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

3.2.7 South Pacific
There is one UKOT in this region: The Pitcairn
Islands.
Observed change
• Annual and seasonal ocean surface
and air temperature increased by 0.6°C
to 1°C since 1910 in much of the Pacific.
• There has been a significant decrease
in the annual number of cool days and
cool nights, particularly after El Niño
events, for the period 1961 to 2003.
• Sea level rise has varied across the
region, ranging from 1.5 mm to more
than 3 mm per year.
• There has been an increase in tropical
storm intensity. Climate scientists have
observed a correlation between ENSO
and the tracks, density and occurence
of cyclones (Walsh, 2004 cited in
Mimura et al., 2007).
Projections
The IPCC suggests that the climate in the
Pacific could be in a permanent El Niño
state with global temperature increases.
A World Bank study of the potential
impacts of climate change scenarios in the
Pacific (World Bank, 2000) projects the following
by 2100:
• Sea level may rise 0.5 m (“best-guess”
scenario) to 1 m (“worst-guess” scenario).
• Air temperature could increase
between 1.6°C and 3.4°C.
• Rainfall could increase or decrease
(most models predict an increase) by
20 per cent, leading to more intense
floods or droughts.
• Cyclones may become more intense,
with wind speeds increasing by as
much as 20 per cent; intensity could
increase by 5 to 10 per cent by 2050
(Walsh, 2004 cited in Mimura et al.,
2007).
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Implications and possible future
impacts
Changes in rainfall will also affect agricultural
production. Loss of coastal land would
reduce the available space for cultivation in
some countries. In low-lying ones, saltwater
intrusion would also affect production
of copra, breadfruit and panadanus. A
decline in the cultivation of some traditional
crops, such as yams and taro, would also
affect the subsistence economy of the
Pacific islands (World Bank, 2000).
The tuna fisheries in the western and central
Pacific could collapse.
Diarrhoeal and vector borne diseases are
expected to increase with warmer temperatures
in the Pacific. As in the Caribbean, the
frequency, severity and distribution of
dengue fever could increase, as warmer
temperatures reduce the incubation period
of the dengue virus and speed up the larval
stage of the mosquitoes.
Climate change could also increase the
incidence of ciguatera poisoning. Habitat
disturbance, including from extreme
weather, and warmer waters cause the
algal blooms that produce the ciguatoxins,
which are ingested by fish. In Kiribati, which
has one of the highest rates of ciguatera
poisoning, for example, by 2050 the incidence
of poisoning is expected to go up
from 35 to 70 people to 160 to 430 per thousand
(World Bank, 2000).
Variations in rainfall will affect water supplies
in some Pacific islands. Ground water
supplies in low-lying islands could be
affected by salt-water intrusion.
Coral reefs are also likely to be affected by
bleaching events, which could lead to
death of the corals and a decline in fisheries
and a long-term reduction in coastal
protection. Mangroves are likely to be
affected by sea level rise and flooding and
inundation will affect the costal zone in
some islands.