As COP30 approaches, new findings from The Lancet Countdown 2025 and Nature expose how fossil fuel pollution is driving millions of premature deaths and intensifying global heatwaves. The reports strengthen calls for corporate accountability, fossil fuel phase-out, and urgent investment in climate-resilient health systems to safeguard lives worldwide.

A new Lancet Countdown report delivers a stark warning: fossil fuel pollution is already killing millions. The analysis finds that in 2022 some 2.52 million deaths worldwide were linked to ambient air pollution from burning coal, oil and gas. Much of this toll comes from particulate matter (PM₂.₅) emitted by power plants, vehicles and industry. The report also documents a dramatic rise in extreme-heat mortality. Heat-related deaths averaged about 546,000 per year in 2012–2021 — a 63% increase over the 1990s baseline. The report warns that if current trends continue, deaths from extreme heat will soon surpass those from cold spells.

Although cold spells still account for more fatalities, the gap is closing quickly; the Lancet warns that without urgent action, heat deaths will soon overtake cold as the leading climate-related killer. The economic and social costs mirror the human toll. Record 2024 heat led to an estimated 639 billion work-hours lost globally – 98% higher than in 1990–99 – worth about $1.09 trillion, nearly 1% of world GDP. Meanwhile climate disasters added another $304 billion in damages that same year, a 59% increase over the early 2010s.

With only about half of such losses insured, the burden is falling heavily on public services and hospitals already stretched thin. As the Lancet notes, “every heatwave, drought, and flood not only costs lives but drains the very systems meant to protect them.”

The Heatwave Fingerprints of Big Oil

A September 2024 study in Nature now provides clear scientific evidence linking the world’s largest fossil fuel producers to deadly heatwaves. Researchers analyzed 213 major heatwaves between 2000 and 2023 and found that every one of them had been made “more intense and more probable” by human-induced climate change.

Crucially, about half of that added intensity can be traced directly to emissions from 180 major oil, gas, and coal companies, collectively known as the carbon majors.

According to the study, each carbon major has contributed significantly to the worsening of global heatwaves. For instance, Saudi Aramco’s emissions alone made about 51 heatwaves possible that would otherwise have been “virtually impossible” in a pre-industrial climate — with ExxonMobil responsible for a similar number. 

“This allows us to say, with scientific confidence, who did what,” said climate scientist Professor Sonia Seneviratne, describing the study as a breakthrough for climate accountability. The authors call it a critical step toward closing the “evidentiary gap” that has long shielded major emitters from liability.

Globally, this extra heat is already deadly: climate-driven heat is thought to cause on the order of 500,000 deaths per year. By implication, a substantial share of these fatalities can be traced back to corporate emissions. The authors emphasize that their framework closes an “evidentiary gap” to hold polluters responsible for specific extreme events. Indeed, judicial bodies are taking notice. In 2024 the International Court of Justice signaled that states could be ordered to compensate for climate damages, and a German court already affirmed that fossil companies may be held liable for the harms their products cause. 

Legal experts believe this research could bolster ongoing and future lawsuits. The International Court of Justice is already exploring whether countries and corporations could be compelled to compensate victims of climate damage, and courts in Germany and the Philippines have affirmed that fossil fuel companies may be held accountable for climate-related harms.

India and the UK on the Frontlines

Both India and the United Kingdom feature prominently in the new data — two countries vastly different in economy but similarly exposed to the fallout from fossil fuels and heatwaves.

In India, for example, the Lancet report’s data platform shows people experienced about 20 life-threatening heatwave days on average in 2024, of which roughly 6.5 days would not have occurred without human-driven warming. In a country of 1.4 billion, that translates into millions facing sustained, deadly heat exposure. The toll on livelihoods in India is staggering: 2024 heat burned through roughly 247 billion work-hours nationwide  equivalent to 420 hours per person due to heat exposure — the highest recorded loss in the world. At the same time, air pollution continues to claim lives. Fossil fuel emissions accounted for an estimated 394,000 deaths from coal and 269,000 from petrol in India in 2022. The convergence of deadly heat and polluted air is putting an immense strain on the country’s healthcare system and economy.

The United Kingdom, often seen as a climate leader for cutting its emissions by half since 1990, has not been spared either. Summers from 2022 to 2024 saw unprecedented temperatures above 40°C and wildfires that scorched parts of southern England. Yet, in 2023, the UK government spent nearly $28 billion subsidizing fossil fuels, which is more than some nations’ entire health budgets.

This contradiction — cutting emissions on paper while continuing to fund fossil fuel industries — has drawn sharp criticism. As the Lancet notes, “vulnerable populations face the greatest health risks, while the most powerful interests continue to profit.” Hospitals and local health services are already shouldering rising costs from heatwaves and floods, with uninsured climate damages increasingly being absorbed by public health budgets.

Who Pays for the Climate Crisis?

The new findings from Nature add urgency to the question of accountability. If scientists can now link deadly heatwaves to emissions from specific companies, then the path to legal and financial responsibility becomes clearer.

Climate advocates argue that major fossil fuel producers should contribute directly to global adaptation and loss-and-damage funds, especially as low-income nations bear the brunt of the crisis. The data also challenge the traditional framing of climate change as a collective problem, instead identifying it as one driven by identifiable corporate actors.

However, the Nature study acknowledges that its global dataset underrepresents regions like Africa, Latin America, and South Asia, where climate impacts are severe but data collection is limited. Only nine of the 226 heatwaves studied occurred in these regions — even though they are among the most vulnerable. This suggests that the real human cost in the Global South is far higher than recorded.

COP30: A Turning Point for Climate and Health

As world leaders head to COP30 in Belém, Brazil, both the Lancet and Nature findings set a moral and scientific benchmark for climate negotiations. The evidence is no longer abstract — it now links fossil fuel emissions to specific deaths, disasters, and damages.

The Lancet report calls for an immediate phase-out of coal, oil, and gas, redirecting nearly $956 billion in global fossil fuel subsidies towards renewable energy, healthcare, and climate adaptation. It emphasizes that “every ton of CO₂ emitted today is a deferred health cost for tomorrow.”

At the same time, scientists behind the Nature study argue that their findings should inform legal and policy frameworks to ensure corporate accountability. With fossil fuel producers responsible for roughly half of the increase in heatwave intensity, the authors say, “those who contributed most to the crisis must contribute most to the solution.”

Public health experts agree that addressing the crisis demands both mitigation and adaptation. This means scaling up cooling centers, green infrastructure, early warning systems, and universal healthcare to safeguard communities against escalating heat. The Lancet also urges that these investments prioritize workers, children, and the elderly — those most at risk from extreme temperatures.

The combined message from both reports is clear: the world’s fossil fuel addiction is now a public health emergency. The deaths are not distant or hypothetical, in fact they are measurable, attributable, and avoidable.

As COP30 convenes, governments face a defining choice: continue subsidizing fossil fuels and count the mounting dead, or hold polluters accountable and invest in a livable, healthier future.

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