My Science School

If you removed everything from your home that contained plastic, how much would be left? Many kitchens would be almost bare. Most carpets and rugs would go, many clothes and perhaps the curtains would vanish. There would certainly be no telephone, hi-fi or television.

And think of all the other things made of plastic, such as riot shields, credit cards, artificial snow and hip joints. Now Australians are even buying their plastic goods with plastic banknotes.

The term ‘plastics’ covers a wide range of materials man-made from two basic ingredients: carbon and hydrogen. By adding extra chemicals, plastics can be given special properties like extra strength, heat-resistance, slipperiness and flexibility.

There is almost no end to the number of plastics that can be created by combining chemicals in different ratios and patterns. Scientists are already trying to develop a plastic as tough as steel, as clear and waterproof as glass and as cheap as paper.

Plastics are made up of large molecules called polymers, which are formed by smaller molecules joining together in long chains. These chains become tangled, giving plastic its strength – considerable force is needed to pull the chains apart.

When most plastics – called thermoplastics – are heated to about 3900ºF (2000ºC) the chains stay intact but move apart enough to slide over one another. This allows thermoplastics to be repeatedly heated and moulded into new shapes. Once the plastic has cooled it holds its neew shape and maintains its strength.

However, there are other plastics which, once moulded, remain hard and keep their shape even when reheard. These are thermosetting plastics.

The process of getting small molecules to join up and form larger ones, called polymerization , differs from one plastic to another. But it often involves high pressures and the use of special agents, called catalysts, to encourage the small molecules to link up.

The carbon and hydrogen atoms that form the base of all plastics come from crude oil. Oil consists of hydrocarbons – hydrogen and carbon molecules bonded together. Hydrocarbons range from simple molecules like methane (a gas made up of one hydrogen atom combined with four carbon atoms) to tars and asphalts, which may have hundreds of atoms.

In the process of refining crude oil many different hydrocarbons are produced, one of them is the gas ethane (two carbon and six hydrogen atoms) which can be converted to another gas, ethylene, and then polymerized to make polyethylene (polythene). Similarly, propane gas becomes polypropylene. These two plastics are used to make bottles, pipes and plastic bags.

PVC – polyvinyl chloride – is chemically similar to polythene, but its hydrogen atom is replaced by a chlorine atom. This slight change makes PVC ‘flame retardant’, making it safer to use in the home. If four fluorine atoms are used rather than the chlorine atom, polytetrafluoroethylene, PTFE, is made. This, known as Teflon, is used for nonstick frying pans and bearings.

Many polymers have been made in the laboratory, but only those with the most useful qualities, like polystyrene, PTFE and nylon, are produced industrially.

 

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One of the advantages of plastic is that it does not rust or rot. But this can also be a problem – plastic cups, bags, wrappers and containers litter the countryside and beaches all over the world. Unless they are picked up, they go on accumulating year after year.

To deal with the problem, various forms of degradable plastic have been developed. The secret is to incorporate into the plastic a chemical that can be attacked by light, bacteria or other chemicals.

Biodegradable plastics can be made by adding starch. If the plastics are buried, bacteria that feed on starch will gradually break them up into tiny pieces that disappear harmlessly into the soil.

Chemically degradable plastics can be broken up by spraying them with a solution that causes them to dissolve. They can be used, for example, as a protective waxy covering for new cars, and washed off at the dealer’s garage by a specially formulated spray. This reacts with one of the components in the plastic and causes it dissolve into harmless materials which can be flushed down the drain.

One of the most successful uses of degradable plastics is in surgery, where stitches are now often made using plastics which dissolve slowly in body fluids, saving the patient the anxiety of having the stitches removed. Drugs are often prescribed in plastic capsules which dissolve slowly, releasing the rug into the bloodstream at a controlled rate.

Photodegradable plastics contain chemicals that slowly disintegrate when exposed to light. In France, strips of photodegradable plastic about 3ft (1m) wide are used in the fields to retain heat in the soil and produce early crops. They last for between one and three years before rotting into the soil. But they have to be used in a country with a consistent amount of sunshine so they decay at a predictable speed.

In the USA, about one-quarter of the plastic ‘yokes’ that link beer cans in a six-pack are made of a plastic called Ecolyte, which is photodegradable. But to stop them decaying too early they must be stored away from direct sunlight, which can be an inconvenience for the retailer.

Degradable plastic has other problems. For example, it cannot be recycled because there is no easy way to measure its remaining life span. The biggest drawback has been the cost of producing it, but Japanese scientists believe they will soon be able to produce a much cheaper multipurpose biodegradable plastic.

 

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High-level radioactive waste is lethal and it remains dangerous for thousands of years. If someone were to stand 30ft (9m) away from a small amount of fresh waste from a nuclear reactor for ten minutes, he would have only a 50 per cent chance of living. A nuclear reactor’s spent fuel contains a deadly cocktail of radioactive products, like plutonium, strontium and caesium.

Fortunately the volume of high-level nuclear waste is small. A typical plant, generating 1000 megawatts of electricity, produces about two and a half cubic yards (two cubic metres) of waste a year.

Storage methods vary. In the USA, some processed waste is stored in double-walled stainless-steel tanks surrounded by 3ft (1m) thick concrete cladding. But most is immersed in special pools near the nuclear plants, in the form of spent fuel rods still inside the original cladding. Unfortunately this is not a long-term solution.

In Britain the waste is stored as a liquid, the colour of strong tea, in steel tanks encased in concrete, similar to those used in America. The waste generates hear as the radioactive atoms decay, so the tanks have to be cooled to prevent the liquid boiling dry, which could eventually cause a radioactive leak. Cold water is pumped through coils inside the tanks.

However, although they have already been used for 40 years, tanks are also only a temporary storage solution.

Possibly the best answer at the moment is to fuse the waste into glass cylinders to be stored deep underground. A demonstration plant in Marcoule, France, has been carrying out this process since 1978.

The waste is dried and reduced to a solid residue by heating it inside a rotating drum. It is then mixed with silica and boron, and other glass-making materials, poured through a vertical chamber and heated to  ( . A stream of molten glass emerges from the bottom, to be cast into stainless-steel containers about twice the size of an old-fashioned milk churn. A year’s output from a 1000 megawatt plant fills 15 of these canisters. After the glass has solidified, the lids are welded on.

The canisters are stored in special ‘pits’ in a neighbouring building at Marcoule. Each consider produces 1.5 kilowatts of heat and is cooled by air. The British and the Americans are also beginning to adopt this process. The waste is safe so long as it is monitored, but ultimately it should be put where it can remain without further human intervention.

One proposal is to surround the canisters with a jacket cast iron or copper, and then store them in underground caverns. The canisters would be placed in holes or trenches, then covered with concrete or a clay called bentonite, which absorbs escaping radioactive material.

The canisters should last up to 1000 years before they become corroded and let any radioactivity escape. After 500 years the radioactivity will have dropped to about the level of the original uranium ore. Experts believe that as long as the caverns are well suited and sufficiently deep – several hundred metres – it would take a million years before any material could seep to the surface, and by that time all but the tiniest traces of the radioactive waste would have decayed. The areas chosen for the ‘dumps’ should contain no valuable minerals; in case some future civilization should stumble across the waste while mining. Eventually the caverns could be sealed off and forgotten. The waste would be sealed behind so many barriers that escape in any imaginable time scale would be impossible.

The difficulty is finding sites where local people agree to have nuclear waste stored. Nobody relishes the idea of a nuclear dump close to their home. In the end, the nuclear waste authorities may well be forced to drill caverns beneath existing reprocessing facilities, or under the sea, rather than try to find new sites on land.

 

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Recycling rubbish is not only makes economic sense – it also helps the environment. Pollution created by burning rubbish is reduced and valuable resources are saved. Some 75,000 tress would be spared every week just by recycling the Sunday edition of the New York Times.

Many countries encourage recycling new technology allows more and more waste to be reprocessed. Most of the world’s rubbish can be reused – paper, metals, glass, even some plastics.

Plastic is one of the most difficult substances to recycle, because it comes in so many varieties. A plastic tomato-ketchup bottle, for example, consists of six layers of different plastics, each designed to give the bottle certain qualities – shape, strength, flexibility. And as yet there is no simple way to turn an old plastic bottle into a new one.

Plastic can only be turned into a product of lower quality – a plastic lemonade bottle might be cleaned, shredded and used to stuff seat cushions or insulate sleeping bags. A mixture of plastic waste can be recycled into plastic ‘timber’ and used to make durable fencing. But a lot of plastic waste still has to be thrown away because its value as scrap is so low.

Metals are different. Any car on the road today will consist, in part, of earlier cars that have been scrapped and recycled into new steel and other metals.

The more valuable the metal, like gold and silver, the more it pays to recycle it. Aluminium is worth recycling because extracting it from bauxite consumes a huge amount of electricity. Largely thanks to recycling programmes the energy used to make aluminium has fallen by a quarter since the early 1970s.

More than 70 billion canned drinks are bought in America every year, and all the cans are made of aluminium. About half are remelted after use and within six weeks they have been made into new tins and are back on the supermarket shelves.

Glass is worth recovering. The most sensible method is to use glass bottles as often as possible. The average British milk bottle makes about 30 trips to and from the dairy.

Many countries now have compulsory deposit schemes to make people return bottles to shops. When such a law was passed in the state of New York in 1983, it was estimated that within two years it had saved $50 million on rubbish collection, $19 million on waste disposal costs, and about $50 million in energy costs.

Some supermarkets now have machines that accept glass bottles and aluminium cans and give cash or redeemable vouchers to the customer. They read the computer codes on the containers to work out how much to pay.

Broken glass, known as ‘cullet’, can also be recycled, and many countries have bottles banks depend on people’s goodwill. The success of bottle banks varies widely from country to country. The Swiss and Dutch recover 50 per cent of their glass, while in Britain only 12 per cent is recovered.

Glass is best separated by colour, since cullet of mixed colours can be used only to make green glass. Broken glass can be remelted in furnaces and then it can easily be shaped into new bottles or other objects.

Half the world’s waste consists of paper. Many countries import waste paper rather than new pulp for their paper mills. The waste is pulped, cleaned and bleached to remove most of the ink and dirt, before it is turned into new paper in the same way as wood pulp or rags. Japan now makes half its paper by recycling.

 

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Every year Americans throw away 250 million tons of rubbish. New York alone generates almost 10 million tons a year. It has been estimated that America’s garbage could provide as much energy as 100 million tons of coal. However, most of it is buried, and never used.

About half of the world’s domestic waste is paper, while kitchen waste makes up a quarter and plastics less than a tenth. Only a fifth will not burn and most of that can be recycled.

Western Europe has more than 200 plants which burn rubbish to produce electricity. A large plant at Edmonton in London, which opened in 1974, burns about 400,000 tons of refuse a year. The burning refuse heats water to create steam which powers the electric generators. Within ten years the plant has saved a million tons of coal.

In Dusseldorf, West Germany, six similar plants supply steam to generate electricity for district heating schemes.

In Peekskill, New York, a plant has been built to handle 2250 tons of refuse a day, generating 60 megawatts of electricity – enough to supply 70,000 people.

Rubbish can also be burned by factories instead of coal or oil, but it must be treated first. The rubbish is separated by feeding it though a vibrating screen which sifts out the fine organic particles to be turned into compost for treating land. In Sweden a quarter of all solid waste is turned into compost and recycled.

Next the heavy part of the rubbish, mainly metals, must be sorted out and removed, leaving mainly paper and textile waste. These are pressed into cylindrical pellets and sold as fuel.

Even rubbish dumped in the ground can be used as a source of fuel. As it begins to rot, it produces methane gas – identical to the natural gas found in pockets under the Earth’s crust. Each ton of refuse can produce over 8000 cubic feet (227 cubic metres) of methane. Left alone, the gas will find its way to the surface and escape, sometimes causing explosions. But it can be tapped very cheaply and used to generate heat or electricity. There are more than 140 such schemes in operation in 15 countries, saving a total of at least 825,000 tons of coal a year. In England, for example, a large tip has been drilled with wells to extract the gas, which is piped to a brickworks where it replaces coal.

Other plants use the gas on site to generate electricity by burning it in simple gas engines. This allows all the gas to be used, rather than trying to match output to the fluctuating demands of a factory.

In the future, production of gas in rubbish tips may be improved by ‘seeding’ the tips with bacteria. Some strains of bacteria break down refuse faster than others. By introducing the best mix of bacteria for the particular waste in a tip, the maximum amount could be produced.

 

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• Dumping of medical waste in the open or disposal of untreated waste can be dangerous.


• A host of infectious diseases is linked to toxic medical waste while garbage collectors, along with those living close to medical centres, are especially at risk.


• The disposal of untreated waste in landfills can lead to the contamination of drinking, surface and ground water if those landfills are not properly constructed.


• The disposal of untreated waste in landfills can cause diseases in animals as well. Animals may consume infected waste and eventually, these infections can be passed on to humans who come in contact with them.


• It is often found that biomedical waste is dumped into the ocean, where it eventually washes up on shore.


• The treatment of healthcare waste with chemical disinfectants can result in the release of chemical substances into the environment if those substances are not handled properly.


• Inadequate incineration or the incineration of unsuitable materials results in the release of pollutants, including carcinogens (cancer-causing chemicals) into the air.


• Incineration of medical devices with heavy metals (in particular lead, mercury and cadmium) can lead to the spread of toxic in the environment.


• If safety measures are not followed, health workers, laboratory personnel and transport workers will also be affected.

 

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• As of 2016, India was generating about 484 tonnes of bio-medical waste per day, from its 1,60,000 health-care centres. It was estimated that the country would generate 77.5 tonnes of medical waste per day by 2022. A 100-bed hospital generates 100-200 kg of hospital waste every day, according to a study.


• Of the total amount of waste generated by health-care activities, 15% is considered hazardous that may be infectious, toxic or radioactive.


• Segregation, treatment and transportation, depends on the type of bio-medical waste. Incineration, deep burial, local autoclaving, microwaving, chemical disinfection, mutilation and shredding and discharge into the drains, followed by disinfection are some of the ways that medical wastes are managed in India.


• Colour-coded containers are used for disposal of biomedical waste.


• India’s bio-medical waste management is ruled by the Bio-medical Waste Management Rules 2016. According to the rules, blood samples and microbiological waste should be pre-treated on-site before being disposed of. It also planned to introduce a bar-coding system, where all biomedical waste containers or bags are going to be tracked by the government. This is to ensure that the movement from its manufacturing to treatment facilities is monitored.


• Common bio-medical waste treatment facilities (CBWTFs) are involved in managing waste. According to the 2016 rules, a CBWTF within 75 km of a healthcare centre has to ensure that waste is collected routinely and regularly.


• The ruling also extends to vaccination camps, blood donation centres and surgical camps.

 

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Infectious medical waste: These are waste materials that can pose a risk of infection to humans, animals, and the overall environment. This includes blood-stained bandages, surgical waste, human or animal body parts, cultures and swabs.

Sharps waste: This includes syringes, needles, disposable scalpels and blades.

Chemical waste: Solvents and re-agents used for laboratory preparations, disinfectants, metals such as mercury in devices such as broken thermometers and batteries.

Pharmaceutical waste: Unused, expired and contaminated medicines.

Radioactive waste: Products contaminated by radionuclides, including radioactive diagnostic material or radiotherapeutic materials.

 

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Morning walkers of Clifton Beach, Karachi, Pakistan, were in for a shock recently as the golden sand was covered in garbage, which included a large amount of bio-medical waste. The tide had brought with it several blood vials and open syringes to the shoreline. Pakistani media criticised the government for going easy on hospitals and research centres that continue to dump toxic waste in the open or directly into water bodies.

To story is not different in India. Despite regulations against the dumping of medical waste in the open, loads of them are disposed of in landfills along with other garbage every day. Other rules of segregation and safety measures are also flouted in some places. Coming in contact with such waster or open burning can prove harmful to the environment and our health.

Waste generated during the diagnosis, treatment or immunisation of human beings or animals in hospitals and clinics and during experiments in research labs are all biomedical waste. It includes used syringes, blood-stained cotton bandages, used I-V tubes, scalpels, blades, glass, microbiological cultures, discarded gloves, and linen. It also includes human or animal tissues, organs and body parts and fluids. Biomedical waste may be solid or liquid.

 

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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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