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While the primary focus of tackling climate change is on carbon dioxide (CO2), a group of other greenhouse gases and aerosols – known as “super pollutants” – is having a profound impact on both global temperature and human health.

They are responsible for around 45% of global warming to date, as well as millions of premature deaths each year.

Cutting emissions of these non-CO2 pollutants, which include methane, hydrofluorocarbons and black carbon, is seen as one of the quickest ways to tackle climate change.

Studies have shown how global action to reduce emissions of super pollutants could avoid four times more warming by 2050 than decarbonisation policies alone.

At the same time, it could prevent some 2.4 million deaths a year caused by air pollution. 

And, yet, emissions of many super pollutants are soaring

In this article, we unpack what super pollutants are and why they have an outsized impact on the climate and public health.

The other 45%

CO2 is responsible for around 55% of global warming to date. The other 45% comes from super pollutants: methane; black carbon; fluorinated gases; nitrous oxide; and tropospheric ozone.

These pollutants are present at lower concentrations in the atmosphere than CO2. But each tonne of these substances has a more powerful warming impact than a tonne of CO2 – up to tens of thousands of times more. As a result, they are still responsible for a lot of warming.

Most super pollutants remain in the atmosphere for less time than CO2, ranging from a few days to a few decades. These are known collectively as “short-lived climate pollutants”.

Others, including nitrous oxide and some fluorinated gases, can have very long lifetimes – even tens of thousands of years in some cases.

As well as being substantial contributors to global warming, super pollutants are a major threat to human health.

Poor air quality caused by these pollutants has been linked to a series of heart and respiratory diseases, as well as lung cancer and strokes.

Methane, black carbon and tropospheric ozone are the super pollutants with the most significant impacts on health.

Illustration of some of the main sources of super pollutants, their average lifetimes in the atmosphere and impacts on local, regional and global scales.
Illustration of some of the main sources of super pollutants, their average lifetimes in the atmosphere and impacts on local, regional and global scales. Credit: The Wellcome Trust

Methane

Methane is the second-largest contributor to climate change after CO2. In its first 20 years in the atmosphere, when it is most potent, methane has a warming potential more than 80 times greater than CO2.

Methane has both human-related and natural sources. Global human-caused methane emissions come from three main areas:

  • Agriculture (~40%), such as from livestock and rice production.
  • Fossil fuels (~35%), as a by-product of fossil fuel extraction, storage and distribution.
  • Waste (~20%), from food and other organic materials decaying in landfills and wastewater.

Recent research has shown that methane emissions have continued to rise, with “no hint of a decline”. According to the World Meteorological Organization, atmospheric concentrations of methane in 2023 were 265% higher than pre-industrial levels.

Methane impacts public health indirectly in a number of ways.

By increasing atmospheric temperatures, disrupting rainfall patterns and contributing to the formation of tropospheric ozone, emissions of the gas contribute to crop failures which exacerbate food insecurity. The gas has been estimated to cause up to 12% of annual agricultural losses of staple crops.

Increased food insecurity has a number of implications for human health. Research has indicated that nearly half of deaths among children under five are linked to undernutrition. These mostly occur in low- and middle-income countries. 

However, the biggest impact methane has on health is its contribution to the creation of tropospheric ozone.

Tropospheric ozone

Tropospheric ozone is among the shortest-lived super pollutants, with an atmospheric lifetime of just days to weeks.

But, despite its short-lived nature, the greenhouse gas has a major impact on human health. It has been linked to around 600,000 to 1 million premature respiratory deaths annually and a similar number of premature cardiovascular deaths

The greenhouse gas does not have any direct sources, but is formed when hydrocarbons – including methane, volatile organic compounds (VOCs) and carbon monoxide – react with nitrogen oxides in the presence of sunlight.

Concentrations of this harmful pollutant are rising. Soaring emissions of its precursor gas – methane – are believed to be responsible for up to half of the observed increase.

As a major component of smog, tropospheric ozone can worsen bronchitis and emphysema, trigger asthma and permanently damage lung tissue. Children, the elderly and people with lung or cardiovascular diseases are particularly at risk from ozone exposure.

In addition to harming human health, studies have shown that many species of plants are sensitive to ozone, including agricultural crops, grassland and trees. Tropospheric ozone damages plants in many ways, including by entering pores in their leaves and burning plant tissue during respiration. 

As a result, ozone emissions are a growing threat to food security

Black carbon

Black carbon is formed by the incomplete combustion of wood, biofuels and fossil fuels in a process which also creates carbon dioxide, carbon monoxide and VOCs.

Commonly known as soot, black carbon has a warming impact up to 1,500 times stronger than CO2 per tonne. The  pollutant dims sunlight that reaches the Earth, interferes with rainfall patterns and disrupts monsoons. Where it settles on snow and ice, it reduces reflectivity and increases melt rates.

Black carbon is a major component of fine particulate matter air pollution (PM2.5), which has been linked to a raft of negative health outcomes, including premature death in adults with heart and lung disease, strokes, heart attacks, chronic respiratory diseases such as bronchitis, aggravated asthma and other cardio-respiratory symptoms.

Each year, around 48 million deaths globally are associated with long-term exposure to PM2.5. 

While untangling how many deaths are directly attributable to black carbon is tricky, there is growing evidence of its specific health impacts.

Studies have shown that exposure to black carbon correlates with high blood-pressure levels more strongly than PM2.5 overall. Exposure to the pollutant in pregnancy has also been found to impact the development and health of newborn children and is associated with reduced birthweight.

An integrated approach to climate and health

There has been growing political momentum around the threat of super pollutants.

One clear example of this is  the Global Methane Pledge, an initiative launched at the COP26 climate summit in Glasgow in 2021. The pledge, which has been backed by 158 countries and the European Union, commits governments to collectively reduce global human-caused methane emissions by at least 30% below 2020 levels by 2030. 

However, methane emissions are going in the wrong direction. Emissions are currently on track to increase by 5-13% above 2020 levels by 2030, according to a 2022 analysis from the Climate and Clean Air Coalition and United Nations Environment Programme.

Building awareness of the health consequences of climate change can encourage policymakers to set ambitious limits on super pollutant emissions. It can also underline the importance of a joined-up policy approach to climate and health, where emissions reduction pledges can help spur policies that improve lives.

The Global Methane Pledge and the Kigali Amendment – an international agreement to reduce the production and use of hydrofluorocarbons – are just two pledges that could have immediate and dramatic effects on public health, if fully implemented. 

Cutting emissions of super pollutants is one of the most effective ways to “keep 1.5C alive” in the near-term, while protecting health and avoiding tipping points that could cause irreversible shifts in the Earth system. 

Combined with the health benefits, rapidly reducing emissions of these pollutants is a clear win-win for people and the planet.

The post Guest post: How ‘super pollutants’ harm human health and worsen climate change appeared first on Carbon Brief.

Guest post: How ‘super pollutants’ harm human health and worsen climate change

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Big fishing nations secure last-minute seat to write rules on deep sea conservation

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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

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    Climate at Davos: Energy security in the geopolitical driving seat 

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    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 

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      A Record Wildfire Season Inspires Wyoming to Prepare for an Increasingly Fiery Future

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      As the Cowboy State faces larger and costlier blazes, scientists warn that the flames could make many of its iconic landscapes unrecognizable within decades.

      In six generations, Jake Christian’s family had never seen a fire like the one that blazed toward his ranch near Buffalo, Wyoming, late in the summer of 2024. Its flames towered a dozen feet in the air, consuming grassland at a terrifying speed and jumping a four-lane highway on its race northward.

      A Record Wildfire Season Inspires Wyoming to Prepare for an Increasingly Fiery Future

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