Abstract:
Extreme climate events are an important concern for a resource constraint country like Bangladesh
due to its impacts on society in the form of loss of economic goods, life and property. Reliable
estimates of future extreme climate events relating to extreme precipitation and extremes of
temperature are a valuable guide for policy makers in determining infrastructure requirements for
the 21st century.
Using a standard set of annual and seasonal climate extreme indices derived from daily temperature
and precipitation data, rate of change of extreme indices and 30- year average values of the indices
are analyzed for the baseline period (1961-1990). Extreme indices from PRECIS (Providing
REgional Climates for Impacts Studies) output data were validated against those calculated from
the observed data of Bangladesh Meteorological Department (BMD), to predict the values of
extreme indices in the coming decades. The results show that PRECIS is able to simulate daily
temperature related extreme indices with lower percentage bias as compared to the precipitation
extreme indices.
From our knowledge of the climate patterns of Bangladesh we know that Sylhet region especially
Srimangal receives heavy precipitation annually with respect to Rajshahi which is arid and known
for infamous drought ridden lands. This is found true for the extreme indices calculated from
PRECIS data during the period (1961-1990) which showed that the maximum value of the 30-year
average of precipitation extreme indices is obtained at Sylhet or Srimangal. For the BMD data the
precipitation extreme indices occur at Sitakunda and Patuakhali in addition to Sylhet and
Srimangal. The temperature extremes are found to occur more at the coastal regions like Cox’s
Bazar and Teknaf than at the inland stations for both the BMD and PRECIS data.
PRECIS predicted that towards the end of coming decades like 2021, 2031 and 2051 Sylhet and
Srimangal will remain as the wettest regions of the country with a stark change to come in 2071 and
2091 when Teknaf, Cox’s Bazar or Patuakhali will be receiving extreme precipitations. From the
results obtained, extremes of maximum temperature will occur more often in Jessore. Furthermore
the extremes for minimum temperature are predicted to occur at Rajshahi.
