Climate Shift Index alert: Spain, July 2023

Analysis: Climate change made this week’s heat in Spain at least 5x more likely.

New analysis by Climate Central indicates that human-induced climate change is making the current heatwave in the Iberian Peninsula – particularly in Spain – at least 5 times more likely, and potentially far more.

Using the Climate Shift Index (CSI), a peer-reviewed scientific methodology which quantifies the contribution of climate change to daily temperatures, the analysis shows that the unusually warm temperature stretching across parts of Spain and Portugal is an exceptional event. CSI levels of 5 indicate that climate change made those temperatures at least 5 times more likely. The methodology used to calculate the CSI is based on peer-reviewed science.

The heatwave comes after new research (published July 10 in the peer-reviewed journal Nature Medicine) found that more than 11,000 people died in Spain last summer as a result of high temperatures. Spain was the second-most affected country in terms of population, with 237 heat-related deaths per million, above the European average of an estimated 114 deaths per million.

Recent coverage of the Climate Shift Index includes the BBC, Guardian, Axios, USA Today, CNN, and Washington Post.

Recently, the CSI tool was used to quantify the contribution of climate change to the deadly heat in Mexico, the six-week heatwave across the US, the triple-digit Texas temperatures, and California’s extreme heat. The CSI tool quantifies how much climate change has changed the odds of daily temperatures that people experience. 

Dr. Andrew Pershing, VP of Science at Climate Central, said: 

“Spain and many places around the Mediterranean are experiencing more and more days of unusual heat. Human-caused climate change made this week’s heat much more likely.”

Friederike Otto, Senior Lecturer in Climate Science at the Grantham Institute for Climate Change and the Environment, and co-lead of World Weather Attribution said:

"Spain's current heatwave has been made hotter by climate change that is the result of human activities like burning coal and other fossil fuels. This is now the case for every heatwave, everywhere in the world. Until net greenhouse gas emissions end, heatwaves in Spain and elsewhere will continue to become hotter and more dangerous.

"Heatwaves are one of the biggest threats posed by climate change. High temperatures are responsible for thousands of deaths across the world every year, many of which go under-reported. Despite this overwhelming evidence, there is still little public awareness of the dangers that extreme temperatures present to human health."

July Heatwave: 

The current heatwave is forecast to last until Wednesday, July 12. According to Spain’s meteorological office, temperatures could reach 44°C in many parts of the Iberian Peninsula, including Granada, Teruel, Zaragoza, Albacete and Mallorca. These regions have been issued “extreme risk” heat warnings. 

The abnormally high temperature in Spain follows a week of record-breaking temperatures across the world. Last week saw the hottest day ever for four days in a row, with July on the way to becoming the hottest month in history:

“Chances are that July will be the warmest ever, and with it the hottest month ever: ‘ever’ meaning since the Eemian which is some 120,000 years ago,” said Karsten Haustein, climate scientist and meteorologist at Leipzig University.

Context: Climate Change and Heatwaves

Heatwaves have increased in frequency, duration and intensity in almost all regions of the world. Heatwaves that occurred once every 10 years in the pre-industrial climate are now expected once every 3.5 years due to global warming, according to the IPCC report, as noted in the World Weather Attribution media guide.

Exposure to unprecedented heat poses a major threat to people’s livelihoods, with implications for human health. 

Europe is one of the fastest-warming regions in the world (IPCC WG1). Heatwaves in Europe in 2003, 2010, 2015, 2017, 2018 and 2019 have all been specifically found to have been made more likely and intense because of climate change. In April 2023, a study by the World Weather Attribution group of climate scientists concluded that the early extreme heat occurring in Spain and Portugal was “almost impossible without climate change.”

Reporting Resources

• The influence of climate change on daily average temperatures across the globe is available on the global Climate Shift Index map.

• Explore quick facts and local analyses on the links between climate change and extreme heat in Climate Central’s Extreme Weather Toolkit: Extreme Heat, World Weather Attribution’s guide to reporting on extreme heat and climate change, and a summary of the connection between heatwaves and climate change from Yale Climate Connections.

About the Climate Shift Index ™

Climate Central’s Climate Shift Index ™, grounded in the latest peer-reviewed science, maps the influence of climate change on temperatures across the globe, every day. 

Climate Shift Index ™ levels indicate how much human-caused climate change has altered the frequency of daily temperatures at a particular location. Level 1 indicates that climate change is detectable in that day’s temperature. Level 2 means that climate change made exceptionally warm temperatures in a given location at least twice as likely. Level 5 is the maximum and indicates temperatures at least 5 times more likely because of climate change.

For this analysis, temperatures come from NOAA’s Global Forecast System model.

Previous Climate Shift Index alerts

June 29, 2023: Western U.S.
June 15, 2023: Southwest
May 11, 2023: Pacific Northwest