Above: Child playing on the Ghormara island in Sunderbans, which is being increasingly affected by rising sea levels Photo: Phys.org
Global ocean levels have risen by about 19 cms in the past century[i]. Over 1961-1993, the global average sea level rose at a rate of 1.4 mm per year. But in the recent past, the rate of rise has gone up. Over 1993-2003, it was observed that the average rate of rise more than doubled to about 3.1 mm per year[ii]. As the earth gets warmer, the threat of land inundation due to sea level rise also increases.
So what is the cause of this rise? According to scientists, this is caused due to thermal expansion of the ocean water and due to melting of glaciers and of ice caps. The amount these have contributed to the above is only speculative as the data available for such estimations is spotty and does not date back far enough. But what is somewhat known is the loss this creates and might create in the future in terms of land inundation, though not really accounting for the loss in the lives of various people, especially the ones living along coasts. The problem today is not that this is happening, the problem is that we do not seem to be doing enough to mitigate the impacts of the sea level rise, nor do we seem to do anything to adapt to it.
In the case of the Indian subcontinent, according to a report published by a group of ecologists led by Dr. M Zafar-ul Islam, there may be a loss of about 14,000 sq. km. of land in case the sea levels rise by one metre[iii]. The report also warns that marine intrusion might affect 18 of the 48 eco-regions in India. This report mainly assesses the losses in the case of sea levels rising by one metre and six metres. In the one metre scenario, which is the estimated rise by 2100, the Sundarbans may lose about half of their area, while the Godavari-Krishna mangrove region is estimated to lose about a quarter of its land. It is also estimated that seven protected areas – Bhitarkanika, Chilka Lake, Point Calimere, Interview Island, Lothian Island, Sajnakhali and Pulicat Lake- would be about 50% flooded in case of a 1 metre riseiii.
In the Sundarbans part of the largest riverine delta of the world, the villagers are struggling to protect their lands as more and more land is being claimed by sea water, sinking villages. The people living on the banks of these islands have observed that the river has widened and is eating into the island on a regular basis, constantly reshaping them. A study by Professor Sugata Hazra, director of the School of Oceanography, Jadavpur University, found that the total land area of 6402.090 sq. Kms of Sunderbans in 2001 was found to be reduced to 6358.048 sq kms in 2009. This would mean an approximate loss of about 44.042 sq kms. This has led to the displacement of approximately 7,000 people in the last 30 years according to this study[iv], but this seems like an under-estimation. The MoEF’s (Union Ministry of Environment and Forests) Climate Change Assessment report, also called 4 X 4 report (since it looks at 4 Sectors in 4 most vulnerable regions), prepared by the Indian Network of Climate Change Assessment, quoted a 2000 study by Goodbread and Kuehl, which said that the rise in sea level can be attributed partially to the subsidence of the Ganga-Brahmaputra delta at the rate of about 4mm/year, as estimated by sedimentological studies[v].
Deltas as sinking as sediments are trapped by dams The sinking of deltas due to upstream interventions are also contributing to impacts felt in the coastal areas, in addition to the impacts due to rising sea levels. In many cases like the above, part of the driving force for effective rise in sea levels is the sinking deltas due to the absence of sediments from the upstream. According to a report by SANDRP earlier this year, the Ganga-Brahmapuptra delta, carrying one of the highest sediment loads of the world, has experienced a 30% reduction in sediment over the past century. Thus the impacts seen in case of the Sundarbans is a mix of two factors: rising sea level and delta sinking. The driving force behind sinking deltas is damming of rivers in the upstream, which blocks sediments from entering the river channel and effectively, the Delta. The reduction in water flow to the deltas due to upstream diversions adds to this.
These dams trap the sediment that should have come downstream with the river and deposited on the delta. Moreover, due to water diversions in the upstream, less and less water is flowing in the deltas, and less flow means less capacity to carry sediment to the deltas. Due to these reasons, the deltas are experiencing reduced silt deposit which then leads to their sinking and the sea eating away the remaining area. According to the report, in the last 50 years, the combined annual sediment flux of the large Chinese rivers has reduced from 1800 million tons (Mt) to about 370 Mt mainly due to the construction of a large number of dams[vi]. The Yellow river delta in China is sinking so fast that the local sea levels are effectively rising by upto 25 cms/year, nearly 80 times the global average.i
It is also interesting to note that in places like Jakarta, Indonesia, which is home to almost 10 million people, the heavily populated areas have sunk by as much as six and a half feet as groundwater is pumped from the earth to drink[vii]. This increases their risk of flooding and even more so if the groundwater levels continue to drop. With this drop in groundwater levels, the river flow in downstream areas decrease. This reduces the capacity of the river to carry silt, thus making the condition even worse[viii].
An estimated half a billion people live on or near deltas, constituting the highly vulnerable populations. The government needs to alter its development plans to suit the vulnerabilities and needs of these people. With its constant imposition of building large dams and barrages without taking into account the impacts they are going to have downstream, the government is just adding to the existing impacts and threats faced due to climate change. Moreover the governmnet anyways refuses to acknowledge that large sections of Indian people, particularly the poor and weaker sections are suffering due to the impacts of climate change, it refuses to identify people who are vulnerable to climate change, it refused to compensate them when they suffer for no fault of theirs and it refuses to demand from the climate polluters in the west and within India to pay for the losses.
Above: A woman wades across water in the Ganga Brahmaputra Delta. The dams hold back sediments crucial to the delta formation. Source: http://www.thethirdpole.net/dams-responsible-for-south-asias-sinking-deltas/
Reports: IPCC In the recent past, there has been much interest in sea levels rising and some research has gone into this direction. The Intergovernmental Panel on Climate Change has been assessing and publishing about the various impacts of climate change and through their assessment reports, but it is not the only body doing this. In fact, it has come under a lot of criticism lately with people outside the body, especially ones who use semi-empirical models for study, showing that the figures of the IPCC under estimate the risk at hand.
In the 4th Intergovernmental Panel on Climate Change (IPCC) report, 2007, global sea levels were observed to be on the rise with the projected rise being about 18-59 cms by 2100. After facing criticism for this figure seen as an underestimation, IPCC came out with a 5th report on climate change. In this, the predictions of global rise in sea level have gone up by 50% and now stand at 28-98 cms by 2100. This is the wide range. For high emissions, the IPCC predicts that there will be a rise by 52-98 cms, whereas, even with emission reductions, the rise is predicted at 28-61 cms[ix]. These projections are made for the global sea level for 2081-2100 relative to 1986-2005. This then puts a lot of low-lying areas at the risk of flooding. These estimates are speculative to some extent due to the complexities inherent to the models used for study and spotty data. These estimates are also likely to be under estimates.
Other reports predict higher sea level rise The models that the IPCC uses for study are process models. This range given by them is derived from these models in combination with climate projections and literature assessment of glacier and ice sheet models. Some other studies done using ‘semi-empirical’ models, give different results. These studies look at how temperatures have changed over hundreds of years and the way sea levels have corresponded to it. They extrapolate based on this and their figures have come to be almost twice as high as what the IPCC found. They argue that the sea levels will rise by as much as 2 metres, and cause floods affecting roughly 187 million people[x]. The IPCC has dismissed these models as divergent and inaccurate, perhaps themselves adopting a more conservative approach than they should.
Maale, capital of the Maldives, an Indian Ocean archipelago that is the lowest, flattest country on Earth is now protected by a seawall. By 2100 rising seas may force Maldivians to abandon their home. Photo: George Steinmetz. Source: http://ngm.nationalgeographic.com/2013/09/rising-seas/steinmetz-photography#/08-maale-maldives-670.jpg
Not being able to put a finger on it: One of the problems pointed out about the IPCC is that it does not provide the upper limit for sea level rise. For instance, if the collapse of marine-based sectors of the Antarctic ice-sheet is initiated, then the sea level could rise by several times more than projected during the 21st century[xi]. Scientists have estimated that the ice caps in the poles and Greenland hold enough water to raise sea level by 65 metresi. In the case of Greenland, scientists have assessed that the entire island is losing weight. The warm shore water is causing glacier calving into the sea. In a recent press release on a study conducted on ice sheets in Antarctica and Greenland, Veit Helm, glaciologist at the Alfred Wegener Institute (AWI) in Bremerhaven said that ice sheets are losing volume at the rate of about 500 cubic km per year[xii]. This study found that the volume loss in Greenland has doubled since the year 2009. At the same time, the loss of the West Antarctic sheet has tripled. This then means that the estimated rise in sea levels needs to be relooked at.
It is the responsibility of the governing authorities to take measures to try and minimize the damage that is occurring and will occur from climate change and its own skewed development projects. The government needs to identify, acknowledge and safeguard the already vulnerable communities and not make them more vulnerable in the face of the dangers they face from climate change. There is a need to integrate these climate change warnings and mitigation measures into planning and development, especially in the coastal areas. This is clearly not happening. There is little effective steps from Indian government to protect mangroves, deltas, or coastal areas either from dams and diversions in the upstream or from sea-level rise in the downstream. On the contrary, the government plans are for accelerating the dam construction in the upstream and destructino of mangroves due to coastal projects. India’s National Action Plan on Climate Change or the state Action Plans on Climate Change do not have any credible assessments or mitigation or adaptation plans in this context.
There have been increased instances and intensities of tsunamis, floods and cyclones in the recent past. In the case of rising sea levels and deltaic changes, the warnings have been there for a long time. It is not going to be a sudden catastrophe, but is a well established danger which lurks on our coasts. Therefore, there is no excuse to let it go unaddressed. There is no excuse for inaction.
Padmakshi Badoni, SANDRP, email@example.com
[viii] For a recent update on the groundwater situation in India, see: https://sandrp.wordpress.com/2014/08/11/groundwater-falling-levels-and-contamination-threaten-indias-water-lifeline-urgent-need-for-community-driven-bottoms-up-management/