Sea levels along almost the entire Indian coast are rising faster than the global average, according to the World Meteorological Organization’s (WMO) State of the Global Climate in 2021 report. Globally, the rate of sea-level rise was 4.5 millimetre per year between 2013 and 2021. This was more than twice the rate between 1993 and 2002.

Reasons

• The major reason for the increase in sea levels is the accelerated loss of ice from the ice sheets in the Arctic and Antarctic regions. The increase happened despite the La Nina phenomenon being prevalent during the beginning and the end of 2021.
• La Nina is the cooler-than-normal phase of the El Nino Southern Oscillation phenomenon in the equatorial Pacific Ocean. Usually during La Nina years, sea levels are less than the mean.
• During El Nino (warmer-than-normal phase) years, they are higher than the mean. In 2021, the global mean sea level rise was close to the long-term trend.
• The increase in sea levels is not happening uniformly in all parts of the global oceans. In the Indian Ocean region, the rate of sea-level rise is the fastest in the south western part, where it is faster by 2.5 mm / year than the global average.
• In other parts of the Indian Ocean region, including the coastlines, the rate is between 0 and 2.5 mm / year, faster than the global average.

Impact

• Such a sea-level rise could have major consequences for the millions of people living along the Indian coastline.
• While gradual erosion of the coastline, subsidence and inundation of deltas are a long-term concern for the people living close to the sea, the immediate concern is to do with the combined impact of tropical cyclones and sea-level rise.

For instance, when a tropical cyclone occurs, the storm surge along with heavier rainfall, sea-level rise and high tides could make the resultant flooding much more intense and hence difficult to manage.

• Storm surge is the increase in the height and energy of sea waves during a cyclone which depends on the wind speeds of the cyclone. The higher the wind speeds of a cyclone, the more is their ability to pile up water towards the centre of the cyclone; hence a stronger storm surge. Storm surges may also get intensified if there is a high tide during the time of the cyclone. The combined effect of a storm surge and a high tide is known as a storm tide. Storm surges and tides bring saline water into agricultural fields and people’s homes, leading to long-term damage, including a decrease in soil quality.
• Coastal Flooding: Eight of the world’s ten largest cities are located on a coast, making them vulnerable to coastal flooding.
• Flooding in low-lying coastal regions is driving people to flee to higher ground, resulting in displacement and dispossession and, as a result, a global refugee crisis.
• Rising seas can pollute soil and groundwater with salt, endangering life further inland.
• Tourism and military readiness: An rise in SLR will have a negative impact on coastal tourism and military readiness.
• Coastal biodiversity destruction: SLR can result in damaging erosion, wetland floods, salt pollution of aquifers and agricultural soil, and biodiversity habitat loss.
• Higher sea levels are resulting in more destructive storms and typhoons, resulting in the loss of lives and property.
• Impact on Infrastructure: The likelihood of rising coastal sea levels puts essential utilities like internet connectivity in jeopardy.
• Recent cyclones in the Indian Ocean region have increased in intensity, with greater wind speeds than before which has meant higher storm surges. As sea levels rise, the storm surges will become even stronger and take more seawater onto land, causing inundation.

Measures

• Relocation: As a mitigating technique, several coastal cities have planned to relocate. Kiribati Island, for example, is planning to migrate to Fiji, while Indonesia’s capital is being moved from Jakarta to Borneo.
• The Dutch city of Rotterdam constructed barriers, drainage, and unique architectural features such as a “water square” with temporary ponds to help control the flow of water.
• Building a Sea Wall: In 2014, the Indonesian government initiated a coastal development project named “Giant Garuda” to safeguard the city from flooding.

If global warming is not kept under the 1.5°C mark as agreed to by countries under the Paris Agreement by rapid reduction of greenhouse gas emissions, the rise in sea levels and intense cyclones will make places like the Sunderbans unliveable, causing a huge migration of people inland and a cascade of other socio-economic problems.

https://www.downtoearth.org.in/news/climate-change/sea-levels-along-indian-coast-rising-at-faster-rate-than-global-average-wmo-report-82910

How to structure

1. Give a brief intro about the climate change induced sea level rise and map the coastal Indian regions
2. Explain the social and economic consequences of this seas level rise
3. Suggest measures
4. Conclude