Climate change-induced sea level rise (SLR) is one of the greatest challenges of the low-lying coastal regions. WMO’s State of Global Climate 2021 report states the mean global sea level rise was 2.1 mm per year between 1993 and 2002 and 4.4 mm per year between 2013 and 2021. The global mean sea level (GMSL) rose by a factor of two within a period of 10 years due to increasing rates of ice loss from the Greenland and Antarctic ice sheets, as well as continued glacier mass loss and ocean thermal expansion.

According to the IPCC Sixth Assessment Report, in the next 2,000 years the sea level rise will be 2–3 metres if the temperature rises by 1.5 degrees, by 2–6 metres if the rise in temperature is 2 degrees and by 19–22 metres if temperature rise peaks at 5 degrees.   If temperature rise will stop at 2 degrees or at 5 degrees, the sea level will continue to rise for about 10,000 years. In the first case it will reach 8–13 metres above pre-industrial level and in the latter case SLR is projected to be around 28–37 metres.

A 2°C increase in global average temperature will cause global sea levels to rise between 0.35 and 0.93 meters by end of this century. This magnitude of sea rise will destroy the coastline and displace people and property by way of severe erosion of coastline, flooding and inundation of low-lying coastal areas, storm damage associated with severe cyclones and storm surges, saltwater intrusion, and wetland loss.

What is RCP?
IPCC AR4 uses four Representative Concentration Pathways (RCP 2.6, RCP 4.5, RCP 6.0 and RCP 8.5) to quantify future greenhouse gas concentrations and the radiative forcing due to increases in climate change. RCP 2.6 will result in the least amount of global warming and only limited climate change. RCP 8.5 will result in more rapid warming and more climate change.

Need for Adaptation:
Adaptation to the rising sea level is considered the most appropriate response measure to face this global challenge. Identifying the most vulnerable coastal regions and acting on them is very much needed for adaptation planning. While planning major infrastructure development projects along the coast, including ports, power plants and highways climate resilient engineering solutions should be considered. Adaptation strategies like coastal defences, land use planning, building setbacks, enhanced drainage and water supply systems, salt water intrusion barriers, cyclone shelters, community awareness and livelihood improvement of coastal communities need to planned and implemented to cope up with challenges posed by the raising sea level.