Climate change in the UKOTs an overview of the ... - JNCC - Defra

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Corals killed by sea warming in BIOT
Credit: Charles Sheppard
of climate change without the presence of
human-induced environmental stresses,
such as pollution and land-use in the
coastal zone.
Observed change
• Rising sea temperatures have contributed
to the death of coral reefs.
There have been several coral
bleaching episodes following the major
bleaching event in 1998, which
destroyed some 80 per cent of live coral
cover to a depth of 30 m after sea surface
temperatures rose to almost 30°C
in the Chagos Archipelago. Bleaching
events have taken place as recently as
2004.
• Some of the islands are experiencing
coastal erosion caused by sea level rise
and possibly the loss of sand production
following the mass mortality of
coral reefs. Some areas have been
more badly affected than others.
• Sea level rise in Diego Garcia has averaged
0.54 cm per year since 1986, but
appears to be accelerating (Sheppard
and Spalding, 2003).
Implications and possible future
impacts
• Loss of reefs is leading to loss of some
fish and other marine species. The biodiversity
of reefs and their biological
integrity is being compromised.
Same coral species in good health
Credit: Charles Sheppard
• Erosion is already causing, and will continue
to cause, damage to the shoreline
and to buildings and structures along
the coast.
• As the sea level rises, the reef flats (the
shallow, flattest part of the reef that is
often uncovered at low tide) at the mean
low tide level will become less effective
in offering the shoreline protection from
waves.
3.2.5 Mediterranean
There are two UKOTs in this region:
Gibraltar and the Sovereign Base Areas of
Akrotiri and Dhekelia in Cyprus.
Observed change
• El Niño events have been associated
with low rainfall in the western and central
Mediterranean.
• Some of the larger river deltas in the
region have been affected by sea level
rise.
• There have been variations in sea surface
temperatures over the last 120
years, but no clear trend has emerged.
However, deep-water records for the
western Mediterranean point to continuous
warming from 1959 (Bethoux et al.,
1997 cited in Karas, 2000).
• Land records show a warming trend for
the western and central part of the
region and a slight cooling in the
eastern part of the basin.