Breathless: The Toll of Fossil Fuels and a Changing Planet
The 2025 Lancet Report on Health and Climate Change and the recent Cradle to Grave Report spell out the tremendous harm and suffering caused by fossil fuel burning and resulting climate changes.
Human emissions of greenhouse gases and other pollutants through the burning of fossil fuels and irresponsible land use change is increasingly claiming lives and harming people’s health worldwide. Mean annual temperatures not only exceeded 1.5°C above pre-industrial in 2024, the average for the last 36 months was also above 1.5° and its looking increasingly likely that 2025 will be the second warmest year on record after the extraordinary 2024. We are on course to pass 2°C of warming by the late 2030s.
This recent acceleration in warming coupled with ever increasing rates of emissions are destabilising the planetary systems and environmental conditions on which human life depends. There is now good evidence that natural carbon sinks, that absorb about half of our emissions, are starting to fail, creating a very poor prognosis for the near future.
The Lancet Countdown on Health and Climate Change1 is authored by 128 worldwide multidisciplinary experts and is the most comprehensive assessment of the current and near future health implications of climate change. It’s not a cheerful read as many indicators set new disturbing records at a time when progress is being reversed in key areas. There are however important opportunities to step up and prevent some of the catastrophic impacts which appear on our current trajectory.
Health hazards, exposure and impacts
From a human health perspective, the changing climate is exposing people to increasing hazards across the globe. The four main hazard groups are exposure to heatwaves, extreme weather related events including their long lasting health implications, expanding climatic suitability for infectious disease transmission and food insecurity and undernutrition. All have individual health, societal and economic implications in addition to putting increasing strain on healthcare systems.
Heatwaves
Globally, the average person now experiences 19 heatwave days per year. Of these, 84% (16 days) would not have happened without climate change, resulting in people being exposed to 530% more heatwave days than would have been expected without climate change. This increased exposure obviously puts pressure on the very young and old, but also affects people’s ability to work outside or even exercise safely. Heat exposure during pregnancy also increases the risk of adverse birth outcomes.
Even light activity such as walking promotes good health and reduces risks of chronic disease, cancer and obesity. In 2024 each person globally was exposed to a record 1,609 hours during which they would have been at least at moderate heat stress risk during light outdoor activity. This figure is 36% higher than the 1990-99 average.
Heat exposure endangers worker’s health, particularly working outside or performing strenuous activity. A record-high 640 billion potential work hours were lost in 2024, a 98% increase compared with the 1990–99 annual average. This not only reduces productivity, but impacts income and livelihoods which further undermines social determinants of healthcare availability. 1.5 billion people earn a living working outdoors, over 25% of the working-age population. Of the working hours lost, 64% were agricultural, 18% construction and 10% service industries.
Night-time temperatures are rising faster than daytime temperatures in many regions, intensifying overnight heat stress and challenging nocturnal recovery. Elevated night-time temperatures can disrupt sleep health and are associated with altered sleep timing, quality, and quantity, as well as adverse downstream mental and physical health outcomes that are separately sensitive to sleep, including cognitive function and cardiovascular disease. Annual sleep loss attributable to suboptimal night-time temperatures rose by an average of 6% in 2020–24 compared with 1986–2005.
Heat related mortality is rising fast. It is not yet as high as cold related mortality. Climate deniers or at least those that discount it’s threat love this statistic. In a recent column by George Mombiot in the Guardian2 though, he looks into this statistic and finds that the data is far from complete, in fact it has gaping holes in it. Data of heat deaths is extremely patchy, for example the study people refer to doesn’t have any data from India, Pakistan, Bangladesh, Afghanistan, the Gulf states (except Kuwait), Indonesia or Melanesia. Only South Africa has data from that entire continent. In other words, most of the world’s hottest and most humid countries are not represented. Even when data is collected, heat deaths are often categorised as heart attacks, liver failure or some other condition.
Heat related deaths will overtake cold deaths in most regions without serious climate mitigation and adaptation measures.
Heat mortality is driven by a combination of heat and humidity. The wet bulb temperature is the important factor. At high humidity, even at 30°C sweat does not evaporate and therefore can’t cool the body. This leads to heat exhaustion, organ failure and death even in young fit adults. Hot humid countries are therefore at much more risk than dry desert environments, even though the latter are often hotter.
In 2012–21 (the latest - incomplete - data available), global heat-related mortality reached an estimated average 546,000 deaths annually, a 63% increase compared with 1990–99. Given the unprecedented jump in global temperatures since 2021, the latest figures are likely much higher still. Between 14 and 19 June 2024, at least 1,300 people on the Hajj pilgrimage in Mecca died due to extreme heat, with temperatures exceeding 50°C.
A new paper by Christopher Callahan et al.3 projected that heat extremes experienced in a +3°C climate could lead to 33,000 heatwave deaths a week in Europe alone. This would rival the peak death rates of the Covid pandemic. Projections based on current trajectories could see 3°C reached by 2050-60. Mass mortality events, such as last year’s Hajj tragedy, will become more common and on larger scales from now on.
Other analysis of social media posts during heatwaves show a 33% worsening of sentiment during the events compared to non-heat stressed days in the same location and season. This can contribute both directly and indirectly to subclinical psychosocial stress, and elevate clinical risks of anxiety, depression, mood, and substance use disorders, as well as self-injury and suicide.
Extreme weather events
Extreme weather events such as floods and storms in 2024 affected at least 166 million people and directly killed 16,000. Over 800,000 people were displaced exacerbating food insecurity and access to medical facilities.
Attribution studies which provide insights into the increased severity and likelihood of extreme events due to climate change show that most of the 2024 events were contributed to by climate change, including 3,700 additional deaths. Carbon Brief compiled a searchable list from the last few decades.4
Changes in weather patterns through climate change, including increased heat and drought have increased ‘fire weather’ conditions around the globe. An increase of 6.6% in 2020-24 compared to 2003-12. Direct fire deaths are dropping thanks to improved prediction and management, but exposure to wildfire derived PM2.5 air pollution is going up. Deaths reached a record-high 154,000 in 2024, up by 36% from the 2003–12 average.
Droughts threaten food productivity and nutritional outcomes, compromise water security and sanitation, and increase the risk of waterborne infectious diseases. They also affect air quality by increasing dust exposure and favouring wildfire occurrence, as well as affecting wellbeing and livelihoods by disrupting power generation and compromising river transportation. The percentage of the global land area affected by at least 1 month of extreme drought reached a record-breaking 60.7% in 2024, 299% above the 1951–60 average.
Weather whiplash is increasing meaning that in addition to extreme drought, when it does rain, the rainfall is more intense, frequent and more likely to cause flooding. The number of extreme rainfall events has increased by 35% globally with 64% of the global land area showing an increase in extreme precipitation frequency during 2015–24, the highest share observed in the indicator’s 30-year record. Flooded areas increase the risk of further health risks such as cholera and typhoid as well as providing opportunities for mosquito infestations.
Tropical storms such as hurricanes and typhoons are also getting stronger as the planet warms. Harm multiplies with windspeed so the increased energisation of these storms, through rising sea surface temperatures, allows them to intensify far faster and to a greater extent than was possible in the past. Hurricane Mellisa which recently devastated Jamaica is a tragic example of this. The elevated sea surface temperature that powered Mellissa were made 300x more likely due to climate change.
The extreme events themselves are the tip of the iceberg in terms of the longterm heath impacts they deliver. In a study published last year of 85 years of US tropical cyclones, Rachel Young and Solomon Hsiang5 found that excess mortality persisted for 15 years after the event with each typical storm resulting in 7,000-11,000 additional deaths compared to the average 24 deaths during the events themselves. Physical and mental stress, damaged or stretched healthcare systems, poorer living conditions and even late diagnosis of chronic disease all contribute.
Infectious disease transmission
Changing environmental conditions are affecting the transmission of vector borne, waterborne, food borne, airborne, and soil borne diseases. Cases and fatalities from dengue, malaria, West Nile virus, Leishmaniasis, vibrio and tick-bourn diseases have all increased in recent years. This year mosquitos were even recorded in Iceland for the first time!
Approximately 7.6 million cases of dengue fever were reported to the WHO between January and April, 2024, a three-fold increase compared with the same period in 2023, resulting in over 16,000 severe cases and more than 3,000 fatalities.
Malaria claims over 500,000 lives annually, children and pregnant women being disproportionately affected. The range and seasonality of malaria transmission are influenced by temperature, rainfall, and humidity, which are all affected by climate change. Tropical regions are showing decreases of the length of season, but temperate regions and highland areas are showing pronounced increases of up to 14% in the last decade.
West Nile virus is a zoonotic pathogen transmitted by Culex mosquitoes, causing potentially fatal neurological disease in humans. The virus is found worldwide and the transmission range is expanding as local temperatures increase.
Leishmaniases are potentially fatal diseases caused by Leishmania parasites and transmitted by sand flies. Endemic in 99 countries or territories, they disproportionately affect the most underserved populations, with an estimated 700,000 to 1 million new cases every year, causing 20,000-40,000 deaths. Climate change driven rises in temperature and humidity affect sand fly activity, metabolism, and development, increasing the length of the vector’s infectious period and therefore infection risk. Globally, the predicted leishmaniasis risk for 2015–24 increased by 30% compared with 1951–60.
Pathogenic Vibrio bacteria are transmitted through contact with marine waters or contaminated seafood, potentially causing severe skin, ear, and gastrointestinal infections and life-threatening sepsis. As climate change increases the temperature, and in some regions reduces the salinity of coastal waters, the potential for Vibrio transmission increases. A record high 91,195 km of coastline waters had environmental conditions suitable for Vibrio transmission in 2024—a 3.2% increase from the previous record in 2023 and a 36% increase above the 1990-99 average. Vibriosis cases also hit a record-high in 2024, with an estimated 723,000 cases globally.
Ticks are the second most important arthropod vector of infectious disease transmission, after mosquitoes. Their potential to transmit disease, shaped by their feeding behaviour and environmental distribution, can be influenced by climate change. Compared with 1951–60, the area climatically suitable for R sanguineus and Hyalomma ticks in 2015–24 had expanded by 6.9% and 3.2%, respectively, putting an additional 364 million people at risk.
Food, undernutrition and unhealthy diets
Between 640 and 720 million people were undernourished in 2024, and 2.6 billion people (about a third of the world population) were unable to afford a healthy diet in 2022. Numerous factors potentially contribute to this food security crisis, including increasing temperature and precipitation extremes, which can reduce crop yields and farm worker labour capacity, jeopardise access to water and sanitation, and disrupt supply chains. Climate change induced coastal sea surface temperature elevation, reduced oxygenation, ocean acidification, and coral reef bleaching are compromising marine resources. Increased food insecurity increases the risk of all forms of malnutrition, which harms both health and economic development.
Analysis of the drought and heat conditions during growing months for global staple foods together with marine conditions for fisheries concludes that 123.7 million more people experiencing moderate or severe food insecurity in 2023.
The increase in carbon intensive unhealthy diets is also a major health issue. Global agricultural greenhouse gas emissions increased by 36% from 2000 to 2022, with red meat and dairy responsible for 55% of agricultural emissions in 2022.
Mortality related to high-carbon, unhealthy diets increased from 148 per 100,000 people to 150 per 100,000 people between 2021 and 2022, resulting in 11.8 million largely preventable deaths, including 1.9 million deaths from excessive red meat and dairy intake.
Fossil fuel use
All of the above impacts, killing people by the hundreds of thousands and negatively affecting the health of hundreds of millions, are as a direct result of climate changes brought about by our burning of fossil fuels. But the damage doesn’t stop there.
2.5 million deaths were caused in 2022 due to air pollution from the burning of fossil fuels. This figure is actually down from from 2.7 million in 2010, not from any reduction in fossil fuel burning and associated CO2 emissions, but through more stringent air pollution measures. However total deaths through human caused air pollution increased to 8.5 million in 2022 from 7.5 million in 2010.
Just let those numbers sink in. 1 in 8 deaths last year were as a result of high PM2.5 air pollution from human emissions, with a third of them from burning fossil fuels. And people say nuclear energy is dangerous!
A few years ago I was given the opportunity to be in an operating theatre during a heart bypass operation at St Mary’s Hospital in London. The patient was a middle aged woman. When the chest cavity was exposed I was surprised that her lungs looked grey and covered with dark spots. I asked the surgeon, a friend and colleague at the time, if she was a smoker. “No”, he replied, “just a Londoner who uses the underground.”
The Cradle to Grave report6 published this year dives into more details about the extent of fossil fuel pollution from every stage of the process from extraction to final use and its detrimental impacts on human health. Here is an excerpt:
Fossil fuel related pollution exposure has been linked to increased risk of low birth weight, childhood cancer, asthma, neurological disorders, cardiovascular disease, and premature death. For instance, during the prenatal period, when vital organs are forming, exposure to pollutants from coal, oil, and gas extraction and combustion is linked to low birth weight, preterm birth, miscarriage, and a range of congenital abnormalities. Many of these health harms are permanent, impairing the child throughout their lifetime. Children are also particularly vulnerable due to their faster breathing rates, narrower airways, and developing organs. Fossil fuel pollutants are linked to a wide range of health harms across multiple body systems. They impair lung function and exacerbate asthma and other respiratory diseases; increase the risk of cardiovascular disease and hospitalisations; disrupt cognitive function and mental health through impacts on the brain and nervous system; elevate the risk of cancers such as leukaemia; cause reproductive damage; and contribute to premature mortality. Older adults face unique vulnerabilities due to declining organ function, pre-existing chronic diseases, and cumulative exposure.
In addition:
The health impacts of fossil fuels are persistent and systemic.
Fossil fuel health harms are unevenly and unjustly distributed in communities and across nations.
Fossil fuels drive wider societal health impacts and exacerbate other pre-existing health disparities in communities and between nations.
Climate policy and health policies have largely ignored these multidimensional health harms of fossil fuels.
The cost of inaction is rising by the day.
The costs of inaction
Obviously the use of fossil fuels has been tremendously advantageous over the last two centuries. It has powered the development of our civilisation and lifted huge numbers out of poverty. A single barrel of oil is capable of providing the equivalent of 4.5 years of human powered effort. We currently burn enough oil to provide the equivalent work of 500 billion human workers.7
We now understand the costs though and fortunately we have viable alternatives. The Stone Age did not end for a lack of stones, we can stop looking for more fossil reserves, leave what’s left in the ground and forge a better, healthier and safer future if we choose to do so.
The dithering, backsliding, fawning to vested interests, even election of bought and paid for politicians has caused the deaths of hundreds of millions of people since it was known that fossil fuel use is harmful. The fossil fuel lobby has successfully prevented the actions demanded under the Paris Agreement and continues to hamper efforts today, arguably even more successfully with the recent failure of COP30 to produce any meaningful progress on phasing out their deadly products.
Today with reduced pressure from powerful political leaders, fossil fuel giants have paused, delayed, or retracted their climate commitments, increasingly pushing the world towards an even more dangerous future. Emissions continue to climb while all the indicators of global warming and climate change are accelerating.
A rapid and just transition away from fossil fuels and to clean, renewable energy, is imperative for health. Solar is now the cheapest energy source in history but still fossil investments flow in. Private banks support this, lending $611 billion in 2024 to the sector, 15% more than clean energy investments.
This failure to transition away from fossil fuels has also come at a major financial cost. Fossil fuel powered economies are very sensitive to shocks. In response to the fossil fuel price spike that followed Russia’s invasion of Ukraine, most countries, still heavily reliant on this source of energy, resorted to subsidies to keep energy affordable and prevent a spike in energy poverty. As a result, 73 (84%) of the 87 countries reviewed (accounting for 93% of global greenhouse gas emissions) provided net explicit fossil fuel subsidies in 2023, allocating a net total of $956 billion to this purpose. Of these, 15 countries allocated more funds to net fossil fuel subsidies than to national health budgets, reflecting the opportunity cost of fossil fuel dependence. The fiscal pressures from the local reliance on fossil fuel subsidies can be eliminated by transitioning away from fossil fuels, making funds available to support activities that benefit, rather than harm, human health.
In the UK, the National Health Service is viewed as the jewel in the crown of society. It is always seen as the most important debating point at elections. Most people (admittedly not myself) put it as the number one most important thing to worry about. Most people unfortunately don’t relate the importance of climate change and our dependance on fossil fuels to the additional strain caused to their cherished NHS. Perhaps if they did, better policies would be forthcoming that would cut subsidies and further fund health.
Signs of hope
There are however some glimpses of light at the end of this dark and deadly tunnel. The growth of the clean energy sector is underway. It’s fair to say the massive expansion of renewable energy is yet to displace legacy fossil energy, but it’s a start and the economics greatly favour continued adoption and expansion. A growing number of countries and economies are decoupling emissions from growth. Just how much longer can the world afford to subsidise fossil fuels by $7 trillion a year (IMF estimate8)? That figure does not include immunity for the millions of deaths the industry causes each year.
China is showing a plateau in emissions for the first time and has set a reduction target by 2035 of 7-10%. China, unlike most other countries delivered on its plans, so I would not bet against this happening. Electric vehicle adoption is accelerating globally and is now believed to be unstoppable as battery prices drop continually. Solar is now the cheapest energy source in history and wind power is also dropping in price and increasing in capacity.
In the UK the clean growth sector is growing 3 times faster and providing more new and better paid jobs than the rest of the economy.
The healthcare sector, a key protector of people’s health and survival, is increasingly rising to the challenge. Healthcare related greenhouse gas emissions fell by 12% between 2021 and 2022.
The evidence in this Lancet report, and the others I’ve referenced reveals priorities and opportunities to deliver these actions and realise transformational public health gains.
With the threats to people’s lives and health growing, delivering a health protective, equitable, and just transition requires all hands on deck. There is no time left for further delay.
If you’re interested in what you could do to improve your health and everyone else’s, here are some suggestions:
Move your bank accounts, pensions and investments away from institutions and funds that invest in fossil fuels
Stop flying
Use public transport
Use active transport - walk or use an e-bike
Eat less red meat and diary
Next time you replace your car, get an EV - they are actually better
Next time you replace your cooking hob get an induction hob - they are just better too
Next time you replace your fossil boiler replace it with a heat pump
If you can, install solar panels and a battery
Switch to a green energy tariff if you can, and if possible one that aggregates you into a Smart Grid.
Vote for people who understand and respect science and are not in the pockets of the fossil fuel lobby or other vested interests
Spread the word
Romanello, Marina et al. The 2025 report of the Lancet Countdown on health and climate change https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(25)01919-1/fulltext
George Monbiot There’s a catastrophic black hole in our climate data – and it’s a gift to deniers, The Guardian 2025 https://www.theguardian.com/commentisfree/2025/nov/21/black-hole-in-climate-data-climate-sceptics-extreme-heat
Callahan, C.W., Trok, J., Wilson, A.J. et al. Increasing risk of mass human heat mortality if historical weather patterns recur. Nat. Clim. Chang. (2025). https://doi.org/10.1038/s41558-025-02480-1
Carbon Brief Mapped: How climate change affects extreme weather around the world, 2024 https://interactive.carbonbrief.org/attribution-studies/index.html
Young, R., Hsiang, S. Mortality caused by tropical cyclones in the United States. Nature 635, 121–128 (2024). https://doi.org/10.1038/s41586-024-07945-5
Cradle to Grave - The health toll of Fossil Fuels and the Imperative for a jJust Transition 2nd Edition 2025, https://climateandhealthalliance.org/cradle-to-grave-the-health-toll-of-fossil-fuels-and-the-imperative-for-a-just-transition-2nd-edition/
N.J. Hagens, Economics for the future – Beyond the superorganism, Ecological Economics, Volume 169, 2020, 106520, ISSN 0921-8009, https://doi.org/10.1016/j.ecolecon.2019.106520.