Coastal Zone & Climate Change

Submitted by: DIVYA SONI

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INTRODUCTION• India’s coastal and marine ecosystems include a wide range of

mangroves, coral reefs, sea grasses, salt marshes, mud flats, estuaries, lagoons, and unique flora and fauna.

• According to Census 2011, nearly 48% of India’s population from coastal regions is currently living in urban areas

• Coastal areas are exposed to frequent occurrence of cyclones, storms, and environmental degradation.

• The change in climate is expected to increase the frequency and intensity of these events and further incite new hazards.

CLIMATE CHANGE EVENTS AS A RESULT OF GLOBAL WARMING

RISING SEA LEVEL STORM SURGES SST VARIATIONS

SEA LEVEL RISE

• With India close to the equator, the sub-continent would see much higher rises in sea levels than higher latitudes.

• IPCC has estimated a sea level rise of 1 to 2 mm per year globally. • 1m rise in sea level will displace more than 7 million people, destroy

more than 5000 square kms of land and 4000 kms of roads.• By the end of the 21st century, it is very likely that sea level will rise

in more than about 95% of the ocean area.• SLR would lead to saltwater intrusion in the coastal areas impacting

agriculture, degrading groundwater quality, contaminating drinking water, and possibly causing a rise in diarrohea cases and cholera outbreaks, as the cholera bacterium survives longer in saline water.

• Other implications - flooding, migration to interior, conflicts over land and water, waste removal problems, health issues

Net sea-level-rise trends from past tide-gauge data

Sea level changes-past, present and future

Potential effects of 1mt sea level rise on India’s coastal area and population

STORM SURGES

• Storm surges are also the major cause of coastal flooding along the east coast of India

• The projected rise in the sea level due to greenhouse warming may affect the storm surges and consequently the coastal flooding in the east coast.

• East coast more vulnerable than west coast due to higher frequency and magnitude of tropical cyclone.

Damage due to Cyclonic Storms/Heavy Rains /Flash Floods/Landslides in coastal

states of India (2010-2011 and 2011-2012)

SEA-SURFACE TEMPERATURES• The warming of the

ocean has contributed significantly to the observed sea level rise, through thermal expansion of sea water

• Increased the heat stress of the coral reefs.

• Affects rainfall patterns.

CURRENT SEA SURFACE TEMPERATURES ANOMALY

• Southeast Indian OceanSouthwest Indian Ocean

IMPLICATIONS OF CLIMATE CHANGE

CORAL REEFS

• Coral reefs constantly police fluctuating sea level changes across low lying coastal terrains

• Protect the coastal populace from strong storm and tidal surges; thus preventing denudation and subsequent inundation of adjoining landforms from the vagaries of nature’s fury.

• As the SST are likely to cross the upper thermal threshold of reef- corals, Bleaching event has been perceived as a major threat to many reef systems, resulting in the collapse of entire stands of mono specific coral gardens

• OCEAN ACIDIFICATION--which occurs when oceans absorb CO2 from the atmosphere--is also a threat to coral. As the oceans become more acidic, the corals' ability to form skeletons through calcification is inhibited, causing their growth to slow.

• The increasing frequency of tropical hurricanes and thunderstorms, exacerbated by climate change are another source of coral reef destruction

• Sea level rise caused by melting sea ice and thermal expansion of the oceans could also cause problems for some reefs by making them too deep to receive adequate sunlight, another factor important for survival.

MANGROVES• The mangroves act as barriers

against cyclones, avoid coastal erosion and serve as habitat for a number of aquatic lives specially fish, prawns and crabs.

• Frequent occurrences of tropical cyclones, storms and tsunamis, have damaged the mangroves of India

• India lost 40% of its mangrove area during the last century

• The mean annual change of mangrove area in India during 1987-2013 is 24.25 ± 82.57 sq.kms

• Due to sea level rise mangroves tend to move landward, but human encroachment prevents this and consequently, the width of the mangroves decreases

Differences in the effect of wave reduction (a) with and (b) without mangroves

COASTAL EROSION

• Waves and storm surges increasingly erode the Indian Coasts• As much as 45% of India’s 8,414-km long coastline is facing

erosion• Close to 19% of the coastline is stable and about 36% is showing

accretion, or expansion. of Bengal.• The Andaman and Nicobar Islands face the most erosion, with

close to 89% of the shoreline eaten away by the Bay • At the other end of the spectrum is Tamil Nadu, which has

gained the most new shoreline, with 62% of its coast gaining land.

• Goa has the highest percentage (52%) of stable shoreline.

SOCIO ECONOMIC CHALLENGES

• Disputes over allocation of water and power• Migration to safe locations – competition for land and

water• Financial burden associated with rehabilitation and

reconstruction• Impact of floods on infrastructure• Setbacks in Coastal Tourism• Impact on industries, ports and trade etc. – current

economic growth maybe haltered