Natural Resources

Global Warming: It is time to act now!

Global warming is one of the major challenges that humans face in the 21st century. What do you know about global warming and what are its effects?

The 18th and 19th centuries were the industrial eras. During this time, massive quantities of fossil fuels were burnt in factories around the world. Burning of fossil fuels leads to the production of greenhouse gasses like carbon dioxide.

So, what is a greenhouse gas?

Many of you may have visited a greenhouse. A greenhouse is a building that is covered by glass on all sides. The glass allows heat inside the building, but it does not allow the heat to escape from the building. This, it traps heat within the building. Greenhouse gasses like carbon dioxide act in a similar manner. These gasses trap the heat produced by the sun within the earth?s atmosphere. Therefore, the temperature of the earth?s (including ocean surface) surface increases. Greenhouse effect is the name of this phenomena. Apart from carbon dioxide, the other major contributors to the greenhouse effect are oxides of nitrogen and sulfur and methane.

global warming

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Cattle produce copious amounts of methane (in their gut). Therefore, large-scale cattle farming leads to increased release of methane and is an important cause of global warming.

Simply put, global warming is the gradual increase in earth?s temperature due to the accumulation of greenhouse gasses in the atmosphere.

How does global warming affect us?

Global warming affects us in many ways. We have heard from our parents and grandparents that the summers are becoming hotter, and winters are reduced in duration in intensity. This (climatic changes) is an outcome of global warming.

Global warming has more sinister outcomes as well. The average temperature has increased by over 2 C in the past one century. The increase in temperature leads to melting glaciers and polar ice caps. This (melting of ice) results in an increase in sea levels. As sea levels increase, low-lying coastal areas get flooded leading to the displacement of millions of human beings living in these regions. Global warming also leads to rapid melting of glaciers. Glaciers are the source of almost all rivers in the world. Rapid melting of glaciers leads to floods along the course of rivers. Apart from these, global warming also leads to unpredictable climate changes like droughts, extremely severe winters, and massive hail storms. Global warming also leads to reduced agricultural productivity thus impacting food security.

What is the relationship between global warming and other forms of pollution like noise pollution?

Apart from atmospheric pollution, water pollution, and noise pollution are also increasing due to human activities. Do these forms of pollution have any relationship with global warming?

Water pollution makes water unfit for consumption. But, it does not increase the temperature of the water. Therefore, water pollution is unlikely to contribute to global warming. Similarly, noise pollution also does not contribute to global warming. On the contrary, global warming may contribute to noise pollution.

Let us do an experiment to demonstrate this effect. Take some ice cubes in a glass and pour hot water over the cubes. What do you see?

You will note that the ice cubes crack and break into small pieces before melting. When the ice cracks, it produces sound, thus leading to noise pollution.

Many researchers have studied the disintegration of icebergs and its effects on the marine environment. They (researchers) have found that the noise produced by disintegration of icebergs is equal to the noise produced by hundred supertankers. The noise produced by breaking of ice affects marine animals and leads to deleterious consequences to the marine ecology.

To conclude, global warming is a major challenge to the human race in the 21st century. If we do not act now, then it may be too late.

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The Pacific garbage patch

In our article on non-biodegradable materials, we had learned a little about the Pacific garbage patch. So what exactly is the Pacific garbage patch? Human activity generates close to 300 million tons of plastic waste every year. About 10-15 tons of this waste finds its way to the rivers, and then the oceans. In the oceans, the plastic waste breaks down into tiny particles under the effect of waves and sunlight.

The oceans, as you know, are interconnected. Water in the oceans is steadily flowing from the warmer regions to the colder areas. These ocean currents carry the plastic waste to convergence zones. Convergence zones behave like a slow whirlpool. The water slowly rotates around a central axis, and this causes the plastic particles to aggregate. Thus, a large patch of plastic waste is formed. There are four such spots in the oceans of the earth. Amongst these, the Pacific garbage patch is the largest.

As imagined, the Pacific garbage patch is not an island made of plastic. In fact, most of the Pacific garbage patch floats beneath the water. Therefore, it is not visible from a satellite or space. The Pacific garbage patch weighs nearly seven million tons. Within this garbage patch, the minuscule fragments of plastic are in close association with the marine flora like plankton and small fish. These fishes eat the plastic particles and finally the plastic finds its way into the food chain.

Apart from entering the food chain, the plastic waste also endangers marine life. Birds and fish eat this plastic and choke to death. The garbage patch also hinders movement of ships through the world?s waterways.

So, how do we clean up this muck?

There is no way to clean up the Pacific garbage patch. It is not possible to scoop up the waste with machines. Nor is it possible to degrade it by biological means. The only thing we could do is to stop it from getting bigger.

We have learned before that plastics stay in the environment for many years. Reducing the use of plastic is the only way to halt the growth of the garbage patch. For starters, we could carry our cloth or jute bags to the market. We can also reduce the use of plastic by recycling the plastic waste.

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The hazard of non-biodegradable materials

Non-biodegradable materials cannot degrade by natural means. Can you name four non-biodegradable materials? Metals are non-biodegradable as they cannot degrade by naturally. Similarly, glass also cannot be degraded by bacteria. Hence, they are also non-biodegradable. What about plastic? Can plastic be degraded naturally? No, plastic cannot be degraded naturally. In fact, plastic lasts in the environment for many years. Therefore, plastic is the most harmful non-biodegradable material we use in everyday life.

Non-biodegradable waste like metal cans and glass bottles can be recycled. They can recycled in a factory where smelters melt the metal items and new metal items produced. Similarly, glass can also be melted to produce new glass. However, plastics cannot be recycled this way. Melting plastic releases a lot of smoke. This smoke not only pollutes the environment, it also has many chemicals that can cause harm to living beings. Therefore, melting is not an appropriate way to dispose of plastic waste. So, how do we dispose of non-biodegradable plastic waste?

There is no environmentally safe way to eliminate non-biodegradable materials like plastic. As of now, most of the plastic we use is dumped in landfills or thrown into rivers. Humans generate up to 300 million tons of plastic every year. About 5-10% of this plastic finds its way to the oceans. In the oceans, waves and sunlight break this plastic into minuscule particles. The ocean currents carry these particles a convergence zone. Here, these plastic particles float as a loose aggregate to form a garbage patch. There are three such garbage patches in our oceans. The largest garbage patch is the Pacific garbage patch. We will learn more about the Pacific garbage patch in another article.

Thus, you see that these is no environmentally safe way to dispose of plastic. Therefore, if we indiscriminately use plastics, then our earth would be filled with plastic waste, thus choking our rivers and causing significant harm to living beings. The only way to prevent the accumulation of plastic waste is by reducing the use of plastic.

Can you think of a few ways how you can minimize the use of plastics?

For starters, you could carry a cloth or jute bag to the market thus reducing the use of plastic bags. Another thing we could do is to recycle most of the waste we generate. Paper, cardboard, metals and glass can be recycled. Recycling, apart from saving trees and water, ?also provides employment opportunities to millions of people.

You could do a small activity that will demonstrate how much your role as an individual can improve the environmental conditions of the planet. Segregate household waste into non-biodegradable and biodegradable materials. Weigh them both and compost the biodegradable waste and send the non-biodegradable for recycling. Waste like plastic that cannot be recycled should be separately stored. At the end of a week, do to math as to how many kilograms of waste your house generates. How much is biodegradable and how much is not? How much plastic waste did you generate? You will now have an idea how much waste you can prevent by composting and recycling your waste.

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Biodegradable materials

We have often heard of biodegradable materials. Can you recollect a few places where you may come across this word? You may have seen this printed on milk cartons, or on a paper bag used for shopping. You may also have noted how your mother segregates waste based on whether it is biodegradable or not. So what are biodegradable materials?

Let us do an activity to know more about biodegradable materials.

Collect waste from your house for one full day. Do not segregate the waste. What kind of waste are you likely to receive? Kitchen waste like leftover food, vegetable and fruit peels, waste paper, packaging, glass, metal cans and plastic are some of the wastes commonly generated in our houses. Bury this waste in your backyard. If you do not have a garden, you can store the waste in a bucket and cover it with about 15 cm of mud. Check on this waste once every few days. What will you observe?
You will note that the kitchen waste (vegetable peels, fruits peels, residual food) degrades within a few days into compost. Waste like newspapers and packaging made of paper degrade next, and glass and plastic do not degrade at all. In fact, plastics can last in the environment for thousands of years.

So why does kitchen waste degrade so quickly? In the chapter on human nutrition, we had learned about enzymes. Enzymes are proteins that catalyse the breakdown of food within the digestive tract. Bacteria in the soil produce similar proteins that break down the kitchen waste to produce compost. The compost is an excellent source of nutrients for plants and using it in the garden can improve yields. Biogas plants produce methane and compost using the?same principle.The enzymes can also act on paper. However, cellulose, the main component of paper takes a longer time to break down, therefore, paper and paper products stay in the environment longer. Enzymes have no action on plastic and metals. Therefore, these items are not degraded by the enzymes.

Therefore, substances that are degradable by biological means are biodegradable materials.Non-biodegradable materials like plastic and glass are not degraded by natural means. Hence, they can persist in the environment for thousands of years. Can you now imagine what would happen if we keep using plastic indiscriminately? All the plastic will stay on earth for thousands for many years and cause immense environmental damage. See this video below to get an idea of the risk posed by plastic to animals and environment, in general.

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Nuclear energy

Nuclear energy is the result of nuclear fission. In a nuclear fission, the nucleus of a heavy atom like uranium or plutonium splits into two lighter elements. The sum of the masses of the products is lower that the reactant atom. This small difference in mass gets converted to energy as per the following equation:

E= MC2

Here ?M? stands for the difference in the mass of the original atom and its products, ?C? is the speed of light in a vacuum. This formula was first derived by Albert Einstein in 1905.

Nuclear reactors generate nuclear energy. A nuclear reactor is a complex equipment where neutrons bombard the atoms of uranium. As a result, the atoms of uranium split into two lighter elements- Krypton and boron. Along with the lighter elements, three neutrons are also produced. The neutrons set up a self-perpetuating reaction, and the reactor is said to have gone critical. This reaction can be controlled using a boron rod and a steady state of fission is established. The energy produced by the fission reaction is used to produce steam, which is then used to drive a turbine, thus producing electricity.

The biggest advantage of nuclear power is that a single atom of uranium can produce an immense amount of energy. The energy produced from one atom of uranium is equal to that from 100 million atoms of carbon. ?One atomic mass unit of uranium can produce more than 900 electron megavolts (eMV) of electricity. Thus, nuclear energy has emerged as a very attractive source of energy.

Presently, nuclear power plants are located in Tarapur, Kalpakam, Rana Pratap Sagar (Rajasthan), Narora (UP), Kakrapar (Gujarat) and Kaiga (Karnataka). The total installed capacity of nuclear energy in India contributes to less than 3% of the energy requirement of the country. In contrast, some countries source nearly 30% of their energy need from nuclear power. Many reactors have been planned to increase the share of nuclear power in power generation in India.

However, nuclear energy is not easy to harness. The biggest problem with nuclear power is the storage and disposal of nuclear waste. Used uranium produces harmful radiation for many years. Therefore, used fuel needs to be stored and disposed properly. The second major problem is with security. Long before being used for power generation, nuclear power was used for destructive purposes- Japan was attacked with nuclear bombs World War II. Used uranium can be used to make atomic bombs. Therefore, stringent standards are required to ensure the safety of the used fuel.

Setting up a nuclear energy plant requires a huge investment. The technology is expensive, and there are safety issues involved. Due to the fear of accidental leakage, there is a lot of unrest in local communities over proposed nuclear plants.

Investment in research will improve the safety of nuclear energy plants and may allow setting up of more nuclear plants. Increased share of nuclear energy will ultimately help feed the immense appetite for energy in the country.

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Wind energy

Man has used the power of the wind for hundreds of years. The earliest seafarers used wind energy to power the ships. We used to use windmills to grind wheat, rice and corn. Now we use windmills to generate electricity. Even, some of our leisure activities like flying a kite also requires wind energy.

If you travel along the southern coast of India, you will see thousands of windmills, which harness the wind energy and convert it into electricity. So how do windmills produce electricity?

The wind has kinetic energy. The blades of the windmill rotate when the wind strikes it. The turbine is connected to the blades converts the kinetic energy of the wind into electric energy. When a magnetic coil rotates around a metal core, it produces electricity. The rotatory movements of the blades rotate a magnetic coil within the turbine to produce electricity. The amount of electricity produced is proportional to the speed of the wind. ?As the electricity produced by a single windmill is small, thousands of windmills are installed where land and wind conditions are favourable, these are called as wind energy farms or simply wind farms. The largest such farm in India is in Kanyakumari District in Tamil Nadu. This farm produces 380 MW of electricity.

Wind energy is one of the clean sources of energy. It is renewable, does not pollute the environment and will be a source of energy for as long as the winds blow. Wind energy can generate nearly 45,000 MW of electricity in India. Due to the concerns about global warming, many countries are focussing on the wind as a source of energy. Denmark is one such country. Nearly 1/4th the energy requirement of Denmark is met through wind power.

The initial costs of setting up a wind farm are high. A 1 MW farm requires about 2 hectares of land. Also, windmills can only come up in areas with wind flow throughout the year. The wind speed should be excess of 15 km/h.

Apart from these, batteries are required to store the energy produced by the wind and then there are maintenance costs. Therefore, wind energy is still a fledgling enterprise. However, once set up, the running costs are fairly low. As the initial investment is high, governments offer subsidies to help promote the wind as a source of energy.

With the improvement in the design and efficiency of the wind turbines, this source of energy may one day be truly affordable without the need for subsidies.

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Solar energy

Man has been using solar energy for many thousands of years. We use solar energy to dry our clothes and food. In fact, the sun plays a critical role in our culture as well. Most communities in India worship the sun. Mythological and religious texts refer to the sun. So, what makes the sun so important?

The sun is the source of all energy in the world. It provides us with light, heat and enables the plants to produce food. It is also responsible for the formation of winds, clouds, and rain. Therefore, it would not be incorrect to say that life on earth would not be possible without the sun.

We in India are lucky because most parts of our country receive abundant sunlight throughout the year. We have been using solar energy to heat up water and to cook food. However, sunlight can only be used during the daytime. Also, if the sky is cloudy, then the amount of solar energy reaching the surface of Earth is much lower.

To rectify this problem, we have developed solar cells. These cells are designed to convert solar power into electricity that we can store for future use. The solar cells are made up of silicon, a mineral found in abundance in the earth?s crust. A single cell will develop a voltage of 0.5 t 1V and can produce about 0.7 Watts of power when exposed to sunlight. As the amount of power generated by a single cell is low, many cells are combined to form a solar panel.

Solar energy has many advantages. It is nearly a limitless source of energy. The sun has been shining for the past 5 billion years, and it is likely to shine for many millions of years. It is renewable and most importantly, it is the cleanest source of energy.

However, solar energy is not without its disadvantages. As the output from a single solar cell is quite small, many millions of cells are required to be assembled to produce enough power. Therefore, large tracts of land are needed to install these panels. In remote, sparsely inhabited areas (like Leh or Rajasthan), it may be possible to get large tracts of lands, but laying transmission lines is expensive in these areas. An innovative solution is to install these panels over irrigation canals. Installation of solar panels over irrigation canals has two advantages- there is no need to use fertile farmland and the solar panels minimise water loss due to evaporation.

Manufacture of solar panels requires Silicon, a mineral abundant in the earth. However, extracting and refining it is expensive. Production of solar panels also requires silver, a rare and precious metal. Therefore, the cost of installation of solar panels is quite high, but the running costs of negligible.

With the improvement in technology, the cost of solar energy is steadily coming down. As awareness increases, it is likely that the use of solar energy will increase. We can reduce our dependence on fossil fuels by increasing the use of solar energy.

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Fossil fuels- advantages and disadvantages

In our previous article, we had discussed the nature of fossil fuels. In this article, we shall discuss the advantages and disadvantages of fossil fuels.

The world is overwhelmingly dependent on fossil fuels for its energy requirements. Coal is the predominant fuel used in our factories and power plants. Almost all our transport runs on oil. In fact, we are so dependent on fossil fuels that we cannot imagine our life without them.

Fossil fuels have some distinct advantages that make them a preferable source of energy. The amount of energy produced by burning of fossil fuels is quite high. Also, fossil fuels are easily available, especially in countries that have deposits of these fuels. It is, therefore, not surprising that we are so dependent on them for our energy needs.

However, there are many disadvantages of using fossil fuels. These fuels are a finite resource. Fossil fuels were formed millions of ago and will take many years to replenish. Therefore, we have to use them with prudence. Also, fossil fuels are a dirty source of energy. Burning of fossil fuels produces carbon dioxide that is the major greenhouse gas in the atmosphere. ?Indiscriminate burning of fossil fuels has led to a rapid rise in world temperature due to the greenhouse effect produced by carbon dioxide. Also to carbon dioxide, burning of fossil fuels produce oxides of sulphur and nitrogen. These cause air pollution and lead to the formation of acid rain that is harmful to plants and animals. These pollutants also increase the risk of allergic and respiratory disorders in humans.

Apart from producing carbon dioxide and oxides of nitrogen and sulphur, burning of coal also produces a fine ash called as fly ash. This fly ash coats the surface of buildings and fields, especially in the vicinity of power plants. Fly ash causes damage to buildings and impairs production of food crops. Most power plants store this fly ash in ponds called as ash ponds. A few years ago, there was a breach in one of the ponds and acres of fertile farmland were cover with fly ash, rendering these lands unfit for cultivation.

Most of our vehicles burn oil for energy. Burning of oil also produces carbon dioxide and oxides of sulphur and nitrogen. Also, engines also produce small particulate matter that remain suspended in air. This particulate matter is particularly harmful, and this is the reason respiratory illness is higher in highly polluted cities like New Delhi and Beijing.

Mining of fossil fuels also leads to environmental degradation. Forests are cut down to mine these fuels. Seas and oceans are the most abundant source of oil. We have to dig deep wells in the seabed to extract this oil. In this process when there is an oil leak, millions of square kilometres of the ocean surface is covered with this oil, leading to an environmental disaster like the one that happened in Gulf of Mexico.

Excessive use of fossil fuels also has an economic impact, especially in countries that no not have adequate reserves. India imports nearly 3/4th its requirement of oil. Paying for this contributes the maximum to our trade deficit and puts a huge strain on our economy.

Therefore, we should use fossil fuels with care. We can reduce our dependence on fossil fuels by cutting down the wasteful expenditure of energy and by using other alternative sources of energy like hydroelectric power or nuclear power.

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Fossil Fuel

Coal, oil, and natural gas are the most commonly used sources of energy. These are all hydrocarbon based and known as fossil fuel. Fossil fuel is a generic term used to describe organic geological deposits that are combustible. Fossil fuels are formed from decaying plant and animal matter that under the influence of heat and pressure, is converted into coal, oil and natural gas.

Many million years ago, most of the land on earth consisted of swamps and oceans. Many huge trees and other leafy plants grew in these swamps. The surface of oceans was covered by millions of algae, which are very small plants. As these plants and algae died, they sunk to the bottom of swamps and oceans. Over a period, this layer of organic matter was covered by sand, clay and other minerals. As the weight of the layer of sand and clay increased, water was squeezed out of organic matter and eventually fossil fuels were produced. This period is called as carboniferous period and it is estimated to have occurred some 300 million years ago.

Coal is a black coloured, rock-like substance. It is made up of carbon, oxygen, nitrogen, sulphur and hydrogen. There are three major types of coal-anthracite, bituminous and lignite. Anthracite has the highest proportion of carbon and is the hardest of the three types of coal. Lignite has the least amount of carbon and is the softest of the three types of coal. Coal is mined from the earth in many different ways. Coal is mined from deep vertical shafts dug into the earth. These mines are called as closed mines. Coal can also be mined by stripping away the top layer of sand and clay above the coal. These mines are called as open mines. Once mined, coal is transported by trains, ships and even through pipelines to distant places where it is used in industry or is used to generate electricity.

Oil is a thick, sticky liquid which has many uses in our life. Sumerians were the first to use petroleum. They used it for medicinal purposes and lighting lamps. Currently, oil is used for transportation, industry and as a raw material for many substances like fertilisers. Oil is found deep in the crust of the earth, between two layers of rocks. Rigs drilled into the crust of the earth?extract oil. Once extracted, this oil is fractionated or refined into its many components- petrol, diesel, natural gas and fuel oil. The waste left over after refining is called pitch and is used to lay roads. Today, oil is found in most countries, but USA, Russia and the countries in the Middle East are the largest producers of oil.

Natural gas is another hydrocarbon based fossil fuel that we commonly use. Natural gas is found in close vicinity to oil and both are extracted together. Natural gas is lighter than air and is colourless and odourless. The primary component of natural gas is methane that consists of one carbon molecule attached to four hydrogen atoms (CH4).

Fossil fuels have been made over millions of years. And they are a finite resource. Once exhausted, it will take millions of years to replenish. Therefore, it is important to conserve them. We can save fossil fuels by cutting down on the wasteful expenditure of energy and by investment in technology that improves efficiency.

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Sources of energy

From the moment we wake up, to the time we sleep, we use energy. We use electricity to heat water for bathing, use gas to cook breakfast and go to school in vehicles powered by petrol or diesel. Electricity, gas, and petrol are all sources of energy.

Sources of energy are classified in different ways. Since times immemorial, man has used wood to produce energy. Then coal was discovered. The widespread use of coal led to the industrial revolution and improved the lives of millions of people. Then came petroleum that enabled the development of mechanised transport. Wood, coal and oil are all called conventional sources of energy. Since they were produced millions of years ago from the fossilisation of organic matter, they are also called as fossil fuels. Fossil fuels are the most common source of energy in the world. They account for nearly 3/4th of the energy requirement of the world. However, this source of energy is a finite resource. If we indiscriminately use fossil fuels, then we will soon run out and stare at a crisis.

To reduce dependence on fossil fuels, man has been developing newer sources of energy. The earliest source was flowing water. The kinetic energy of flowing water can be harnessed to produce energy. Dams store water from rivers, which then flows through pipes producing electricity from the kinetic energy of flowing water. Power produced from water is also known as hydroelectric power. ?Similarly, we have harnessed the power of wind to generate energy. These sources of energy are called non-conventional energy. Some other non-conventional sources of energy include solar power, geothermal energy, nuclear energy and tidal energy. However, these are only a minor source of energy.

Energy is also classified on whether it is renewable or non-renewable. We can produce energy from sunlight as long as the sun shines. Similarly, as long as the wind continues to blow and rivers continue to flow, we can harness their energy for our use. These are called renewable sources of energy. However, fossil fuels are a limited in availability. Also, these will take many millions of years to renew. Therefore, fossil fuels are called as non-renewable energy.

We have all seen cow dung being used as a source of energy. Similarly, we have also seen firewood being used for cooking in villages. As these are procured from living beings, these are called biomass energy. Although a renewable source, they have low efficiency and produce a lot of smoke. With the improvement in technology, it is now possible to produce gas from biomass. As cow dung is the predominant ingredient, this is also called as ?gobar-gas?.

Based on the above, what would you consider a good source of energy?

A good source of energy should have high efficiency, must not produce a lot of smoke, should be easily available, should be renewable and should not require complicated technology to use. The current sources of energy do not?satisfy all these criteria. Therefore, man is always working to find newer sources of energy which will meet all the criteria.

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