Rural land cover surrounding a city has the potential to reduce the “urban heat island” (UHI) effect and cool the city centre by more than 0.5C, new research shows.
While heatwaves around the world are becoming more frequent and intense because of human-caused warming, they are made even more severe in cities by the UHI effect, which traps heat in urban areas and keeps them warmer than their rural surroundings.
The study, published in Nature Cities, analyses 20 years of data from 30 cities in China and finds that a ring of rural land around a city can bring the urban temperature down. A buffer ring that is at least half the city’s width can have the biggest cooling effect.
To optimise the land cover and reduce the UHI intensity, the authors recommend “joining up patches of rural land, planting more woodland around a city and having fewer, bigger lakes”.
Previous work on mitigating the UHI effect has mostly “focused on strategies that seek solutions within the city limits”, the study says.
However, a co-author tells Carbon Brief that as urban land is often limited, the findings show that making changes to land use “outside a city can make a big difference to temperatures downtown”.
Urban heat dome
Temperatures in cities are consistently higher than in the surrounding countryside due to the heat-trapping properties of urban infrastructure. Closely packed buildings, heat-absorbing surfaces, such as concrete, and human activity, such as driving cars, all contribute to the urban heat island effect (UHI).
The specific difference between the hotter city and cooler countryside is known as the UHI “intensity”. In London in summer, estimates suggest the temperature inside the city is an average of 5C more than surrounding rural areas at night and 3C more during the day.
In comparison, natural landscapes, such as trees or water bodies, can reduce surrounding temperatures through shade and water evaporation. Adding more green spaces inside a city can help to cool it down, but research shows the effects are generally limited without significant and well-distributed coverage.
Prof Shi-Jie Cao, director of the Center for Sustainable Built Environment at the School of Architecture, Southeast University in China and visiting professor at the University of Surrey’s Global Centre for Clean Air Research (GCARE), is a co-author on the new study. He tells Carbon Brief that “urban land is precious and limited” for heat mitigation strategies within cities. He continues:
“This study presents the first comprehensive quantification of how rural land cover mitigates the UHI and opens new avenues for addressing high-temperature urban catastrophes”.
Higher temperatures in cities lead to the formation of a “heat dome”, roughly twice the size of the city boundary, the study says.
The diagram below shows how hotter (red) and colder air (blue) circulate through the dome. Cooler breezes from the neighbouring rural areas around the city blow into the urban centre, exchanging heat within the dome.
UHIs also exacerbate the effect of heatwaves, which are becoming more likely and more severe due to climate change. This increases the vulnerability of the more than 4.5 billion people living in urban regions globally.
Dr Eunice Lo, a researcher of climate change, extreme weather and human health at the University of Bristol, explained in a 2020 Carbon Brief guest post:
“Urban inhabitants can be more susceptible to heat-related illnesses and deaths in hot summers because of the UHI effect.”
Cooling green ring
Vegetation is often sparse in cities, typically becoming more plentiful away from the city centre. The study investigates how the location and type of rural land cover affects the temperature within the city.
The researchers model the land inside the heat dome with concentric rings, investigating the relationships between land cover and temperature in different zones.
Using satellite images of 30 major cities in China, the authors categorise the rural land cover into four types represented by colours in the rural area below – woodland (green), cropland (yellow), and water body (blue) and impervious surface (brown).
By changing variables including the size, diversity and fragmentation of the different land cover types in computer simulations of the environment, the study evaluates which variables have the biggest effects on UHI intensity and by how much they can reduce the temperature.
The authors divide up the landscape into “patches” – areas of land that differ from their surroundings. The size and fragmentation of the patches are “pivotal factors”, each with the potential to individually lower city temperatures by 0.5C, the study finds, noting that larger, less fragmented rural land patches produce a greater cooling effect.
Cao tells Carbon Brief that, in theory, this result means that by optimising both factors, UHI could be reduced by as much as 1C. However, he says the analysis does not account for “slight overlaps in the heat island mitigation effects among different landscape parameters”.
The authors also analyse how land cover at different distances from the urban boundary affects UHI intensity. They find that the best cooling effects come from the rural ring “within a 10-15 km radius from the urban boundary”. This range sits inside the heat dome, meaning the air flow and exchange of heat is most effective at these distances.
Rural land within this range can “contribute up to a 30% reduction of UHI intensity”, with the most significant cooling felt at the very centre of the city, the study finds.
To achieve these levels of reduction, “synergistic regulation” that coordinates best practices for multiple land management factors is needed, Cao tells Carbon Brief. Explaining the paper’s recommendations on how to effectively manage the rural buffer zone, he said in a press release:
“We found that urban overheating was mitigated more by joining up patches of rural land, planting more woodland scattered around a city, and by having fewer, bigger lakes rather than lots of little bodies of water.”
Global relevance
The study focuses on cities in China that exceed 200 square kilometres and have a single centre, so they could be more easily categorised into concentric rings according to urban population density.
While most of the cities selected – including Shanghai, Wuhan and Chengdu – experience a subtropical monsoon climate zone, the paper suggests that “the majority of mitigation strategies identified in China are transferrable to different climate zones”.
Consequently, the researchers claim the findings have “relatively high generalisability and applicability in different cities”, but advise that future research should investigate cities of “different shapes, development levels, geographical locations and climatic conditions”.
Dr Chloe Brimicombe – a climate science and extreme heat researcher at the University of Graz in Austria and visiting fellow at LSE’s Grantham Research Institute, who is not affiliated with the research – says the study could be improved by “adjusting more carefully for the climate of each city”. She adds:
“Small differences in elevation or proximity to the coast can influence the UHI effect. In addition, cities have different designs; if such a study was reproduced for Europe this could also be taken into account.”
Temperatures are rising across the globe, with 2024 now very likely to be the hottest year on record. Study co-author Prof Prashant Kumar, founding director of the University of Surrey’s GCARE and co-director of Surrey’s Institute of Sustainability, adds in the press release:
“We hope planners and governments can use our findings to help urban communities become more resilient against rising global temperatures. Our findings show that if we want to cool our cities down, we need a joined-up approach between urban and rural planning.”
The post Rural ‘buffer ring’ can reduce urban heat island effect by more than 0.5C appeared first on Carbon Brief.
Rural ‘buffer ring’ can reduce urban heat island effect by more than 0.5C
KOROR, PALAU, Friday 4 September 2026 – At the closing of the 55th Pacific Islands Forum Leaders Meeting in Palau overnight, Greenpeace Australia Pacific called out Australia for promising climate action while expanding fossil fuel production, and is urging Pacific leaders to unite ahead of the Pacific Pre-COP.
The meeting was rocked by the UN’s 1.5°C overshoot report a day before Australia approved the extension of one of the country’s largest coal mines.
Speaking from Palau, Shiva Gounden, Head of Pacific at Greenpeace Australia Pacific, said:
“Against the backdrop of the 1.5°C UNEP report, this Forum was a vital opportunity for Pacific leadership to shine by firmly calling out fossil fuels and banding together for our shared Pacific future. While the final communique reaffirmed the need to accelerate the transition away from fossil fuels, Pacific leaders missed the opportunity to hold the Australian government accountable for their continued approval of new coal and gas projects.
“At Pacific Pre-COP in Nadi, we are calling for Pacific priorities to be centred and respected by Australia and our global partners: they must support the ambition of a Fossil Fuel Free Pacific, ensure access to adequate climate finance and lead a global push to hold the line on 1.5°C as a matter of Pacific survival.
“Leaders fell short at the Pacific Islands Forum, and Pacific Pre-COP is the opportunity to match the ambition with urgency, and set the vaka on course toward a peaceful, just Pacific future.”
Speaking from Palau, Dr Simon Bradshaw, COP31 Lead and climate expert at Greenpeace Australia Pacific, said:
“The Pacific Islands Forum was an opportunity for Prime Minister Albanese to show real commitment to climate action and to its Pacific partnership. Instead, this week the Australian Government ‘celebrated’ the first extraction of polluting gas from the Beetaloo Basin and approved an extension of one of Australia’s largest coal mines. All amidst a still unfolding flood crisis in Nepal-Tibet and the devastating news that the world will blow through 1.5°C of warming — a survival line for Pacific communities.
“These are not the actions of a government aspiring to be a global climate leader and effective middle power in turbulent times, they are the actions of a government still beholden to the fossil fuel industry. Australia, get it together.
“As we head towards the Pacific Pre-COP, our Prime Minister and Government must remember the responsibility we have taken on. We must hold the line on returning warming to 1.5°C as our legal and moral obligation. This means doing everything possible to accelerate the global transition away from fossil fuels, starting at home.”
—ENDS—
Australia blows PIF climate opportunity as Pacific leaders urged to band together
As efforts to expand energy access across Africa grow, experts and policymakers have called this week for greater coordination and investment to power food production with renewables, arguing the sector has been treated separately from energy policy and therefore faces barriers in going green.
Hailemariam Desalegn, former prime minister of Ethiopia, said energy is critical across the food value chain – from irrigation and processing to cold storage and transport – and should therefore be considered a key pillar of strengthening food systems for the future.
“Energy is not separate from the nutrition challenge. Irrigation needs energy. Cold storage, transport, processing, as well as markets – all need reliable energy,” Desalegn told a panel at the 20th session of the Africa Food Systems Forum in Kigali. He said investments in sustainable energy systems could help reduce post-harvest losses and make nutritious food more accessible and affordable.
Africa loses up to 30% of its food before it reaches markets annually, largely due to poor roads, weak storage and inadequate cold chains, according to a 2025 report by the Alliance for a Green Revolution in Africa (AGRA).
-
Climate adaptation helps African nations tackle rising conflict over resources
The growing overlap between insecurity and climate vulnerability is forcing governments and development agencies to rethink adaptation efforts
Akinyi Walender, Africa director at development charity Practical Action, said poor energy supply in rural communities – where much of Africa’s food is produced – is also limiting productivity. Across the continent, about 600 million people currently live without access to electricity.
“The lack of energy access goes well beyond the inconvenience of not having lighting at home,” Walender said, adding that renewable energy has the potential to power local economies. “When people can access this sort of energy, it can raise rural incomes, improve food security, improve resilience, empower women and stimulate enterprise while creating jobs,” she added.
Breaking down silos
Unlocking the potential of energy across food systems requires greater coordination, Walender argued, pointing to institutional fragmentation and isolated pilot projects as major barriers.
“Organisations working on agriculture and energy often operate according to different modalities and the interdependence between agricultural and energy markets is often overlooked,” Walender said, adding that finance institutions also tend to work in silos.
Dana Rysankova, global lead for energy access at the World Bank, told a separate event at the forum that the bank is working to break down those barriers through its newly established Productive Use of Energy (PUE) Centre of Excellence based in Nairobi, which has a mandate to foster collaboration and help develop and design programmes across different sectors.
Can giant batteries unlock Africa’s green industrial future?
In June, the World Bank Group and the African Development Bank Group said that over 50 million people had been connected to electricity across 40 African countries under their Mission 300 initiative, which aims to provide electricity access to 300 million Africans by 2030.
Rysankova said the programme has shown that energy access is just the foundation for linking with other sectors to deliver real economic transformation by boosting productivity and local incomes.
Mission 300 also aims to electrify schools and healthcare services, as well as bringing power to farmers so that they can use it for irrigation, cold storage and other agricultural activities, she added.
Bridging the finance and infrastructure gap
Experts said bigger investments are needed in infrastructure and finance to turn energy access into increased productivity and economic value.
AGRA’s 2026 foresight report, launched at the forum, puts the annual agrifood financing gap at $180 billion, while estimating that closing Africa’s yearly $67 billion-$108 billion shortfall in infrastructure finance could halve post-harvest losses and increase farmer incomes by up to 40%.
However, the cost of transitioning to clean energy is still a major barrier for farmers and agribusinesses.
Atinuke Lebile, CEO of Nigerian food processing company Cato Foods, told Climate Home News she would like to switch to using renewables but has been held back by the upfront cost of setting up the systems the firm needs.
Rwandan farmer Gezel also said she would like to invest in a solar irrigation pump, but “it is so expensive”.
Practical Action’s Walender said the challenge is no longer whether solutions exist, but how financial support can reach the communities and businesses where it could have the greatest impact.
“Customers are dispersed and have low incomes. Markets are fragmented, and there are high upfront costs for much energy equipment,” Walender said, adding that financial institutions also often perceive agriculture as a high-risk sector.
Egypt seeks to unlock renewable potential to power regional clean energy hub
For food processing, the business case for using cleaner energy more efficiently is particularly strong, said Vivian Maduekeh of Partners in Food Solutions, which has worked with more than 2,000 companies across Africa.
Maduekeh said food processing firms account for between 42 and 70% of energy use across food systems, while energy represents 15-22% of their total production costs. African food businesses also use roughly twice as much energy per kilogramme of product as their global competitors, putting them at a competitive disadvantage.
The problems they face in shifting to clean energy are “risk, perception of risk and the cost”, she explained, adding that financial mechanisms are needed to help businesses overcome those issues.
Maduekeh encouraged policymakers to consider measures like tax rebates on imported equipment and spending more on research and development to bring down the cost of productive-use technologies.
Making a range of affordable equipment available – such as smaller irrigation pumps – could also help make the transition more accessible, she said. The evidence in favour “is very clear”, she added. “We just need to package it and communicate it to the priorities of investors.”
The post More support needed to power Africa’s food systems with renewables, experts say appeared first on Climate Home News.
More support needed to power Africa’s food systems with renewables, experts say
Andy Burnham, the UK’s latest prime minister, has suggested reducing the amount the British government gives as climate finance grants and providing some of its climate finance through loans instead, in a move it anticipates will save £400 million.
The government plans to use the savings to fund a cap on bus fares in the UK, triggering accusations from the development sector that Burnham’s proposal “throws Global South countries under the bus”. One likely destination for these new loans is the Tropical Forest Forever Facility (TFFF).
Will new UK PM’s green measures at home cause climate finance pain overseas?
The TFFF is a new initiative designed to provide payments to countries that protect their rainforests by raising money from governments and private investors, channeling that money into riskier and therefore higher return assets, and using the returns it earns to fund forest protection. But there is a catch.
The UK has committed to provide around £6 billion in climate finance funded through aid (or official development assistance, ODA) over the next three years. If switching from grants to a loan to the TFFF reduces government spending, it will likely reduce the amount that counts as ODA as well.
In other words, the government can make the £400 million saving, or meet its £6 billion aid budget-funded climate finance commitment, but it probably cannot do both. The UK cannot have its cake and eat it.
How will it score as ODA?
Whether any loan to the TFFF scores as ODA depends on the OECD’s Development Assistance Committee (DAC) which is currently deliberating on this topic.
A plain reading of the DAC’s current reporting rules suggests that the TFFF would count as a multilateral organisation: the independent investment arm, the Tropical Forest Investment Fund, would ultimately be a global, official entity (with sovereign governments appointing the board and being sole equity holders), which pools capital from sponsor governments. This would mean that to count as ODA, any loan to it would have to charge less than 5% interest.
Tropical forest protection fund at risk after UK stalls on pledge
The current concept note suggests a return for sponsor capital equivalent to US borrowing costs of a similar duration: currently around 5.2%, which would make any such loans ineligible. The UK could choose to charge less, but if the UK charges less than it borrows (also above 5%), the difference will add to the deficit in future years. And ODA accounting is not binary: if the UK charges just under 5%, only a small fraction of the loan would count.
At the same time, the risk profile of TFFF is not the same as your average multilateral, and there is speculation that the DAC could allow higher interest loans to TFFF to partially count (by changing the ‘discount rate’ used to measure how concessional the loan is). The TFFF’s own modelling suggests that the risk of the UK losing money on the loan would be fairly limited: roughly a 1% chance of some capital impairment in the riskiest scenario. But some analysts doubt the accuracy of this model and view the risk as much greater.
Would it really save money?
If the risk really is higher, then it might justify counting more ODA on a loan to the TFFF, but it also undermines the arguments that this would create savings for the government. Loans generally don’t count towards the deficit because they create an asset. But that only works if the loan is expected to be fully repaid. If there is a material risk of losing money, then at least some of the transaction will also count towards the deficit.
One possibility is that the loan will be ‘partitioned’ into a financial asset (the part which is expected to be repaid and wouldn’t count towards the deficit) and a ‘capital transfer’ (the part not expected to be repaid). The greater the risk, the larger that second component, and the bigger the impact on the deficit.
This would be the ODA and public accounting rules working as intended. ODA is a measure of ‘donor effort’, usually taken to mean fiscal impact. If it counts as ODA, it should have an impact on the deficit. And the fiscal treatment itself is governed by numerous international accounting standards, a key purpose of which is preventing politically motivated obfuscation of how governments spend their money. If it costs money, there should be an impact on the deficit even if it is a loan. If it doesn’t, it shouldn’t count as ODA (even if there have been exceptions in the past).
UK halves Green Climate Fund contribution, as it spends more on security
Base funding on need, not accounting
We still know too little about the details to be sure how a loan to the TFFF (or a more exotic transaction) would count towards either ODA or the UK’s headline measures of debt and deficit. The key parameter for each is risk: the lower risk, the more likely it is that the transaction will save money, but the greater the chance that the government would have to spend more ODA elsewhere to meet its climate finance target.
If the UK believes in the TFFF business model and wants to preserve tropical forests, then it should invest. But this decision should not be driven by optimistic accounting tricks. The government cannot expect to reduce the real value of climate finance to partner countries by giving less in grant money, without this having an impact on commitments to spend that money.
The post UK’s budget juggling trick with rainforest loan for bus-fare cap needs transparency appeared first on Climate Home News.
UK’s budget juggling trick with rainforest loan for bus-fare cap needs transparency
-
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