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
Climate Change
Big fishing nations secure last-minute seat to write rules on deep sea conservation
As a treaty to protect the High Seas entered into force this month with backing from more than 80 countries, major fishing nations China, Japan and Brazil secured a last-minute seat at the table to negotiate the procedural rules, funding and other key issues ahead of the treaty’s first COP.
The Biodiversity Beyond National Jurisdiction (BBNJ) pact – known as the High Seas Treaty – was agreed in 2023. It is seen as key to achieving a global goal to protect at least 30% of the planet’s ecosystems by 2030, as it lays the legal foundation for creating international marine protected areas (MPAs) in the deep ocean. The high seas encompass two-thirds of the world’s ocean.
Last September, the treaty reached the key threshold of 60 national ratifications needed for it to enter into force – a number that has kept growing and currently stands at 83. In total, 145 countries have signed the pact, which indicates their intention to ratify it. The treaty formally took effect on January 17.
“In a world of accelerating crises – climate change, biodiversity loss and pollution – the agreement fills a critical governance gap to secure a resilient and productive ocean for all,” UN Secretary-General António Guterres said in a statement.
Julio Cordano, Chile’s director of environment, climate change and oceans, said the treaty is “one of the most important victories of our time”. He added that the Nazca and Salas y Gómez ridge – off the coast of South America in the Pacific – could be one of the first intact biodiversity hotspots to gain protection.
Scientists have warned the ocean is losing its capacity to act as a carbon sink, as emissions and global temperatures rise. Currently, the ocean traps around 90% of the excess planetary heat building up from global warming. Marine protected areas could become a tool to restore “blue carbon sinks”, by boosting carbon absorption in the seafloor and protecting carbon-trapping organisms such as microalgae.
Last-minute ratifications
Countries that have ratified the BBNJ will now be bound by some of its rules, including a key provision requiring countries to carry out environmental impact assessments (EIA) for activities that could have an impact on the deep ocean’s biodiversity, such as fisheries.
Activities that affect the ocean floor, such as deep-sea mining, will still fall under the jurisdiction of the International Seabed Authority (ISA).
Nations are still negotiating the rules of the BBNJ’s other provisions, including creating new MPAs and sharing genetic resources from biodiversity in the deep ocean. They will meet in one last negotiating session in late March, ahead of the treaty’s first COP (conference of the parties) set to take place in late 2026 or early 2027.
China and Japan – which are major fishing nations that operate in deep waters – ratified the BBNJ in December 2025, just as the treaty was about to enter into force. Other top fishing nations on the high seas like South Korea and Spain had already ratified the BBNJ last year.
Power play: Can a defensive Europe stick with decarbonisation in Davos?
Tom Pickerell, ocean programme director at the World Resources Institute (WRI), said that while the last-minute ratifications from China, Japan and Brazil were not required for the treaty’s entry into force, they were about high-seas players ensuring they have a “seat at the table”.
“As major fishing nations and geopolitical powers, these countries recognise that upcoming BBNJ COP negotiations will shape rules affecting critical commercial sectors – from shipping and fisheries to biotechnology – and influence how governments engage with the treaty going forward,” Pickerell told Climate Home News.
Some major Western countries – including the US, Canada, Germany and the UK – have yet to ratify the treaty and unless they do, they will be left out of drafting its procedural rules. A group of 18 environmental groups urged the UK government to ratify it quickly, saying it would be a “failure of leadership” to miss the BBNJ’s first COP.
Finalising the rules
Countries will meet from March 23 to April 2 for the treaty’s last “preparatory commission” (PrepCom) session in New York, which is set to draft a proposal for the treaty’s procedural rules, among them on funding processes and where the secretariat will be hosted – with current offers coming from China in the city of Xiamen, Chile’s Valparaiso and Brussels in Belgium.
Janine Felson, a diplomat from Belize and co-chair of the “PrepCom”, told journalists in an online briefing “we’re now at a critical stage” because, with the treaty having entered into force, the preparatory commission is “pretty much a definitive moment for the agreement”.
Felson said countries will meet to “tidy up those rules that are necessary for the conference of the parties to convene” and for states to begin implementation. The first COP will adopt the rules of engagement.
She noted there are “some contentious issues” on whether the BBNJ should follow the structure of other international treaties such as the Convention on Biological Diversity (CBD), as well as differing opinions on how prescriptive its procedures should be.
“While there is this tension on how far can we be held to precedent, there is also recognition that this BBNJ agreement has quite a bit to contribute in enhancing global ocean governance,” she added.
The post Big fishing nations secure last-minute seat to write rules on deep sea conservation appeared first on Climate Home News.
Big fishing nations secure last-minute seat to write rules on deep sea conservation
Climate Change
Climate at Davos: Energy security in the geopolitical driving seat
The annual World Economic Forum got underway on Tuesday in the Swiss ski resort of Davos, providing a snowy stage for government and business leaders to opine on international affairs. With attention focused on the latest crisis – a potential US-European trade war over Greenland – climate change has slid down the agenda.
Despite this, a number of panels are addressing issues like electric vehicles, energy security and climate science. Keep up with top takeaways from those discussions and other climate news from Davos in our bulletin, which we’ll update throughout the day.
From oil to electrons – energy security enters a new era
Energy crises spurred by geopolitical tensions are nothing new – remember the 1970s oil shock spurred by the embargo Arab producers slapped on countries that had supported Israel during the Yom Kippur War, leading to rocketing inflation and huge economic pain.
But, a Davos panel on energy security heard, the situation has since changed. Oil now accounts for less than 30% of the world’s energy supply, down from more than 50% in 1973. This shift, combined with a supply glut, means oil is taking more of a back seat, according to International Energy Agency boss Fatih Birol.
Instead, in an “age of electricity” driven by transport and technology, energy diplomacy is more focused on key elements of that supply chain, in the form of critical minerals, natural gas and the security buffer renewables can provide. That requires new thinking, Birol added.
“Energy and geopolitics were always interwoven but I have never ever seen that the energy security risks are so multiplied,” he said. “Energy security, in my view, should be elevated to the level of national security today.”
In this context, he noted how many countries are now seeking to generate their own energy as far as possible, including from nuclear and renewables, and when doing energy deals, they are considering not only costs but also whether they can rely on partners in the long-term.
In the case of Europe – which saw energy prices jump after sanctions on Russian gas imports in the wake of Moscow’s invasion of Ukraine – energy security rooted in homegrown supply is a top priority, European Commission President Ursula von der Leyen said in Davos on Tuesday.
Outlining the bloc’s “affordable energy action plan” in a keynote speech at the World Economic Forum, she emphasised that Europe is “massively investing in our energy security and independence” with interconnectors and grids based on domestically produced sources of power.
The EU, she said, is trying to promote nuclear and renewables as much as possible “to bring down prices and cut dependencies; to put an end to price volatility, manipulation and supply shocks,” calling for a faster transition to clean energy.
“Because homegrown, reliable, resilient and cheaper energy will drive our economic growth and deliver for Europeans and secure our independence,” she added.
Comment – Power play: Can a defensive Europe stick with decarbonisation in Davos?
AES boss calls for “more technical talk” on supply chains
Earlier, the energy security panel tackled the risks related to supply chains for clean energy and electrification, which are being partly fuelled by rising demand from data centres and electric vehicles.
The minerals and metals that are required for batteries, cables and other components are largely under the control of China, which has invested massively in extracting and processing those materials both at home and overseas. Efforts to boost energy security by breaking dependence on China will continue shaping diplomacy now and in the future, the experts noted.
Copper – a key raw material for the energy transition – is set for a 70% increase in demand over the next 25 years, said Mike Henry, CEO of mining giant BHP, with remaining deposits now harder to exploit. Prices are on an upward trend, and this offers opportunities for Latin America, a region rich in the metal, he added.
At ‘Davos of mining’, Saudi Arabia shapes new narrative on minerals
Andrés Gluski, CEO of AES – which describes itself as “the largest US-based global power company”, generating and selling all kinds of energy to companies – said there is a lack of discussion about supply chains compared with ideological positioning on energy sources.
Instead he called for “more technical talk” about boosting battery storage to smooth out electricity supply and using existing infrastructure “smarter”. While new nuclear technologies such as small modular reactors are promising, it will be at least a decade before they can be deployed effectively, he noted.
In the meantime, with electricity demand rising rapidly, the politicisation of the debate around renewables as an energy source “makes no sense whatsoever”, he added.
The post Climate at Davos: Energy security in the geopolitical driving seat appeared first on Climate Home News.
Climate at Davos: Energy security in the geopolitical driving seat
Climate Change
A Record Wildfire Season Inspires Wyoming to Prepare for an Increasingly Fiery Future
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A Record Wildfire Season Inspires Wyoming to Prepare for an Increasingly Fiery Future
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