Severe Heat Waves in Europe and Africa Linked to Climate Change

Countries in South Western Europe, particularly Spain, Portugal, and Morocco, have experienced higher-than-normal temperatures this summer.

The World Weather Attribution reports that in April 2023, some areas in Spain and Portugal 2023 were 20°C warmer than average during this time of year. The national temperatures in Portugal and mainland Spain in April of 36.9°C and 38.8°C, respectively, have broken records by a “very large margin”. Some cities in Morocco have had temperatures above 41°C, record-breaking temperatures for the country.

Reuters reports that heatwaves and lack of rain in Spain, the largest olive oil producer at 40% of the world’s output, have reduced this year’s production in half. This could mean higher prices for the precious commodity.

“It’s a catastrophe,” said Primitivo Fernandez, head of Spain’s National Association of Edible Oil Bottlers, as he highlights the co-occurrence of the economic crises and the war in Ukraine, which has made matters worse when it comes to the olive oil prices.

The article says that in 2022, bottles of olive oil rose by around 60%. The price increase was initially caused by the scarcity of sunflower oil last year due to Russia’s invasion of Ukraine; however, inflation, high fertiliser costs, and drought have all pushed prices up.

Aside from high commodity prices, heatwaves in Spain also affect classrooms, especially those without air conditioning. CNN reports that schools in central and southern Spain are considering changing their classroom schedules – putting outdoor activities earlier in the day when it is more relaxed.

The World Weather Attribute report that the heatwave in 2022 has also contributed to nearly 4000 deaths and over 1000 deaths in Portugal. Each year, 100 to 260 people die from heat-related illnesses in Algeria, Morocco, and Tunisia. In Tunisia, a review between 2005 to 2007 shows that for every Celsius degree over 31.5°C, is a 2% increase in daily deaths.

Does climate change have anything to do with these extreme and record-breaking temperatures in Southwestern Europe and Northern Africa?

It is always in the aftermath of an extreme weather event that we hear questions about the role of climate change and how it can be attributed to the climate crisis. This is where the field of extreme event attribution comes in, and the field is witnessing the growth of new methods and approaches being developed. In the last few years, many attribution studies have been performed to answer the effect of climate change on recent extreme events.

The paper, A protocol for probabilistic extreme event attribution analyses,  details the protocol developed by the World Weather Attribution group in the last four years and the lessons learned from over 24 rapid and slow attribution studies covering warm, cold, wet, dry, and stormy extremes. The paper notes the protocol “starts from the choice of which events to analyse and proceeds with the event definition, observational analysis, model evaluation, multi-model multi-method attribution, hazard synthesis, vulnerability and exposure analysis and ends with the communication procedures.”

The World Weather Attribution also provides a summary of the scientific paper.

To answer the likelihood of climate change intensifying the 3-day heatwave that occurred on 26-28 of April 2023 in Southwestern parts of Europe and Northern Africa, scientists from Morocco, France, the Netherlands, the US and the United Kingdom collaborated to assess what extent human-induced climate change altered the likelihood and intensity of this early season heatwave. Below are the main findings of the study using the peer-reviewed methods:

• Heatwaves are among the deadliest natural hazards, with thousands dying yearly from heat-related causes. However, the full impact of a heatwave is often not known until weeks or months afterwards, once death certificates are collected, or scientists can analyse excess deaths. Many places lack good record keeping of heat-related deaths. Therefore currently available global mortality figures are likely an underestimate.
• Early heatwaves and associated drought conditions also threaten the yield for many crops, such as wheat, because it hinders grain filling. This heatwave has come at a critical time for the crop season in the Western Mediterranean countries.
• While Europe and North Africa have experienced heatwaves increasingly frequently over the last years, the recent heat in the Western Mediterranean has been so extreme that it is also a rare event in today’s warmer climate. Our estimate of observed temperatures averaged over three days was estimated to have a return period of approximately 400 years (at least 60 years) in the current climate, meaning they have roughly a 0.25% chance of happening in any given year.
• We combine climate models with observations to estimate the influence of human-caused climate change on this extreme heat. Observations and models show a strong increase in likelihood and intensity, but the change is systematically lower in the models than in the observations. The fact that extreme heat is increasing faster than climate models simulate is a known problem in summer in Western Europe, in all climate models, and is also found here.
• The combined results, giving an increase in the likelihood of such an event to occur of at least a factor of 100, is therefore likely too conservative. At the same time, a heatwave with a chance of occurrence of 0.25% in any given year (return period of 1-in-400 years) would have been at least 2°C cooler in a 1.2°C colder world.
• These discrepancies between the modelled and observed trends and variability also hinder confidence in projections of future trends. In a future 0.8°C warmer climate (reaching global warming of 2°C above pre-industrial levels), such a heatwave would be another 1°C hotter, but as above, this is probably a very conservative estimate.
• Heat-related fatalities have decreased in cities with urban planning for extreme heat. This has proved effective in Spain and notably in Lisbon, Portugal, where the urban heat island effect has been reduced by incorporating more green and blue spaces. In addition, early warning systems for heat, simple self-protective behaviours such as drinking enough water, city heat action plans, strong social ties, and improved risk perception have been shown to reduce heat-related health impacts