My Science School

 

The intentional clearing of forested land is called deforestation. Throughout history and into current times, forests have been cleared in order to convert the forest land to farms, ranches, or urban uses. While deforestation has greatly changed the world's landscapes, the greatest concentration of deforestation today is taking place in tropical rainforests. Deforestation not only results in more carbon dioxide being released into the atmosphere, but also threatens the world's biodiversity as these forests are usually home to many species of plants and animals.

The Food and Agriculture Organization of the United Nations defines deforestation as the conversion of forest to other land uses (regardless of whether it is human-induced). "Deforestation" and "forest area net change" are not the same: the latter is the sum of all forest losses (deforestation) and all forest gains (forest expansion) in a given period. Net change, therefore, can be positive or negative, depending on whether gains exceed losses, or vice versa.

The removal of trees without sufficient reforestation has resulted in habitat damage, biodiversity loss, and aridity. Deforestation causes extinction, changes to climatic conditions, desertification, and displacement of populations, as observed by current conditions and in the past through the fossil record. Deforestation also reduces biosequestration of atmospheric carbon dioxide, increasing negative feedback cycles contributing to global warming. Global warming also puts increased pressure on communities who seek food security by clearing forests for agricultural use and reducing arable land more generally. Deforested regions typically incur significant other environmental effects such as adverse soil erosion and degradation into wasteland.

The resilience of human food systems and their capacity to adapt to future change is linked to biodiversity – including dryland-adapted shrub and tree species that help combat desertification, forest-dwelling insects, bats and bird species that pollinate crops, trees with extensive root systems in mountain ecosystems that prevent soil erosion, and mangrove species that provide resilience against flooding in coastal areas.] With climate change exacerbating the risks to food systems, the role of forests in capturing and storing carbon and mitigating climate change is important for the agricultural sector.

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Important ocean habitats that offer us compelling evidence about the risks posed by climate change, coral reefs are large underwater structures made up of the skeletons of colonial marine invertebrates called coral. Also referred to as "the rain forests of the seas", scientists believe that one out of every four marine species live in and around coral reefs. This makes them one of the most diverse habitats of the planet, providing for a huge portion of Earth's biodiversity.

Each individual coral is referred to as a polyp. Coral polyps live on the calcium carbonate exoskeletons of their ancestors, adding their own exoskeleton to the existing coral structure. As the centuries pass, the coral reef gradually grows, one tiny exoskeleton at a time, until they become massive features of the marine environment.

Corals are found all over the world's oceans, from the Aleutian Islands off the coast of Alaska to the warm tropical waters of the Caribbean Sea. The biggest coral reefs are found in the clear, shallow waters of the tropics and subtropics. The largest of these coral reef systems, the Great Barrier Reef in Australia, is more than 1,500 miles long (2,400 kilometers).

Scientists have explored only about 20 percent of the ocean's floor, according to the National Oceanic and Atmospheric Administration (NOAA). As such, ocean explorers continue to discover previously unknown coral reefs that have likely existed for hundreds of years.

Most of the substantial coral reefs found today are between 5,000 and 10,000 years old, according to CORAL. They are most often found in warm, clear, shallow water where there's plenty of sunlight to nurture the algae that the coral rely on for food.

Coral reefs cover less than 1 percent of the ocean floor — all the reefs combined would equal an area of about 110,000 square miles (285,000 square km), only about the size of the state of Nevada. Nonetheless, they are among the most productive and diverse ecosystems on Earth.

About 25 percent of all known marine species rely on coral reefs for food, shelter and breeding. Sometimes referred to as "the rainforests of the sea" for their biodiversity, coral reefs are the primary habitat for more than 4,000 species of fish, 700 species of coral and thousands of other plants and animals, according to CORAL.

Coral reefs are typically divided into four categories, according to CORAL: fringing reefs, barrier reefs, patch reefs and atolls. Fringing reefs are the most commonly seen reef and grow near coastlines. Barrier reefs differ from fringing reefs in that they are separated from the coastlines by deeper, wider lagoons. Patch reefs typically grow between fringing and barrier reefs on the island platform or continental shelf. The rings of coral that make up atolls create protected lagoons in the middle of the oceans, typically around islands that have sunk back down into the ocean.

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The long-term shifts in temperature and weather patterns is referred to as climate change. While these shifts have been natural for the longest period of humanity, human activities have become the main driver of climate change since the 1800s. This is mainly due to the burning of fossil fuels like coal oil and gas, which then produces heat-trapping gases to alter the delicate equilibrium governing the Earth in a negative fashion.

What Causes Climate Change?

There are lots of factors that contribute to Earth’s climate. However, scientists agree that Earth has been getting warmer in the past 50 to 100 years due to human activities.

Certain gases in Earth’s atmosphere block heat from escaping. This is called the greenhouse effect. These gases keep Earth warm like the glass in a greenhouse keeps plants warm.

Human activities — such as burning fuel to power factories, cars and buses — are changing the natural greenhouse. These changes cause the atmosphere to trap more heat than it used to, leading to a warmer Earth.

When human activities create greenhouse gases, Earth warms. This matters because oceans, land, air, plants, animals and energy from the Sun all have an effect on one another. The combined effects of all these things give us our global climate. In other words, Earth’s climate functions like one big, connected system.

Thinking about things as systems means looking for how every part relates to others. NASA’s Earth observing satellites collect information about how our planet’s atmosphere, water and land are changing.

By looking at this information, scientists can observe how Earth’s systems work together. This will help us understand how small changes in one place can contribute to bigger changes in Earth’s global climate.

Credit : Climate kids 

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Any of several organic compounds composed of carbon, fluorine, and chlorine, chlorofluorocarbons (CFCS) are non-toxic non-flammable chemicals. If it contains hydrogen in place of one of the chlorines, they are called hydrochlorofluorocarbons (HCFCS) Originally developed as refrigerants in the 1930s. CFCs gained commercial and industrial value as they found use in the manufacture of aerosol sprays, solvents and foam-blowing agents. CFCS, however, were eventually discovered to pose an environmental threat at a serious: level as they contribute to the depletion of the ozone layer and hence are being phased out throughout the world.

What are the applications of CFC?

Chlorofluorocarbons are used in a variety of applications because of their low toxicity, reactivity and flammability. Every permutation of fluorine, chlorine and hydrogen-based on methane and ethane has been examined and most have been commercialized.

Furthermore, many examples are known for higher numbers of carbon as well as related compounds containing bromine. Uses include refrigerants, blowing agents, propellants in medicinal applications and degreasing solvents.

How do CFCs impact the environment?

However, the atmospheric impacts of CFCs are not limited to their role as ozone-depleting chemicals. Infrared absorption bands prevent heat at that wavelength from escaping the earth’s atmosphere. CFCs have their strongest absorption bands from C-F and C-Cl bonds in the spectral region of 7.8–15.3 µm—referred to as “atmospheric window” due to the relative transparency of the atmosphere within this region.

The strength of CFC absorption bands and the unique susceptibility of the atmosphere at wavelengths where CFCs (indeed all covalent fluorine compounds) absorb creates a “super” greenhouse gas (GHG) effect from CFCs and other unreactive fluorine-containing gases such as perfluorocarbons, HFCs, HCFCs, bromofluorocarbons.

Use of certain chloroalkanes as solvents for large-scale application, such as dry cleaning, have been phased out, for example, by the IPPC directive on greenhouse gases in 1994 and by the volatile organic compounds (VOC) directive of the European Union in 1997. Permitted chlorofluoro alkane uses are medicinal only.

According to scientific communities, the hole in the ozone layer has begun to recover as a result of CFC bans. India is one of the few countries that are pioneers in the use of non-Ozone Depleting technologies and have a low Global Warming Potential (GWP).

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Biodiversity is the name we give to the variety of all life on Earth. Bacteria to baboons, plants to people - the range of life on our planet is incredible.

All living things exist within their own communities, or ecosystems - oceans, forests, deserts, ice caps and even cities. All this put together is biodiversity: the volume of life on Earth as well as how different species interact with each other and with the physical world around them.

The word biodiversity is a contraction of 'biological diversity'. The concept is broad and complex, but that complexity is what makes Earth a perfect place for humans to live.

Biodiversity and species richness

When we talk about biodiversity, we often talk about species richness as well. Species richness is the number of different species in an area, a way of measuring biodiversity.

Studying species richness helps us to understand the differences between places and areas.

For example, the Amazon rainforest very species-rich as it is home to 10 million species. In contrast, the Sahara Desert is far less rich, with just a few thousand species.

About 1.5 million species have been described by scientists, and most of them are insects. But it is thought that there are millions more sharing our planet with us.

Endangered species and mass extinction

Overall biodiversity loss can speed up extinction. More and more animals and plants are facing an uncertain future.

The International Union for Conservation of Nature (IUCN) is the global authority on the status of the natural world. It keeps a Red List of endangered species, an important indicator of the health of the world's biodiversity.

Currently, more than 30,000 species are listed as threatened with extinction, which is 27% of all assessed species.

We know that millions of species have already gone extinct over the long history of planet Earth. Biodiversity rates have always ebbed and flowed. In fact, at least 99% of all the organisms that have ever lived are now extinct. Researchers agree that five huge mass extinction events have already happened, including the one that wiped out the dinosaurs 66 million years ago.

However, extinction rates have been accelerating as human populations continue to grow, and many scientists argue we are living through a sixth mass extinction. This time, humans rather than natural events are to blame. Species diversity in more than half of land ecosystems is now critically low.

A 20% drop is widely considered the threshold at which biodiversity's contribution to ecosystem services is compromised. It's estimated that over a quarter of Earth's land surface has already exceeded this.

Causes of biodiversity loss

Biodiversity is in trouble in the UK and across the globe, and its loss can refer to local and worldwide extinctions. Species and ecosystems can be fragile, so small changes can have large consequences.

The causes of biodiversity loss are complicated, but we know the human population is making the problems worse.

In the short time humans have been on the planet we have increasingly disrupted the balance of biodiversity through changing land use, overexploitation of resources and the impact we are having on climate.

We are converting natural habitats into farms, factories, roads and cities. In the ocean, we are overfishing, drilling and mining.

Cities and towns have a smoothing effect on biodiversity, tending to favour generalist species like feral pigeons. Those that require a particular habitat, or are intolerant of disturbance or pollution, often can't survive. This is called biotic homogenization.

Animals and plants that can only live in one small area of land - like unique butterflies or flowers - can go locally extinct if the city's conditions are unfavorable to them.

A lichen specimen held in the crypt herbarium at the Museum. All living things, including plants and fungi, are represented by the word 'biodiversity'.

Credit : Natural history museum 

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The word biodegradable, used in conjunction with a substance or object, denotes the capability of being decomposed by bacteria or other living organisms and thereby avoiding pollution. While this adjective describes things that can be broken down into basic substances through natural environmental techniques, the products it is used along with can vary greatly in the time they take to break down. For instance, while a loaf of bread requires only a couple of weeks. a piece of paper might need months and a biodegradable plastic carton could take even years to break down.

Some items are obviously biodegradable. Examples include food scraps and wood that hasn't been treated with chemicals to resist bugs and rot. Many other items, such as paper, also biodegrade relatively easily. Some products will biodegrade eventually, but it may take years. This includes steel products, which eventually will rust through and disintegrate, and some plastics.

However, conditions are important to encourage biodegradability. Products that will biodegrade in nature or in home compost heaps may not biodegrade in landfills, where there's not enough bacteria, light, and water to move the process along.

Many organic companies use biodegradable packaging for products or produce organic biodegradable products, but the items may not be as biodegradable as customers think. To make matters more confusing, many items are labeled as "compostable."

Compostable products are all biodegradable, but they are specifically intended for a composting environment. In the right setting, these products break down even more quickly, usually within 90 days, and they leave behind a nutrient-rich organic material called humus, which creates a healthy soil environment for new plant growth.1

Whether an item is compostable or simply biodegradable, it needs to be placed in an environment that facilitates its breakdown. Compostable products require composting environments. But, even some biodegradable items need to be degraded in a controlled composting environment or facility—and very few of these facilities exist in the United States. These large facilities are designed to keep materials at 140 degrees Fahrenheit for 10 consecutive days.

For example, PLA, a popular biodegradable material for green companies, will only decompose into carbon dioxide and water in a controlled composting environment, not in a backyard composting arrangement, according to standards developed by the Biodegradable Products Institute.

With all of these variables, business owners need to communicate clearly with their customers about what they mean when they say "biodegradable." Even better are those businesses that take it a step further and educate their customers about how to properly dispose of their products.

Credit : The balance small business 

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The Air Quality Index (AQI) is a measurement used to report daily air quality. Employed by most government agencies, it helps communicate to the public as to how clean or polluted your air is, how polluted it is forecast to become and associated health effects that might be a concern. Based on ambient concentration levels of different pollutants and their impact on human health, the National Air Quality Index in India has six categories: good, satisfactory, moderately polluted, poor, very poor, and severe.

Air quality index (AQI) is used by government agencies  to communicate to the public how polluted the air currently is or how polluted it is forecast to become. AQI information is obtained by averaging readings from an air quality sensor, which can increase due to vehicle traffic, forest fires, or anything that can increase air pollution. Pollutants tested include ozone, nitrogen dioxide, sulphur dioxide, among others.

Public health risks increase as the AQI rises, especially affecting children, the elderly, and individuals with respiratory or cardiovascular issues. During these times, governmental bodies generally encourage people to reduce physical activity outdoors, or even avoid going out altogether. The use of face masks such as cloth masks may also be recommended.

Different countries have their own air quality indices, corresponding to different national air quality standards. Some of these are the Air Quality Health Index (Canada), the Air Pollution Index (Malaysia), and the Pollutant Standards Index (Singapore).

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A broad term that includes all forms of precipitation with acidic components like sulphuric acid or nitric acid, acid rain, or acid deposition, falls to the ground in wet or dry forms from the atmosphere. When sulphur dioxide or nitrous oxides emitted into the atmosphere react with Oxygen, water and other chemicals it forms acids, which then further mix with water and other materials before falling to the ground as rain, hail, snow, fog, or even acidic dust.

What are the effects of acid rain?

The ecological consequences of acid rain are seen most strongly in marine habitats, such as streams, lakes and marshes where fish and other wildlife can be toxic. Acidic rainwater can leach aluminium from soil clay particles as it flows through the soil and then floods into streams and lakes.

What will happen if we don’t stop acid rain?

Sulphur dioxide and nitrogen oxide are the principal chemicals for acid rain. It can also influence humans since the acid goes into fruits, vegetables and animals. In other words, we can get really sick if acid rain doesn’t stop, and we eat those things. In general, acid rain affects men, but not directly.

What is acid rain? What are its harmful effects?

It has been shown that acid rain has detrimental effects on trees, freshwaters and soils, destroys insects and aquatic life-forms, causes paint to peel, corrosion of steel structures such as bridges, and weathering of stone buildings and sculptures, as well as impacts on human health.

What are three ways to reduce acid rain?

Alternative energy sources should be used, such as solar and wind power. Renewable sources of energy are helping to reduce acid rain, as they produce much fewer emissions. There are other electricity sources as well, such as nuclear power, hydropower, and geothermal energy. Among these, the most extensive use is among nuclear and hydropower.

How does acid rain affect plants?

Acid rain can affect the health of plants. Acid rain changes the pH of the land where the plant is growing, thereby affecting the overall growth of the plants. Moreover, it binds or dissolves essential soil minerals such as nitrogen and phosphorus and carries them away.

What is acid rain made of?

Acid rain comprises highly acidic water droplets due to air emissions, specifically the disproportionate levels of sulphur dioxide and nitrogen dioxide emitted by vehicles and manufacturing processes. Sulphur dioxide and nitrogen dioxide combine with water molecules to form sulphuric and nitric acid.

What is the primary source of acid rain?

The power plants primarily cause acid rain. It releases most of the sulphur dioxide and nitrogen dioxide while burning fossil fuels. Sulphur dioxide and nitrogen dioxide combine with water molecules to form sulphuric and nitric acid causing acid rain.

Can acid rain damage buildings?

Yes, acid rain harms buildings. It strips away the materials and corrodes the metals of the buildings. Example: Tarnishing of Taj Mahal.

Can acid rain burn your skin?

No, acid rain can not burn the skin.

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Many of our busy national highways cut deep through forests. Animals that cross these roads may sometimes get run over by fast-moving vehicles. To avoid this, the National Highways Authority of India (NHAI) has built nine dedicated underpasses for wildlife on the national highway NH47 that passes through the Kanha-Pench forest belt.

The cameras installed in the underpasses have revealed that a number of wild animals use them. The animals, including tigers, used the underpasses mostly at night to cross over to the other side of the forest. While some stayed back to take a nap or to have some fun with their playmates, a few others prowled the dark underpasses hoping for a good catch!

The concept was first developed in France in the 1950s. It took off in the Netherlands, where more than 600 crossings have been constructed to protect badgers, elk and other mammals. The Dutch built the world's longest animal crossing, the Natuurbrug Zanderij Crailoo, an overpass that spans more than 0.8 kilometers (0.5 miles). Wildlife crossings can also be found in Australia, Canada and other parts of the world. The idea took a little longer to catch on in the United States, but wildlife bridges and tunnels began appearing there in the 21st century.

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The sacred grooves are the trees which are considered as socially, culturally, medicinally or religiously important. The common examples of sacred grooves are Ficus Religiosa (Peepal) tree and Ficus benghalensis (Banyan) tree. They are known as sacred groves because there are small shrines or temples inside them honouring local deities. They are pockets of forests where people are forbidden to cut the trees or disturb the animals for fear of angering the resident gods. They can only collect honey, twigs, medicinal herbs and litter.

Sacred groves are found in every state of India though they are known by different names. There are more than 20,000 sacred groves with the most - 5000-found in Himachal Pradesh. Some are small, occupying a few hectares, while others, like the Hariyali grove in Uttarakhand and the Deodar grove near Shimla, are spread over hundreds of hectares.

In Maharashtra they are called devarahi, in Karnataka, devarakaadu, in Rajasthan oran, in Himachal, devbhumi, in Kerala kaavu and kovil kaadu in Tamil Nadu.

The groves are extremely important because they are biodiversity hotspots. Not only do they contain hundreds of rare and valuable plants and trees, some of which are used in traditional medicines, but also different species of insects, birds and mammals. The trees help anchor the fertile topsoil and the litter provides valuable humus that local farmers cart away to replenish their fields. Ponds and streams run through these sacred groves helping to raise the water table.

Sacred groves have reduced in number and size over the years. In some groves, the trees have been cut to increase the space for religious activities - the shrines now attract too many pilgrims. Others have been taken over for cultivation. Unless local people become more involved in protecting and restoring them, sacred groves, and with them a treasure trove of ecosystems, will soon be gone forever.

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Forest bathing, better known as Shinrin Yoku in Japanese culture, is the practice of walking in the woods mindfully. In 1982, the Japanese Ministry of Agriculture, Forestry, and Fisheries created the term shinrin-yoku, which translates to “forest bathing” or “absorbing the forest atmosphere.” The practice encourages people to simply spend time in nature — no actual bathing required.

Anasuya Menon

Have you walked in a forest? Under the towering trees, with sunlight streaming down in thick long columns? Have you listened to the song of the birds or the sounds of a gurgling stream? Have you felt and probably smelt the fresh forest air? If you have done all of the above, you have forest bathed.

'Forest bathing' is nothing but. a mindful walk in the woods. The practice has its origins in Japanese culture, where it is called shinrin-yoku. The idea is to take in the forest through the senses. Being in the midst of nature refreshes the mind, energises and rejuvenates the body, says practitioners of forest bathing.

Re-connecting with nature

 The concept has caught on in India, especially in the past few years with nature groups organising forest-bathing tours to help people reconnect with nature. "Forest bathing is not activity-oriented. It is a contemplative process, where the participants are guided to take in the forest through their senses. As a guide, I only help participants experience the energy of the forest," says Dipika Sharma from Noida, who has been conducting forest bathing walks for groups in Delhi since 2019. "People are now increasingly aware of the therapeutic effect of nature especially after two years of being confined at home because of the pandemic," says Dipika, who founded Forest Therapy, an organisation that conducts forest bathing tours.

Introducing children to forest bathing would help them form a lasting bond with nature, says Verhaen Khanna, commercial pilot-turned environmental activist, who has been conducting forest bathing workshops for school and college students.

"When children are out in the wild, their instincts are most alive. It instills a sense of curiosity in them. While on these walks, children usually ask me a lot of questions about the sights, smells and sounds of the forest. At times, it might be about a strange insect they have seen or it could be about a sound they heard. They become very aware of their surroundings," says Verhaen. Being amid trees is also believed to boost immunity, says Verhaen, whose organisation, New Delhi Nature Society organises a variety of programmes for children starting from listening to birds to creating art, planting trees, mediation, tree climbing, yoga in the park and saving trees. "We have children as young as four years of age taking part. I have seen that children enjoy the time in the wilderness," says Verhaen. The most receptive are children in the four to seven age group. "They are very attentive. They are curious about snakes and spiders. We ensure their safety, of course," he adds.

The basic idea is to help children appreciate nature and understand how important it is to to be able to co-exist with nature. "We are also, in a way, helping them create memories. And the experience of a forest will stay with them for a long time," Verhaen says.

In addition to building a bond with nature, children also develop their personalities by learning how to interact with others in the group.

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