing nations, in particular by the US and Saudi Arabia.

      This week, countries delivered statements outlining their views on the measures in a session that ran from Wednesday into Thursday. Then, late on Friday afternoon, they discussed when to negotiate these measures and what proposals they should discuss.

      After a lengthy debate, which the talks’ chair Harry Conway joked was confusing, governments agreed to hold a week of behind-closed-door talks from 1 September to 4 September and from 23 November to 27 November.

      Following these meetings, which are intended to negotiate disagreements on the NZF and rival watered-down measures proposed by the US and its allies, there will be public talks from November 30 to December 4.

        Last October, talks intended to adopt the NZF provisionally agreed in April 2025 were derailed by the US and Saudi Arabia, who successfully persuaded a majority of countries to vote to postpone the talks by a year.

        Those talks, known as an extraordinary session, are now scheduled to resume on Friday December 4 unless governments decide otherwise in the preceding weeks. While this Friday session will be in the same building with the same participants as the rest of the week’s talks, calling it the extraordinary session is significant as it means the NZF can be voted on.

        Em Fenton, senior director of climate diplomacy at Opportunity Green said that the NZF “has survived but survival is not a victory” and called for it to be adopted later this year “in a way that maintains urgency and ambition, and delivers justice and equity for countries on the frontlines of climate impacts”.

        NZF’s supporters

        The NZF would penalise the owners of particularly polluting ships and use the revenues to fund cleaner fuels, support affected workers and help developing countries manage the transition.

        Many governments – particularly in Europe, the Pacific and some Latin American and African nations – spoke in favour of it this week.

        South Africa said the fund it would create is “the key enabler of a just transition” and its removal would take away predictable revenues from African countries. Vanuatu said that “we are not here to sink the ship but to man it”.

        Australia’s representative called it a “carefully balanced compromise”, as it was provisionally agreed by a large majority after years of negotiations, and warned that failing to adopt it would harm the shipping industry by failing to provide certainty.

        Santa Marta summit kick-starts work on key steps for fossil fuel transition

        Canada’s negotiator said that if it was weakened to appease its critics like the US and Saudi Arabia, this would disappoint those who think it is too weak already like the Pacific islands.

        A large group of mainly big developing countries like Nigeria and Indonesia did not rule out supporting the framework but called for adjustments to help developing countries deal with the changes. Nigeria called for developing countries to be given more time to implement the measures, a minimum share of the fund’s revenues and discounts for ships bringing them food and energy.

        According to analysis from the University of College London’s Energy Institute, the countries speaking in support of the NZF include five countries which voted with the US to postpone talks in October and a further ten countries which did not take a clear position at that time. Most governments support the NZF as the basis for further talks, the institute said.

        Opposition remains

        But a small group of mainly oil-producing nations said they are opposed to any financial penalties for particularly polluting ships.

        They support a proposal submitted by Liberia, Argentina and Panama which has proposed weakening emission targets and ditching any funding mechanism for the framework involving “direct revenue collection and disbursement”.

        Argentina argued that the NZF would harm countries which are far from their export markets and said concerns over that cannot be solved “by magic with guidelines”. They added that, as a result, the NZF itself needs to be fundamentally re-negotiated.

        The UCL Energy Institute said that just 24 countries – less than a quarter of those who spoke – said they supported Argentina’s proposal.

        While this week’s talks did not see the kind of US threats reported in October, their delegation did leave personalised flyers on every delegate’s desk which were described by academics, negotiators and climate campaigners as misleading.

        One witness told Climate Home News that junior US delegates arrived early on Wednesday and placed flyers behind governments’ name plates warning each country of the costs they would incur if the NZF is adopted.

        The figures on a selection of leaflets seen by Climate Home News ranged from $100 million for Panama to $3.5 billion for the Netherlands. “They are trying to scare countries away from supporting climate action with one-sided information”, one negotiator told Climate Home News.

        A flyer left on Pakistan’s desk, shared by a witness with Climate Home News

        They added that the calculations, by the US State Department’s Office of the Chief Economist, ignore the fact that the money raised would be shared to help poorer countries’ transition as well as ignoring the economic costs of failing to address climate change.

        Tristan Smith, an academic representing the Institute of Marine Engineering, Science and Technology, told the meeting that the calculations were “opaque” and flawed as they overstate the contribution of fuel cost to trade costs.

        A US State Department Spokesperson said in a statement that they “firmly stand behind our estimates” which were shared “in good faith” and to “provide an additional tool to policymakers as they contemplate the true economic burden over the NZF”.

        The post Key green shipping talks to be held in late 2026 appeared first on Climate Home News.

        https://www.climatechangenews.com/2026/05/01/key-green-shipping-talks-to-be-held-in-late-2026/

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