Climate
Change
Present and Future Perspective of Sri Lanka |
| By
Dr. B.R.S.B. Basnayake |
| Introduction |
| Climate
Change is defined as statistically significant variation
in either mean state of the climate or in its variability,
persisting for an extended period (typically decades
or longer). Climate change may be due to natural
internal processes or external forcing or to persistent
anthropogenic changes in the composition of the
atmosphere or in land use (IPCC, 2001).
Since
the industrial revolution, change of climate has
been occurring at an accelerated rate as a result
of human activities such as fossil fuel burnings,
change of land use practices (in particular deforestation),
emission of industrial gases etc. The global warming
of the earth-atmosphere system is brought about
by enhanced greenhouse effect. Greenhouse effect
makes the surface of the earth some 33 0C warmer
than it would otherwise be (i.e. with a mean surface
temperature of 14 0C instead of –19 0C) and
allows life forms to exist The gases that are responsible
for this enhanced greenhouse effect in the natural
atmosphere are Water vapor (H2O),
Carbon Dioxide (CO2), Nitrous
Oxide (N2O), Methane (CH4),
Ozone (O3), Hydrofluorocarbons
(HFCs), Sulphur Hexafluoride (SF6)
and Perfluorocarbons (PFCs). Atmospheric concentration
of CO2 has rapidly been increased from 280 ppm during
the pre industrial era to 365 ppm at present, due
to enhanced anthropogenic activities to make human
lives more comfort. |
| |
| Rainfall
Change |
| Annual
average of rainfall over Sri Lanka has been decreased
by an amount of 144 millimeters, about seven percent,
during 1961 to 1990 period compared to 1931 to 1960
period (Chandrapala 1997) with the standard deviation
increasing from 234 to 263 millimeters. Northeast
monsoon rainfall over Sri Lanka has been decreased
from 1931 – 1960 to 1961-1990 periods, with
an increased variability. Southwest monsoon rainfall
has not shown any significant change during these
two periods; however variability has been decreased
during 1961-1990 compared to 1931-1960. High variability
of annual rainfall is reported at Baticaloa, Kurunegala,
and Rathnapura (Fig. 1) meteorological stations
in the recent past compared to other meteorological
stations. No significant trends of annual rainfall
have been noticed during the last century. High
variability of rainfall patterns could probably
be due to global climate change with the increase
of Greenhouse gases in the atmosphere. |
| |
| |
| Temperature
Change |
| Annual
mean air temperature anomalies have shown significant
increasing trends during the recent few decades
in Sri Lanka (Basnayake et al 2002). The rate of
increase of mean air temperature for the 1961-1990
period is in the order of 0.016 0C per year (Chandrapala,
1996). Annual mean maximum air temperatures have
shown increasing trends in almost all stations with
the maximum rate of increase about 0.021 0C per
year at Puttalam. Nighttime annual mean minimum
air temperatures have also shown increasing trends
with higher gradients. The maximum rate of increase
of nighttime annual mean minimum air temperature
is reported about 0.02 0C per year at Nuwara-Eliya
(Fig. 2). |
| |
| It
has been evident that increase in average annual
surface temperatures across the country during recent
time is largely due to the increase in nighttime
minimum temperature than that of the daytime maximum
temperature. This trend is similar to the global
trend of rising temperature during the last century.
Enhanced greenhouse effect could partly be responsible
for this warming in addition to the local heat island
effects caused by the rapid urbanization that has
been taken place during the recent past. |
| |
| Baseline
Climatology of Rainfall and Temperature |
| During
the Northeast Monsoon (NEM) period (December, January
and February), highest rainfalls are confined to
the eastern slopes of the central highlands of which
the maxima of about 1200 mm is located just below
the tip of the central hills (Fig. 3). This is mainly
due to the somewhat rich moist flow of northeasterlies
during this period. During March and April, when
the 1st inter-monsoon is in effect, heavy fall are
clearly observed in the southwestern parts of the
island. |
| |
| Future
Scenarios of Rainfall >>> |
| |
| |
| Related
Topics |
| |
| Impacts
of Climate Change on Extreme Weather Events |
| Ozone
Layer Depletion and Climate Change |
| Impact
of Climate Change on Agriculture in Sri Lanka and
Possible Response Strategies |
| Climate
Change and Mitigation Options in Energy Sector in
Sri Lanka |
| Implementation
of United Nations Framework Convention on Climate
Change and Kyoto Protocol |
| Impacts
of Climate Change on Water Resources and Adaptation
Measures |
| Impacts
& Adaptation of Climate Change in Health |
| Climate
Change and Mitigation Options in Industrial Sector
in Sri Lanka |
| |
