Environmental Engineering Reference
In-Depth Information
to play a significant role in shaping the changes
of the sea surface temperature, sea level, sea ice
cover, salinity, ocean circulation and climate
related oscillations. Some of the main features
of observed and projected changes in the char-
acteristics of ocean systems include:
•
Increased level of flooding, loss of wet-
lands and mangroves and saline water in-
trusion into freshwater habitats.
•
Severity and increase of cyclonic events
leading to coastal erosion, loss of ecologi-
cal diversity along shorelines.
•
An increase of the global ocean heat con-
tent since the 1950s.
Marine ecosystems are also likely to be affected
by changes in sea water temperature, oceanic
circulation patterns which may lead to changes in
composition of marine biota, timing of migratory
patterns, disturbances in ecosystem function. The
increased amounts of CO2 absorbed by oceans
are also likely to have significant impacts on the
acidity of ocean waters which in turn can have
serious consequences for certain marine animals
like mollusks, corals etc.
The Fourth Assessment Report of the IPCC
(IPCC 2007b) has suggested that climate change
is likely to have significant impacts on the coastal
regions of India. Some of these include:
•
Global average sea level rise of between
0.1 -0.2 m due to thermal expansion of
water and the loss of mass from glaciers
and ice caps. This is expected to increase
to 0.6m or more till 2100. (IPCC 2007b)
•
A decrease in the extent of sea ice in the
Northern hemisphere of more than 10%
including a decrease of 40% in recent de-
cades of sea ice thickness
•
An increase in the frequency, persistence
and intensity of extreme weather events
based on the El Nino southern oscillation
(ENSO) cycle since the mid -1970's.
•
Increased frequency of hotter days and
multiple-day heat wave in the past century
with increase in deaths due to heat stress in
recent years.
Over the past few years changes in rainfall,
currents, and sea level associated with global
warming, are already affecting the world's coastal
ecosystems and fisheries. The recent IPCC report
has also provided ample evidence of the impli-
cation of climate change on our biodiversity
and the increasing vulnerability of some of our
critical ecosystems and consequences for liveli-
hoods of people. Erratic weather and monsoon
patterns, along the Indian coastline along with
frequent extreme climatic events like cyclones
are major threats to the ecosystem including in
some cases low-lying islands some of which are
already facing partial submergence resulting in
shoreline changes.
Coastal ecosystems are particularly sensitive
to physical and biochemical changes with refer-
ence to:
•
Sea-level rise has led to intrusion of sa-
line water into the groundwater in coastal
aquifers and thus adversely affecting local
freshwater resources. e.g. for two small
and flat coral islands at the coast of India,
the thickness of freshwater lens was com-
puted to decrease from 25 m to 10 m and
from 36 m to 28 m respectively, for a sea
level rise of only 0.1 m.
•
Warmer climate, precipitation decline and
droughts in most delta regions of India
have resulted in drying up of wetlands and
severe degradation of ecosystems
•
Ganges-Brahmaputra delta: More than 1
million people are likely to be directly af-
fected by 2050 from risk through coastal
erosion and land loss, primarily as a result
