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.
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 4–8 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
Electrification of transportation and the power grid all but require lithium to make batteries—but mining it takes a toll on delicate ecosystems. Still, there are reasons for hope.
From our collaborating partner Living on Earth, public radio’s environmental news magazine, an interview by Paloma Beltran with Thea Riofrancos, the author of “Extraction: The Frontiers of Green Capitalism.”
A new panel of experts, bringing together some of the world’s top climate scientists, has called on governments to develop roadmaps for phasing out fossil fuels “anchored in science and justice”.
Launched on Friday in Santa Marta, Colombia, along with a set of 12 initial policy recommendations, the panel’s appeal came ahead of a key ministerial meeting on equitable ways to reduce dependence on coal, oil and gas during next week’s “First Conference on Transitioning Away from Fossil Fuels”.
Sixty countries head to Santa Marta to cement coalition for fossil fuel transition
Presenting the panel’s recommendations in a packed Santa Marta Theatre, Johan Rockström, director of the Potsdam Institute for Climate Impact Research (PIK), said the push for a global transition away from fossil fuels offers “a light in the tunnel” during a “very dark moment” of geopolitical conflict and climate extremes.
“Science is here to serve,” Rockström said. “We’re today launching the Science Panel for the Global Energy Transition (SPGET) as a service, as a global common good for all countries, all sectors, all regions to connect to the best science enabling a transition away from fossil fuels.”
The panel is urging countries to create “whole-of-government” plans to “dismantle legal, financial and political barriers” to the energy transition. Its insights are intended to inform top officials from 57 governments who will gather in Santa Marta for high-level discussions on Tuesday and Wednesday.
Draft roadmap for Colombia
Colombian Environment Minister Irene Vélez Torres said the panel “addresses a longstanding shortcoming” in international climate science, by creating a scientific body dedicated solely to overcoming the world’s reliance on fossil fuels.
“It’s a first-of-its-kind, designed to organise in the next five years the scientific evidence that allows cities, regions, countries and coalitions to take the big leap,” Vélez told the event in Santa Marta.
As an example of how countries can move forward – even when their economies are closely tied to the production and use of dirty energy – a group of European scientists presented a draft roadmap to phase out fossil fuels in Colombia, with inputs from the Colombian government. It will be used as a basis for further consultation in the Latin American nation to define the way forward.
To phase out fossil fuels, developing countries need exit route from “debt trap”
Piers Forster, director of the Priestley Centre for Climate Futures at the University of Leeds and co‑author of the roadmap, said it shows “a clear pathway to economic and societal benefit”, with average annual investment of $10.6 billion producing net economic benefits of $23 billion per year by 2050.
The document says fossil fuels in Colombia can be phased out through energy efficiency measures, coupling renewable generation with energy storage, and switching to electrified transport. But, it adds, the government will need to plan for reduced revenue from fossil fuel exports, which roughly half by the mid-2030s.
“What matters now is moving beyond headline targets to create credible, policy-relevant roadmaps, enabling a just and effective transition,” Forster said in a statement. Brazil is also working on a national roadmap for its own economy, as well as leading a voluntary process to produce a global roadmap.
IPCC hobbled by politics
Currently, the world’s top climate science body – the Intergovernmental Panel on Climate Change (IPCC) – requires countries to sign off on each “summary for policymakers” of its flagship science reports. This has led to a politically fraught process that has increasingly seen some oil-producing governments making efforts to weaken its recommendations.
In a bid to focus scientific debates on the phase-out of fossil fuels, the new SPGET was created based on a mandate from last year’s COP30. It is also meant to come up with scientific recommendations at a faster pace than the IPCC’s seven-year cycle.
Natalie Jones, senior policy advisor at the International Institute of Sustainable Development (IISD), called the new scientific panel “historic”, as it will be “more specific, more targeted and potentially more agile” with its advice on phasing out coal, oil and gas than the IPCC’s exhaustive scientific synthesis reports.
Why the transition beyond fossil fuels depends on cities and collective action
One of the SPGET members, Peter Newell of the UK’s University of Sussex, said “there are many different challenges along the way – and not all of them have to do with lack of evidence”, but the phasing out of fossil fuels “is one part of the story and it’s important to address it”.
The panel will be co-chaired by Cameroonian economist Vera Songwe, PIK’s chief economist Ottmar Edenhofer and Gilberto M. Jannuzzi, professor of energy systems at Brazil’s Universidade Estadual de Campinas. It will be composed of between 50 and 100 scientists divided into four working groups: transition pathways, technological solutions, policies and finance.
Under the 12 insights for the Santa Marta process, the panel recommended banning new fossil fuel infrastructure, mandating “deep cuts” in methane emissions, implementing carbon levies on imports, and de-risking clean energy investments via interventions from central banks, among others.
The post New panel of climate scientists calls for fossil fuel transition roadmaps appeared first on Climate Home News.
New panel of climate scientists calls for fossil fuel transition roadmaps
Despite not yet paying out any money, a UN-backed fund meant to address the loss and damage caused to developing countries by climate change could face “liquidity issues” by the end of next year, its head warned today.
With ten projects already requesting $166 million in total, the fund’s Executive Director Ibrahima Cheikh Diong warned a board meeting in Zambia that the fund was likely to be “oversubscribed” and should anticipate cashflow problems.
A framing paper prepared by the fund’s secretariat similarly warns that “given the current status of the capitalization of the Fund, there is a risk of the Fund exhausting its capital by the end of 2027, which could result in a loss of operational momentum and expose the FRLD to reputational risk”.
Since governments agreed to set up the fund at UN climate talks in Egypt in 2022, wealthy nations have promised $822 million, but delivered just $449 million.
The fund is expected to approve its first projects at its next board meeting in July. Early proposals submitted include strengthening responses to floods in Bangladesh and the Nigerian city of Lagos, and improving water infrastructure in Jamaica following Hurricane Melissa last year.
Millions not billions
ActionAid Zambia climate justice coordinator Michael Mwansa told the board meeting that he was concerned about “the failure of the Global North governments to deliver on their climate finance obligations, making it largely impossible to scale up [the fund’s initial stage] significantly, if at all”.
“Pledges remain nowhere near the billions and even the trillions needed to address loss and damage to the Global South”, Mwansa added, highlighting reports which found that financing loss and damage could cost developing countries up to $400 billion a year.
The fund’s board discussed its strategy for raising more money at its meeting this week while climate campaigners called, in an open letter, for it to aim to secure $50 billion a year from developed countries starting next year, rising to $100 billion a year by 2031 and $400 billion by 2035.
The World Bank-hosted fund aims to have revenue-raising rounds known as replenishments every four years, with the first in 2027.
Governments have agreed to “urge” developed countries to contribute but only to “encourage” other nations to do so and the fund’s secretariat wants to appoint a “high-level champion” to lead the replenishment team.
The fundraising strategy will be discussed further at the next board meeting in the Philipines in June.
Campaigners’ open letter calls for developed countries to contribute more and for them to introduce taxes on fossil fuel companies, financial transactions, luxury air travel and wealth to raise money for the fund.
“Rich countries must be held strictly accountable for the devastation they have caused,” said Climate Action Network International head Tasneem Essop. “Their failure to fulfil their responsibility to the Loss and Damage Fund is not just an oversight; it is a shameful betrayal of humanity.”
The post New loss and damage fund could run out of money next year appeared first on Climate Home News.
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