The Impact of Climate Change on Natural Disasters - Reducing Disaster: Early Warning Systems for Climate Change - page 36

consequence he then argues that all weather events are impacted by climate change,
because climate change altered the background environment in which they occur
(Trenberth 2012 ). So the task then would be to prove that an extreme event is not
infl uenced by climate change.

2.3.3 Examples of Event Attribution Studies

To date, only a few studies have attempted extreme events attribution; for example,
the heat wave in Europe in 2003 (Stott et al. 2004; Christidis et al. 2010) or in
Moscow in 2010 (Dole et al. 2010), the fl ood in the United Kingdom in 2000 (Pall
et al. 2011), the increased extreme precipitation events over the Northern Hemisphere
(Min et al. 2011), and recently the drought in Somalia in 2011 (Lott et al. 2013 )
have been subject to event attribution research. Some studies found that a certain
fraction of the cause of climate extreme events could be attributed to human infl u-
ence on climate, others could not.
In the case of the European heat wave in 2003, Stott et al. (2004) concluded that
“human infl uence has at least doubled the risk of a heatwave […]” with mean sum-
mer temperatures as high as those recorded in Europe in 2003. Pall et al. (2011)
examined the fl ood event that occurred in the United Kingdom in the year 2000
during the wettest summer since records started in 1766. They found that “[…] in
nine out of ten cases their model results indicated that twentieth-century anthropo-
genic greenhouse gas emissions increased the risk of fl oods occurring in England
and Wales in autumn 2000 by more than 20 %, and in two out of three cases by more
than 90 %.” Similarly, Min et al. (2011) examined the increased intensity of extreme
precipitation events in the Northern Hemisphere and found that human infl uenced
greenhouse warming played a role in the pattern of extreme precipitation events.
Studies that assessed the human impact on the 2010 Russian heat wave published
controversial results. Dole et al. (2011) concluded that the heat wave was most
likely from natural origin, Rahmstorf and Camou ( 2011 ) concluded that it was
affected by anthropogenic infl uence. Otto et al. ( 2012 ) demonstrated that the dis-
crepancy between the Dole et al. (2011) and Camou (2011) results stems from the
different attribution questions asked: magnitude (Dole et al. 2011) versus the prob-
ability of the heat wave (Rahmstorf and Camou 2011 ). This showcases the impor-
tance of the focus of the attribution question as mentioned in Sect. 2.3.2 .
The most recent publication by Lott et al. ( 2013 ) assessed whether or not the
unusual rainy season preceding the drought in Somalia in 2011 can be attributed to
human-induced climate change. They found that the rainy season in 2010 was
mostly affected by the teleconnections of the ongoing La Niña event. However,
human infl uence most likely played a role in the unusual dry rainy season in the
following year in 2011. Between 24 % and 99 % of the causes of the dry rainy sea-
son in 2011 could be attributed to human infl uence on the climate (Lott et al. 2013 ).
It is important to note that not all climate extreme events are attributable to
human impacts on climate. Perlwitz et al. ( 2009 ) showed that the cold snap in North