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Annual<br />

DJF<br />

MAM<br />

JJA<br />

SON<br />

Observed<br />

Mean<br />

1970-99<br />

<strong>Turks</strong> <strong>and</strong> <strong>Caicos</strong> Isl<strong>and</strong>s: Country scale changes in Rainfall Extremes<br />

Observed<br />

Trend<br />

1960-2006<br />

mm Change<br />

in mm<br />

per<br />

decade<br />

A2<br />

A1B<br />

B1<br />

A2<br />

A1B<br />

B1<br />

A2<br />

A1B<br />

B1<br />

A2<br />

A1B<br />

B1<br />

A2<br />

A1B<br />

B1<br />

3.10. Hurricanes <strong>and</strong> Tropical Storms<br />

Projected changes by Projected changes by Projected changes by<br />

the 2020s<br />

the 2050s<br />

the 2080s<br />

Min Median Max Min Median Max Min Median Max<br />

Maximum 5-day Rainfall (RX5day)<br />

Change in mm Change in mm<br />

28<br />

-14 -1 17 -18 -3 11<br />

-18 0 12 -16 0 29<br />

-13 0 23 -15 -4 18<br />

-9 0 9 -9 1 9<br />

-7 0 9 -9 0 9<br />

-7 -1 8 -8 0 3<br />

-12 -4 14 -18 -7 6<br />

-14 -3 12 -15 -4 13<br />

-8 -1 12 -10 0 25<br />

-16 -3 11 -21 -6 -1<br />

-16 -3 3 -28 -5 0<br />

-13 -2 18 -13 -3 5<br />

-11 -4 13 -18 -2 12<br />

-19 0 12 -13 0 33<br />

-11 0 22 -13 -3 10<br />

Historical <strong>and</strong> future changes in tropical storm <strong>and</strong> hurricane activity have been a topic of heated debate in<br />

the climate science community. Drawing robust conclusions with regards to changes in climate extremes is<br />

continually hampered by issues of data quality in our observations, the difficulties in separating natural<br />

variability from long-term trends <strong>and</strong> the limitations imposed by spatial resolution of climate models.<br />

Tropical storms <strong>and</strong> hurricanes form from pre-existing weather disturbances where sea surface<br />

temperatures (SSTs) exceed 26˚C. Whilst SSTs are a key factor in determining the formation, development<br />

<strong>and</strong> intensity of tropical storms, a number of other factors are also critical, such as subsidence, wind shear<br />

<strong>and</strong> static stability. This means that whilst observed <strong>and</strong> projected increases in SSTs under a warmer<br />

climate potentially exp<strong>and</strong> the regions <strong>and</strong> periods of time when tropical storms may form, the critical<br />

conditions for storm formation may not necessarily be met (e.g. Veccchi <strong>and</strong> Soden, 2007; Trenberth et al.,<br />

2007), <strong>and</strong> increasing SSTs may not necessarily be accompanied by an increase in the frequency of tropical<br />

storm incidences.<br />

Several analyses of global (e.g. Webster et al., 2005) <strong>and</strong> more specifically North Atlantic (e.g. Holl<strong>and</strong> <strong>and</strong><br />

Webster, 2007; Kossin et al., 2007; Elsner et al., 2008) hurricanes have indicated increases in the observed<br />

record of tropical storms over the last 30 years. It is not yet certain to what degree this trend arises as part<br />

of a long-term climate change signal or shorter-term inter-decadal variability. The available longer term<br />

records are riddled with in homogeneities (inconsistencies in recording methods through time) - most<br />

significantly, the advent of satellite observations, before which storms were only recorded when making<br />

l<strong>and</strong>fall or observed by ships (Kossin et al., 2007). Recently, a longer-term study of variations in hurricane

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