More consistent refrigeration of foods as they move from one part of the supply chain to another could cut almost 2bn tonnes of greenhouse gas emissions from food loss each year, according to a new study.
Around one-third of all food produced goes to waste, producing climate-warming greenhouse gases as it rots.
New research, published in Environmental Research Letters, finds that poorly temperature-controlled food supply chains could be causing up to 620m tonnes of food losses each year.
This loss results in 1.8bn tonnes of CO2-equivalent (GtCO2e) emissions – more than three times the annual emissions of Canada.
Using more refrigeration when food is processed and transported could more than halve the food-loss emissions in south and south-east Asia, the study says.
In addition, shortening food supply chains could significantly reduce emissions and prevent food loss around the world, the study finds.
A scientist who was not involved in the research tells Carbon Brief that the results “reflect a worrying reality” on food waste, but notes that the findings are “uncertain”.
The lead author of the study says that there are caveats to some of the findings and adds that not every region can, or should, base their food supply system on refrigeration.
Wasted food
Along a supply chain that sees food grown, processed, transported and consumed, around one-third of all food goes to waste.
If it were a country, this food waste would be the third-largest source of greenhouse gas emissions in the world, according to the UN Food and Agriculture Organization.
A 2023 study also found that greenhouse gases from food loss and waste make up almost half of all food-system emissions.
Food loss refers to all of the edible parts of food that are thrown away in the early parts of the supply chain, according to a report from the UN Environment Programme.
This includes vegetables that rot in fields before being picked, crops hit by disease and meat that spoils due to lack of transport refrigeration.
Food waste, on the other hand, is discarded food that is not consumed by people at a retail, food service or household level.
Food loss and waste produces methane as it rots in landfills or dump sites. Emissions from food loss also stem from the land-use change, energy and resources required to grow the food in the first place, particularly animal products.
The new study examines whether more consistent access to refrigeration throughout the supply chain could impact food loss – and the resulting greenhouse gas emissions – for different food types around the world.
Alongside the benefits of refrigeration, the study finds that supplying foods more locally can greatly reduce food losses.
This was the most surprising finding, according to Aaron Friedman-Heiman, the lead author of the study. Friedman-Heiman, a recent graduate from the school for environment and sustainability at the University of Michigan, tells Carbon Brief:
“The thing that shocked me the most was actually how comparable shortened food supply chains were to technologically optimised food supply chains.
“We can make all these systems really efficient, but also if we just get rid of a lot of the steps, that is another kind of way of optimising these systems.”
Prof Ian Vázquez-Rowe, an engineering professor at the Pontifical Catholic University of Peru who was not involved in the research, says that the study is “thorough” and relevant, “especially in countries and households with poor refrigeration systems”. He tells Carbon Brief:
“The results are probably quite uncertain, as in most planetary-based estimations, but they reflect a worrying reality: food supply chains are inefficient, especially in emerging and developing nations, and this leads to higher amounts of food loss and waste in the agri-food sector.”
Estimating food loss
The researchers developed a model to see whether consistent access to refrigeration could impact food losses and greenhouse gas emissions for seven groups of food: seafood; fruit and vegetable; oilseeds and pulses; root and tuber crops; meat; dairy; and cereals.
The study focuses solely on food that is lost between harvesting and reaching a supermarket shelf. It does not look at food waste, which is the food discarded in shops, restaurants and households.
The researchers look at the improvements that could occur with better refrigeration throughout the food supply chain. They also look at the impact of making food more locally available, thereby shortening these supply chains.
The study focuses on seven regions around the world: Europe, “industrialised Asia” (countries such as China), Latin America, north Africa and central Asia, North America and Oceania, south and south-east Asia and sub-Saharan Africa.
For each combination of region and food type, the researchers investigate three scenarios: a “baseline” scenario, using current loss rates; an “optimised” scenario, using minimum loss rates with added refrigeration capacity; and a “short” scenario, using current loss rates across a reduced supply chain.
The chart below outlines the baseline and optimised scenarios for food loss and the resulting greenhouse gas emissions. It shows that although fruit and vegetable losses are largest in terms of weight, meat losses are the source of the largest emissions by far.
Combining refrigeration and shorter supply chains
Sub-Saharan Africa and south and south-east Asia would stand to see the biggest reductions in food loss and related greenhouse gas emissions with better refrigeration and localised supply chains, the study finds.
For example, improved refrigeration could save more than 100m tonnes of fruit and vegetables each year in south and south-east Asia. It could also reduce overall food loss in the region by 45% and more than halve the associated emissions. In sub-Saharan Africa, it could cut these emissions by two-thirds.
Globally, better refrigeration of meat could cut emissions linked to meat loss by more than 40%.
Meat accounts for more than half (2.7 gigatonnes) of food loss and waste greenhouse gas emissions – despite making up less than 10% of global food loss and waste, the study says.
The benefits of refrigeration in reducing food loss are more modest in global north countries with existing temperature-controlled food supply chains.
The study finds that, on a global level, making food supply chains more local can have a bigger impact on saving food than improving refrigeration.
Localised supply chains could reduce emissions from rotting meat in industrialised countries by more than 300m tonnes of CO2e emissions each year, the study adds.
Combining the two solutions – shorter supply chains and better refrigeration – can help to reduce food losses and slash the energy burden and emissions from refrigeration.
Other factors
Vázquez-Rowe says that the study findings are “plausible” and that they “reflect a structural problem of food systems”. But, he adds:
“There is a lack of uncertainty and sensitivity analyses, which does not allow for a full analysis of the certainty of the results they provide.”
The authors acknowledge other limitations in the study, such as not considering the emissions from refrigerators in their calculations.
Previous research indicates that refrigeration may even increase food emissions through higher energy use and the dietary shifts that refrigeration allows.
The study also does not consider various social, cultural, political, nutritional and economic factors that influence food systems.
Areas with unreliable energy systems may not want to – or may not be able to – rely more heavily on refrigeration technologies. Friedman-Heiman explains:
“If a region doesn’t have stable energy infrastructure, then the idea of basing a food system off of refrigeration is actually maybe less sustainable in terms of food loss and waste than what they currently have.”
He is hopeful researchers, policymakers and others in the food industry can use the model and further the research on a wider level. He tells Carbon Brief:
“I would love for this model to incorporate regional energy grids and what that impact might be in terms of changing the emissions equation…[alongside] pitting the food savings against the refrigeration [emissions].”
The study also acknowledges that shorter supply chains are not always feasible, depending on geographical location and the seasonality of different foods.
The post Better refrigeration could avoid almost 2bn tonnes of CO2 per year from food loss appeared first on Carbon Brief.
Better refrigeration could avoid almost 2bn tonnes of CO2 per year from food loss
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.