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Aven (2015) has further developed the concept of black swans and claims that
black swans are surprisingly extreme events relative to current knowledge
. Hence,
the concept always has to be viewed in relation to whose knowledge we are talking
about, and at what time. This means one type of natural disaster at one point in time
or in a particular geographical area can be seen as a black swan, but not in another
area. According to Aven and Krohn (2014), there are three main types of black swan
events.
The first type of black swans encompasses known events judged to have a
negligible probability of occurring, and thus are not expected to occur, or to only
occur very rarely. An example of this type of event is a flood that is expected to
occur once every 1000 years. These are natural disasters we know can occur, but due
to their low incidence, emergency preparedness measures are not scaled to
necessarily meet the extreme threats they pose. Another example of this type of black
swan would be an earthquake in Norway’s densely-populated areas (The Directorate
for Civil Protection, 2015b). We know that this type of scenario could occur, but its
probability is considered negligible.
The second type of black swans includes events associated with a great
amount of uncertainty. These events might be known to some, but not all,
stakeholders. Examples of such black swans are the fires in Lærdal and Flatanger in
2014. These fires occurred during winter in Norway – which is usually not very dry.
However, due to extremely dry weather conditions, the fires spread rapidly and
caused major damage to surrounding buildings. In the aftermath of these events,
several researchers claimed there is a lack of knowledge in Scandinavia concerning
this type of fire and that climate change could contribute to the occurrence of similar
fires in the future (Steen-Hansen
et al
. 2016, this volume).
The third type of black swans are events that are completely unknown to
decision makers. Examples of such events would be tornadoes of great magnitude,
major ice storms, or severe hailstorms. These are weather phenomena that occur
annually in North America, but if they were to occur in Norway, they would be
considered black swans of the type “unknown unknown”.
New perspectives on risk management acknowledge that black swan events
should also be a part of risk analysis. To classify different scenarios according to the
three types of black swan could be an exercise to anticipate scenarios of extreme
weather becoming a reality in the future. Broadening the range of scenarios would
also be beneficial to building capacity, or resilience, to meet a greater variety of
threats.
How to build resilience against future climate change
In recent years, the resilience concept has been used on a societal level in reference
to how societies can “bounce back” in the face of a disturbance. The image of an
uncertain world, in which new types of risks and threats can become a reality in the
future, has moved the focus away from safety from one type of threat to society`s
ability to tackle all kinds of possible scenarios that might unfold. As a consequence,