Geoscience Reference
In-Depth Information
3
Changes in extreme weather
Karl Braganza, Kevin Hennessy, Lisa
Alexander and Blair Trewin
Introduction
Extreme weather events, interacting with exposed and vulnerable systems, can
lead to disasters (IPCC, 2012). In Australia, vulnerability to extreme weather
events has been recently highlighted by:
●
the south-east Australian heat wave in late January 2009, which resulted in
374 excess deaths in Victoria over what would be expected (Vic DHS, 2009);
●
the Victorian bushfires in early February 2009, which killed 173 people and
more than a million animals, destroyed more than 2,000 homes, burnt about
430,000 hectares, and cost about $4.4 billion (Victorian Bushfires Royal
Commission, 2010);
●
the floods in Queensland in 2010-2011, which killed 33 people and affected
more than 78 per cent of the state and over 2.5 million people, with 29,000
homes and businesses suffering some form of inundation, and a cost in excess
of $5 billion (Queensland Floods Commission of Inquiry, 2011).
Changes in such weather events, and changes in exposure and vulnerability,
will alter the impact of disasters. Recent observational evidence shows changes
in the frequency of extreme weather events that are consistent with a warming
climate. Most of the global warming since the mid-20th century is very likely
due to increases in greenhouse gases from human activities such as burning fossil
fuels. Further increases in greenhouse gases are expected due to human activities,
leading to more warming and changes in extreme weather events.
This chapter first provides a global perspective on observed changes in
extreme weather. It then reviews changes in extreme weather that have already
been observed in Australia over the twentieth century and concludes with a
discussion of projected changes to Australian weather extremes in a Four Degree
World.
A global perspective on observed changes
A changing climate leads to a variety of changes in the frequency, intensity,
spatial extent, duration and timing of many extreme weather and climate events.
