Geoscience Reference
In-Depth Information
Australia—for example, in Europe in 2003 and 2007, Russia in 2010, USA in 2012, and
Australia in 2009 and 2014. There is also evidence that more storms are occurring in the
Northern Hemisphere. Wave height in the North Atlantic Ocean has been monitored since
the early 1950s, from lightships, Ocean Weather Stations, and more recently from satel-
lites. Between the 1950s and 1990s, the average wave height increased from 2.5 m to 3.5
m, an increase of 40 per cent. Storm intensity is the major determinant of wave height,
which provides evidence for an increase in storm activity over the last 40 years. This also
fits with the observed increase in winter extra-tropical cyclones, that is those occurring in
the mid-latitudes, which have increased markedly over the last 100 years, with significant
rises in both the Pacific and Atlantic sectors since the early 1970s. There is also evidence
for an increase in intense tropical hurricane activity since the 1970s in the North Atlantic.
