This year's historic heatwaves largely caused by 180 "carbon majors" - study

More than a quarter of over 200 heat waves recorded globally since 2000 were impossible without human-driven climate change, with emissions from the world’s largest fossil fuel and cement companies playing a significant role in intensifying the sweltering summers, a new study published in Nature found.

The research, led by scientists at ETH Zurich, is the first comprehensive assessment of the historical role that climate change has played in large-scale heat waves, Bloomberg reports.

The paper analysed 213 separate heatwaves between 2000 and 2023, concluding that emissions from 180 of the largest carbon emitters accounted for roughly half the increase in heat wave intensity since preindustrial times. Europe suffered from an unprecedented heatwave this summer that sent a reported 2,500 people to an early grave.

The increase in intensity has grown over time: the median intensity increase relative to 1850-1900 is about +1.4°C for heatwaves in 2000-2009, about +1.7°C in 2010-2019, and about +2.2°C in 2020-2023.

The increase in the probability of a heatwave occurring in a given year has also soared versus in the preindustrial era: during 2000-2009 heatwaves are ~20 times more likely, and for 2010-2019 the factor is ~200 times more likely.

As bne IntelliNews reported, just over 100 companies account for over half the emissions and Russia’s state-owned gas champion Gazprom along with the Kingdom of Saudi Arabia’s oil and gas giant Saudi Aramco are responsible for a fifth of the total, by themselves. Collectively, these companies are responsible for over $28 trillion worth of economic damage caused by extreme weather conditions.

The heatwave study identified the same usual suspects as responsible for the heatwaves. It named 14 companies, including US’ ExxonMobil, Saudi’s Aramco and Russia’s Gazprom, as leading contributors to more than 50 heat waves that would otherwise have been almost impossible to occur in a cooler, preindustrial climate.

The found that emissions from these “carbon majors” account for a large share of historical warming: in 2023, global mean surface temperature increase relative to 1850-1900 is estimated at about 1.30°C, of which 0.67°C is due to emissions from all 180 carbon majors; of that, 0.33°C comes from the 14 largest carbon majors alone.

In conclusion, the paper argues that some carbon majors have made heatwaves possible, where previously heatwaves were “impossible” under pre-industrial climatic conditions. For instance, emissions from the biggest emitters in the Former Soviet Union have made 53 of the 213 events at least 10,000 times more likely, the authors calculate.

While previous studies have focused on national and regional emissions, lead author Yann Quilcaille said this analysis marked a shift by focusing on individual corporate emitters. Quilcaille, a postdoctoral researcher at ETH Zurich, said this approach aims to address the evidentiary gap in a growing wave of climate litigation against major polluters.

The study is another brick in the wall being built to hold leading corporate emitters of GHGs responsible for their failure to cut emissions. The International Court of Justice (ICJ) ruled in July that a sustainable environment is a human right and that governments have a legal obligation to contain and reduce emissions. However, the world’s top court has no jurisdiction over government’s and its rulings are non-binding. Nevertheless, climate activists say the ruling sets a legal president and opens a path to holding large companies liable for the damage they cause by not limiting emissions.

The study comes amid a global increase in lawsuits seeking to hold corporations accountable for environmental damage. A related Nature study earlier this year estimated that Saudi Aramco and Gazprom each contributed to roughly $2tn of lost global economic output due to heat-related damages.

Karsten Haustein, a climate scientist at Leipzig University, said in an accompanying Nature essay that the findings are “another reminder that denial and anti-science rhetoric won’t make climate liability go away, nor will it reduce the ever-increasing risk to life from heat waves across our planet,” Bloomberg reported.

To estimate the effect of warming, the researchers used climate models to simulate how heatwaves would have unfolded without human emissions. The results showed a sharp increase in frequency and severity: heatwaves were 20 times more likely between 2000 and 2009 compared with the preindustrial era, and up to 200 times more likely between 2010 and 2019.

Greenhouse gas emissions continue to intensify extreme weather. In 2022, heat waves were linked to over 60,000 premature deaths across Europe, Bloomberg reports, and rising temperatures are behind the worst wildfires season ever seen this year that burnt over a million square kilometres of woodland.

And heatwaves during the annual disaster season are only going to get worse as temperatures continue to climb. The United Nations’ Intergovernmental Panel on Climate Change (IPCC) says that the goal of limiting temperatures to a 1.5C-2C increase above the pre-industrial baseline has already been missed and the world is on course for a 2.7C-3.1C increase in temperatures by 2050.