A lengthy drought that caused widespread disruption to commercial ships passing through the Panama Canal in 2023 would have been “unlikely” without the influence of El Niño, according to a rapid attribution study.
Last year was Panama’s third driest on record. The low rainfall caused water levels in Gatún Lake – a crucial part of the country’s internationally important canal and key fresh water supply for millions of people – to drop to record-low levels.
Authorities reduced shipping through the canal to conserve the lake’s fresh water, resulting in queues of ships waiting for weeks to cross the canal. As shipments of everything from fruit to gas were delayed and rerouted, knock-on effects rippled across the globe.
The new study, by the World Weather Attribution service, did not find a significant long-term drying trend in rainfall over Panama. However, it noted that since 1900, four of the five driest years in the region have occurred in El Niño years,
El Niño reduced last year’s rainfall by about 8%, the authors find.
With the canal’s water use expected to more than double by 2050, the study warns that authorities “may need to re-introduce shipping restrictions to safeguard drinking water supplies, particularly in El Niño years”.
Shipping backlog
Opened in 1914, the Panama Canal – an engineered waterway connecting the Pacific and Atlantic Oceans – is a cornerstone for global marine shipping. Around 14,000 ships pass through the canal every year, accounting for 5% of all global maritime trade.
Using the canal, rather than travelling around the southern tip of South America, ships can cut some 13,000km off their journey. Ships pay a toll for using the canal, which adds more than $2.5bn to Panama’s economy every year.
Gatún Lake is pivotal for the canal’s operation. This artificial, rain-fed lake sits near the centre of the canal, around 26 metres above sea level. Ships travelling into the canal pass through a series of locks, each of which fills with water to raise the ship up to the level of the lake. After travelling through the lake, another series of locks lower the ships back down to sea level.
For every ship that moves through the canal – a process which takes between eight and 10 hours – around 200m litres of fresh lake water is used, most of which is flushed out to sea.
Panama is the fifth wettest country in the world and sees most of its rainfall in its May-December rainy season.
However, total rainfall in 2023 was 30% lower than average. October was especially dry, recording 41% less rainfall than usual.
As a result, water levels in the rainfall-fed Gatún Lake reached a record low in the second half of 2023.
The map below shows water levels in Gatún Lake since 1965, where each line represents one year. The solid black line indicates 2023-24, while the dashed line shows projected lake water levels until mid-June 2024.
Under normal circumstances, the Panama Canal allows 36 “transits” every day. However, as lake levels dropped, the Panama Canal Authority (APC) began taking measures to conserve water. It reduced the number of daily crossings first to 32, then 31. And finally in November 2023 it announced that only 25 crossings would be allowed per day.
Ships began waiting in line for weeks to cross the canal, often paying millions of dollars to jump the queue if another ship with a booked reservation dropped out. By late August, around 135 ships were waiting to cross – 50% more than normal.
Around the world, shipments of everything from food to fuel were delayed.
Rainfall trends
The Panama Canal watershed is a series of natural and artificial rivers, sub-basins and lakes covering some 3,000 square kilometres on either side of Gatún Lake. According to the WWA study, all of the water used by the Panama Canal comes from this area.
The study authors say a network of around 65 weather stations operate in and around the watershed, providing some of the best rainfall records across the entirety of central America and the Caribbean.
To put Panama’s drought into its historical context and determine how unlikely it was, the authors analysed a timeseries of rainfall around the catchment of Gatún Lake in the 2023 rainy season, between May and December.
The map below shows the 2023 rainy season compared to the 1990-2020 average. Brown indicates that 2023 was drier than average and green that it was wetter. Gatún Lake is shaded grey and the study area is outlined in red.
Dr Clair Barnes – a researcher at Imperial College London’s Grantham Institute and author on the study – told a press briefing that there was some evidence of an overall drying trend in some of the stations, while others saw a wetting trend.
Overall, she said the study finds a slight drying trend, but notes the high uncertainty in this finding. She adds:
“We’re not sure exactly what is causing that drying trend or if it is an anomaly. Future trends in a warming climate are also uncertain.”
The authors investigated the impact of El Niño – a global weather phenomenon that originates in the Pacific Ocean – on rainfall in Panama.
During El Niño years, a weakening in the trade winds across the equatorial Pacific brings warm ocean temperatures to the eastern Pacific, off the coast of South America. In Panama, El Niño years are linked with below-average rainfall.
During La Niña years, the opposite effects are seen. Both phases together are known as the El Niño-Southern Oscillation (ENSO).
Steven Paton is the director of the physical monitoring programme at the Smithsonian Tropical Research Institute and an author on the study.
He told a press briefing that 2023 was “the third driest year ever recorded [in Panama] in the 143 years that we have data”. He noted that all of the three driest years on record were recorded during an El Niño event.
The researchers find that in today’s climate, during an El Niño year, Panama has a 5% chance of seeing rainfall levels as low as those in 2023. Given the current frequency of El Niño events, this means that similar events would be expected to occur around once every 40 years in the present climate, they say.
The authors find that El Niño reduced the volume of rainfall that fell in 2023 by about 8%, compared to an ENSO-neutral year, adding that it “is unlikely that Panama could experience such a low rainy season without the influence of El Niño”.
The researchers also assess whether human-caused climate change played a role in Panama’s very low rainfall levels.
To conduct attribution studies, scientists use models to compare the world as it is today to a “counterfactual” world without climate change. This study aimed to identify any potential “signal” of climate change in Panama’s rainfall pattern.
However, only one of the climate models used in this study was able to capture rainfall patterns over the study region accurately, and the authors were unable to determine whether any trend in rainfall over the region was due to climate change.
(These findings are yet to be published in a peer-reviewed journal. However, the methods used in the analysis have been published in previous attribution studies.)
Compounding impacts
The Panama drought shows how changes in weather conditions, such as rainfall patterns, can interact with other hazards.
Maja Vahlberg is a risk consultant at the Red Cross Red Crescent Climate Centre and author on the study. She told the press briefing that disruptions to the Panama Canal interacted with those in the Suez Canal – caused by Yemen’s Houthi group attacking commercial ships in the Red Sea – to drive “compounding and cascading impacts” on global shipping patterns.
This also exacerbated the existing disruptions caused by Russia’s invasion of Ukraine and the Covid pandemic.
As a backlog of ships in the Panama Canal grew, delays lengthened from days to weeks. Al Jazeera described the affected shipments:
“Bananas from Ecuador to Florida. Poultry from Chile to northern Europe. Liquid Natural Gas from the US to Asia. And virtually anything under the sun out of China.”
Around December, newspapers began to warn that shipments of Christmas goods may fail to reach retailers in time for the festive season.
Europe typically imports fresh produce from South and Central America during the winter months, with food and drink making up 77% of container shipments between the west coast of South America and Europe in 2022.
For example, Peru supplies the UK with £2bn worth of goods every year, including more than £350m of “fresh produce”. However, many ships carrying fruits, vegetables and meat from South America to Europe were stuck in the backlog, resulting in “excessive delays”.
The drought also impacted shipments of oil and gas. The US uses the canal as a major trade route for carrying liquefied natural gas (LNG) from the Gulf coast to Asia. However, average waiting times for tankers carrying LNG north through the canal rose from eight days in July to 18 days in August.
Meanwhile, Gatún Lake also supplies drinking water for more than half of Panama’s 4.3 million people. As a result, the government was required to balance the demands of international shipping with the water usage needs of the locals.
Vahlberg told the press briefing that “Indigenous, Afro-Panamanian and some rural communities have very water-dependent livelihoods”. She explained that these communities often have “higher rates of poverty and limited access to basic services”, meaning that “even small changes in precipitation can bring disproportionate impacts on their livelihoods”.
She added that urban expansion and population growth, combined with ageing infrastructure that loses water through leaks, are putting increasing pressure on the country’s water supplies.
The study notes that by 2050, the canal’s water use is expected to be more than double 2015 levels. It warns that, in future, authorities “may need to re-introduce shipping restrictions to safeguard drinking water supplies, particularly in El Niño years”.
The post Drought behind Panama Canal’s 2023 shipping disruption ‘unlikely’ without El Niño appeared first on Carbon Brief.
Drought behind Panama Canal’s 2023 shipping disruption ‘unlikely’ without El Niño
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 mor