Climate change was responsible for just over one-third of the simultaneous soya bean crop failures across Argentina, Brazil and the US in 2012, according to a new attribution study.
The research, published in Communications Earth & Environment, analyses the impact of hot and dry extreme weather that hit the three countries in 2012.
Although soya beans are an important crop for global food supplies most often in the form of animal feed – their production is concentrated in just three countries, leaving them susceptible to weather-related disruption.
Using climate and crop models, the researchers determine what the yield of the crop would have been in a world without warming.
They find that the impact of climate change – through warmer temperatures and drier soils – accounted for 35% of the yield reduction in 2012.
Furthermore, they warn, the impacts of similar events will only become stronger as the world continues to warm.
One researcher, who was not involved in the study, tells Carbon Brief that the novel application of existing methods in the study is “new and noteworthy”.
Soya bean shock
Soya is one of the “big four” staple crops – along with maize, rice and wheat – that together comprise almost 65% of global calories consumed and 45% of the world’s planted farmlands.
In 2021, the world produced nearly 365m tonnes of soya beans. Less than 4% of this harvest fed humans directly, with the vast majority of it being processed into animal feed, vegetable oil or biofuel.
Just three countries – Argentina, Brazil and the US – grow nearly three-quarters of the world’s supply of soya beans, the study says. The concentration of production in these three countries “makes the global soybean supply vulnerable to regional production shocks” – and especially those due to extreme weather events, the authors write.
Such was the case in 2012, when hot and dry extremes across the Americas caused a 10% drop in global production. This production drop was accompanied by record-high price spikes.
The strength of the 2012 simultaneous failure was a primary reason for studying it, despite the fact that the event happened more than a decade in the past, says lead author Dr Raed Hamed, a climate scientist at Vrije Universiteit Amsterdam.
Another reason is that the selected soya-growing regions have well-understood links to El Nino-Southern Oscillation (ENSO), the large-scale climate pattern in the Pacific Ocean that influences global weather patterns and crop yields.
The low yield in 2012 came at the end of a three-year La Niña event. La Niña is the “cold phase” of ENSO, marked by cooler temperatures in the Pacific Ocean, but it is known to cause hotter- and drier-than-normal conditions in south-eastern South America and the US, respectively. According to the US National Oceanic and Atmospheric Administration, the 2012 La Niña was the third-warmest such event on record.
The charts below show the annual global production of soya as absolute totals (left) and relative to a baseline adjusted for the long-term production trend over 1980-2014 (right).
Soya storylines
In order to tease out the effects of climate change on the 2012 growing season, the researchers use a “storyline” approach.
Many attribution studies take a “probabalistic” approach, running climate models both with and without warming thousands of times to determine how climate change affected the duration, likelihood or intensity of an event.
By contrast, the storyline approach imposes a fixed atmospheric circulation – in this case, the 2012 La Niña event – on top of three different levels of warming: a pre-industrial world, the factual 2012 world and a world that has warmed by 2C. Hamed explains:
“So we remove the question of how likely it is, but we say: ‘Given a similar event in a warmer climate, what would the impact be like?’”
This approach was necessary, Hamed says, because “there is a big question mark” around how further warming will impact ENSO and, in particular, the atmospheric circulation.
Then, the researchers use the temperature and soil moisture outputs from each warming scenario to calculate the soya bean yield in three major growing regions: the US, central Brazil and south-eastern South America, which encompasses parts of Brazil and Argentina. By comparing the actual yield changes in 2012 to those from the pre-industrial model runs, they quantify how much of the lower yield can be attributed to climate change.
They find that, overall, climate change – in the form of warmer temperatures and drier soils – was responsible for 35% of the “production deficit” during the 2012 failure.
However, the impact of the hot-and-dry event differed significantly between regions. In the US, warming caused a 3.5% decrease in production, compared to a world with no climate change, while in south-east South America, production fell by 222%. In central Brazil, climate change actually improved production by 14%.
While this type of approach is not necessarily “novel”, the “application is new and noteworthy”, says Dr Dáithí Stone, a climate scientist at New Zealand’s National Institute of Water and Atmospheric Research. Stone, who was not involved in the study, adds:
“Soya bean is one of the [main] staple crops on the planet and one that’s very much growing in demand. So it’s very important and there are susceptibilities. We do have these sensitivities, these risks, if we have production concentrated in these three areas.”
Future yields
In addition to comparing the event to one in a pre-industrial climate, the researchers use the same approach to project the potential impacts of the same event occurring in a world with 2C of warming above pre-industrial temperatures.
While the effects of the 2012 event were mainly concentrated in the south-east South America region, the impacts are felt in each of the three regions. Furthermore, at higher temperatures, the impact of the interactions between temperature and soil moisture becomes more significant, particularly in the south-east South America region.
The chart below shows the soya bean production anomaly for each region under (left to right) the pre-industrial climate, the actual climate in which the event occurred and the climate with 2C of warming.
The “simple” setup of the analysis means there are many caveats to the study, Hamed says. For example, there is no consideration of adaptation, such as the possibility of farmers planting a larger area or implementing an irrigation system.
It also does not consider future improvements to technology and yields. (Global soya bean yield has been steadily climbing since the 1960s, although, Stone points out, “you can only increase the yield so much”.)
Stone tells Carbon Brief:
“These sorts of studies which look at the impacts of extreme weather in the context of climate change are very useful.
“The impacts of climate change tend to be in these extreme events. They’re the things that stress test us normally, so they’re stress testing us more. And so understanding these events and how their impacts cascade down the system as well…is becoming increasingly important as we enter a warmer world.”
The post ‘One-third’ of 2012 soya crop failure in the Americas was due to climate change appeared first on Carbon Brief.
‘One-third’ of 2012 soya crop failure in the Americas was due to climate change
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.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)