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Here is why Rain-bearing Clouds have been thinning out across India in last 50 Years!

India gets around 70 per cent of its annual rainfall and snowfall during the monsoon, from June to September

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Monsoon Clouds,. Wikimedia
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  • The study has found that the decline during the monsoon has been 1.22 per cent per decade on an average
  • IMD defines a rainy day as a day when total precipitation is 2.5 mm or more
  • According to the study, the number of rainy days is also declining during the monsoon season at an average rate of 0.23 days for every decade

June 12, 2017: The India Meteorological Department (IMD) has predicted that this year’s monsoon rainfall will be around 98 per cent of the long-period average, which is good news in this drought-prone era. But another study by the same IMD shows a more worrying trend. It has found that rain-bearing clouds have been thinning out across the country over the last 50 years.

The study, published in the IMD journal Mausam, shows that between 1960 and 2010, annual mean low cloud cover (responsible for the bulk of the rainfall) over India has been decreasing by 0.45 per cent per decade on average. Low clouds are declining over various seasons as well, the most significant one being during the monsoons. The study has found that the decline during the monsoon has been 1.22 per cent per decade on an average.

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India gets around 70 per cent of its annual rainfall and snowfall during the monsoon, from June to September.

According to the study, the number of rainy days is also declining during the monsoon season at an average rate of 0.23 days for every decade. This means that the country has lost approximately one rainy day over the last five decades. IMD defines a rainy day as a day when total precipitation is 2.5 mm or more.

“It is for the first time that low cloud cover has been studied in India, so it is a first-of-its-kind study,” A.K. Jaswal, retired scientist from IMD and leader of the study, told indiaclimatedialogue.net. “We have on an average lost one rainy day at each location that was studied across India, and that is of significance.”

As expected, the study found a strong correlation between low cloud cover and the number of rainy days. A thinning of this cloud cover also seems to lead to rising maximum temperature.

“Since monsoon season alone contributes to approximately 70 per cent of annual rainfall, the significant decrease in LCC (low cloud cover) as well as NRD (number of rainy days) in monsoon season during 1961-2010 obtained in this study is a cause of worry,” says the paper.

For the study, observations of cloud cover were made at 215 surface meteorological stations by trained observers who can distinguish low clouds from medium and high ones. Annual low cloud cover was found to have decreased at 61 per cent of the stations studied.

During the monsoon season, the thickest low cloud cover was recorded in 1961 (46.7 per cent), and the thinnest in 2009 (33.5 per cent).

The study found there has been an increase in the low cloud cover over the Indo-Gangetic plains and northeast India, while it has decreased over the rest of the country. The authors say more studies are needed to account for these regional differences.

Rainfall and temperature data was also obtained for all the stations to find out their correlations with the low cloud cover.

Around 60 per cent of the earth’s surface is covered by clouds. They play a critical role in weather and climate by reflecting sunlight, blocking outgoing longwave radiation and producing rain and snow, recycling water vapour and in global energy balance. Cloud cover variability is one of the most uncertain aspects of climate model predictions.

The study says, “At present, it is not known whether changes in cloudiness will exacerbate, mitigate, or have little effect on the increasing global surface temperature caused by anthropogenic greenhouse radiative forcing. Due to their high albedo, low clouds have cooling effect, whereas high clouds trap outgoing infrared radiation contributing to warming of earth’s surface.”

Given that agriculture in India is hugely dependent on monsoon rainfall, there is a strong case for learning to adapt to a thinning low cloud cover.

“We are seeing so many farmer suicides. Agriculture is in lot of stress. And farmers have to adapt to the changing climate by storing water through traditional methods, changing crop patterns, creating ponds to augment groundwater depletion,” said Jaswal.

The study found that while the number of rainy days is decreasing, there is not much change in the total amount of rainfall. This shows a trend towards shorter, heavier bursts of rain. That is bad news, because heavier raindrops can dislodge wheat and rice grains from their stalks. It also means rainwater flows down a slope that much faster instead of percolating underground.

Globally, various factors are being blamed for declining cloud cover — climate change, aerosols and other pollutants. But given the complexities of multiple factors impacting weather, more studies are needed to find the cause.

Though the study does say, “One factor causing decrease in low cloud cover may be the direct effect of aerosols. As aerosols can cool the earth’s surface by reflecting sunlight and warm the aerosol layer by absorbing downward longwave radiation, the lapse rate will decrease and atmospheric stability will increase, suppressing cloud formation and reducing the cloudiness.”

Jaswal however points out that in some studies in other parts of the world, it has been found that aerosols (which form the skeleton of the clouds) can also have a positive impact on the cloud cover. “I hope that someone will take up the logical second part of the study to see what kind of changes are happening within the low cloud cover itself,” he said. Wwhether stratus clouds are increasing or the non-rain making clouds are increasing in the low cloud cover.” (IANS)

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Sundarbans’ activists are against the upcoming NTPC power plant in the area

Local activists said that with the assurance of cheap power from the project, over 300 industrial units, 190 within ECA, had made a beeline to the area. "Had you visited the region a few years back, you would've found a different Poshur," Jamil said.

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A diesel ferry cuts through the Poshur river -- the lifeline of Sundarbans -- with travelers watching its heavily industrialized bank, which is rapidly increasing at the cost of world’s largest contiguous mangrove forest.
Sundarbans, wikimedia commons

A diesel ferry cuts through the Poshur river — the lifeline of Sundarbans — with travelers watching its heavily industrialized bank, which is rapidly increasing at the cost of world’s largest contiguous mangrove forest.

Activists are looking with a wary eye at the upcoming 1,320 MW coal-based power project being set up by India’s NTPC, a mere 14 km north of the Sundarban Reserve Forests and four kilometres from the Ecologically Critical Area (ECA), which they say would pose a threat to the wildlife and dependent communities.

The Maitree Super Thermal Power Project at Rampal in Khulna division is being constructed in an area of over 1,832 acres on the eastern bank of Poshur. In August 2010, a pact was signed between India and Bangladesh to set up the project.

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While journalists and protestors are not allowed near the project, a small group of visiting journalists from India could see for themselves the massive erosion, waterless canals, huge waterway traffic, oil spills and major infrastructure coming up along the river.

Some 10 km before the busy Mongla Port is a broad 5.5 km-long road west of the Mongla-Khulna highway that goes to the project site. Around this road there were some 5,000 families which were displaced, we are told.

Sushanto Das, one of the land owners in Bagerhat district, lost over 33 acres of land. “My house was burned down by the local goon with support of the local Member of Parliament. I approached the court. Now they don’t even allow us to protest at the site,” he told IANS from his residence in Ranjitpur, a town between Khulna and Sunderbans.

As per official count, Sundarbans had 180 tigers in 2015. Now, those in the area are under threat.
NTPC Ramagundam, wikimedia commons

At places, the river, along this special economic zone, has become much broader because of excessive erosion of its banks. Ferrymen say that because of this, the Poshur is becoming more aggressive. The western bank, where forest communities dwell and ECA begins, is also being industrialized.

A 2016 joint report by the governments of India and Bangladesh — and supported by the world bank — on the status of tigers in the Sundarbans, a copy of which is with IANS, criticized this coal-fired project, saying it would further “exacerbate the problem” of climate change, pollution and tiger conservation. As per official count, Sundarbans had 180 tigers in 2015. Now, those in the area are under threat.

The report, which labels vessels plying on the Poshur as “mobile bombs”, reminds everyone of the December 2014 incident when 358,000 liters of oil spilled into the Sela.

Spread across 10,000 sq km — of which 62 per cent is in Bangladesh — the Sundarbans, lying in the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal, were declared a World Heritage Site by UNESCO in 1997. For Bangladesh, it accounts for 44 per cent of its forest area, generating 50 percent of the forest revenue from tourism, fishery and the sale of honey.

A wetland of global importance, the ecosystem saves the inlands from cyclones, stabilizes sediments and makes the region a nursery of major fisheries, playing a key role in food security.

“All this stand threatened. The power plant is located to make best use of the river but existing power industries are already discharging effluents into the river and ash in the atmosphere,” Dr Abdullah Harun Chowdhury, Professor Environment Science at Khulna University, told IANS, warning of a micro-climate change altering different patches of the Sundarbans.

With warming of water, Chowdhury observed that soil quality had dropped and salinity in the area had increased over time, threatening its flora and fauna. “The government doesn’t check how natural resources are being overexploited. The DoE (Department of Environment) gives license to industries under pressure,” Chowdhury said.

UNESCO and the International Union for Conservation of Nature, a global organization, have already raised an alarm over the Rampal project. “There is only one Sundarbans in the world, once destroyed, no amount of money could replicate it,” he said.

The $1.6 billion power project is controlled by Bangladesh-India Friendship Power Company Ltd (BIFPCL), a 2012 private venture comprising India’s NTPC and the Bangladesh Power Development Board (BPDB). India’s Bharat Heavy Electricals Ltd (BHEL) is constructing the plant which is scheduled to start operations in 2019.

Spread across 10,000 sq km -- of which 62 per cent is in Bangladesh -- the Sundarbans, lying in the delta of the Ganges, Brahmaputra and Meghna rivers on the Bay of Bengal, were declared a World Heritage Site by UNESCO in 1997.
NTPC logo, wikimedia commons

Queries sent to NTPC and BIFPCL went unanswered.

Ironically, India plans to phase out coal-power and not sanction any new project after 2022.

While the Bangladesh government has judged the project location to be at a “safe” distance from the mangrove forest, facts suggest otherwise.

According to a Bangladesh’s Department of Environment (DoE) document, available with IANS, several “red-category” industries — oil refinery, ship building, cement, gas cylinder, brick kilns, LPG, saw mills and

others — operate deep within the ECA across Khulna, Bagerhat and Satkhir districts. Also, a railway line is being set up there to import coal from West Bengal to Jessore.

The Bangladesh government in 1999 declared a 10 km radius from the reserve forest as ECA. However, DoE permitted setting up of over 190 industries, located 1.5 to 9 km from the forest reserve, of which 24 units are listed as “Red” or “extremely harmful”, 63 are “Orange (A)” or “harmful” and 103 are “Orange (B)” or “less-harmful”. Not a single industry within ECA is “Green” or “safe”.

According to environment experts, heavy industrialization in the region had blocked canals, eroded the banks and sunk several villages. “Over 50,000 people suffered, mostly from the minority Hindu community, and many have migrated to India,” environmentalist Sharif Jamil from Bangladesh Poribesh Andolan (BAPA) told IANS.

Local activists said that with the assurance of cheap power from the project, over 300 industrial units, 190 within ECA, had made a beeline to the area. “Had you visited the region a few years back, you would’ve found a different Poshur,” Jamil said.

Sundarbans has thousands of interconnected canals which balances the pressure on the main river.

“Industries level those canals, putting extra pressure on the river, causing erosion,” Jamil said, adding that Banishanta, Laudob, Shelabuniya, Amtali, Sindurtala, Kalabari and Joymoni areas suffered the maximum erosion.

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“Crocodile nestings have vanished from Joymoni near Mongla, tiger too,” Professor Chowdhury said, adding that a “proper study” was difficult since the government doesn’t allow it.

According to academicians in Dhaka, an anti-India feeling is slowly taking shape. Some locals who were affected told IANS that they had got death and rape threats and were attacked by musclemen while protesting. Several refused to talk. Many cases have landed in the courts.

“We approached the Left parties in India too for help. But D. Raja (National Secretary of the Communist Party of India) told us that they cannot help as Bangladesh itself had asked for it (the power plant),” Anu Muhammad, Professor of Economics at Jahangirnagar University, Dhaka, told IANS. He was later denied a visa to attend a conference in New Delhi. Even a tourist visa to India was declined. (IANS)