THESE 2 Indian cities are at risk due to sea level rise | Mint – Mint

The team further stated that several Asian megacities that may face especially significant risks by 2100 if society continued to emit high levels of greenhouse gases. Apart from Chennai and Kolkata, other Asian cities like Yangon, Bangkok, Ho Chi Minh City, and Manila are also at risk. The study was published in the journal Nature Climate Change.

Last year in April, a study had also shown that several Indian cities that lie near the sea may get submerged in the next 28 years due to the rise in water level. According to the analysis by RMSI, some critical properties and road networks in Mumbai, Kochi, Mangalore, Chennai, Vishakapatnam, and Thiruvananthapuram will be drowned by 2050 because of the rise in sea level.

In December last year, Union Minister Jitendra Singh had said that the average sea level rise increased from 1.3 mm/year between 1901-1971 to 3.7 mm/year between 2006-2018

Coming to the latest study, it showed that internal climate variability could increase sea level rise in some locations by 20-30 percent more than what would result from climate change alone, exponentially increasing extreme flooding events.

In Manila, for example, coastal flooding events are predicted to occur 18 times more often by 2100 than in 2006, based solely on climate change, the study said. But, in a worst-case scenario, they could occur 96 times more often based on a combination of climate change and internal climate variability, it said.

The study was conducted looked at the effects of natural sea level fluctuations on the projected rise due to climate change, it said. It did so by mapping sea level hotspots around the globe. 

Scientists have long known that sea levels will rise with increasing ocean temperatures, largely because water expands when it warms and melting ice sheets release more water into the oceans. However, What is notable about this study is the way it incorporates naturally occurring sea level fluctuations caused by such events as El Nino or changes in the water cycle, a process known as internal climate variability, the study said.

According to the study, by using both a computer model of global climate and a specialized statistical model, the scientists could determine the extent to which these natural fluctuations can amplify or reduce the impact of climate change on sea level rise along certain coastlines.

Internal climate variability will also increase sea level rise along the west coasts of the United States and Australia, it said.

The study drew on a set of simulations conducted with the National Center for Atmospheric Research (NCAR)-based Community Earth System Model that assume society this century emits greenhouse gases at a high rate. The simulations were run at the NCAR-Wyoming Supercomputing Center.

The paper stressed that the estimates of sea level rise come with considerable uncertainties because of the complex and unpredictable interactions in Earth’s climate system.

But the authors said it is critical for society to be aware of the potential of extreme sea level rise in order to develop effective adaptation strategies.

NCAR scientist Aixue Hu, who co-authored the paper 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 per cent of what is due to climate change alone, thus posing significant risks of more severe flooding to coastal megacities and threatening millions of people,” said Hu.

Meanwhile, in January, a study had also said that the biggest inundation will happen after the first two metres of sea level rise, which would cover more than twice the land as was predicted in older elevation models. The highest level of impact would happen after the sea level rises by several metres. The study was published in the journal Earth’s Future. The study used high-resolution measurements of land elevation. The measurements were taken from NASA’s ICESat-2 lidar satellite, launched in 2018, to improve upon models of sea level rise and inundation. The radar-based data are, however, less precise, researchers have said, If there is a sea level rise of two metres, nearly 240 million people will live below the mean sea level. If there are three and four metres of rise, there will be an increase of 140 million and 116 million, respectively.

(With inputs from PTI)