By Richard Mahapatra

Are Orissa's coastal villages paying the price of global warming? The scientific community studying Orissa's tryst with disasters is polarised on the issue. But most scientists agree that the state's geographical location at the head of the Bay of Bengal, with a landlocked sea and a deltaic plain, makes the state extremely vulnerable to rises in sea level caused by global warming

As village after village in Orissa’s coastal Kendrapara district vanishes into the Bay of Bengal, one thing is clear: sea levels are rising. Why is this happening?

Many say these villages, which themselves have virtually zero emissions of greenhouse gases, could be paying the price of global warming. The local people blame climate change for changes in the sea level. This correspondent interviewed about 70 residents of Satabhaya and Kanhapur villages near the port of Paradip. They all felt that the local climate has indeed changed and that rising seal levels are a result of increasing sea temperatures. Importantly, people also link higher temperatures to the increasing number of low-pressure areas in the Bay of Bengal. One trend clearly emerged: higher sea temperatures are causing more cyclonic conditions and, as a result, rising sea levels.

“There is a sharp increase in the number of low pressure areas in the Bay of Bengal. Just a decade ago it was not that frequent,” says Sukhadeva Parida, a resident of Kanhapur. In fact, during 2005, the Bay of Bengal witnessed 10 low-pressure phenomena, six of which were in the post-monsoon period of October-December. The locals believe that the increase in the number of low-pressure phenomena is aggravating coastal erosion in their villages. “Low pressure often triggers huge tidal waves that take away our villages,” says Nalinikant Biswal of Satabhaya village. The intensity of cyclones, in terms of wind speed and severity, has also increased; the 1999, 1982 and 1971 cyclones battered villages along the coast. People say that after each cyclone the sea level rose significantly and the submergence was quicker. They also say that there are more low-pressure conditions, often after the monsoons.

Another important perception is that overall temperatures are rising, and that low-pressures are directly linked to rising sea temperatures. Budha Charan Behera, 90, the oldest resident of Satabhaya, says: “Summer days are more now, and one can easily feel the warmer seawater. My father used to tell me that when the temperature of the sea rises, cyclones happen. For the first 60 years of my life I saw only one cyclone and very few low-pressure situations. Now, they happen almost every month. That is the reason the sea is rising.” Sixty out of the 70 people interviewed agreed with this point.

During a people’s perception study of climate change in Kendrapara district by scientists from the National Centre for Agricultural Economics and Policy Research, New Delhi, in 2002, 94% of respondents said the climate in their area had changed and that this induced calamities like cyclones and droughts. Interestingly, 90% of respondents said that rather than frequency, the intensity of cyclones had increased, thereby posing greater risk to life and property. The results of this study are similar to those of this correspondent’s survey.

The scientific community studying Orissa’s tryst with disasters stands polarised on the issue, although most do somewhat hesitantly blame global warming for rising sea levels. “This phenomenon may well be the preliminary impact of global warming-induced sea level rise. Going by simulated models of the impact of climate change on the Indian coast, this is one of the most probable impacts,” says Dr Murari Lal, a coordinating lead author of the Inter-governmental Panel on Climate Change (IPCC), a global body of scientists studying climate change. Lal, an atmospheric scientist, has extensively studied the impact of climate change in India. He says that, given Orissa’s geographical location at the head of the Bay of Bengal, a landlocked sea, and the state’s deltaic plain character, Orissa’s coast is extremely vulnerable to rises in sea level. “My calculations and research show that the phenomenon is a direct impact of climate change induced by global warming,” he says.

There is a strong similarity between people’s perceptions of the phenomenon and the scientific community’s simulations with global warming and rises in sea level along the Indian coast. “People’s perceptions are very important as that is the first symptom to diagnose climate change. People’s perceptions of rising sea levels due to overall warming and climate change are in line with scientific studies on this issue,” says Kalipada Chatterjee, a scientist working on the vulnerability and impact of climate change in India. Chatterjee is currently an advisor to Winrock International on climate change. In fact, Orissa’s climate trends confirm people’s perceptions: there has been an overall increase in temperatures; the number of cyclones has been increasing; sea levels are rising along the east coast.

For years, environmentalists have warned that one of the first and most reliable signs of global warming-induced climate change would be an upsurge in violent cyclones, like the Orissa cyclone of 1999. Global warming, in theory, exacerbates cyclonic conditions such as low-pressure phenomena. Warmer air easily translates into warmer oceans -- and warm oceans are the perfect trigger for low-pressure conditions and, consequently, severe cyclones. A statistical analysis of 98 years (1891-1988) has revealed that global warming in the present century is linked with the increasing frequency of pre- and post-monsoon cyclones in the Bay of Bengal. On the other hand, during the monsoon, cyclones have become less frequent, according to the Indian Institute of Tropical Meteorology, Pune. However, post-monsoon cyclones/low pressure phenomena have increased, indicating a warmer sea.

Going by the Indian Meteorological Department’s cyclone statistics for 1877-1990, the Orissa coast has been hit the hardest. Of the 964 cyclones that crossed the east coast during this period, 422 struck Orissa.

It is almost certain that an increase in sea surface temperature will be accompanied by a corresponding increase in cyclone intensity. Recent studies suggest a possible increase in cyclone intensity of around 10-20% for a rise in sea surface temperature of 2-4 degrees Centigrade. In low altitude and land-locked locations, such as the Bay of Bengal, tropical cyclones are the major cause of storm surges. Amplification in storm surge heights result from the stronger winds and low pressure associated with more intense tropical storms. Thus, an increase in sea surface temperature due to climate change should lead to higher peaks of storm surges and greater risk of coastal disasters along the east coast of India, as a result of rising sea levels. The Satabhaya situation looks a lot like this.

Warmer seas also trigger a phenomenon called thermal expansion. Scientifically, when any liquid heats up, its volume expands. In the case of the sea -- a massive store of liquid -- rising surface temperatures lead to expansion thus causing sea levels to rise. But the most popular reason for sea level rises in a warmer world is that ice stores like glaciers melt faster, adding to the water in the sea. “The Bay of Bengal is showing these symptoms at a preliminary level,” says Pujari. “Sea temperatures are rising for sure. That means it is under thermal expansion. That could well explain the Satabhaya phenomenon,” says Lal. According to him, global warming will manifest in similar local changes.

Estimates of rising sea levels during the 20th century rely on tide-gauge data and the recent satellite altimeter data. Global sea levels are estimated to have risen by 10-25 cm over the last 100 years (IPCC, 2001). There has, however, been no detectable acceleration of rises in the 21st century. Projections based on Coupled Atmospheric Ocean Global Circulation Models (AOGCMs) for scenarios of future concentrations of GHGs over the period 1990-2100 suggest that global mean sea levels could rise by 0.09-0.88 m as a result of thermal expansion and the melting of glaciers and polar ice.

India is one of the 27 countries most vulnerable to rising sea levels, according to a 1989 United Nations Environment Programme assessment. There have been few studies that have explored the impact of rising sea levels on India. One of the first studies was carried out by the Jawaharlal Nehru University (1993), in which the consequences of a 1 metre rise in sea level were evaluated. The study concluded that, in the absence of protection, approximately 7 million people would be displaced and 5,764 sq km of land and 4,200 km of roads would be lost. The dominant cost estimated was due to loss of land, accounting for 83% of all damage. A subsequent study by the Tata Energy Research Institute (1996) explored the relative vulnerability of various coastal regions including the Orissa coast, the effects of adaptive responses to the impact of rising sea levels, and the value of coastal protection for selected regions.

Existing records of climate variability point at rising sea surface temperatures as a result of global warming and a consequent rise in sea levels along the Orissa coast. Future climate change and estimated rising sea levels in the Indian coastal zone, based on past observations on mean sea levels along the Indian coast, indicate a long-term rising trend of about 1.0 mm/year on an annual mean basis. However, recent data suggests a rising trend of 2.5 mm/year in sea levels along the Indian coast. The oceanic region adjoining the Indian subcontinent is likely to warm up on the surface by about 1.5-2.0 degrees Centigrade by the middle of this century, and by around 2.5-3.5 degrees Centigrade by the end of the century. The corresponding thermal expansion-related rise in sea level is expected to be in the range of 15-38 cm by the middle of this century and 46-59 cm by the end of the century.          

State-wise distribution of cyclonic events from 1877-1990

According to the National Institute of Oceanography, Goa, which monitors sea-level rises along the Indian coast, in a study of 24 stations during 1878-1994, the sea level computed for 11 stations out of the 24 showed rising sea levels at 5% level of significance. The only exceptions were two stations in Vizag and Chennai.

Rises in sea level at a particular location are the combination of global rising sea levels and local trends. It is expected that global sea levels will rise between 9-88 cm by 2100, according to IPCC, 2001. However, in many coastal regions, local factors often dominate the global signal. Therefore, while assessing the impact of rising sea levels it is important to account for long-term local sea level trends. The IPCC has estimated that an increase of 0.5 degrees in temperature will raise sea levels by 10 cm in a study in the Sunderbans. Satabhaya has a similar topography but does not have mangroves; it therefore suffers greater inundation.

Back in Kanhapur village no new school has come up. It has been over three months since the children stopped going to school. The sarpanch says the government is not willing to invest money in a place that will be washed away in a few years. Local administrative officials refuse to speak, as the situation continues to baffle them. “We don’t know why the sea is rising. So there is no need to speak,” was the prompt reply of one senior district official.

(Richard Mahapatra has been awarded this year’s CCDS-InfoChangeIndia Research Fellowship for reportage on issues related to sustainable development and social justice. His research is on the impact of climate change in Orissa. Mahapatra has been reporting on environment and development issues for several years. He has written extensively for journals such as Down to Earth.)

InfoChange News & Features, May 2006

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