Spiking food prices have made headlines around the world this year, from eggs in the US to vegetables in India.
The UN Food and Agriculture Organization’s Food Price Index has been slowly increasing over the past six months following declines over much of 2023.
For example, the price of orange juice concentrate in the US was 42% higher in April than it was a year ago, while the price of fresh orange juice in the UK has risen 25% over the last year.
In Greece, the price of olive oil rose by nearly 30% over 2023 and by more than 63% in April of this year.
No single factor alone can explain the rising prices.
But geopolitical conflict, extreme weather events, high input costs and increased demand are all playing a role.
The FAO’s recent Food Outlook report finds that, despite positive forecasts, “global food production systems remain vulnerable to shocks stemming from extreme weather events, geopolitical tensions, policy changes and developments in other markets”.
Carbon Brief has asked a range of scientists and policy experts from around the world what they think are the biggest factors driving spiking global food prices.
These are their responses, first as sample quotes, then, below, in full:
- Prof Elizabeth Robinson: “Whilst one can argue that food crises are not primarily caused by climate or weather, often food price spikes are due to a combination of weather and non-weather related factors.”
- Levi Sucre: “The overexploitation of agricultural lands and the intensive use of agrochemicals have led to a growing need for fertilisers to maintain production, which further increases production costs.”
- Dr Álvaro Lario: “Most food commodity markets present a stable outlook for 2024-25, which should help contain prices for consumers. However…many factors can tip the delicate demand-supply balance.”
- Siraj Hussain: “For long-term and stable food security, the yield has to go up and food losses have to come down.”
- Prof Andrew Challinor: “Put plainly, climate change is beginning to outpace us because it is interacting with our complex interrelated economic and food systems.”
- Dr Rob Vos: “Food prices in global markets are most sensitive to weather conditions and supply disruptions in major producing countries.”
- Prof Alan Matthews: “The rapid recovery of consumer demand following the disruptions caused by the measures to contain the Covid-19 pandemic, extreme weather events, animal disease outbreaks and tight global markets all contributed.”
- Xiomara Paredes: “In short, every time a new regulation is created, it increases production costs, makes market access difficult and thus makes food products more expensive.”
- Dr Manuel Otero: “Food prices have experienced significant increases due to various interrelated economic, social, environmental and political causes.”
- Dr Shouro Dasgupta: “Conflicts are one of the main reasons behind price shocks…Many of these events have also disrupted supply chains and infrastructure.”
Prof Elizabeth Robinson
Director, Grantham Research Institute on Climate Change and the Environment.
London School of Economics and Political Science
Back in 2008, broad underinvestment in the agriculture sector, increasing demand for biofuels, changing diets and speculation – encouraged by declining global food stocks – were already putting longer-term upward pressure on food prices.
The 2008 food crisis was triggered by sequential poor wheat harvests in Australia, a breadbasket country. However, the extreme spike in wheat and rice prices was driven by a combination of export restrictions, panic buying and increased speculation, which amplified the short-term harvest shocks and the longer-term pressures.
More recently, the changing climate, the Covid-19 pandemic and Russia’s invasion of Ukraine have disrupted food production and globally integrated food supply chains, putting rapid upwards pressure on food prices. Whilst one can argue that food crises are not primarily caused by climate or weather, often food price spikes are due to a combination of weather and non-weather related factors.
Earlier this year cocoa prices rapidly increased, a consequence of extreme weather conditions, linked in part to El Niño, resulting in multiple poor harvest seasons in west Africa, combined with longer-term pressures, including disease and ageing cocoa trees, and short-term pressures, particularly speculation, exacerbating the situation further.
Given the changing climate, and in particular increasing extremes of heat and precipitation, food price spikes are likely to be an increasingly common feature of our highly integrated global food systems, in which shocks in one part of the world can relatively easily be amplified and transmitted around the globe.
Levi Sucre
Coordinator
Mesoamerican Alliance of Peoples and Forests
There are several factors causing the increase in food prices worldwide.
Firstly, the high dependency on oil, whose price keeps rising, drives up the costs of food production and transportation. Agricultural machinery, fertilisers and product transportation rely heavily on oil, so any increase in its price directly affects the final cost of food.
Additionally, the overexploitation of agricultural lands and the intensive use of agrochemicals have led to a growing need for fertilisers to maintain production, which further increases production costs.
Monocultures are also degrading the soil, reducing its capacity to produce food sustainably. The lack of crop rotation depletes soil nutrients, diminishing its fertility and forcing farmers to use more fertilisers and pesticides. This not only increases costs but also has negative effects on the environment and health.
The effects of climate change are impacting agricultural production; for example, rising temperatures are disrupting previously predictable agricultural seasons, making crop production more difficult. High temperatures in Mesoamerica continue to destroy crops and reduce food reserves, worsening shortages and driving up prices, affecting nearly 8 million people in El Salvador, Guatemala, Honduras and Nicaragua.
Furthermore, economic injustice, inequality and lack of equity exacerbate the situation. The people with the least resources are the most affected by rising food prices, putting their food security at risk. On the other hand, small-scale producers, who do not use harmful soil practices, do not receive the necessary support to increase their production. These farmers cannot compete with large companies that dominate the market with their monocultures.
Dr Álvaro Lario
President
International Fund for Agricultural Development
International food prices have declined since their historic peak after the start of the war in Ukraine. According to the recently released biennial FAO Food Outlook, most food commodity markets present a stable outlook for 2024-25, which should help contain prices for consumers. But as the report reminds us, many factors can tip the delicate demand-supply balance, impacting food prices and global food security.
The drop in global food prices does not automatically mean that prices have decreased in real terms in local markets, especially considering the strong depreciation of local currencies in most low- and middle-income countries against a robust US dollar.
This is also true for rural communities in these countries, where 80% of the world’s poorest live. In these areas, people can spend up to 70% of their income on food, leaving them with no capacity to absorb any price hikes and pushing them into poverty and hunger. Since Covid-19 emerged, we have seen multiple crises, such as climate change, conflict and record-high food prices, have compounded to push 122 million more people into hunger.
And, despite the current trend, we must remember how fragile our food systems are. They are increasingly threatened by more frequent and intense weather extremes, and volatile geopolitics. Our food systems are overly concentrated on a few crops, countries and producers, and are inefficient, with significant food losses along the value chain and high levels of food waste at the consumer level.
Siraj Hussain
India’s former agricultural secretary. Trustee.
World Food Programme Trust for India
Food inflation has been a source of major concern for a vast majority of Indians.
It is quite an enigma that even cereals, in which India is surplus, have seen double-digit inflation in the last year. Despite the erratic monsoon in 2023, India produced 137m tonnes of rice. Yet in every month since April 2023, the consumer price index inflation for rice was 11-13%.
In the case of wheat, inflation was more than 12% from April to July 2023. The Indian government released 10m tonnes of wheat under an open market sales scheme to cool down wheat prices and the intervention was quite successful as inflation has come down to about 3-7% since July 2023.
The reasons behind inflation in basic cereals of wheat and rice are not well understood. Despite low monsoon rains in 2023-24 due to El Niño, the production of both was not too low in 2023-24. As per the Indian government, wheat production was 113m tonnes.
The real concern in the basket of food inflation comes from vegetables, where inflation in the last year has reached more than 25%. This is attributed to losses in the supply chain from harvesting to marketing. India’s food surpluses are quite small except for rice and sugar. For long-term and stable food security, the yield has to go up and food losses have to come down.
Prof Andy Challinor
Professor of Climate Impacts.
University of Leeds
Every five years, the UK is mandated to report on climate change risks. The scientific evidence for the second of these reports was published in 2017. It highlighted risks from weather-related shocks to international food production and trade as a key risk.
The final report, which is the responsibility of the government, not scientists, endorsed all the conclusions of the evidence report “with the exception of some of those on food security”. The reason? It said: “The government takes a more optimistic view of the levels of resilience that are achieved through functioning markets and diverse sources of supply.”
In the same month that the government response was written, reports of a UK courgette deficit, resulting from climate extremes abroad, soon deepened into wider concerns across a range of vegetables and rationing was commonplace across supermarkets. The World Economic Forum’s 2017 report on global risks identified extreme weather events – already ranked as the most likely global risk in every WEF report since 2014 – as both the most likely and most impactful risk, after weapons of mass destruction.
Skip forward to 2022, when the evidence for the new UK assessment was published. Amongst other additions, an increased underlying vulnerability to climate risk was identified along with a new specific risk of “risk amplification from the interactions and cascades of named risks across systems and geographies”.
The way we as a society (consumers, citizens, government, businesses) choose to set up our food systems has huge implications for stability and resilience – or lack thereof. The 2022 report makes clear that the UK is struggling to keep pace with climate change impacts because of both the pace of change and the way in which the many potential risks to food systems interact with each other.
Put plainly, climate change is beginning to outpace us because it is interacting with our complex interrelated economic and food systems. Until we find ourselves able to look at the big picture and adjust accordingly, we can expect more of the same.
Dr Rob Vos
Director for Markets, Trade and Institutions.
International Food Policy Research Institute
The war in Ukraine caused world market prices for staple foods, especially wheat and vegetable oils, to skyrocket in the first half of 2022. Since then, however, those world market prices have come down to pre-war levels.
At the same time, consumers around the world have felt soaring domestic food price inflation well into 2023. People in some low- and middle-income countries, such as in Argentina, Egypt, Ethiopia, Gaza, Haiti, Sudan, Ukraine and Venezuela, are still seeing the cost of their daily bread and meals going up at high rates today.
What is driving these price fluctuations in global food markets and why are consumer prices not following the same pattern?
Food prices in global markets are most sensitive to weather conditions and supply disruptions in major producing countries. For instance, floods in India caused by the El Niño phenomenon disrupted rice production in India during 2023, pushing up rice prices worldwide.
The war in Ukraine caused shortages in global wheat, maize, sunflower seeds and fertiliser supplies as both Russia and Ukraine are major producers, pushing up wheat, vegetable oil and fertiliser prices.
I should add that the Ukraine war was not the only factor and, in fact, just exacerbated the surge in international food and fertiliser prices induced by the global economic recovery from the Covid-19 recession and the supply chain disruptions (recall the containership pile-up at harbours) that sent oil prices and shipping costs soaring and increasing the cost of farming and food trade worldwide.
Global market prices are further sensitive to misguided policy responses. Governments often respond to expected food supply shortages and price surges by imposing restrictions on exports (such as India’s bans on rice exports in 2023) or lowering import restrictions (as many rice-importing countries did in 2023). While trying to protect their consumers, these “insulation” measures end up just magnifying the price increase.
Why do domestic food prices not necessarily follow the same pattern?
In fact, most countries are relatively insulated from global price shocks as they rely predominantly on their own food production to feed their populations; typically, only 10-15% or less of food consumption is imported.
Domestic conditions for food production and distribution systems thus matter more than global prices. These conditions vary across countries, but countries with the highest rates of consumer price inflation have seen food systems disrupted by intensified conflict (as in Ethiopia, Gaza, Haiti and Sudan, for instance) and those suffering macroeconomic constraints and weak currencies that have kept both general and food price inflation high (e.g. Argentina, Venezuela, Turkey, and many highly indebted low-income countries).
Prof Alan Matthews
Professor Emeritus of European Agricultural Policy
University of Dublin Trinity College
Food prices in the EU rose dramatically in 2022 and 2023. EU food prices were 41% higher in May 2023 relative to the price level in 2015, while the overall price level rose by just 26% during this period. The monthly annual rate of food price inflation peaked at 19.2% in the EU in March 2023.
Even higher rates were recorded in central and eastern Europe, with Hungary a particular outlier, with food price inflation of 46% in February 2023. Since then, food prices have not fallen, but are now increasing at a rate below the general inflation rate for the first time in two years.
There have been multiple drivers of this food price inflation. The rapid recovery of consumer demand following the disruptions caused by the measures to contain the Covid-19 pandemic, extreme weather events, animal disease outbreaks and tight global markets all contributed.
For Europe, the impact of the Russian invasion of Ukraine has been particularly important. There was a direct impact through the increased price of energy, and thus fertilisers and fuel, given the EU’s dependence on imports particularly of Russian gas, but also an indirect impact through the knock-on effect of higher world market crop prices due to the subsequent curtailment of Ukrainian exports to the world market.
Extreme weather events have contributed to food price increases. High temperatures and drought badly affected olive oil production in 2022-23 as well as production of cereals in southern Europe, while heavy rains and wet weather have delayed planting and harvests and damaged fruit quality in northern Europe.
Despite these production losses, a March 2024 study in Communications Earth & Environment estimated that the 2022 extreme summer heat had increased food inflation in Europe by 0.43-0.93 percentage points – so making a relatively minor contribution to the overall 19% increase in food prices at that time. Nonetheless, in more normal times that would cause a more noticeable uptick in food prices, and the authors suggest that the warming projected for 2035 could amplify these numbers by 30-50%.
Xiomara Paredes
Executive Director, Latin American and Caribbean Coordinating Association of Small Fair Trade Producers and Workers
The new regulations that the EU has recently implemented, such as the deforestation-free regulation, changes in organic regulation, human rights and environmental due diligence, entail the investment of additional resources, thus raising production costs.
For example, to comply with the deforestation-free regulation, producers must first invest in geolocation equipment and have technical staff who can survey the points or polygons on the plots of each producer member of the organisation. Geolocating all the producers’ plots also takes time and effort that must be diluted in the installed capacity of the producer organisations.
In short, every time a new regulation is created, it increases production costs, makes market access difficult and thus makes food products more expensive.
Dr Shouro Dasgupta
Environmental Economist
Fondazione CMCC
Visiting Senior Fellow
Grantham Research Institute, LSE
The issue of increasing food prices is multifaceted and is due to a complex set of reasons including conflicts, climate change and supply chain disruptions.
Conflicts are one of the main reasons behind price shocks. For instance, Russia’s invasion of Ukraine, known as the breadbasket of Europe, has substantially reduced exports of wheat, maize and sunflower, resulting in food price fluctuations. While global food prices have decreased from their peak levels at the onset of the conflict, they remain higher than the pre-conflict levels.
Climate change, manifested by increasing temperatures and the increasing intensity and frequency of extreme events such as heatwaves, droughts and floods, has led to crop failures and reduced yields in many parts of the world. This, in turn, has pushed up food prices through supply shocks.
Many of these events have also disrupted supply chains and infrastructure, such as roads, and lowered water levels of major rivers such as the Rhine. Whether due to conflicts or climate change, several countries have imposed export bans on major agricultural commodities (for example, India, Myanmar and Russia on rice; Thailand on sugar; Argentina on beef). These restrictions affect countries that are highly dependent on imports the most.
Several policy failures in the global food system also contribute to food inflation. One such issue is the inadequacy of storage facilities, especially in low- and middle-income countries. Another is the concentration of food production in certain regions and on selected crops (60% of the plant-based calorie intake is provided by rice, wheat and maize) and the fact that global food chains are dominated by a small number of multinational corporations.
Dr Manuel Otero
Director-general, Inter-American Institute for Cooperation on Agriculture
In recent years, food prices have experienced significant increases due to various interrelated economic, social, environmental and political causes. Armed conflicts have disrupted supply chains and food production and distribution, exacerbating shortages and driving up prices. These conflicts have also displaced millions of people, affecting their ability to produce and access food.
Economic shocks, such as the Covid-19 pandemic and its repercussions, plus the slowdown of economies, have reduced consumers’ purchasing power, decreasing incomes and increasing unemployment, which has raised relative demand and prices.
Extreme weather events, such as droughts and storms, have affected agricultural production, reducing supply and increasing production costs, resulting in higher prices for consumers. Volatility in fertiliser markets, driven by trade restrictions and armed conflict, has also increased agricultural production costs, reflected in higher prices for food products.
Trade restrictions, such as export bans, have exacerbated the global food crisis, limiting international food trade and further driving up prices in global markets. According to our Observatory of Public Policies for Agrifood Systems tool, since the pandemic, food inflation has reached 28% annually on a global average – compared to a general inflation of 19% annually.
This is despite the fact that international food prices fell 9% annually for the same comparison period, suggesting that other economic, political and environmental factors contribute to food inflation.
Latin America and the Caribbean is home to 16 net-exporting and 16 net-food-importing countries, so the region has benefited from the increase in international food prices, but has also been one of the most affected by food insecurity due to factors such as increasing poverty.
The post Experts: What is causing food prices to spike around the world? appeared first on Carbon Brief.
Experts: What is causing food prices to spike around the world?
N.C. Gov. Josh Stein wants state lawmakers to rethink tax breaks for data centers. The industry’s opacity makes it difficult to evaluate costs and benefits.
Tax breaks for data centers in North Carolina keep as much as $57 million each year into from state and local government coffers, state figures show, an amount that could balloon to billions of dollars if all the proposed projects are built.
The Global Environment Facility (GEF), a multilateral fund that provides climate and nature finance to developing countries, has raised $3.9 billion from donor governments in its last pledging session ahead of a key fundraising deadline at the end of May.
The amount, which is meant to cover the fund’s activities for the next four years (July 2026-June 2030), falls significantly short of the previous four-year cycle for which the GEF managed to raise $5.3bn from governments. Since then, military and other political priorities have squeezed rich nations’ budgets for climate and development aid.
The facility said in a statement that it expects more pledges ahead of the final replenishment package, which is set for approval at the next GEF Council meeting from May 31 to June 3.
Claude Gascon, interim CEO of the GEF, said that “donor countries have risen to the challenge and made bold commitments towards a more positive future for the planet”. He added that the pledges send a message that “the world is not giving up on nature even in a time of competing priorities”.
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Donors under pressure
But Brian O’Donnell, director of the environmental non-profit Campaign for Nature, said the announcement shows “an alarming trend” of donor governments cutting public finance for climate and nature.
“Wealthy nations pledged to increase international nature finance, and yet we are seeing cuts and lower contributions. Investing in nature prevents extinctions and supports livelihoods, security, health, food, clean water and climate,” he said. “Failing to safeguard nature now will result in much larger costs later.”
At COP29 in Baku, developed countries pledged to mobilise $300bn a year in public climate finance by 2035, while at UN biodiversity talks they have also pledged to raise $30bn per year by 2030. Yet several wealthy governments have announced cuts to green finance to increase defense spending, among them most recently the UK.
As for the US, despite Trump’s cuts to international climate finance, Congress approved a $150 million increase in its contribution to the GEF after what was described as the organisation’s “refocus on non-climate priorities like biodiversity, plastics and ocean ecosystems, per US Treasury guidance”.
The facility will only reveal how much each country has pledged when its assembly of 186 member countries meets in early June. The last period’s largest donors were Germany ($575 million), Japan ($451 million), and the US ($425 million).
The GEF has also gone through a change in leadership halfway through its fundraising cycle. Last December, the GEF Council asked former CEO Carlos Manuel Rodriguez to step down effective immediately and appointed Gascon as interim CEO.
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New guidelines
As part of the upcoming funding cycle, the GEF has approved a set of guidelines for spending the $3.9bn raised so far, which include allocating 35% of resources for least developed countries and small island states, as well as 20% of the money going to Indigenous people and communities.
Its programs will help countries shift five key systems – nature, food, urban, energy and health – from models that drive degradation to alternatives that protect the planet and support human well-being by integrating the value of nature into production and consumption systems.
The new priorities also include a target to allocate 25% of the GEF’s budget for mobilising private funds through blended finance. This aligns with efforts by wealthy countries to increase contributions from the private sector to international climate finance.
Niels Annen, Germany’s State Secretary for Economic Cooperation and Development, said in a statement that the country’s priorities are “very well reflected” in the GEF’s new spending guidelines, including on “innovative finance for nature and people, better cooperation with the private sector, and stable resources for the most vulnerable countries”.
Aliou Mustafa, of the GEF Indigenous Peoples Advisory Group (IPAG), also welcomed the announcement, adding that “the GEF is strengthening trust and meaningful partnerships with Indigenous Peoples and local communities” by placing them at the “centre of decision-making”.
The post GEF raises $3.9bn ahead of funding deadline, $1bn below previous budget appeared first on Climate Home News.
GEF raises $3.9bn ahead of funding deadline, $1bn below previous budget
Tropical cyclones that rapidly intensify when passing over marine heatwaves can become “supercharged”, increasing the likelihood of high economic losses, a new study finds.
Such storms also have higher rates of rainfall and higher maximum windspeeds, according to the research.
The study, published in Science Advances, looks at the economic damages caused by nearly 800 tropical cyclones that occurred around the world between 1981 and 2023.
It finds that rapidly intensifying tropical cyclones that pass near abnormally warm parts of the ocean produce nearly double – 93% – the economic damages as storms that do not, even when levels of coastal development are taken into account.
One researcher, who was not involved in the study, tells Carbon Brief that the new analysis is a “step forward in understanding how we can better refine our predictions of what might happen in the future” in an increasingly warm world.
As marine heatwaves are projected to become more frequent under future climate change, the authors say that the interactions between storms and these heatwaves “should be given greater consideration in future strategies for climate adaptation and climate preparedness”.
‘Rapid intensification’
Tropical cyclones are rapidly rotating storm systems that form over warm ocean waters, characterised by low pressure at their cores and sustained winds that can reach more than 120 kilometres per hour.
The term “tropical cyclones” encompasses hurricanes, cyclones and typhoons, which are named as such depending on which ocean basin they occur in.
When they make landfall, these storms can cause major damage. They accounted for six of the top 10 disasters between 1900 and 2024 in terms of economic loss, according to the insurance company Aon’s 2025 climate catastrophe insight report.
These economic losses are largely caused by high wind speeds, large amounts of rainfall and damaging storm surges.
Storms can become particularly dangerous through a process called “rapid intensification”.
Rapid intensification is when a storm strengthens considerably in a short period of time. It is defined as an increase in sustained wind speed of at least 30 knots (around 55 kilometres per hour) in a 24-hour period.
There are several factors that can lead to rapid intensification, including warm ocean temperatures, high humidity and low vertical “wind shear” – meaning that the wind speeds higher up in the atmosphere are very similar to the wind speeds near the surface.
Rapid intensification has become more common since the 1980s and is projected to become even more frequent in the future with continued warming. (Although there is uncertainty as to how climate change will impact the frequency of tropical cyclones, the increase in strength and intensification is more clear.)
Marine heatwaves are another type of extreme event that are becoming more frequent due to recent warming. Like their atmospheric counterparts, marine heatwaves are periods of abnormally high ocean temperatures.
Previous research has shown that these marine heatwaves can contribute to a cyclone undergoing rapid intensification. This is because the warm ocean water acts as a “fuel” for a storm, says Dr Hamed Moftakhari, an associate professor of civil engineering at the University of Alabama who was one of the authors of the new study. He explains:
“The entire strength of the tropical cyclone [depends on] how hot the [ocean] surface is. Marine heatwave means we have an abundance of hot water that is like a gas [petrol] station. As you move over that, it’s going to supercharge you.”
However, the authors say, there is no global assessment of how rapid intensification and marine heatwaves interact – or how they contribute to economic damages.
Using the International Best Track Archive for Climate Stewardship (IBTrACS) – a database of tropical cyclone paths and intensities – the researchers identify 1,600 storms that made landfall during the 1981-2023 period, out of a total of 3,464 events.
Of these 1,600 storms, they were able to match 789 individual, land-falling cyclones with economic loss data from the Emergency Events Database (EM-DAT) and other official sources.
Then, using the IBTrACS storm data and ocean-temperature data from the European Centre for Medium-Range Weather Forecasts, the researchers classify each cyclone by whether or not it underwent rapid intensification and if it passed near a recent marine heatwave event before making landfall.
The researchers find that there is a “modest” rise in the number of marine heatwave-influenced tropical cyclones globally since 1981, but with significant regional variations. In particular, they say, there are “clear” upward trends in the north Atlantic Ocean, the north Indian Ocean and the northern hemisphere basin of the eastern Pacific Ocean.
‘Storm characteristics’
The researchers find substantial differences in the characteristics of tropical cyclones that experience rapid intensification and those that do not, as well as between rapidly intensifying storms that occur with marine heatwaves and those that occur without them.
For example, tropical cyclones that do not experience rapid intensification have, on average, maximum wind speeds of around 40 knots (74km/hr), whereas storms that rapidly intensify have an average maximum wind speed of nearly 80 knots (148km/hr).
Of the rapidly intensifying storms, those that are influenced by marine heatwaves maintain higher wind speeds during the days leading up to landfall.
Although the wind speeds are very similar between the two groups once the storms make landfall, the pre-landfall difference still has an impact on a storm’s destructiveness, says Dr Soheil Radfar, a hurricane-hazard modeller at Princeton University. Radfar, who is the lead author of the new study, tells Carbon Brief:
“Hurricane damage starts days before the landfall…Four or five days before a hurricane making landfall, we expect to have high wind speeds and, because of that high wind speed, we expect to have storm surges that impact coastal communities.”
They also find that rapidly intensifying storms have higher peak rainfall than non-rapidly intensifying storms, with marine heatwave-influenced, rapidly intensifying storms exhibiting the highest average rainfall at landfall.
The charts below show the mean sustained wind speed in knots (top) and the mean rainfall in millimetres per hour (bottom) for the tropical cyclones analysed in the study in the five days leading up to and two days following a storm making landfall.
The four lines show storms that: rapidly intensified with the influence of marine heatwaves (red); those that rapidly intensified without marine heatwaves (purple); those that experienced marine heatwaves, but did not rapidly intensify (orange); and those that neither rapidly intensified nor experienced a marine heatwave (blue).
Dr Daneeja Mawren, an ocean and climate consultant at the Mauritius-based Mascarene Environmental Consulting who was not involved in the study, tells Carbon Brief that the new study “helps clarify how marine heatwaves amplify storm characteristics”, such as stronger winds and heavier rainfall. She notes that this “has not been done on a global scale before”.
However, Mawren adds that other factors not considered in the analysis can “make a huge difference” in the rapid intensification of tropical cyclones, including subsurface marine heatwaves and eddies – circular, spinning ocean currents that can trap warm water.
Dr Jonathan Lin, an atmospheric scientist at Cornell University who was also not involved in the study, tells Carbon Brief that, while the intensification found by the study “makes physical sense”, it is inherently limited by the relatively small number of storms that occur. He adds:
“There’s not that many storms, to tease out the physical mechanisms and observational data. So being able to reproduce this kind of work in a physical model would be really important.”
Economic costs
Storm intensity is not the only factor that determines how destructive a given cyclone can be – the economic damages also depend strongly on the population density and the amount of infrastructure development where a storm hits. The study explains:
“A high storm surge in a sparsely populated area may cause less economic damage than a smaller surge in a densely populated, economically important region.”
To account for the differences in development, the researchers use a type of data called “built-up volume”, from the Global Human Settlement Layer. Built-up volume is a quantity derived from satellite data and other high-resolution imagery that combines measurements of building area and average building height in a given area. This can be used as a proxy for the level of development, the authors explain.
By comparing different cyclones that impacted areas with similar built-up volumes, the researchers can analyse how rapid intensification and marine heatwaves contribute to the overall economic damages of a storm.
They find that, even when controlling for levels of coastal development, storms that pass through a marine heatwave during their rapid intensification cause 93% higher economic damages than storms that do not.
They identify 71 marine heatwave-influenced storms that cause more than $1bn (inflation-adjusted across the dataset) in damages, compared to 45 storms that cause those levels of damage without the influence of marine heatwaves.
This quantification of the cyclones’ economic impact is one of the study’s most “important contributions”, says Mawren.
The authors also note that the continued development in coastal regions may increase the likelihood of tropical cyclone damages over time.
Towards forecasting
The study notes that the increased damages caused by marine heatwave-influenced tropical cyclones, along with the projected increases in marine heatwaves, means such storms “should be given greater consideration” in planning for future climate change.
For Radfar and Moftakhari, the new study emphasises the importance of understanding the interactions between extreme events, such as tropical cyclones and marine heatwaves.
Moftakhari notes that extreme events in the future are expected to become both more intense and more complex. This becomes a problem for climate resilience because “we basically design in the future based on what we’ve observed in the past”, he says. This may lead to underestimating potential hazards, he adds.
Mawren agrees, telling Carbon Brief that, in order to “fully capture the intensification potential”, future forecasts and risk assessments must account for marine heatwaves and other ocean phenomena, such as subsurface heat.
Lin adds that the actions needed to reduce storm damages “take on the order of decades to do right”. He tells Carbon Brief:
“All these [planning] decisions have to come by understanding the future uncertainty and so this research is a step forward in understanding how we can better refine our predictions of what might happen in the future.”
The post Marine heatwaves ‘nearly double’ the economic damage caused by tropical cyclones appeared first on Carbon Brief.
Marine heatwaves ‘nearly double’ the economic damage caused by tropical cyclones
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