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.”

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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

Every increment of global warming above 1.5C increases the risk of crossing key tipping points in the Earth system – even if the overshoot is only temporary, says new research.

It is well established that if global temperatures exceed 1.5C above pre-industrial levels, there is a higher risk that tipping points will be crossed.

The new study, published in Nature Communications, investigates the risk of crossing four interconnected tipping points under different “policy-relevant” future emissions scenarios.

The authors investigate the risk of tipping where warming temporarily overshoots 1.5C, but global temperatures are then brought back down using negative emissions technologies. They find that the longer the 1.5C threshold is breached, and the higher the peak temperature, the greater the risk of crossing tipping points.

The most pessimistic scenario in the study sees global warming hit 3.3C by the end of the century – in line with the climate policies of 2020 – before dropping back below 1.5C over 2100-2300. Under this pathway, there is a 45% chance of crossing tipping points by 2300, the authors say.

The authors also warn that if global temperatures rise above 2C, the additional risk of tipping for every extra increment of warming “strongly accelerates”.

For temperatures between 1.5C and 2C, the risk increases by 1-1.5% for every 0.1C increase in overshoot temperature. However, for temperatures above 2.5C, tipping risk increases to 3% per 0.1C of overshoot.

The research “underlines the need for urgent emission cuts now that do not assume substantial carbon dioxide removal later”, a scientist not involved in the study tells Carbon Brief.

Overshoot scenarios

Scientists have warned for decades that as the planet warms, there is an increasing risk that Earth systems will cross “tipping points” – critical thresholds that, if exceeded, could push a system into an entirely new state.

For example, if climate change and human-driven deforestation push the Amazon rainforest past a critical threshold, large parts of the forest could experience “dieback”. This would cause entire sections of lush rainforest to eventually shift to dry savannah.

(See Carbon Brief’s explainer on the nine tipping points that could be crossed as a result of climate change.)

The planet has already warmed by 1.3C above pre-industrial levels, and a recent study warned that five tipping elements – including the collapse of the west Antarctic ice sheet – are already within reach.

That study emphasised the importance of limiting global temperature rise to 1.5C above pre-industrial levels – in line with the 2015 Paris Agreement. It finds that warming of 1.5C would render four climate tipping elements “likely” and a further six “possible”. Meanwhile, 13 tipping elements will be either “likely” or “possible” if the planet warms by 2.6C, as expected under current climate policies.

Many of the potential pathways to limiting global temperature rise to 1.5C by 2100 see the planet initially “overshoot” the threshold before negative emissions methods are used to bring temperatures back down.

The new paper investigates 10 future warming scenarios which run to the year 2300. The authors use the PROVIDE v1.2 emission pathways, which they describe as “an extended version of the illustrative pathways identified” used in the recent sixth assessment of the Intergovernmental Panel on Climate Change (IPCC).

The original scenarios run over 2015-2300, but the authors carried them forward for another 50,000 years by following the temperature trajectory set over 2290-2300. All scenarios stabilise at 1.5C, 1C or pre-industrial temperatures. However, many include overshoots, with peak temperatures ranging from 1.57C to 3.30C.

These scenarios show a range of options for how global temperatures change under these 10 scenarios in the “medium term” – until the year 2300 – as well as in the “long term”, which runs 50,000 years into the future to see how the planet eventually stabilises.

Scenarios that reach net-zero or negative emissions by 2100 and maintain them thereafter are classified as “NZGHG emission scenarios”. The table below gives more detail on each scenario.

Table showing the 10 scenarios used in this study. Source: Möller et al (2024).

There is quite a range between the 10 pathways.

At the high end, the “CurPol-OS-1.5C” scenario sees a continuation of the global climate policies implemented in 2020 until the year 2100, with warming peaking at 3.3C. It then sees a decline in global temperature until reaching a stabilisation of 1.5C by the year 2300.

At the low end, “Neg-OS-0C” scenario initially overshoots 1.5C to 1.67C, but then returns warming to 1.5C by 2100 using “heavy carbon dioxide removal deployment”. It also then sees average global temperatures drop to pre-industrial levels by the year 2300.

In the middle, the Ref-1p5 scenario is the only one that does not include an overshoot, instead stabilising quickly at 1.5C.

The chart below shows greenhouse gas emissions (top) and corresponding global temperature changes (bottom) associated with each scenario, identified by the different-coloured lines. The bottom chart illustrates the range in how quickly the pathways return to 1.5C or below.

Dr David McKay is a research impact fellow at the University of Exeter’s Global Systems Institute, who has published extensively on climate tipping points, but was not involved in this study.

He also notes that some of the scenarios shown in this study “may not be possible”, because there is debate about whether or not “the substantial carbon dioxide removal needed for large overshoots is feasible”.

Cascades

Many Earth systems are interlinked, so crossing one tipping point can increase the likelihood of crossing others. This is often described as a “domino effect” or “tipping cascade”.

The study focuses on four interconnected tipping points – collapse of the Greenland ice sheet and west Antarctic ice sheet, shutdown of the Atlantic Meridional Overturning Circulation and dieback of the Amazon rainforest.

Annika Högner is a researcher at the Potsdam Institute for Climate Impact Research (PIK) and co-lead author on the study. She tells Carbon Brief these four tipping points were chosen because they “play a significant role in the functioning of the Earth system” and “their tipping would have severe global impacts”.

The graphic below shows how the tipping points interact with each other. A “+” symbol indicates that crossing one tipping point can destabilise another. For example, a collapse of the Greenland ice sheet makes the AMOC more likely to shut down, as a result of the sudden influx of freshwater into the north Atlantic Ocean. A “±” symbol indicates that the relationship between two tipping points is uncertain.

A “-” symbol indicates that crossing one tipping point stabilises another. Högner tells Carbon Brief that the interaction between the Greenland ice sheet and AMOC is the only stabilising interaction in this study. She explains that if the AMOC were to cross a tipping point, “we [would] expect to see strong cooling in the northern hemisphere”, which will contribute to stabilising the Greenland ice sheet.

Earth system models “often don’t resolve tipping processes very well”, making them less suited to modelling full tipping cascades, Högner tells Carbon Brief.

Instead, she explains that the authors developed a “conceptual model”. This model does not attempt to simulate the entire Earth system, but instead just models the likelihood of tipping at different temperatures, based on existing knowledge about tipping elements from other studies.

The model takes temperature trajectories as an input and gives the state of the tipping elements after a specified time – that is, whether or not the element has tipped – as an output.

Importantly, these models include “hysteresis” – a feature of tipping systems, in which a system that has moved to a different state does not easily move back to the original state even if temperatures are reduced again.

Tipping risk

The authors use their conceptual model to calculate “tipping risk” under the 10 future warming scenarios. Högner tells Carbon Brief that tipping risk “refers to the model of all four interacting tipping elements analysed in the study”. For example, a 50% tipping risk means there is a 50% chance that at least one of the four climate elements will tip.

The top row of the graphic below shows the risk of tipping in the year 2300 (left) and in 50,000 years from now (right). Bars placed higher up indicate a greater likelihood of tipping. The dot shows the average value for each data point, while the bars show the 10-90% range.

The text on the right hand side gives likelihood levels in the calibrated language used by the IPCC: very likely means a likelihood of 90-100%, likely is 66-100%, about as likely as not is 33-66%; unlikely is 0-33%; and very unlikely is 0-10%.

The middle row shows the peak temperature under each scenario (left) and stabilisation temperature (right). The bottom row shows how long temperatures overshoot before stabilising in each scenario.

The longer the 1.5C threshold is breached for, and the higher the peak temperature is, the greater the risk of crossing tipping points by the year 2300, the study shows.

The authors find the greatest risk of crossing tipping points in the CurPol-OS-1.5C scenario (red), which follows the climate policies of 2020 until the year 2100 and then reaches 1.5C by 2300, as this scenario has the greatest overshoot temperature and duration.

Under this scenario, there is a 45% tipping risk by 2300 and a 76% chance in 50,000 years, according to the paper.

The five pathways that do not return warming to 1.5C by the year 2100 have the greatest medium-term risks, and those with less than 0.1C overshoot have the lowest medium-term risks.

In the long-term – looking to the next 50,000 years – the authors find that stabilisation temperature is “one of the decisive variables for tipping risks”. They find that even in the Ref1p5 scenario – which sees global temperatures stabilise at 1.5C without any overshoot – there is a 50% risk of the system tipping over the next 50,000 years.

The results “illustrate that a global mean temperature increase of 1.5C is not ‘safe’ in terms of planetary stability, but must be seen as an upper limit”, the study warns.

Högner tells Carbon Brief that the paper “underlines the importance of adhering to the Paris Agreement temperature goal”.

Tessa Möller – a researcher at the International Institute for Applied Systems Analysis (IIASA) and co-lead author on the paper – tells Carbon Brief that “we have a wide portfolio of technologies available” to limit warming to 1.5C, and just need to “implement” them.

However, she also highlights the “large credibility gap” between pledges from individual countries and the policies they have actually implemented. She tells Carbon Brief that not only do we need “stronger pledges”, but it is also essential that countries follow through on them.

Long-term climate

The authors also explore the risk of each individual tipping point being crossed in different scenarios.

The plot below shows the tipping risk by 2300 under different scenarios, at different temperatures, on the left. Each colour represents one scenario. Dots positioned further to the right indicate a greater peak temperature and dots positioned higher up indicate a greater tipping risk.

The plot on the right shows the percentage change in tipping risk for every additional 0.1C of overshoot, for different peak global temperatures, for the Amazon (cross), AMOC (plus), West Antarctic ice sheet (black dot) Greenland Ice sheet (square) and overall (yellow dot).

The authors find that AMOC collapse and Amazon dieback would likely be the first components to tip. This could be in the next 15-300 years and 50-200 years, respectively, depending on the scenario, they find.

Meanwhile, the Greenland and west Antarctic ice sheets have tipping timescales of 1,000-15,000 years and 500-13,000 years, respectively.

However, they note that as temperatures increase, the relative risk of each element tipping changes. The graph shows that while AMOC is the main driver of tipping risk at lower temperatures, the Amazon becomes the main driver once global temperatures exceed 2C.

Finally, they find that as global temperatures rise, the risk of tipping accelerates. Overall, tipping risk increases by 1-1.5% per 0.1C increase in overshoot temperature, for temperatures below 2C, according to the study. However, above 2.5C, tipping risk increases to 3% per 0.1C increase overshoot.

McKay notes that there are some limitations in the study. For example, he notes that the paper “has to rely on tipping threshold and timescale estimates with often wide ranges and sometimes low confidence, while tipping interaction estimates are based on dated expert judgement”.

However, he adds:

“This work makes it clear that every fraction of warming increases the chance of tipping points, even if global temperature subsequently falls, and underlines the need for urgent emission cuts now that do not assume substantial carbon dioxide removal later.”

Q&A: What does deep-sea mining mean for climate change and biodiversity loss?

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The post ‘Every 0.1C’ of overshoot above 1.5C increases risk of crossing tipping points appeared first on Carbon Brief.

‘Every 0.1C’ of overshoot above 1.5C increases risk of crossing tipping points

Welcome to Carbon Brief’s Cropped. 
We handpick and explain the most important stories at the intersection of climate, land, food and nature over the past fortnight.

Key developments

Still at sea

DARK OXYGEN: Scientists discovered “dark oxygen” being produced in the deep ocean, “apparently by lumps of metal on the seafloor”, BBC News reported. The study challenges the “long-held assumption” that oxygen is produced exclusively through photosynthesis, CNN reported. Ocean scientist and lead author Dr Andrew Sweetman “observed the phenomenon time and time again over almost a decade” at several locations in the mineral-rich Clarion-Clipperton Zone in the Pacific, the outlet added. Canada’s The Metals Company, which partially funded Sweetman’s research, “attempted to poke holes in the study”, according to E&E News, but Sweetman stood by his team’s findings.

O CAPTAIN, MY CAPTAIN: The study created ripples at the ongoing seabed mining talks in Kingston, Jamaica, delegates told Carbon Brief. However, nations negotiating rules to govern the sector are also “face[d with] a critical vote” to decide who will head the International Seabed Authority (ISA), a decision “that could impact the nascent industry for years”, the Guardian wrote. Ahead of “one of the world’s most important elections…you’ve never heard of”, Foreign Policy carried an in-depth interview with Brazilian oceanographer Leticia Carvalho. Carvalho is standing for election against the ISA’s current chief Michael Lodge, “who has been criticised for allegedly having cosy ties to eager mining firms”.

RUDDERLESS WORLD: Despite heated talks, the meeting is drawing to a close with mining rules “still far from finalised”, but no mining authorised, according to the Deep Sea Conservation Coalition. Malta, Honduras, Tuvalu and Guatemala announced they were joining in the call for a “precautionary pause” on deep-sea mining, taking the number of countries pushing for a moratorium, pause or ban to 31 countries, according to the Earth Negotiations Bulletin. Palau’s president lamented: “We are once again at the mercy of powerful external forces, reminiscent of colonial exploitation that scarred our history.” For a detailed breakdown of country positions, evolving science and state of play, read Carbon Brief’s new Q&A on deep sea mining, published today.

UN hunger report

FOOD INSECURITY: Around one in five people in Africa faced hunger in 2023 as “major drivers”, including climate change and conflict, became “more frequent and severe”, a new report from the UN Food and Agriculture Organization (FAO) found. More than 700 million people around the world were undernourished in 2023, the report estimated – an increase of around 150 million people compared to 2019. “Transforming agrifood systems is more critical than ever,” the director general of the FAO, Dr Qu Dongyu, said in a statement. He added that the FAO is “committed to supporting countries in their efforts to eradicate hunger and ensure food security for all”.

AFRICA IMPACTS: Food insecurity is an issue in many parts of the world, “but Africa is at the epicentre of the crisis, with hunger on the rise across the continent”, Context News said in its coverage of the report. East Africa had the highest number of people going hungry on the continent – more than 138 million people in 2023, the outlet noted. Dr David Laborde, director of the agrifood economics division at FAO, told the New Humanitarian that “hunger level remains high, higher than in 2015” – the year that countries adopted the UN sustainable development goals for 2030, which include an aim to end hunger.

DROUGHT: Meanwhile, the prime minister of Lesotho, Sam Matekane, declared a “national food insecurity disaster” as around 700,000 people in the small African country face drought-related hunger, according to the Lesotho Times. The “critical” situation needs “national, regional and international humanitarian intervention”, the president said. Lesotho and other southern Africa countries including Zambia, Zimbabwe and Malawi were hit by drought in recent months, scorching crops and leaving millions at risk of hunger, the Associated Press reported earlier this year. A rapid attribution study found that the El Niño weather pattern was the key driver behind this drought.

Spotlight

What Venezuela’s election means for the Amazon

In this Spotlight, Carbon Brief looks at what Venezuela’s disputed election results could mean for illegal mining in the Amazon rainforest.

Earlier this week, Nicolás Maduro was declared the winner of the Venezuelan presidential election by the “government-controlled electoral authority”, the Guardian reported.

The country’s opposition disputed the results as “fraudulent”, BBC News said, while protests broke out in the country’s capital of Caracas.

Pre-election polls showed Maduro, who has served as Venezuela’s president for the past 11 years, falling behind as “voters express[ed] exhaustion over Venezuela’s economic crisis and political repression”, Al Jazeera said.

According to Mongabay, there was “little room for discussion about environmental issues” in the build-up to the election amid focus on whether the vote would be “anything close to free and fair”. The outlet said that this is “despite the fact that the country has plunged into a crisis so severe that many observers now call it an ecocide”.

Amazon impacts

Venezuela is among the world’s most biodiverse countries and it holds almost 7% of the Amazon region.

In 2022, Mongabay reported that more than 140,000 hectares of primary forest were lost in the Venezuelan areas of the Amazon over 2016-20.

New Scientist also reported in 2022 that pristine forest loss in the Venezuelan Amazon “is estimated to be increasing by around 170% annually” due to “a state-sanctioned boom in gold mining”.

Luis Jiménez, the general coordinator of the Venezuelan conservation NGO Phynatura, believes that Maduro remaining in power would continue the “exponentially accelerated” destruction of the Amazon.

He tells Carbon Brief that mining has impacted “important protected natural areas” in Venezuela, such as the Canaima and Yapacana national parks, which “apart from protecting large, megadiverse forest spaces, are home to 31 Indigenous ethnic groups”.

Jiménez believes another Maduro term would continue this “extractivist economy, which in no way benefits local communities or the rest of Venezuelans”.

Indigenous rights

In 2022, the NGO Human Rights Watch “documented horrific abuses” of Indigenous peoples “by groups controlling illegal gold mines in southern Venezuela, operating with government acquiescence”.

Last year, the Venezuelan government launched a military option to “expel more than 10,000 illegal miners from the Amazon, according to an Agence France-Presse article published in Deutsche Welle.

The article noted that Maduro said illegal mining was “destroying” the Amazon.

On deforestation, Venezuela and Bolivia were the only Amazon countries to not sign a 2021 global pledge to work towards halting deforestation by 2030.

But, in 2022, Venezuela and Colombia proposed relaunching the 1978 Amazon Cooperation Treaty Organisation, a pact between Brazil, Bolivia, Guyana, Peru, Suriname and Venezuela to protect the Amazon.

The countries then met for the first time in 14 years last August, committing to act together to prevent the rainforest “from reaching the point of no return” – but stopped short of agreeing on a common target to end deforestation.

Politicians in the US, Chile, Argentina and around the world have cast doubt over the Venezuelan election results, Reuters said. Maduro has allegedly pledged to release the full voting records, a Brazilian government official told Bloomberg, amid continued protests and tension in the country.

News and views

MILKING THE SYSTEM: Big meat and dairy corporations are “mobilis[ing] significant resources to delay and derail progressive environmental legislation”, a Changing Markets Foundation investigation found. An examination of 22 of the biggest meat and dairy corporations across four continents revealed the use of distract, delay and derail tactics, mirroring those of “big oil”. Distraction tactics, such as greenwashing, steer the spotlight away from the lack of climate action, the report said, adding that companies are using “industry-funded academic research to downplay” the sector’s environmental impact. Delay tactics “ask governments to slow down any regulation by claiming that [companies] are already taking voluntary action”. Finally, the “most aggressive” derail tactics focus on political activity, including millions spent on donations and lobbying, the report said.

COP16 THREAT MONITORING: The organising committee of the COP16 UN biodiversity summit, which will be held in Cali, Colombia in October, sought to reassure delegates after online threats from a “dissident rebel group”, reported the Guardian. The organisers reiterated that “the safety and wellbeing of all participants, attendees and collaborators are our top priority”, the newspaper added. This came after threats made by the Central General Staff (EMC) in a post on Twitter that was addressed to Colombian president Gustavo Petro and said that COP16 would “fail”. The threat came during a ceasefire breakdown between the Colombian government and factions of the EMC, which is active near Cali. The organising committee has assured that it is “closely monitoring the situation and working to establish the validity of the [threats] on social media”.

NEW GROUPS: The new European parliament agriculture committee has been formed of “predominantly right-leaning” politicians, Euronews reported. The “heightened political significance” of the committee after EU farmer protests earlier this year “has attracted top-tier MEPs and lawmakers with little ties to the agricultural world”, Euractiv reported. Some “unexpected faces” in the committee formed after the June parliament elections include a “Spanish far-right YouTuber Luis ‘Alvise’ Pérez”. Meanwhile, the bloc’s yet-to-be-announced agriculture commissioner could be Luxembourg’s Christophe Hansen from the European People’s Party, Politico speculated.

BIRD FLU BROILER: Extreme heat may have played a key role in the bird flu outbreak that infected five workers in the US state of Colorado earlier this month, the Guardian reported. The newspaper said the workers, tasked with culling poultry with the virus, became infected themselves, as their protective gear failed to work correctly amid extreme temperatures. CNN said temperatures at the time were above 40C, with large industrial fans being used to try to control the heat. “We understand those large fans…were moving so much air…the workers were finding it hard to maintain a good seal or a good fit either between the mask or with eye protection,” said Dr Nirav Shah, principal deputy director of the US Centers for Disease Control and Prevention, told CNN.

WASTE NOT: Leaders of Pacific Island states have come to an agreement with Japan over the latter’s “controversial” discharge of treated nuclear wastewater into the Pacific Ocean, according to the Pacific Islands News Association. Japanese prime minister Fumio Kishida assured the Pacific Islands Forum that the practice was being done “in compliance with international safety standards and practices”, while Pacific leaders “emphasised the need for Japan to continue providing sincere and transparent explanations” about the process. However, Prof Robert Richmond, the director of the University of Hawaii at Manoa’s Kewalo Marine Laboratory, “voiced significant concerns” about the efficacy of the treatment and the monitoring programme that is currently in place, the outlet said.

DAMAGED GOODS: A cattle rancher in Brazil has had his assets frozen in the “largest civil case brought for climate crimes in Brazil to date”, the Guardian reported. Dirceu Kruger will be compelled to pay more than $50m in “compensation for the damage he had caused to the climate through illegal deforestation”, according to the newspaper. The price tag was calculated based on the number of hectares that Kruger was found to have deforested, the average greenhouse gas emissions from damaging the rainforest and a calculation of the “social cost” of carbon. The money will be paid into the country’s climate emergency fund and the rancher will also “have to restore the land he degraded so it can become a valuable carbon sink again”, the outlet said.

Watch, read, listen

CLIMATE FINANCE: Dialogue Earth explored uncertainties around ocean communities being able to access “loss and damage” funding for those impacted by climate change.

US ELECTION: The “record on the environment” of Kamala Harris – US vice president and Democratic frontrunner for the country’s presidential election – was discussed on the NPR Living on Earth podcast.

GROWING PAINS: A feature in Al Jazeera looked at the “uncertain future” for women coffee farmers in the “conflict-ridden” eastern Democratic Republic of the Congo.

HOT WATER: The Financial Times examined the “dangerous effects of rising sea temperatures”.

New science

Indigenous food production in a carbon economy

Proceedings of the National Academy of Sciences

A new study has revealed that replacing locally harvested foods with imported market substitutes in Canada’s Inuvialuit Settlement region “would cost over C$3.1m [US$2.3m]…and emit over 1,000 tonnes of CO2-equivalent emissions” annually. The study modelled the cost of substituting local food harvests with market replacements in the region. The study found that gasoline use would add about “C$295,000 [US$213,611] [to harvesting costs] and result in 315 to 497 tonnes of emissions”, in contrast to the much higher costs and emissions associated with substituting local foods with imports. Disregarding local food systems could, therefore, “undermine emissions targets and adversely impact food security and health in Arctic Indigenous communities”, the study added.

Global atmospheric methane uptake by upland tree woody surfaces

Nature

New research found that tree bark can absorb methane from the atmosphere, meaning that the climate benefits of protecting forests “may be greater than previously assumed”. Researchers measured the methane exchange on tree stems in a range of forests in the Amazon, Panama, UK and Sweden. They found that microbes in bark could help trees to take in between 25-50m tonnes of atmospheric methane each year, with tropical forests taking in the highest levels of methane. The researchers conclude that identifying tree species that can absorb the most methane could help to tackle the global growth of the potent greenhouse gas in the atmosphere.

Cost-effectiveness of natural forest regeneration and plantations for climate mitigation

Nature Climate Change

A new research effort has created global maps illustrating what is likely to be the most cost-effective reforestation method in 138 low- and middle-income countries. To create the maps, the researchers used machine learning to combine data on the likely implementation costs of passive natural regeneration and reforestation through plantations, as well as household survey data on the opportunity costs of reforestation, data on the most suitable tree species to plant in each area and the likely carbon accumulation in each area. The research found that plantations offer the most cost-effective form of reforestation over 54% of the land included in the study, while natural regeneration would be most effective over 46% of the land.

In the diary

• 9 August: International day of the world’s Indigenous peoples
• 11-15 August: World Water Congress and Exhibition | Toronto
• 12-16 August: Working group on benefit-sharing from the use of digital sequence information | Montreal, Canada

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