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
Drought and heatwaves occurring together – known as “compound” events – have “surged” across the world since the early 2000s, a new study shows.
Compound drought and heat events (CDHEs) can have devastating effects, creating the ideal conditions for intense wildfires, such as Australia’s “Black Summer” of 2019-20 where bushfires burned 24m hectares and killed 33 people.
The research, published in Science Advances, finds that the increase in CDHEs is predominantly being driven by events that start with a heatwave.
The global area affected by such “heatwave-led” compound events has more than doubled between 1980-2001 and 2002-23, the study says.
The rapid increase in these events over the last 23 years cannot be explained solely by global warming, the authors note.
Since the late 1990s, feedbacks between the land and the atmosphere have become stronger, making heatwaves more likely to trigger drought conditions, they explain.
One of the study authors tells Carbon Brief that societies must pay greater attention to compound events, which can “cause severe impacts on ecosystems, agriculture and society”.
Compound events
CDHEs are extreme weather events where drought and heatwave conditions occur simultaneously – or shortly after each other – in the same region.
These events are often triggered by large-scale weather patterns, such as “blocking” highs, which can produce “prolonged” hot and dry conditions, according to the study.
Prof Sang-Wook Yeh is one of the study authors and a professor at the Ewha Womans University in South Korea. He tells Carbon Brief:
“When heatwaves and droughts occur together, the two hazards reinforce each other through land-atmosphere interactions. This amplifies surface heating and soil moisture deficits, making compound events more intense and damaging than single hazards.”
CDHEs can begin with either a heatwave or a drought.
The sequence of these extremes is important, the study says, as they have different drivers and impacts.
For example, in a CDHE where the heatwave was the precursor, increased direct sunshine causes more moisture loss from soils and plants, leading to a drought.
Conversely, in an event where the drought was the precursor, the lack of soil moisture means that less of the sun’s energy goes into evaporation and more goes into warming the Earth’s surface. This produces favourable conditions for heatwaves.
The study shows that the majority of CDHEs globally start out as a drought.
In recent years, there has been increasing focus on these events due to the devastating impact they have on agriculture, ecosystems and public health.
In Russia in the summer of 2010, a compound drought-heatwave event – and the associated wildfires – caused the death of nearly 55,000 people, the study notes.
The record-breaking Pacific north-west “heat dome” in 2021 triggered extreme drought conditions that caused “significant declines” in wheat yields, as well as in barley, canola and fruit production in British Columbia and Alberta, Canada, says the study.
Increasing events
To assess how CDHEs are changing, the researchers use daily reanalysis data to identify droughts and heatwaves events. (Reanalysis data combines past observations with climate models to create a historical climate record.) Then, using an algorithm, they analyse how these events overlap in both time and space.
The study covers the period from 1980 to 2023 and the world’s land surface, excluding polar regions where CDHEs are rare.
The research finds that the area of land affected by CDHEs has “increased substantially” since the early 2000s.
Heatwave-led events have been the main contributor to this increase, the study says, with their spatial extent rising 110% between 1980-2001 and 2002-23, compared to a 59% increase for drought-led events.
The map below shows the global distribution of CDHEs over 1980-2023. The charts show the percentage of the land surface affected by a heatwave-led CDHE (red) or a drought-led CDHE (yellow) in a given year (left) and relative increase in each CDHE type (right).
The study finds that CDHEs have occurred most frequently in northern South America, the southern US, eastern Europe, central Africa and south Asia.
Threshold passed
The authors explain that the increase in heatwave-led CDHEs is related to rising global temperatures, but that this does not tell the whole story.
In the earlier 22-year period of 1980-2001, the study finds that the spatial extent of heatwave-led CDHEs rises by 1.6% per 1C of global temperature rise. For the more-recent period of 2022-23, this increases “nearly eightfold” to 13.1%.
The change suggests that the rapid increase in the heatwave-led CDHEs occurred after the global average temperature “surpasse[d] a certain temperature threshold”, the paper says.
This threshold is an absolute global average temperature of 14.3C, the authors estimate (based on an 11-year average), which the world passed around the year 2000.
Investigating the recent surge in heatwave-leading CDHEs further, the researchers find a “regime shift” in land-atmosphere dynamics “toward a persistently intensified state after the late 1990s”.
In other words, the way that drier soils drive higher surface temperatures, and vice versa, is becoming stronger, resulting in more heatwave-led compound events.
Daily data
The research has some advantages over other previous studies, Yeh says. For instance, the new work uses daily estimations of CDHEs, compared to monthly data used in past research. This is “important for capturing the detailed occurrence” of these events, says Yeh.
He adds that another advantage of their study is that it distinguishes the sequence of droughts and heatwaves, which allows them to “better understand the differences” in the characteristics of CDHEs.
Dr Meryem Tanarhte is a climate scientist at the University Hassan II in Morocco, and Dr Ruth Cerezo Mota is a climatologist and a researcher at the National Autonomous University of Mexico. Both scientists, who were not involved in the study, agree that the daily estimations give a clearer picture of how CDHEs are changing.
Cerezo-Mota adds that another major contribution of the study is its global focus. She tells Carbon Brief that in some regions, such as Mexico and Africa, there is a lack of studies on CDHEs:
“Not because the events do not occur, but perhaps because [these regions] do not have all the data or the expertise to do so.”
However, she notes that the reanalysis data used by the study does have limitations with how it represents rainfall in some parts of the world.
Compound impacts
The study notes that if CDHEs continue to intensify – particularly events where heatwaves are the precursors – they could drive declining crop productivity, increased wildfire frequency and severe public health crises.
These impacts could be “much more rapid and severe as global warming continues”, Yeh tells Carbon Brief.
Tanarhte notes that these events can be forecasted up to 10 days ahead in many regions. Furthermore, she says, the strongest impacts can be prevented “through preparedness and adaptation”, including through “water management for agriculture, heatwave mitigation measures and wildfire mitigation”.
The study recommends reassessing current risk management strategies for these compound events. It also suggests incorporating the sequences of drought and heatwaves into compound event analysis frameworks “to enhance climate risk management”.
Cerezo-Mota says that it is clear that the world needs to be prepared for the increased occurrence of these events. She tells Carbon Brief:
“These [risk assessments and strategies] need to be carried out at the local level to understand the complexities of each region.”
The post Heatwaves driving recent ‘surge’ in compound drought and heat extremes appeared first on Carbon Brief.
Heatwaves driving recent ‘surge’ in compound drought and heat extremes
Greenhouse Gases
DeBriefed 6 March 2026: Iran energy crisis | China climate plan | Bristol’s ‘pioneering’ wind turbine
Welcome to Carbon Brief’s DeBriefed.
An essential guide to the week’s key developments relating to climate change.
This week
Energy crisis
ENERGY SPIKE: US-Israeli attacks on Iran and subsequent counterattacks across the Middle East have sent energy prices “soaring”, according to Reuters. The newswire reported that the region “accounts for just under a third of global oil production and almost a fifth of gas”. The Guardian noted that shipping traffic through the strait of Hormuz, which normally ferries 20% of the world’s oil, “all but ground to a halt”. The Financial Times reported that attacks by Iran on Middle East energy facilities – notably in Qatar – triggered the “biggest rise in gas prices since Russia’s full-scale invasion of Ukraine”.
‘RISK’ AND ‘BENEFITS’: Bloomberg reported on increases in diesel prices in Europe and the US, speculating that rising fuel costs could be “a risk for president Donald Trump”. US gas producers are “poised to benefit from the big disruption in global supply”, according to CNBC. Indian government sources told the Economic Times that Russia is prepared to “fulfil India’s energy demands”. China Daily quoted experts who said “China’s energy security remains fundamentally unshaken”, thanks to “emergency stockpiles and a wide array of import channels”.
‘ESSENTIAL’ RENEWABLES: Energy analysts said governments should cut their fossil-fuel reliance by investing in renewables, “rather than just seeking non-Gulf oil and gas suppliers”, reported Climate Home News. This message was echoed by UK business secretary Peter Kyle, who said “doubling down on renewables” was “essential” amid “regional instability”, according to the Daily Telegraph.
China’s climate plan
PEAK COAL?: China has set out its next “five-year plan” at the annual “two sessions” meeting of the National People’s Congress, including its climate strategy out to 2030, according to the Hong Kong-based South China Morning Post. The plan called for China to cut its carbon emissions per unit of gross domestic product (GDP) by 17% from 2026 to 2030, which “may allow for continued increase in emissions given the rate of GDP growth”, reported Reuters. The newswire added that the plan also had targets to reach peak coal in the next five years and replace 30m tonnes per year of coal with renewables.
ACTIVE YET PRUDENT: Bloomberg described the new plan as “cautious”, stating that it “frustrat[es] hopes for tighter policy that would drive the nation to peak carbon emissions well before president Xi Jinping’s 2030 deadline”. Carbon Brief has just published an in-depth analysis of the plan. China Daily reported that the strategy “highlights measures to promote the climate targets of peaking carbon dioxide emissions before 2030”, which China said it would work towards “actively yet prudently”.
Around the world
- EU RULES: The European Commission has proposed new “made in Europe” rules to support domestic low-carbon industries, “against fierce competition from China”, reported Agence France-Presse. Carbon Brief examined what it means for climate efforts.
- RECORD HEAT: The US National Oceanic and Atmospheric Administration has said there is a 50-60% chance that the El Niño weather pattern could return this year, amplifying the effect of global warming and potentially driving temperatures to “record highs”, according to Euronews.
- FLAGSHIP FUND: The African Development Bank’s “flagship clean energy fund” plans to more than double its financing to $2.5bn for African renewables over the next two years, reported the Associated Press.
- NO WITHDRAWAL: Vanuatu has defied US efforts to force the Pacific-island nation to drop a UN draft resolution calling on the world to implement a landmark International Court of Justice (ICJ) ruling on climate, according to the Guardian.
98
The number of nations that submitted their national reports on tackling nature loss to the UN on time – just half of the 196 countries that are part of the UN biodiversity treaty – according to analysis by Carbon Brief.
Latest climate research
- Sea levels are already “much higher than assumed” in most assessments of the threat posed by sea-level rise, due to “inadequate” modelling assumptions | Nature
- Accelerating human-caused global warming could see the Paris Agreement’s 1.5C limit crossed before 2030 | Geophysical Research Letters covered by Carbon Brief
- Future “super El Niño events” could “significantly lower” solar power generation due to a reduction in solar irradiance in key regions, such as California and east China | Communications Earth & Environment
(For more, see Carbon Brief’s in-depth daily summaries of the top climate news stories on Monday, Tuesday, Wednesday, Thursday and Friday.)
Captured
UK greenhouse gas emissions in 2025 fell to 54% below 1990 levels, the baseline year for its legally binding climate goals, according to new Carbon Brief analysis. Over the same period, data from the World Bank shows that the UK’s economy ha