Summer Heat

source: Le Monde

author: Simon Roger

translation: doxa-louise

Global Warming seems at work in Northern Europe

For the relevant experts, our extreme temperatures are not only

those of a fickle climate, but human in origin.

For the second year in a row,  experts at  World Weather Attribution (WWA)

have analysed the summer heat wave at work in part of Europe. In September

2017, a study of the WWA, starting from the observation of the extreme heat episode

of July and August in the South and East portions of the continent - characterized by 

temperatures higher than 40°C - had concluded that heat waves of that sort could 

become the norm by 2050.

‘At the beginning of the 1900s, a summer like that we have just been through would

be an extremely rare occurrence, stated Geert Jan van Oldenborgh, from the Royal 

Meteorological Institute of the Netherlands. For all the South of Europe, the probability 

of getting in any one year a summer as hot as that observed last year is already at 10%.’

This year, it is Northern Europe which the group of climatologists is concerned with. 

Absolute temperature records were broken in July for Norway with values around 33°C,

which is more than 15 degrees over normal values, and there were extreme highs near 

the Artic Circle.

In the analysis meant to become public Friday July 27, the WWA experts - group which 

brings together the Environment Change Institute Oxford University (ECI), the Royal 

Meteorological Institute the Netherlands (KNMI) and the Laboratoire des sciences du 

climat et de l’environnement en France (LSCE) - put forward preliminary conclusions 

with respect to the persistence of high pressure systems at the origin of exceptionally high temperatures and drought from Scandanavia to the Netherlands.

To this end, they have isolated, in seven different places, the highest average of three 

consecutive day temperatures from the period between May 1  and July 24, and compared 

the results with those from previous years. The seven chosen cities - Dublin in Ireland, 

De Bilt in the Netherlands, Copenhagen in Danemark, Oslo in Norway, Linköping in 

Sweden and two sites in Findland - make up a homogeneous panel insofar as 

these represent the same quality of information, tells us Robert Vautard, the LSCE 

researcher associated with the study.

The authors prudently agree that we will need to see results from August before

making definitive conclusions about the hot season of the last few months baring d

own on the Old Continent, yet they have identified elements of fact. The researchers 

thus mention a level of heat ‘quite extreme’ ensconced in the Artic Circle, which lessens 

as one travels South of the observation zone.

Many Models

‘For Ireland, the Netherlands and Danemark, observations are clear as to a tendency toward a greater number of heat waves, conclude the principal authors of the study, Geert Jan van 

Oldenborgh for KNMI and Friederike Otto from Oxford ECI. The probability is almost t

wice as strong for Dublin and four times higher for Oslo.’

‘These temperature anomalies which we are seeing in the North of Europe are linked to the meteorological context, explains the French meteorologist. The anticyclone has been 

immobile over Scandanavia for two months and the disturbances pushed toward the 

South and the Mediterranean. But to that we must changes brought by climate change.’

Because Robert Vautard as well as his European colleagues are of the view that

‘climate change of human origin heightens the risks of heat waves as we have experienced 

in 2018 in Scandanavia, even when it remains complicated to quantify precisely to what extent’.

To back up their analysis, the experts at the WWA ran many climate models which

integrated expelled greenhouse gases in the atmosphere attributable to human activities. ‘It is important to realize that what contributes to the heightening of temperatures is not 

fluctuations in the emission of greenhouse gases, but the quantity of CO2 already there, 

for a long time, in the atmosphere’, points out Robert Vautard.  Consequently, one should 

not expect to see a lowering, but in the best case scenario, a stabilization of temperatures, 

according to the LSCE researcher.