The European Heat Wave of 2003: A Multi-Layered Issue

European heat wave

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Ignacio Navarro Ramírez

The European Heat Wave of 2003: A Multi-layered Issue

“Breaking record temperature” was the headline of all newspapers around Western Europe at the beginning of August 2003, during “the hottest summer in the northern hemisphere to date” (Luterbacher, 2004). The severe effects caused by the European heat wave of 2003 (EHW03) have arisen more alarming discussions about global warming and casted doubts on the social cohesion and efficiency of European health care systems. How is it possible that such an episode could kill almost 15,000 people in a span of a little over a week, in one of the most highly developed countries in the world? To answer these issues, this research evaluates the multi-layered factors that played a substantial role in the disaster. To begin with, the weather conditions that prompted the disaster and its relationship with the climate change will be presented. Green house emissions have contributed to higher temperatures in recent years, which means that events like EHW03 will become more frequent in the future. Secondly, it is primordial to focus on the cracks in our social foundation that exacerbate the effects of the EHW03. Heat waves have been underestimated and ignored in the past because its victims are usually the most isolated people. Thus, no emergency reactions had been planned and, as a consequence, when the heat wave hit, people were more vulnerable. The negative repercussions EHW03 has had, goes beyond extremely high temperatures; it is a concern regarding social structures and their current crisis.

High temperatures in Europe began in June 2003 and continued until 13th August. The extreme heat was persistent during the first half of august, when the temperatures broke records across Western Europe, reaching values from 20 to 30% higher than the summer average. This increase in temperatures was shown in the State of Climate in 2003 report, which stated that European average summer temperature exceeded by 1.9ºC the reference period (1961-1990). The heat wave had greater impact in Western Europe, where highest values were recorded. Daily maximum temperatures in this period surpassed 36◦–38◦C across southern and central France and 40◦C across most of interior Spain and central Portugal. Broadly speaking, these temperatures were 7.5º-12.5º above the usual. (García-Herrera, 2010).

This extreme prolonged heat and the associated drought led to a several health, socioeconomic and environmental impacts. Firstly, it caused the death of thousands of people. The estimated death toll of EHW03 was approximately 35,000, meaning a 60% excess above the expected mortality (WHO, 2004). The most affected country was France with 14,082 casualties, followed by Germany, Spain and Italy, with death tolls of 7,000, 4,200, and 4,000 respectively (UNEP, 2004). Regarding the environmental impacts, there was a 10% loss of mass of Alpine glaciers, a weakening of plants, many major rivers at record-low levels and more than 25,000 fires recorded in the west of Europe leading to a total burned area of almost 650,000 ha. In third place, the heat wave also had a serious impact upon the agricultural sector as the excessive temperatures and drought decreased the quality and quantity of the harvest. The fall in production was especially marked in arable sector (10% or 186 million tons, MT), common wheat (11% or 10MT), and maize (21% or 9MT). The European potatoes production was also negatively affected showing a deficit going from 30%, in countries like Spain and Germany, to 60% in France. Water and energy supplies were likewise threaten. Focusing on the economic impact, the EHW03 cost roughly $13 billion dollars to EU (WHO, 2004).

As can be deduced, the EHW03 was exceptional not only because of the high temperatures, but also because of its duration and its adverse impacts. Based on historical archives, several researches suggest that 2003 has been the warmest summer in Europe since 1540 (Pfister, 1999) and the deadliest natural disaster in the last 50 years in Europe.

What factors influenced such exceptionally high temperatures? Some authors have considered the following contributing factors as the better explanatory ones: the persistent anticyclonic anomalies (Azores anticyclone and west African ITCZ were both displaced to the north); the southward shift of the extra tropical storm tracks; the tropical Atlantic anomalies (wetter-than-average conditions in the Caribbean); the strong loss of moisture from the European land surface; and the high sea surface temperatures in the North Atlantic and Mediterranean related to anomalously clear skies and downward net radioactive fluxes (Black, 2004).

Undoubtedly, these factors have contributed to the increase in the persistent high temperatures during 2003 summer, but they are not the only ones. Many authors believe that the ultimate cause of the EHW03 was anthropogenic, rather than natural. In the last century, temperatures near the Earth’s surface have risen globally due to increasing atmospheric concentrations of greenhouse gasses; this phenomenon is known as Global Warming or Climate change. Several experts declare that past human gas emissions are responsible for a relevant portion of the European Summer warming. According to past models linking risk of extremely hot summers and past anthropogenic emissions, natural drivers have no influence in the recent warming; however, there is a probability of more than 90% that “over half the risk of European summer temperatures exceeding a threshold of 1.6 K is attributable to human influence on climate” (Stott, 2004). In consequence, the model’s results attribute 75% of the increased risk of such a heat wave to human contribution. On the other hand, it is true that a single phenomenon as the EHW03, however intense, cannot be totally linked to global warming (Intergovernmental Panel on Climate Change, 2012). But the fact is that both events are more related than what we think, because this type of occurrence is expected to happen more frequently as consequence of the Global warming.

The extreme heat experimented in 2003 cannot be explained by common seasonal shifts in average temperatures. There is a trend towards higher values of temperature mean and dispersion. In fact, this increase in temperature variance associated with vaster greenhouse gas concentrations was discovered to be due primarily to soil moisture-temperature and precipitation feedbacks (Seneviratne et al., 2006). Another author claimed: “for the extreme hot weather of the recent past there is virtually no explanation other than climate change, the odds that