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The Heat Health Warning System
as an example of climate services
at the Deutscher Wetterdienst
S. Rösner, Dr P. Becker and Dr Christina Koppe, Deutscher Wetterdienst
T
he German Heat Health Warning System (HHWS) is
among the first measures to adapt to a warming climate in
Germany. It demonstrates how climate and health services
need to collaborate in order to protect human health in the face
of an anticipated increase in the number of heat waves.
1
The German Adaptation Strategy (Deutsche Anpassungs Strategie
or DAS)
2
was developed to systematically address the changes
ahead, creating a framework for adaptation to the consequences
of climate change in Germany at the federal level. It describes the
possible consequences of future climate for 15 sectors and areas,
including human health. In August 2011 the German Government
also adopted an ‘Action Plan Adaptation’ of the DAS.
3
The HHWS
represents an already implemented activity to support adaptation
measures in the human health sector.
In summer 2003 an extensive heat wave hit many European coun-
tries, causing between 35,000 and 50,000 heat-related extra deaths.
4
Older and sick people, as well as the very young, were most at risk.
In Germany the number of additional casualties attributable to the
heat wave probably exceeded several thousand. An investigation for
Baden-Württemberg showed excess mortality of about 1,100.
5
Some
of these casualties could have been avoided if precautionary meas-
ures had been taken, and an early warning system would enable the
preparation of such measures.
Until 2003 there were only two operational HHWS in Europe:
in Lisbon and Rome. Heat load was forecasted and communicated
in Germany, but not as a warning. However, the high numbers of
heat-related deaths that summer across Europe led to an increase
in HHWSs. A survey in spring 2006 by the German weather service
Deutscher Wetterdienst (DWD), in the context of the EuroHEAT
project, showed that heat warnings were issued in 16 countries
and that several countries were planning to implement a HHWS
in the near future. By 2009, 28 countries in Europe were issuing
heat warnings.
HHWSs use a variety of methods to identify heat episodes. These
differ from country to country or even from city to city, mainly
because the term ‘heat wave’ has not yet been defined and there is
no consensus in the scientific community on which indicator is most
closely linked to adverse health outcomes.
Following the 2003 event the Federal Ministry for Health and
Social Safety, on the initiative of DWD, appointed a commission to
develop recommendations for a heat warning system in Germany.
In 2004 the federal states of Baden-Württemberg and Hesse devel-
H
ealth
oped pilot heat warning systems. These were successful,
and DWD decided to introduce a regionalized HHWS
for all of Germany, developed in close cooperation with
public health authorities.
6
At that time DWD already
had a long history in providing thermal load forecasts
to various user communities, and this enabled the quick
implementation of the German HHWS.
During the development phase there were frequent
discussions with health administrations from Hesse and
Baden-Württemberg, which are responsible for turning
information from the HHWS into concrete actions and
advice. It was agreed not to communicate excess casu-
alties – which cannot be reliably estimated and would
give the HHWS negative associations – but to produce
a heat load index.
The HHWS
HHWSs consist of two parts: a meteorological compo-
nent (monitoring the weather situation, triggering
and issuing warnings) and a public health component
(action plans, intervention measures). The meteorologi-
cal component is based on a heat load indicator.
7
It is
important to identify a heat load indicator related to
human health impacts, and a threshold to trigger inter-
vention actions.
Image: matchka/pixelio.de
Heat waves are an emerging public health problem in
many parts of the world