Strategic Panorama 2009 - 2010 - IEEE

Climate change and its security implications
The observed decrease in snow and ice cover is also consonant with
warming.
Satellite data collected since 1978 indicate that annual average Arctic
sea ice extent has shrunk by an average of 2.7 % (between 2.1 and 3.3 %)
per decade, with even more accentuated decreases in summer of 7.4 %
(between 5.0 and 9.8 %) per decade. On average, mountain glaciers and
snow cover have decreased in both hemispheres.
Between 1900 and 2005, precipitation increased significantly in the eastern
areas of South and North America, northern Europe and northern Asia,
although it decreased in the Sahel, the Mediterranean, southern Africa and
certain parts of southern Asia. There is a likelihood of over 66% that throughout
the world the area affected by drought has grown since the 1970’s.
It is very likely that over the past 50 years cold days, cold nights and
frost have been less frequent in most land areas, and hot days and nights
have been more frequent. It is likely that heat waves have been more frequent
in most land areas and the frequency of intense precipitations has
increased in most areas.
Observations show an increase in intense tropical cyclonic activity in
the North Atlantic since approximately 1970, with little evidence of increases
in other regions. No clear trend is observed in the annual number of
tropical cyclones. It is difficult to identify longer-term trends in cyclonic
activity, particularly before 1970.
On average, temperatures in the Northern Hemisphere during the
second half of the twentieth century were very likely to be higher than
those in any other 50-year period in the past 500 years and likely to be the
highest in the past 1,300 years at least.
Observed impacts on natural and human environments
All the continents and most of the oceans show that climate change,
particularly the rise in temperature, affects many natural systems. The
following impacts in particular have been detected:
• Enlargement and increased numbers of glacial lakes.
• Increasing land instability in permafrost regions and rock avalanches
in mountainous regions.
• Changes in some Arctic and Antarctic ecosystems.
• Increase in surface runoff and earlier spring peak discharge in many
rivers fed by snow melt and glacier melts.
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