Study links world’s top oil and gas firms to 200 ‘more intense’ heatwaves
Original article by Ayesha Tandon republished from Carbon Brief under a CC license. A group of tourists huddled under a tree whilst visiting the Acropolis, Athens, Greece. Credit: Dimitris Aspiotis / Alamy Stock Photo Global warming linked to the world’s biggest oil and gas companies made all “major” 21st century heatwaves more intense and frequent. This is according to new research, published in Nature, which uses “extreme event attribution” to assess the impact of climate change on all 21st-century heatwaves that were classified as “major disasters”. The authors find one-quarter of the 213 heatwaves would have been “virtually impossible” without human-caused global warming. They add that the effect of climate change on heatwave frequency and intensity is becoming more pronounced as the planet warms. The study estimates the emissions stemming from the operations and production of more than 100 “carbon majors”, such as ExxonMobil, BP, Saudi Aramco and Shell. The fossil fuels produced by these companies account for 60% of all human-caused CO2 emissions over 1850-2023, the study says. The authors find that heatwaves recorded over 2000-23 were made, on average, 1.7C hotter due to climate change, with half of this increase due to the emissions originating from carbon majors. This study “could be used to support future climate lawsuits and aid diplomatic negotiation”, according to a scientist not involved in the research. Worsening heatwaves As the planet warms, heatwaves are becoming more intense and frequent, driving economic losses, ecosystem damage and a rise in heath-related deaths. The EM-DAT database catalogues all “major disasters” that have been reported since the year 1900 – defined as events that cause at least 10 fatalities, affect at least 100 people, or result in the declaration of state of emergency or a call for international assistance. Between 2000 and 2023, the database lists more than 200 heatwaves. These are shown on the map below, where darker pink indicates a greater number of heatwaves. Countries with no reported heatwaves are shown in grey. The map below shows the number of heatwaves per country recorded over 2000-23 on the EM-DAT database. Data: Quilcaille et al (2025). The study authors acknowledge that heatwave reporting is “highly uneven”, with only nine of the heatwaves reported in the database since the year 2000 in Africa, Latin America or the Caribbean. (This is largely because extreme heat events in these regions are not routinely monitored.) They then carried an attribution analysis on each heatwave to identify whether it was made more likely or intense due to human-caused climate change. The chart below shows how climate changes increased the intensity and frequency of the 78 heatwaves assessed over 2000-09 (left), 54 heatwaves assessed over 2010-19 (middle) and 81 heatwaves assessed over 2020-23 (right). The authors find that climate change increased the intensity and probability of all 213 heatwaves in the study. They add that the influence of climate change on heatwaves is strengthening over time. In each panel, the bars show the percentage of heatwaves in that time period that were made 0.25-1.0C (yellow), 1.0-2.0C (orange) or 2.0-3.0C (red) hotter due to climate…