Padmashree Anandhan

Europe’s southern hemisphere is experiencing its highest temperatures in July across Greece, Southern France, eastern Spain, Sicily, and southern Italy. According to the report from Copernicus Climate Change Service, the expansion of the heat dome is responsible for the change in the weather pattern. The peaking temperatures and heatwaves after the summer of 2022 are beginning to become a trend in 2023. To analyze this trend, it is necessary to look at the occurrence of such peak temperatures so far, map the occurrences geographically, examine the causal factors and fallouts, and compare this with the state and regional response.

When it comes to Europe, heatwaves in the 20th century are nothing new as they began in 1920, with a dry autumn and a winter first affecting the water supply, agriculture, and livestock farming. This developed into wildfires, severe drought, and dry hazards in England, the Czech Republic, and parts of central Europe. Such phenomenon continued through the summers of 2003, 2010, and 2015. Later, with the rise in global temperatures, soil moisture deficit and increase in GHGs caused hot summers to occur frequently from 2018, 2019, 2020, and 2022. The first severe heatwave which began in 2003, recorded 35 to 40 degrees Celsius according to the UNEP data. Between 1982 and 2018, sea surface temperature increased by between around 0.3 degree Celsius per decade in the North Atlantic, and around 0.6 degree Celsius per decade in the Black Sea. Although the increasing trend is expected to progress, it is slow when compared to the air and land temperatures. The frequency and magnitude of marine heatwaves have increased significantly both globally and in European seas, and are projected to continue, with increasing expected impacts on climate and ecosystems. The increase in sea surface temperatures led to more marine heatwaves in European seas. This has resulted in ecological impacts, the promotion of harmful algal blooms, and increased risks to human health and aquaculture. For example, recent marine heatwaves led to vibriosis infections along the Baltic Sea and North Sea coasts. Marine heatwaves also affect the climate on land, with those in the Mediterranean Sea contributing to amplifying heatwaves and heavy precipitation events over central Europe, and triggering intense weather anomalies.

In 2023, the peak temperatures, have led the areas of southern France, Greece, Italy, Portugal, and Spain, to face climate extremities in the form of heatwaves, wildfires, floods, and melt of glacier alps. According to the World Meteorological Organisation (WMO), climate change combined with a new El-Niño has resulted in a change of weather pattern that has warmed up the Pacific Ocean.

Geographic Mapping
In the summer of 2023, southern Europe and especially countries near the Mediterranean Sea, experienced the highest temperatures ranging from 45 to 47 degrees Celsius (Figure 1). The land-atmosphere, the New York Times, reported on extreme heat across Algeria, Croatia, Greece, eastern Spain, Sardinia, Sicily, southern Italy, and Catalonia.

The heatwaves were observed to be concentrated in the northern hemisphere, with a wave of heat across France, Central, and Eastern Europe, coupled with unusually hot temperatures persisting in Spain, Italy, and the Balkans.

The first record of high temperatures was seen in July followed by August in 2022. The European Centre for Medium-Range Weather Forecasts (ECMWF) predicted the temperature would persist till October, marking the longest period of heatwaves since 1980. As per the weather anomaly chart of ECMWF, the temperature has increased 10 degrees Celsius above average in (46) Portugal, (45) northern Spain, (40) western France, and southern England. With the hot air moving north, the Benelux countries, Baltic region, Ireland, (40.3) the UK, Belgium, Luxemburg, the Netherlands, northern Italy, Switzerland, and western Germany recorded six degrees Celsius higher than the average temperatures. Northern Europe is expected to heat up by three degrees Celsius. The European Space Agency used Sentinel 2 & 3 (Earth observatory satellite), and separated air and land surface temperatures to find that the land surface temperature amounted to 55 degrees Celsius due to increasing weather and climate shifts. Between 2010 to 2020, extreme temperatures differed widely across Europe in terms of frequency, duration, and severity. In 2010 eastern Europe and Russia experienced severe heat whereas it was less in the west. In 2015, southern Europe and the Baltic states were exposed to extreme heatwaves, and on the contrary, northern and Scandinavian countries experienced peak temperatures in 2018.

At the sea surface, the heatwave was strong in the north-east Atlantic in June 2023, ranging from two degrees to three degrees Celsius (Figure 2), and continues to switch between extreme, moderate, and locally strong in the Iberian Peninsula, and the northern part of the North Sea located between the British Isles and Norway. The heatwave is concentrated in the tropical north Atlantic, extending through the basin from strong to severe in the east, and fluctuating from moderate to strong in the west. In the case of the north-east Pacific, the heatwave remains moderate to strong (Figure 3). In 2022, the Mediterranean Sea remained the hotspot, impacting the Med5 countries (Malta, Cyprus, Greece, Italy, and Spain). The Arctic Ocean has shown a slow heating trend whereas the land surrounding had a faster rate of rising temperatures.

Historically, the sea surface temperatures of all five European seas- Black Sea, Baltic Sea, Mediterranean, North Sea, and the North Atlantic- began incresaing in 1870. The Mediterranean Sea is the warmest of all, and is now seconded by the North Atlantic Ocean. The latest hotspot in the North Atlantic is reportedly experiencing multiple marine heatwaves. The National Oceanic and Atmospheric Administration (NOAA), a US-based marine watch agency, categorized heatwaves into categories, with category 5 (Beyond Extreme 4-5 degree Celsius) being the maximum and category 1 being the area with existing marine heatwave conditions since June 2023. In accordance with these categories, areas around Ireland, the UK, and the Baltic Sea were marked as Category 4 with “extreme” marine heatwaves and Category 2 “strong” heatwaves near the Bay of Biscay, stretching to the northwest coast of Africa.

Issues
First, the jet stream and double jets. The causal factors for the heatwaves and rising temperatures are increased human activities and rising global temperatures. Whereas, the high concentration of carbon dioxide gases, the flow of jet streams where the hot air from Africa, circulation of the atmosphere and the ocean is attributed to Europe.

A study published in Nature Communications, keeping Europe as the center of heatwave hotspots, found that the increased occurrence of double jets marked extreme heat since the 2003 heatwave. The scientists from the Potsdam Institute of Climate Impact Research (PIK) were able to find out that the reason behind 35 per cent of the extreme heatwaves in Western Europe was continuing double jets. According to experts from ECMWF, heatwaves can be the result of a stationary high-pressure system with clear skies and weak winds.
These conditions can create longer heatwaves, such as the recent one in mid-August of 2022. According to one of the experts: “The effect on near-surface temperature depends on how much energy is used to evaporate water from the ground and plants, and how much is heating the air. If the soil is already dry or the surface is just concrete and tarmac, there is little cooling of the near-surface temperature due to evaporation. Instead, most of the energy will heat the air and thus increase the magnitude of the heatwave.”

In simple terms, the extreme heat in 2023 is due to anticyclone and a high-pressure system that controls the upper atmosphere over southern Europe. Due to compressed and warm air, high-pressure systems occur with “reduced cloud cover,” resulting in more solar radiation reaching the ground. This leads to extensive heating of Earth’s surface by the sun, heat which then moves upwards into the atmosphere. It is assessed by the long days and short nights of summer, which indicate the maximizing of the heating effect.

Second, rise in sea temperatures. The slow increase of water temperatures due to long-term anthropogenic change and increased occurrences of marine heat waves have been having devastating effects on local ecosystems. Marine heat waves have also been associated with the likelihood of extreme weather events, such as cyclones and heavy precipitation. The rise in ocean temperature is one of the major drivers for the migration of marine species to higher latitudes. More subtropical and tropical marine species are replacing temperate water fish, and reshaping fisheries and catch compositions. Warmer Mediterranean SSTs lead to enhanced evaporation and moisture transport in the atmosphere, therefore making this region a major climate change hot spot for the coming decades.

The same can be confirmed from the Copernicus Climate Change Service (C3S*) report of early July (Figure 5). It reported that the Atlantic Ocean heatwave to was warmer between June and July, compared to the other basins close to North America and Europe. According to the report, sea surface temperatures in the eastern North Atlantic have reduced (except in June), but the marine heatwaves tend to continue across different areas. The Mediterranean Sea is one of the major hotspots for marine heatwaves, the North Atlantic Ocean has followed pursuit after record-breaking sea-surface temperatures influencing Europe’s weather conditions.

Marine heatwaves could arise from various individual and combined factors, including atmospheric and oceanographic processes, which significantly impact marine life and bring about extreme weather events. The new El Ni ño is also expected to affect the atmospheric circulation till October. At the atmospheric level, circulation, air pollution, and climate change are the contributing factors to rising temperatures. The North Atlantic Ocean experienced an unusual atmospheric circulation. It is due to surface wind speeds linked to sea surface temperatures, meaning any reduction in the wind speed will reduce the mixing of the surface water with the cooler water below, increasing sea surface temperatures.

Third, heat stress. A newly identified causal factor of the heatwaves is the “Heat Stress.” Like a domino effect, if one heat dome (a high-pressure circulation) is not controlled, it leads to subsequent heat waves across Europe and the Arctic Ocean. This will tend to continue until there is a shift in the atmospheric circulation. Such episodes lasted in Southern Spain up to 60 days, in small areas across 70 days, but mostly concentrated in Southern Europe lasting a greater number of days. C3S projects the heat stress to vary from strong to very strong and southern Europe, and it may experience “extreme heat stress,” in the long run.

Fourth, Climate Change. Traces of climate change can be found all over heatwaves across Southern Europe, such as warm gases in the air leading to stronger and frequent heatwaves. PBS, a US public broadcast service, reported that the high intensity of heat domes and increased air pressure were found to be formed from increased burning of coal, oil, and gas, which increased the possibility by 50 times for a heatwave to occur. Therefore, a persisting warm atmosphere filled with carbon dioxide and other gases led to a 2.5 degrees Celsius hotter heatwave. According to a scientist at the Imperial College of London, Mariam Zachariah, if it had not been for climate change, such extreme heatwaves would not have occurred.

Fifth, decreased particulate pollution. In the last four decades, Europe has been one of the key players in reducing particulate air pollution from industries, automobiles, and energy. According to the research by Oceanic and Atmospheric Research (OAR), the increased absence of air pollution by humans in the northern hemisphere has dropped by 50 per cent between 1980 and 2020. It has led to surface warming of the tropical Atlantic Ocean. This is because the amount of particulate pollution that needs to be present to reflect sunlight was less, thereby making the oceans absorb more heat and warm faster. Along with the sea, the land and atmosphere also get warmed, affecting the movement of the jet stream and causing tropical storms.

Fallouts
First, economic fallout. A study published in Nature on the regional economic impact due to heatwaves in Europe found how extreme temperature affects occupational health, undermines human capital accrual, and impacts the economy. The study investigated the heatwaves of 2013, 2010, 2015, and 2018 as a sample to analyse the contributing factors to the economic impact. First, the human influence doubled the possibility of heatwaves forming threats to labour productivity. Second, the intensity of the heatwaves had varied economic impacts across Europe. Between 2013 and 2018, the heatwaves affected Europe’s economic growth by 0.3 to 0.5 per cent. When split between the north and south of Europe the warm temperature remains proportional, but in terms of economic losses, southern Europe was affected the most. This was due to higher contributions from outdoor production in southern Europe such as agriculture, industrial, and transport services. Those who worked indoors were less exposed to solar radiation, and the low metabolic intensity of indoor jobs helped protect the labourers. According to the study, Europe is expected to steadily incur GDP loss in the next 40 years. Cyprus, Portugal, Spain, and Croatia are expected to see a two to three per cent loss in GDP by 2040-2060 from extreme heat. Measures such as rescheduling of tasks, increased breaks, and shifting of outdoor activities into indoor have been taken to decrease the productivity loss. Widely across Europe and companies, heat-insulation measures, and air conditioning have been adopted, but are likely to protect only the indoors, leaving out outdoor sectors exposed to economic damages.

Second, human health adversities. The WMO warned of the increasing deaths due to extreme heat in Europe. According to the report by the UN, 60,000 people died in the summer of 2022, despite the regional efforts in early warning and health action plans. WMO stated the need to build an adaptive infrastructure to endure extreme heat and raise awareness among people against the risks. Although extreme temperature warnings are given across Asia, North Africa, and the US, Europe remains more vulnerable due to fastening urbanization, increased heat, and the aged population. Those who remain in low-income neighbourhoods are prone to poor health, reduced economic yield, and poor living arrangements.

In terms of age bracket, the increased intensity of heatwaves affect the elderly living in cities more. Those who are more than 65 years have twice the chance of being subject to heart-related mortality. Apart from the age factor, pre-existing medical issues, social deprivation, economically deprived locations (living in urban set-up) are the factors for Europeans exposed to chronic conditions, cardiovascular, respiratory, and kidney diseases. Research published in the Multidisciplinary Digital Publishing Institute journal, taking the case studies of Spain and Greece located in the Mediterranean hotspot, showed a U-shaped relationship between mortality and peak temperatures which had a nonlinear relationship. According to the study, cardiological and cardiorespiratory mortality in Spain was on a downward trend, with a higher trend in respiratory mortality. This was different in Greece, which had an upward trend of respiratory and cardiorespiratory mortality, with a stable cardiological mortality rate.

Responses
According to the European Climate and Health Observatory, since 2003, collaboration between weather services, civil protection, and public health departments began at national, subnational, and local levels. Two key responses established by the regional and national governments are the heat-health action plan (HHAP) and its subsequent component, the heat-health warning system (HHWS). The HHWS, which helps in weather forecast, provides ways to assess weather-health relations and aims to reduce the heat stress effect on human health. This is done from the data collected from National Meteorological services connected to HHAP, but the data surveys are yet to be responded to by many countries. In such surveys, governance remains one of the key objectives to interlink actions and collaborations amongst actors. According to a research article published in Health Research Policy and Systems, many European countries involved “stakeholders” in line with different levels of warning systems and not by the roles. Thereby the article suggests for clear assigning of roles and responsibilities to remove confusion and promote effective implementation. 

For building resilience against such extreme heat, the EU’S adaptation strategy adopted in 2021, looks at limiting economic costs from weather and climate events, to close down the gap in climate protection. In the strategy, the severity of the heatwaves and subsequent triggers of wildfires, droughts in the Mediterranean region, the impact on the health of Europeans, water shortage, spillover effects on food security, aggravation of social inequalities, and threat to cultural heritage have been recognized. In terms of an action plan, it mandates the need to understand risks to counter the threats to human health, proposing the creation of “One Health” to address the human health risks arising from climate change. The report published in March 2022 by the “Climate Adapt” under the European Climate and Health Observatory, provides details of the policies adopted by the 32 EU member countries only. Despite the limitations compared to the rest of the world, EU has a well-structured policy measure to prevent risks to human health. The topmost are heatwaves (Figure 6) and drought, followed by floods, temperature rise, storms, and later sea level rise, landslides, and forced migration.

The policy measures mainly focus on addressing the human health-related risks in National Adaptation Strategies (NAS) and National Health Strategies (NHS) through physical, social, and institutional interventions. Of the three, social interventions played a common role in NASs and NHSs (Figure 7). The prime measure adopted at the national level was enhancing monitoring and surveillance systems to record the climate change impact and implementation of early warning systems. Second was the awareness-raising campaign followed by research and education promotion measures among health professionals.

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