Chennai, Calcutta in India, at particular risk due to sea level rise
A new study on climate change has revealed that Chennai and Kolkata are at high risk if the sea level rises.
Other Asian cities at risk include Yangon, Bangkok, Ho Chi Minh City, Manila, western tropical Pacific islands and the western Indian Ocean, PTI reported.
The study published in the journal Nature Climate Change warned that several Asian cities may bear significant consequences by the year 2100 if emission of high levels of greenhouse gases is not controlled. The study focused on the effects of natural sea level fluctuations on the projected rise due to global warming and climate change.
According to the World Meteorological Organisation, sea level rise is a major threat for India and other countries with large coastal populations.
Global mean sea level increased by 0.20m between 1901 and 2018, with an average rate increase of 1.3 mm/ year between 1901 and 1971,1.9 mm/year between 1971 and 2006, and 3.7 mm/year between 2006 and 2018, WMO said in its report.
The study revealed that global warming is a major cause of an increase in the sea level as the water expands when it warms and melting ice sheets release more water into the oceans.
The study significantly highlighted the consequences of internal climate variability – a process of naturally occurring sea level fluctuations caused by El Nino or changes in the water cycle. It indicated that internal climate variability may increase sea level in certain locations by 20-30% more than the consequences of climate change, leading to an exponential rise in flooding events, the report added.
The report has predicted coastal flooding events to occur 18 times more often by 2100 than in 2006 based on climate change in the Philippines’ Manila. However, they could occur 96 times more often based on a combination of climate change and internal climate variability.
Aixue Hu, National Center for Atmospheric Research (NCAR) scientist and co-author of the research said, “The internal climate variability can greatly reinforce or suppress the sea level rise caused by climate change. In a worst-case scenario, the combined effect of climate change and internal climate variability could result in local sea levels rising by more than 50% of what is due to climate change alone, thus posing significant risks of more severe flooding to coastal megacities and threatening millions of people.”
The study drew on a set of simulations conducted with the NCAR-based Community Earth System Model that assumed society would emit greenhouse gases at a high rate in this century. The authors stressed the fact that society needs to be aware of the potential of extreme sea level rise in order to develop effective adaptation strategies.