My Science School

Sambhar, India’s largest inland salt lake, is a Ramsar site – a wetland designated to be of international importance. It attracts a staggering diversity of birds every year. Every year, from November to March, about 2,00,000 migratory birds across 65 species arrive – particularly pink flamingos, the great crested grebe, little grebe, little cormorant, black stork and great white pelican. Some parts of the lake are used for salt production.

A picture of neglect

The avian deaths have turned the lens on the region. According to reports, the Ramsar site is a picture of neglect. It is surrounded by huge salt pans, and illegal salt mining is rampant in the region.

Environmental degradation due to salt mining, excessive groundwater extraction and effluents from salt manufacturing units are a big problem here.

According to reports, parts of the wetland area are covered by invasive organisms. Ecologists hope that the government would now put an end to illegal mining and take more measures to safeguard avian and marine life.

 

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Avian botulism is a serious neuro-muscular illness caused by a toxin produced by the bacterium Clostridium botulinum. Avian botulism typically results in paralysis – with the infected birds exhibiting unusual behaviour. For example, water birds may not be able to hold their head up and as a result, often drown. Gulls can often walk, but not fly. Other birds may drag one or both wings, exhibiting poor posture while standing. In general, outbreaks of avian botulism occur only when a variety of ecological factors occur concurrently. This typically involves warmer water temperatures, oxygen deprivation in water, and higher levels of bacterial substrate in the form of decaying plants, algae or animal materials.

In Rajasthan

According to the IVRI report, the outbreak at Sambhar was caused by the climate. The neurotoxin production may have been triggered by warm weather, it said. Further, water levels were fluctuating throughout the year. Due to a good monsoon this year, the water level reached the lake bed after a gap of 20 years. The monsoon might have provided a favourable environment for the bacteria to spread. The monsoon also brought with it a large population of crustaceans (such as shrimps, crabs and prawns), invertebrates (snails) and plankton (such as algae). These organisms are capable of hosting the bacteria for a long period of time.

Transmission

Avian botulism is not contagious: it is not spread directly from bird to bird. But it can spread to birds through their consumption of maggots infected with the bacteria. When an infected bird dies, the maggots that feed off it become infected themselves. These maggots are in turn consumed by other birds, thus getting infected. This was observed in Sambhar too as researchers found only insectivorous and omnivorous birds affected and not herbivores.

Treatment

The sick birds are receiving supportive treatments as there is no cure for avian botulism. A bird ICU has been set up. They are administrated antibiotics, multivitamins, eye drops, fluid and oxygen as well as nutritious feed.

 

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Many of the birds had travelled from as far as Europe, Africa and Northern America through oceans and mountains, crossing continents and countries with, perhaps, little idea that death awaited them at their wintering destination – Sambhar Lake, Rajasthan.

Early November, bird carcasses began appearing on the banks of the Sambhar Lake, a 230-sq. km. inland saltwater body located 80 km southwest of Jaipur. Tourists, birdwatchers and villagers who visited the lake spotted lifeless birds dotting the lake’s bank.

The initial death toll was at 1,500. Soon rescue teams, including civil workers, volunteers, forest officials and NGOs swung into action – counting and collecting the carcasses. Live and suck ones were rescued and transferred to rescue centres for treatment. However, the toll steadily rose, and by mid-November, the official death count was at 18,000 birds, excluding the casualty towards the Nagaur side of the lake. As this article took shape, reports said that about 100 birds were being found dead every day.

Scientists were initially at a loss to explain the mysterious deaths. Samples of bird carcasses were sent to the Indian Veterinary Research Institute (IVRI) in Bareilly, the High Security Animal Disease Laboratory (HSADL) in Bhopal, the Wildlife Institute of India in Dehradun and the Salim Ali Centre for Ornithology and Natural History (SACON) in Coimbatore.

The initial lab results ruled out avian flu, and subsequent reports confirmed that the birds were hit by avian botulism – typical symptoms of which include weakness, lethargy and inability to fly. Birds of 29 species were found to be affected. These included water birds such as stilts, shovellers and sandpipers, gulls, terns, and also bee-eaters and kites. Many of them were migratory birds.

However, the cause was being debated by scientists and conservationists. Some biologists said that food sources for migratory birds could greatly decline with low water levels and high salt content in salt water lakes and that could have led to the mass deaths. Other explanations include effluents from salt manufacturing degradation due to illegal salt mining and excessive groundwater extraction.

 

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Greenhouse Effect

Earth maintains its heat balance with the help of greenhouse gases in the atmosphere. The right mixture of water vapour, carbon dioxide, methane, nitrous oxide and chlorofluorocarbons are responsible for making the planet habitable. When the sun’s energy reaches Earth, these gases in the atmosphere absorb some of it on the way down, and then absorb more when that energy reflects back off the surface during the day. This keeps the lower atmosphere and the surface of the Earth warm. Without this greenhouse effect, Earth’s average temperature would be – 19 degree Celsius, making it hostile to life.

Global warming

Human activities such as burning of fossil fuel and deforestation lead to the release of more greenhouse gases into the atmosphere, especially CO2. This results in the trapping of more energy from the sun, which, in turn, increases Earth’s temperature. This is called global warming.

(while scientist stress that green house gas emissions are the primary factor pushing temperatures higher both in the past decades and into the future, deforestation is also a key contributor. Tress play a huge role in the carbon cycle. They convert the CO2 in the air to oxygen, through the process of photosynthesis, and in this way, they act as natural regulator of the carbon dioxide. The more trees, the less carbon dioxide in the atmosphere. Unfortunately, deforestation is preventing this job to be fully accomplished and the amount of carbon dioxide is rising)

Sea-Level Rise

The ocean covers about 70% of the Earth’s surface and acts as its primary reservoir of heat and carbon, absorbing over 90% of the surplus heat. When water heats up, it expands. When the ocean water expands, it takes up more space. This is called thermal expansion, and it is responsible for one-third of the sea-level rise, according to studies. (Melting of glaciers and polar ice sheets due to global warming also contribute to the unusual rise in sea level.)

The impact of sea-level rise includes flooding of coastal areas, increased soil erosion, disappearance of low-lying islands, saltwater intrusion and habitat destruction in coastal areas. Rising sea levels also make storm surges capable of much greater damage. (Storm surge is the abnormal rise in seawater level during a storm. Storm surge can penetrate well inland.) many birds use coastal ecosystems to find food, live and breed. Sea turtles lay their egg on beaches, returning to the same location every year. When beaches erode, these animals and birds will be affected.

Forest Fire

As warmer temperatures increase evaporation, the land becomes drier and drier, enhancing the chances of wildfires. Drier conditions and higher temperatures have also enhanced the duration and the severity of a forest fire.

Climate system

Warmer the water, stronger the storm: Ocean temperature is a powerful driving force of storms. In tropical regions of the globe, warm temperatures over the surface of oceans can provide the energy for the formation of storms and influence the development of monsoon winds. Storms are formed when warm, moist air over the ocean rises upward from near the surface – warmer the water, stronger the storm.

Change in ocean temperature also affect oceanic currents: Ocean currents help regulate Earth’s climate by facilitating the transfer of heat from warm tropical areas to colder areas near the poles. Changes in ocean currents would cause changes in rainfall and air temperatures.

Coral Bleaching

If the sea temperature becomes too hot, the zooxanthellae – that reside in corals in a symbiotic relationship – develop heat stress, and stop producing carbohydrates. Under stress, it also starts producing toxic waste that poison the coral. So the corals expel the zooxanthellae. When this happens, the corals turn white, and this is known as coral bleaching. Bleached coral isn’t necessarily dead. If the sea temperature drops relatively quickly, the coral will survive, and within a few months, they will have recovered their zooxanthellae. However, if sea temperature stays too high for too long, the corals may not be able to feed themselves effectively and the polyps will eventually die.

Animal and bird behavior

The life cycles of animals and plants are aligned with seasons and resource availability. During cold winters, to cope with food scarcity and to conserve energy, some animals hibernate while birds migrate to a warmer place. As rising temperature alters the length of seasons, these activities are affected.

For instance, some animals rely on air temperature as a cue to come out from hibernation. With warming temperatures, they are emerging earlier than usual and find that the temperature is not warm enough to thaw the snow off the grass and other plants, which are their food. With a dense snowpack, they either starve or get eaten up by predators.

Water scarcity and other problems

If global temperatures continue to rise, rainfall will increasingly become a thing of extremes: long dry spells here, dangerous flood there – and in some place, intense water shortages. This will also affect agriculture. Worldwide, farmers are struggling to keep up with shifting weather patterns and increasingly unpredictable water supplies. Extreme weather patterns also destroy life, property and livelihood.

 

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This decade is set to be hottest in history, according to the annual assessment report of the United Nations released at the COP25 climate summit in Madrid Spain.

The World Meteorological Organisation (WMO) said global temperatures so far this year were 1.1 degrees Celsius above the pre-industrial average between 1850-1900. That puts 2019 on course to be in the top three warmest years ever recorded, and possibly the hottest non-EI Nino year yet..

More from the report

Oceans, which absorb 90% of the excess heat produced by greenhouse gases, are now at their highest recorded temperature.

The world’s seas are now a quarter more acidic than 150 years ago, threatening vital marine ecosystems upon which billions of people rely for food and jobs.

In October this year, the global mean sea level reached its highest on record, fueled by the 329 billion tonnes of ice lost from the Greenland ice sheet in 12 months.

More than 10 million people were internally displaced in the first half of 2019 – seven million directly due to extreme weather events such as storms, flooding and drought. By the end of the year, the WMO said, new displacements due to weather extremes could reach 22 million.

The report said each of the last four decades has been hotter than its previous one.

Global effort

Nations were in crucial talks in Madrid aimed at finalizing rules for the 2015 Paris climate accord, which enjoins countries to work to limit global temperature rises to “well below” 2 degree C.

The intergovernmental panel on climate change(IPCC) last year outlined how vital it was for humankind to aim for a safer cap of 1.5 C – ideally by slashing greenhouse gas emissions and retooling the global economy towards renewable energy. The UN said in its annual “emissions gap” assessment that the world needed to cut carbon emissions by 7.6% each year, every year, until 2030 to hit 1.5 C.

And while governments spend hundreds of billions of dollars subsiding fossil fuels, there appears to be no consensus over how countries already dealing with climate-related catastrophe can fund efforts to adapt to the new reality.

Even if Paris pledges were honored, Earth is still on course to be more than 3C warmer by the end of the century, say scientists.

 

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Tide gauge is among the oldest methods to measure sea level. A tide gauge is fitted with sensors and placed on piers. It continuously records the height of the surrounding water level. Water older tide-measuring stations used mechanical floats and recorders, modern monitoring stations use advanced acoustics and electronics. Sea level is also measured from space using laser altimeters, which determine the height of the sea surface by measuring the return speed and intensity of a laser pulse directed at the ocean. The higher the sea level, the faster and stronger the return signal is.

You can see that getting an accurate reading (for example, down to the millimeter level) is extremely difficult. Satellites are now used as well, but they suffer from many of the same problems. Scientists do the best they can, using extremely long time spans, to try to figure out what the sea level is and whether or not it is rising. The general consensus seems to be that the oceans rise about 2 millimeters per year.

 

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• The impact of sea-level rise includes flooding, habitat destruction and salt water intrusion in coastal areas, increased soil erosion and disappearance of low-lying islands. Rising sea levels also make storm surges capable of much greater damage. (Storm surge is the abnormal rise in seawater level during a storm. Storm surge can penetrate well inland.)


• Higher sea levels are coinciding with more hurricanes, contributing to more powerful storm surges that can strip away everything in their path.


• Saltwater intrusion is the flow of seawater into water bodies such as rivers and aquifers (underground water bearing rocks). It is a major concern as it can induce contamination of water resources, used for drinking, household purposes and agriculture. Increased salinity of coastal freshwater can threaten vegetation and wildlife of the region.


• Many birds use coastal ecosystems to find food, live and breed. Sea turtles lay their eggs on beaches, returning to the same location every year. When beaches erode, these animals and birds will be affected.


• Rising sea level will lead to the displacements of people. It could create 187 million climate refugees by 2100, according to a study.

 

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The rise in sea-levels is linked to two primary factors, both induced by global warming.

Thermal expansion:

The oceans are absorbing more than 90% of the increased atmospheric heat associated with greenhouse gas emissions. When water heats up, it expands. The ocean water expands to fill a greater volume and takes up more space. This is called thermal expansion, and it is responsible for one-third of the sea-level rise, according to studies.

Melting of glaciers and ice caps:

Warmer temperatures cause land-based ice such as glaciers and ice sheets to melt, and the meltwater flows into the ocean to increase sea level. Melting ice causes about two-thirds of the rise in sea level.

If all the ice in glaciers and sheets melt then the sea level would rise by 216 feet. That could cause some countries to disappear under the oceans. That’s a scenario scientists think would probably take many centuries, but it could eventually happen if the world keeps burning fossil fuels indiscriminately.

 

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A rise in sea level may put some of the Indian cities, including Mumbai, Chennai and Kolkata, in the flood-risk zone, and it could affect a total of 36 million people in the country by 2050, according to a research report by the New Jersey-based science organisation Climate Central. By 2100, this number could increase to 51 million. Parts of these coastal cities could be completely wiped out, the report said.

Showing that many of the world’s coastlines are now for lower than earlier, the report projected that worldwide, some 300 million people could be affected by 2050. The threat is particularly concentrated in six Asian countries: China, India, Vietnam, Thailand, Indonesia and Bangladesh.

Sea-level rise and flooding could have profound economic and political consequences within the lifetimes of people alive today, showed the findings of the study.

Even if emission is zero

According to another study published last month, the dramatic rise in sea levels will continue even if the world manages to slash greenhouse gas emissions to zero by 2030. Emissions between 2015 and 2030 would be enough to raise levels by 8 cm by 2100, according to research by experts based in Germany.

The average sea level is expected to swell by at least a metre by 2300 in the extremely unlikely event that greenhouse gas emissions fall to zero in the next 11 years.

If planets heats up further

In the worst-case scenario – in which the planet heats up by 5 degrees Celsius in the next 80 years – melted ice could raise sea levels worldwide by more than 6.5 feet, according to a study published in May 2019. That could result in a loss of 6,91,120 square miles of land, the report said. That’s an area larger than France, Germany, Spain and the U.K. combined.

The water could swamp major coastal cities such as New York and Shanghai. Small Pacific island nations such as Vanuatu would be rendered uninhabitable or disappear entirely.

In Earth’s geological past, sea level has risen and fallen dramatically. For instance, during the last Ice Age, ice covered the planet and sea level was at least 394 ft lower than what it is today. And during the Eocene – 40 million years ago, the Earth was almost ice-free and the sea level was around 230 ft higher than today.

These changes are part of Earth’s natural glacial cycles and have occurred over millions of years. But the current sea-level rise is caused mainly due to human activities.

The burning of fossil fuels, deforestation, decomposition of waste in landfills and livestock have released enormous amounts of greenhouse gases into the atmosphere. These emissions have caused the Earth’s surface temperature to rise, causing global warming, which directly contribute to sea-level rise.

 

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• During photosynthesis, trees absorb CO2 from the atmosphere, and store it as carbon for long time periods. At present, forest store as much as 45% of all land carbon. Deforestation affects this carbon cycle.


• Deforestation is considered to be one of the contributing factors to global warming and climate change. Trees absorb not only the carbon dioxide that we exhale, but also the heat-trapping greenhouse gases that human activities emit. With increase in deforestation, larger amount of these gases will enter the atmosphere and global warming will increase further. About 300 billion tonnes of carbon, 40 times the annual greenhouse gas emissions from fossil fuels, is stored in trees, according to Greenpeace.


• While fossil fuel combustion is the largest source of carbon dioxide emission, deforestation is the second largest. When trees die (or are cut or burnt), they release the stored carbon dioxide into the air.


• Forests release large quantities of water into the atmosphere via perspiration. This replenishes the clouds and triggers rain, which in turn, maintains the forests. When forests are destroyed, it affects rainfall and thereby causes drought.


• As much as 70% of the world’s plants and animals live in forests. They are losing their habitats due to deforestation. Loss of habitat can lead to species extinction. For instance, in Malaysia and Indonesia, Bornean rainforests are cut down to make way for producing palm oil. The effect of deforestation is so much that it is driving the extinction of orangutans, the world’s largest tree-dwelling great apes, native to the rainforests of Borneo and Sumatra. Removing trees deprives the forest of its canopy, which blocks the sun’s rays during the day and retains heat at night. That disruption leads to more extreme temperature swings that can, in turn, affect plants and animals.


• Trees roots stabilize the soil around the tree and hold them in place. When they are cut, the soil is free to wash or blow away, which can lead to soil erosion.


• Deforestation can also cause flooding. Coastal vegetation lessens the impact of waves and winds associated with a storm surge. Without this vegetation, coastal villages are susceptible to damaging floods.

 

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Deforestation is the destruction of forests in order to make the land available for other uses. The Earth loses 18.7 million acres of forests per year, which is equal to 27 football fields every minute, according to the World Wildlife Fund (WWF).

Common methods of deforestation are clear cutting and burning of trees. These methods leave the land completely barren. Clear cutting is when large swaths of land are cut down all at once. This sudden change causes severe damage to the ecosystem.

Cause of deforestation

• A major contributor to deforestation is the practice of slash-and-burn technique of farming. Farmers clear forest by cutting down trees, burn them and then grow crops in the soils fertilized by the ashes. Typically, the land produces for only a few years. The farmers abandon the area and move on to a new patch of land and begin the process again.


• Grazing of livestock, mining and drilling are the other major causes.


• Trees are also cut to be used as fuel.


• Forests are also cleared for housing and urbanisation; for industries, dams and other infrastructural projects.


• Wood is used in the making of paper, furniture and the construction of buildings. Some of the loggers act illegally. They also build roads to access more and more remote forests, and this leads to further deforestation.


• Not all deforestation is intentional. Some are caused by a combination of human and natural factors such as wildfires, which may prevent the growth of young trees.

 

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• In the concrete jungle that Mumbai is, Aarey Milk Colony is a treasured green patch. It has over 5, 00,000 trees. On October 4, 2019, when the Bombay High Court allowed the State government to go ahead with the felling of 2,600 trees to make space for a proposed Metro Rail car shed, the residents protested. But it was too late, as the Brihanmumbai Municipal Corporation (BMC) acted soon after the order and had already cut 1,500 trees (under the cover of darkness). The issue became bigger and uglier – clashes broke out between the police and environmental activists, leading to the arrest of at least 29 persons. Thea matter was taken to the Supreme Court and it, in a special hearing on October 7, 2019, ordered the BMC to halt the felling of trees in the Aarey forest. But it did not order the halt or shifting of the metro shed project from Mumbai’s Aarey in its subsequent hearing.


• In September, reports emerged that the Jharkhand’s Water Resources Department has approved the cutting of around 3.44 lakh trees in Jharkhand’s Palamau Tiger Reserve to make way for the North Koel reservoir, also known as Mandal dam. As per latest estimation, the reserve has nil tigers. However, the felling of so many trees will damage the ecosystem, warn wildlife experts. The reserve has already suffered significant damage because of the expansion of road and railway network.

Development projects such as these are among the top reasons for the deforestation. According to the central government statistics, between 2015 and 2018, about 20,000 hectares of forest land was cleared for development activities such as mining, thermal power plants, dams, roads, railways and irrigation projects. Under the Forest (Conservation) Act, 1980, forest areas can be diverted by the environment ministry for non-forestry purposes such as mining. To compensate, authorities should carry out afforestation at a different place. However, they are in no way a substitute the diverse and natural forests that have been lost permanently due to deforestation, say experts.

It is an irony that the world, while seeking to slow the pace of climate change on the one side, continues to cut down trees in large numbers on the other hand. Trees are part of the solution in our fight against climate change.

 

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An ecological footprint compares the total natural resources people consume with the land and water area that is required to replace these resources.

The ecological footprint works like an accounting balance sheet. On the minus side are the resource consuming activities like energy usage, logging, farming, fishing, etc. On the plus side is Earth’s bio capacity – its ability to replace these resources and absorb the waste.

The ecological footprint measures the demands humans place on Nature. It includes estimates of the sea and forest-covered land areas needed to absorb greenhouse gases like carbon dioxide. The more the greenhouse gases, the more the water and forest area required for absorbing them.

Thus a large carbon footprint would mean a larger ecological footprint. In short, the ecological footprint tells us how much of Earth is required to support human life if a particular lifestyle is followed.

Since the mid-1980s, humans have been consistently, leaving a larger ecological footprint. For example, for 2007 humanity’s ecological footprint was estimated at 1.5 Earths.

It means that humans consumed resources 1.5 times faster than Earth can reproduce them, the deficit was made up by drawing up on stored resources like fossil fuels which Earth does not replenish every year. The UN estimates that if current trends continue, by the mid-2030s we will need two Earths to sustain ourselves!

 

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                    The world’s tropical rainforests are being lost at an alarming rate, and already the effects of this loss can be seen. Rainforest trees are cut down to provide timber as well as land for grazing and raising crops, The remaining scrub and branches are usually burned, providing a rich source of fertilizer for one or two years, Then the land becomes barren. Rainfall washes away the topsoil, leaving bare rock in which very little grows.

                    The results of deforestation are seen in countries such as Bangladesh, where heavy rains are no longer soaked up by the forests in the foothills of the Himalayas. Instead the rainwater sweeps down the valleys, causing enormous flooding and loss of life.

The parts of the world affecting our lives are called the ‘environment’. This includes the Earth’s crust, oceans, atmosphere, plants and animals. If the balance between things added and things taken away from the environment is upset, the environment will change.

Many of the things we take from the Earth, like metals and fossil fuels, take millions of years to be replaced naturally. Other things, like wood from trees, are replaced more quickly, but if we use them too fast, they will disappear. Some things we produce, like poisons and waste, are not removed as quickly as we add them to the environment, so they build up as pollution.

Household waste is a serious pollution threat – the UK produces 27 million tonnes each year.

 

 

 

 

Cutting down huge forests can cause changes in the Earth’s atmosphere.

 

 

 

 

 

 

Pollution from industry can also disturb the Earth’s balance.