Ahead of the Paris Olympic Games this summer, the organising committee was concerned about two principal diseases: Covid, which Europe is fully familiar with, and dengue fever.
Dengue, a climate-sensitive infectious disease spread by mosquitoes, is traditionally considered a “tropical” infectious disease.
But authorities closely monitored and prepared for dengue in Paris due to its potential to spread in the increasingly warm climate of the region.
A great deal of progress has been made over recent decades in the fight against some infectious diseases, such as malaria, yet this progress is at risk due to climate change.
Mosquitoes carrying the dengue virus are now a threat in France and other European countries because of warmer summers.
Extreme weather events and warming temperatures are giving many infectious diseases opportunities to expand to new regions, putting billions of people at risk.
Climate-sensitive infectious diseases
Any infectious disease whose transmission and spread are influenced by changes and variations in climate and weather is considered a climate-sensitive infectious disease (CSID).
These include diseases that are spread by air, food, water or vectors.
The CSIDs that have received most media attention are vector-borne. They are caused by pathogens that have been transmitted to a human by a vector, such as a snail, fly, tick or mosquito.
Vector-borne diseases include dengue, Zika virus, malaria, Chikungunya and yellow fever.
Ideal breeding conditions
Almost all vector-borne diseases have a climate dimension. Both pathogens – the microorganisms that cause the disease itself – and vectors are very sensitive and highly responsive to the environments they live in. Changes in temperature and rainfall can have significant impacts on their spread.
In 2024, global temperatures reached record highs. These extreme conditions have been linked to a surge in dengue fever cases worldwide and contributed to the spread of other infectious diseases.
Pathogens and vectors typically thrive in warmer climates – in part because there is a longer season in which the vectors can live, breed and pass on the disease.
Higher temperatures change the behaviour of insect vectors. Adult mosquitoes reproduce more quickly and bite more frequently in warmer weather.
Pathogens also multiply faster within the vector in warmer conditions. This means there is a higher concentration of the disease-causing pathogen transmitted within insect bites, increasing the chance of infection. In turn, this leads to quicker and more intense disease outbreaks.
Temperature is only one part of the picture. Changes in rainfall patterns contribute to creating ideal breeding conditions for mosquitoes and other vectors too.
Pakistan, for example, has had increasingly heavy monsoon seasons – linked to climate change – that result in severe flooding. When the floods recede, stagnant water pools are left creating ideal breeding sites for some mosquitos.
Flooding in 2024 has seen 1.3m cases of malaria recorded in Pakistan so far, with cases likely to continue rising. In 2021, there were 500,000 cases recorded in total.
Unequal risks
Vulnerable populations are typically at greater risk from CSIDs – including children, the elderly, pregnant women and people with weakened immune systems.
Additionally, communities with limited healthcare, inadequate housing and poor sanitation are more susceptible to outbreaks of CSIDs due to reduced capability to prevent, detect and treat infections.
Currently, lower-income countries – particularly those in tropical regions – bear the higher burden of CSIDs. Tropical regions are more exposed to vector-borne diseases for several reasons – from the warm and humid climate and the existence of disease-carrying insects to inadequate housing, infrastructure and healthcare.
This combination of factors leads to heightened risk and less resilience against the spread of such infectious diseases in many tropical countries.
However, as temperatures rise, cooler regions, such as Europe, are also becoming more vulnerable to climate-sensitive diseases.
Warmer temperatures increase the geographic range where vectors – such as mosquitoes and ticks – can survive and breed.
This pattern is exemplified by Lyme disease, an illness transmitted by ticks. Increasingly prevalent throughout the UK, it is also steadily moving into northern areas of Canada and even the Arctic – where it was previously absent as ticks could not survive the cold temperatures.
Due to climate and land-use change, ticks can now spread Lyme disease into these new areas and could lead to year-round tick seasons, which could be expected in areas of Scotland and elsewhere.
Reducing risks
While curbing the spread of CSIDs requires global action to slow climate change, there are adaptation measures that can be put in place now.
These measures are particularly important in lower-income countries, where the impacts of climate change on health are most acutely felt.
Wellcome is funding 24 research teams from both climate and health backgrounds in 12 countries to develop new digital tools to respond to the emerging threat of CSIDs.
Integrating climate data with health information can improve the prediction and management of disease outbreaks to, for example, create better early warning systems.
For example, a research team based in Vietnam is developing a new digital tool called E-DENGUE to predict dengue outbreaks as early as two months in advance. It will be tailored for the Mekong Delta region of Vietnam.
This will allow public health practitioners to be one step ahead of dengue outbreaks, giving them time to mobilise resources and concentrate interventions to the most affected areas.
Reducing the ability of mosquitoes to transmit viruses is another promising approach being used to regain control of CSIDs.
The World Mosquito Program is releasing mosquitoes infected with Wolbachia, an extremely common bacterium that occurs naturally in 50% of insect species. This bacterium was found to reduce the ability of tiger mosquitoes to transmit viruses such as dengue and Zika.
However, extreme heat can reduce the effectiveness of this method, highlighting the need for heat-resistant strains of the Wolbachia bacterium in future control programmes.
Recent advances in vaccine development also offer hope. A vaccine for dengue fever has been approved in several countries and more effective vaccines are under development.
For malaria, the vaccine Mosquirix has been recommended by the World Health Organization for use in moderate- and high-transmission areas, and a second-generation malaria vaccine, known as R21/Matrix-M, has demonstrated high efficacy in trials. This summer, Ivory Coast became the first country to roll out R21/Matrix-M.
These vaccines represent strides forward in preventing these diseases and complement other control measures.
Addressing the most acute problems
Climate change is reshaping the global landscape of infectious diseases, with vector-borne diseases at the forefront of this shift.
As temperatures rise and extreme weather becomes more severe, the risk of disease outbreaks increases – both for regions where a disease is already endemic and for those that are experiencing it anew.
Countries that have made the smallest contribution to greenhouse gas emissions are often the ones most affected by climate change’s health impacts and the least well equipped to deal with them.
Ensuring that these countries have access to tools and resources and the support needed to strengthen their health systems will help stem the spread of CSIDs. But much more will be needed to ensure that they can adapt to and mitigate the wider health effects of climate change.
The post Guest post: The growing threat of climate-sensitive infectious diseases appeared first on Carbon Brief.
Guest post: The growing threat of climate-sensitive infectious diseases
When José Antonio Kast took office as Chile’s new president in March, one of his first moves was to put the brakes on plans to expand two protected marine parks – raising doubts about the country’s high-profile bid to host the headquarters of the High Seas Treaty.
But during the UN General Assembly last month, the right-wing leader reaffirmed his leftist predecessor’s ambition for Chile to host the landmark global pact, which came into effect in January and provides a legal framework to protect the waters of the high seas beyond national jurisdiction that cover about two-thirds of the world’s oceans.
Hailing the country’s “maritime vocation”, Kast’s government said the bid to host the treaty’s secretariat in the port city of Valparaíso was state policy and testament to its commitment to multilateralism.
“For the government of Chile, it is of high interest to achieve this recognition, and we will carry out all the efforts to obtain the necessary support,” Foreign Minister Francisco Pérez Mackenna was quoted as saying by local media.
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Tough competition from Chinese, Belgian bids
But to garner the votes it needs, Chile must fend off competing bids by Belgium – which has proposed its well-connected capital, Brussels – and China, whose well-funded bid includes the provision of free premises in the coastal city of Xiamen and five years of free utility costs.
Parties to the treaty, formally called the Agreement on Marine Biological Diversity of Areas Beyond National Jurisdiction (BBNJ), will choose the headquarters at their first summit (COP1), in New York from January 11 to January 22, 2027. They will seek consensus, falling back on a two-thirds majority in successive secret ballots.
Chile has offered to provide a restored waterside warehouse “at its own expense” as office space, pitching itself to developing countries as a Global South alternative to Europe-centred Brussels. Among richer countries, it is promoting its democratic credentials and greater transparency as an alternative to China.
Rolling back environmental safeguards at home?
While the South American country remains the top pick among environmental campaigners and other civil society groups, critics of Kast’s government say recent policy moves may make it harder for the country to garner the support it needs.
On March 12, the day after Kast took office, the Environment Ministry withdrew 43 decrees awaiting legal approval, including a push to expand the Mar de Juan Fernández and Nazca-Desventuradas marine parks – vast protected areas in Chile’s Pacific Ocean waters. Both remain under review, the ministry told Climate Home News.
The decrees also included an emission standard for coal power plants and regulations for Chile’s new biodiversity and protected areas service.
A month after holding up the decrees, Kast questioned aspects of Chile’s urban wetlands protection law, suggesting it was sometimes an unjustified obstacle to much-needed housing development, and his administration has also sought to ease the rules on salmon farming in the world’s second-largest producer.
In August, the Constitutional Court struck down the salmon farming reform after a challenge by opposition lawmakers and warnings from green groups including Greenpeace, which said it could help farms relocate into protected areas such as the Kawésqar National Reserve.
Valparaíso mayor Camila Nieto, from former leftist President Gabriel Boric’s party, backs the bid to host the High Seas Treaty, but said she hoped “the government’s support also translates into public policies consistent with the goals of protecting and conserving the oceans”.
“The decisions a country makes on environmental matters can influence international perceptions of its commitment to protecting the oceans. That is something we cannot ignore,” Nieto told Climate Home News.
China’s bid stirs concerns over data access, fishing
Chile’s past record on marine protection – it has protected 43% of its jurisdictional waters – could yet give it an edge.
“Chile deserves it for its conservation record as a state. For more than 15 years Chile has been following this path,” Liesbeth van der Meer, executive director at conservation group Oceana in Chile, told Climate Home News.
Concerns in some quarters about the rival bid by China – for example, over a potential conflict of interest due to the vast Chinese fishing industry – may also weigh in Chile’s favour, experts say.
Chinese-flagged vessels did about 30% of detected high seas fishing between 2022 and 2024, according to an Oceana analysis of Global Fishing Watch data. China also sponsors five of the International Seabed Authority’s 31 deep-sea mining exploration contracts, more than any other country.
The secretariat would host sensitive marine data, making transparency paramount, experts say.
China says hosting the secretariat in Xiamen would help make the treaty more globally representative, fostering cooperation between rich and developing countries and aiding equitable access to marine science and technology.
Wang Yi, China’s minister of foreign affairs, said in a statement that the country has “all along championed true multilateralism” and “firmly defended” UN institutions. Given Xiamen’s $38-billion ocean industry, the city lives up to the treaty’s “significance and promising future”, he added.
Meanwhile, Chile is proposing the treaty’s first high seas marine protected area for the Salas y Gómez and Nazca ridges, a chain of more than 110 seamounts stretching about 4,000 km from off Peru to Rapa Nui (Easter Island) that is rich in endemic fish and other marine species.
The ridges are “a true oasis of productivity”, said Carlos Gaymer, director of the Centre for Ecology and Sustainable Management of Oceanic Islands at Universidad Católica del Norte and co-author of a 2021 scientific review of the area.
The water is so clear that phytoplankton thrive around 200 metres down, feeding zooplankton, small fish and, up the chain, sharks and seabirds. Whales, turtles and sharks use the ridges as “a real highway” across the Pacific, Gaymer said. Parts of the Nazca ridge are likely nursery grounds for jack mackerel and swordfish.
Chile has already asked the body that regulates the industry in the area – the South Pacific Regional Fisheries Management Organisation (SPRFMO) – to close the ridges to all fishing vessels. According to Chilean data, more than 80% of fishing in the area involves Chinese vessels.
Meeting on the Chilean request in early September, SPRFMO’s scientific committee agreed only to recommend closing the area to bottom fishing. SPRFMO’s commission will take the final decision at its next meeting, in early 2027.
For Gaymer, Chile’s push to close the area to fishing should be seen as a “starting point” for the treaty proposal.
“Every time there’s a new expedition, species new to science appear,” Gaymer said. “If you don’t protect areas like these … those species simply disappear from the planet.”
The post Race to host High Seas Treaty HQ heats up as Chile reaffirms bid appeared first on Climate Home News.
Race to host High Seas Treaty HQ heats up as Chile reaffirms bid
Mohamed Adow is the founder and director of Power Shift Africa.
What does it mean to ask a continent to adapt to a crisis it did little to create? For Africa, that question has stopped being philosophical as it is answered every day in flooded communities, failed harvests, disappearing livelihoods and public budgets stretched by disasters they cannot afford.
Africa produces a negligible share of global emissions, but between 1970 and 2021 it accounted for around 35% of climate-related deaths worldwide. The continent is therefore confronting a brutal contradiction that is exemplified by the fact that those who have contributed least to the climate crisis are carrying some of its heaviest costs.
And that explains why, for us, it is worrying that much of the climate debate treats adaptation as a technical exercise. Build better infrastructure, they say. Improve early-warning systems, they urge. Develop drought-resistant crops, they preach. Strengthen disaster preparedness, they yell. All of these things matter, but they do not answer the harder question of why some people and countries are so much more vulnerable in the first place.
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That is the question we have spent the last couple of years trying to answer, and it culminates in our recently launched thought-provoking report that shows how Africa’s vulnerability is not an accident of geography, but has instead been shaped by history, economics and power.
Colonial extraction, unequal development, debt dependency, global economic asymmetries and exclusion from international decision-making have all constrained the resources and choices available to African countries, and climate change is intensifying those existing inequalities, shows the report, titled “A Just Transition for Adaptation: A Framework and Vision for Africa”.
Widening adaptation finance gap
I say it is ‘thought-provoking’ because it asks us to rethink adaptation itself – not as a collection of projects designed to help people cope with climate impacts, but as a question of justice, power and structural change.
That distinction might not sit well with some people, but for Africa it matters, because there is a danger in asking vulnerable countries simply to become more “resilient”. Resilient against what? How can you ask people to toughen up while letting them be strangled by a system that continues to reproduce the very inequalities that have made resilience so difficult?
If you want to know where the problem is, see where the money is coming from and where it is going. That becomes quite stark when you consider the fact that Africa’s annual adaptation needs are close to $70 billion but its adaptation finance flows are only around $14 billion.
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At the same time, a growing proportion of climate finance is being delivered through commercial loans rather than grants. That means countries already under severe fiscal pressure are being asked to borrow to protect themselves from climate impacts they did little to cause.
There is something deeply wrong with a system in which climate-vulnerable countries are spending more of their own public money on adaptation than they receive in international support, because that system turns climate injustice into a financial transaction, with those least responsible carrying more of the cost.
From extractivism to African ownership
And, as the new report shows, the problem goes beyond finance. Africa’s land, minerals, forests and other resources have become central to the global transition towards lower-carbon economies. Markets and green industrial projects may offer genuine opportunities, but without African ownership, participation and accountability, there is a risk that old patterns of extraction will simply be repackaged in the language of the green economy, and that is why we argue that a transition can be low-carbon and still be unjust.
It is precisely because of this risk that the report’s idea of a just transition for adaptation becomes important as it expands the idea beyond the familiar focus on emissions and energy systems. It asks what justice looks like when the goal is not simply to reduce carbon, but to enable societies to withstand a changing climate without reproducing the inequalities that made them vulnerable.
The report places four dimensions of justice at the centre: recognition, participation, distribution and restoration.
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Recognition means taking African realities and knowledge seriously. Indigenous and local knowledge has too often been treated as peripheral to “real” climate expertise, even though communities possess generations of detailed understanding of ecosystems, rainfall, soils, water and livelihoods. That knowledge should inform adaptation policy from the beginning, rather than being added after decisions have already been made.
Participation means giving affected communities a genuine voice in decisions about their land, resources and futures. Adaptation governance should be inclusive, democratic, rights-based and rooted in free, prior and informed consent.
Climate justice must confront unequal development
Meanwhile, distribution asks who actually receives adaptation finance, technology and protection? Money that is announced internationally but fails to reach vulnerable communities does little to change their reality.
And, finally, restoration recognises that present-day vulnerability has a history. Climate justice cannot begin and end with today’s emissions, but must also confront the structural conditions that have shaped unequal development and continue to limit African countries’ room to respond.
This report, therefore, is an invitation to change the terms of the conversation on just transition. Africa definitely needs adaptation, but that should not m