A New Potential Weapon against TB

A team of researchers from University of Wisconsin-Madison School of Veterinary Medicine, Texas A&M University, and University of Saskatchewan in Saskatoon, Canada has discovered a unique copper-repressing protein in the bacterium that causes tuberculosis in humans. This finding could pave the way for new strategies to halt tuberculosis infection.

When TB bugs invade, host immune cells dump excessive amounts of copper onto the invaders in an effort to kill them. Though all cells need copper, but too much of it causes cell death. But the present study has found that the TB bugs fight back by generating a copper-repressing protein. This helps the TB bugs block excess copper in host’s body. With this discovery, we can now pursue ways to deactivate the repressor protein leading to novel antidote to tuberculosis infection, say the researchers in a paper that will appear in January 2007 issue of Nature Chemical Biology.

A Vaccine for Ebola Virus is Safe in Healthy Adults

A DNA vaccine for Ebola virus was found to be safe in healthy adults, according to a study published in the November issue of journal Clinical and Vaccine Immunology. The vaccine developed by a research team from Vaccine Research Centre at National Institute of Allergy and Infectious Diseases, Bethesda, Maryland and Statistical Center for HIV/AIDS Research and Prevention, Fred Hutchinson Cancer Research Center, Seattle, Washington was well-tolerated, with no significant adverse events or coagulation abnormalities.

Since 1976, Ebola virus has been spreading panic in developing countries of Africa like the Democratic Republic of the Congo (formerly Zaire) and Sudan. In recent years, it (especially Ebola-Zaire subtype) has surfaced in Uganda, Gabon and The Republic of Congo. This virus is deadly as it causes death in 50 and 90 per cent of all clinically ill cases.


The vaccine encoding the envelope glycoprotein (GP) from the Zaire and Sudan/Gulu species of Ebola virus as well as nucleoprotein was administered to 21 adults aged between 18 and 44. Each healthy volunteer received three injections of the vaccine. Of them, five received at a dose of 2 mg, 8 at 4 mg and 8 at 8 mg and these vaccinated adults were compared with 6 placebo subjects. The treated group showed specific antibody responses as well as generation of lymphocytes (CD8+ T-cell and CD4+ T-cell), a type of white blood cells, which are capable of killing the whole virus and help generate antibodies in response to GP of Ebola virus.

The lurking threat is the natural reservoir of the Ebola virus, which seems to reside in the rain forests of the African continent and in areas of the Western Pacific. On the African continent, Ebola infections of human cases have been linked to direct contact with gorillas, chimpanzees, monkeys, forest antelope and porcupines found dead in the rainforest. So far, the Ebola virus has been detected in the wild in carcasses of chimpanzees (in Côte-d’Ivoire and Republic of Congo), gorillas (Gabon and Republic of Congo) and duikers (Republic of Congo).

As any time, humans can come into contact with this natural reservoir during their day-to-day activities, most of which revolve around forest and wild life. No specific treatment or vaccine is yet available for Ebola haemorrhagic fever. Several vaccine candidates are being tested but it could be several years before any are available. The present study which highlights the safety of a DNA vaccine for Ebola virus, which has wreaked havoc in recent years, is very important and encouraging for developing countries in Africa as well as Asia.

Moon: Dead or Alive?

If you are with conventional wisdom that any volcanic activities on the moon have ceased billions of years ago, then you are mistaken. A new study points to evidence that the moon has been geologically active within the past 10 million years. The site that bears the signs of recent geological activities is ‘Ina’, in Lacus Felicitatis, a lake of ancient, hardened lava located at lunar coordinates 19o N, 5o E, according to a report published in the 9 November issue of journal Nature.

Apollo astronauts first noticed Ina. Since then it became the object of intense scrutiny of astronomers. “It is shaped like a letter D and two kilometers wide,” says Peter Schultz of Brown University in US, who led the research team in uncovering the mysteries of Ina. Several features of Ina prove that it is young. One of them is that Ina has sharp edges. As small meteoroids constantly rain down on the moon’s surface, sharp edges are unlikely to survive. Further, Ina is sparsely cratered. According to Schultz, there are only two clear impact craters larger than 30 meters on the 8 square kilometers of the structure’s floor.

Schultz and his teammates found that patches of lunar regolith in the Ina structure were recently removed. “The number of superimposed small craters and the freshness of the regolith together indicate that features within this structure must be very young and perhaps are still forming today,” concludes Schultz.

Deodorant Damage:Lungs get affected

A CHEMICAL compound found in many air fresheners, toilet bowl cleaners, mothballs and other deodorising products may leave harmful effects on lungs, says a research team from the National Institute of Environmental Health Sciences, a part of the National Institutes of Health in the USA. The team found that exposure to a Volatile Organic Compound called 1, 4 dichlorobenzene (1, 4 DCB) causes reductions in lung function. “Even a small reduction indicates some harm to the lungs,” says Stephanie London who led the study.

“The best way to protect yourself, especially children who may have asthma or other respiratory illnesses, is to reduce the use of products and materials that contain these compounds,” she says.

In search of evidence, she and her team examined the relationship between blood concentrations of 11 common VOCs and lung function measures in 953 adults. VOCs are a diverse set of compounds emitted as gases from thousands of commonly used products, including tobacco smoke, pesticides, paints, cleaning products and also released through automotive exhaust. Of the common VOCs (benzene, styrene, toluene, and acetone), only the compound 1, 4 DCB was linked to reduced pulmonary function, according to the study.

This effect was seen even after careful adjustment for smoking. The researchers found that 96 per cent of the population samples had detectable 1, 4 DCB blood concentration levels. The findings were published in a recent issue of Environmental Health Perspectives.

The VOC (1, 4 DCB) accused of causing damage to lungs is a white solid with distinctive aroma, similar to mothballs used as a space deodorant in products such as room deodorisers, urinal and toilet bowl blocks, and as an insecticide fumigant for moth control.

“Because people spend so much time indoors where these products are used, it is important that we understand the effects that even low levels might have on the respiratory system,” says Leslie Elliot, a researcher involved in the NIEHS study.

The above article was written by this blogger and originally published in the Sci & Tech section of The Statesman on 8th Day on 15 October, 2006.

Cure for Blood, Breast and Cervical Cancers

Researchers from Kolkata’s Chittaranjan National Cancer Institute have found two plants frequently used in Ayurvedic medicines effectively battle out four types of cancer in lab.

They discovered the root extract of Tiliacora racemosa (Tiliacoru) and the nut oil of Semecarpus anacardium (Dhobi nut) eliminated cultured human tumour cells from acute myeloblastic (myeloblast is a bone marrow cell) leukaemia, chronic myelogenic (associated with bone marrow) leukaemia, breast and cervical cancers.

“The herbal preparations from T racemosa and S anacardium selectively force cancer cells to commit suicide, sparing healthy neighbouring cells,” claims Madhumita Roy, who headed the team of researchers.

“The anti-cancer active compounds identified in the root extract of T racemosa are a number of bisbenzyl isoquinoline alkaloids, a type of organic compound and phenolic substances, also organic compounds, in the nut oil of S anacardium,” writes the researcher in a recent issue of the journal Phytotherapy Research (Vol 18, No 8).

“The findings of the research are indicative of a potential therapeutic role of these herbal preparations in human cancer,” says co-author Sutapa Chakraborty.

To study the anti-cancer effects of the plant extracts, the team produced an ethanol (alcohol) extract of T racemosa root (TA), an alkaloid-containing root extract of T racemosa (TR) and extracted the S anacardium nut oil (SO) using Ayurvedic principles. When tumour cells were exposed to these extracts, TA annihilated all the four types of cancer cells. TR and SO only caused the demise of leukaemic cells while breast cancer cells’ growth was partially inhibited by so and TR.

The above article was written by this blogger and originally published in ‘Down To Earth’, a science and environment fortnightly from New Delhi on 28 Feb’ 2005.

Herbal cure for snakebite

A TEAM from Kolkata-based Indian Institute of Chemical Biology and University of Calcutta have found that the seed extract of Strychnos nux vomica (SNV) — an Indian herb — could neutralise the toxins present in the venom of viper (Daboia russelii) and cobra (Naja kaouthia). The researchers isolated the active compound from the seed extract and found that it protected animals against the toxic effects of the venom. “The active compound, probably a organic compound, may lead to the development of a herbal drug more effective than snake venom antiserum (serum with antibodies against snake venom),” says Antony Gomes, the lead author. “We think that it works by inactivating the toxic enzymes of the venom,” he adds. The findings of their research are published in a recent issue of Indian Journal of Experimental Biology (Vol 42, No 5).

The venom contains a host of lethal enzymes that wreak havoc on healthy cells. Viper venom leads to excessive bleeding and build-up of abnormal body fluid. Cobra venom cripples cardiac muscles and nerve cells. After preparing the seed extract of SNV, Gomes and his colleagues measured the lethal dose (in other words that killed lab mice) by injecting the venom of viper and cobra into the tail vein of male mice. The lethal doses for viper and cobra venom were found to be 2.4 microgrammes and 3.09 microgrammes respectively. The extract even neutralised the adverse affects in guinea pigs and rats. The team also found that a combination of antiserum and seed extract was more potent against venom than antiserum alone.

The above article was written by this blogger and originally published in 'Down To Earth, a science and environment fortnightly published from New Delhi on 15 Nov'2004

Sixth Extinction: Will it be man-made?

The entire basis of organic evolution is underpinned by the appearance of some species and the disappearance of others; extinction is therefore a natural process.

According to the fossil record, as few as 2-4% of the species that have ever lived are believed to survive today. The remainders are extinct, the vast majority having disappeared long before the arrival of humans.

But, the rapid loss of species that we are witnessing today is estimated by some experts to be between 100 and 1,000 times higher than the “background” or expected natural extinction rate.

Unlike the mass-extinction events of geological history, the current extinction phenomenon is one for which a single species - ours - appears to be almost wholly responsible. Such a deteriorating situation is being referred to as “the sixth extinction crisis”, after the five known extinction waves in the Ordovican, Devonian, Permian, Triassic and Cretaceous Periods.

Man-made Prehistoric Extinction
Extinctions caused by humans are generally considered to be a recent, modern phenomenon. However, humanity's first significant contribution to the rate of global extinction may have occurred during the past 100,000 years, when North
and South America and Australia lost 74 to 86% of the genera of "megafauna" - mammals greater than 44 kg.

In Australia, where the earliest human remains are dated to approximately 64,000 years, the great majority of the 22 identified genera of large land animals disappeared between 30,000 and 60,000 years ago.

In the Americas, almost 80% of large-bodied genera became extinct. Extraordinary creatures, such as sabre-toothed cats, mammoths, giant armored glyptodonts and giant ground-sloths, all disappeared some time between 11,000 and 13,000 years ago, coinciding with the dates of the first clear evidence of a human presence there.

Recent Extinction
Island megafaunas - like giant birds known as moas in New Zealand, the dodo on Mauritius, giant lemurs and the extraordinary elephant bird in Madagascar, or large rodents and ground-sloths in the Caribbean - survived until much more recently than the continental faunas. All seem to have disappeared within a few hundred years after the arrival of humans - in the case of the moas within the last 300 years.

In the last 500 years, human activity has forced 844 species to extinction (or extinction in the wild).


Current Status

A total of 15,589 species of plants and animals are known to face a high risk of extinction in the near future, in almost all cases as a result of human activities. This includes 32% of amphibian species, 24% of mammal species, 12% of bird species, 25% of conifers and 52% of cycads.

Of the 129 recorded bird extinctions, 103 are known to have occurred since 1800, indicating an extinction rate 50 times that of the background rate.

The total number of threatened animal species has increased from 5,205 to 7,266 since 1996.

Habitat loss and degradation affect 86% of all threatened birds, 86% of mammals, and 88% of threatened amphibians.

Main Culprit Countries
Indonesia, India, Brazil and China are among the countries with the most threatened mammals and birds, while plant species are declining rapidly in South and Central America, Central and West Africa, and Southeast Asia.

Ballooning Urbanisation

In 1800 only about 2 percent of the world's population lived in urban areas. In only 200 years, the world's urban population has grown from 2 percent to nearly 50 percent of all people. At the beginning of the 20th century some 250 million people lived in cities – only about 15 per cent of the world’s population. At the end of century, nearly half of the 6000 million people on the planet lived in urban areas.

The most striking examples of the urbanization of the world are the megacities of 10 million or more people. In 1975 only four megacities existed; in 2000 there were 18. And by 2015 the UN estimates that there will be 22.

Overexploitation: The Culprit Homo sapiens

Exploitation, including hunting, collecting, fisheries and fisheries by-catch, and the impacts of trade in species and species' parts, constitutes a major threat for birds (30% of threatened birds), mammals (33% of threatened mammals), amphibians (6% of threatened amphibians), reptiles and marine fishes.

International Trade

Many animals and plants are increasingly threatened because of international trade in wildlife and wildlife products. In some cases (pets, rare plants) the living organism is in demand; in other cases, specific body parts like skins, furs, bones, ivory, sex organs, bile, skeletons, and claws are highly valued for ornaments, jewelry, or for putative medicinal or aphrodisiac qualities

These are mostly luxury items in demand in industrialized countries, by consumers that have very little knowledge of how endangered some of these animals are. International wildlife trade has grown and become very profitable with increased prosperity, improvements in shipping and fast air transport.

The major exporters are tropical and subtropical countries of Africa, Southeast Asia and South America (see chart) while the major importers are Europe, Japan and the U.S.

The U.S. is both an exporter and importer and is the largest market in the world for these items, importing and exporting about $1 billion worth of wildlife and wildlife products each year (out of a total world trade of $5 billion).


Three of the eight species of tiger are already extinct and all the others are threatened because of a combination of habitat loss and poaching for the Asian traditional medicine market. The total tiger population has declined by 95% in the 20th century, leaving only about 5,000. The Siberian tiger, with only 200 animals, could be extinct within a few years if China does not take effective measures immediately.

Population Explosion, Affluence and Technology Bring Disasters for Environment

Impact on the environment has often been defined as the effect of
population x affluence x technology

I=PAT, (I for Impact, P for Population, A for Affluence, and T for Technology)

Population Growth: Growth of the human population is a major factor affecting the environment. Simply put, overpopulation means that there are more people than there are resources to meet their needs. Almost all the environmental problems we face today can be traced back to the increase in population in the world. The human population is at 6 billion; with an annual global growth rate of 1.8%, three more people are added to the earth every second. This represents an increase of almost 60% since 1970 and over 150% since the Second World War.

Affluence: Affluence is a problem because with increasing affluence comes an increase in the per capita resource utilization. Less than 20% of the world's population controls 80% of the world's wealth and resources. The high standard of living that accompanies the increased production and consumption of goods is the major cause of pollution and environmental degradation.

The problems of overpopulation, overconsumption, development and industrialization are intertwined and the causes are not singular and straightforward.

Humans have been altering their environment for thousands of years. The process probably began with the setting of fires in savannah grassland to aid hunting. Most forests contain the marks of human-set fires, clearance and tree planting, and little strictly “virgin” vegetated land surface now remains.

In the past 10 000 years the dominant technological influences have been the use of timber for building and the spread of crop cultivation. This has accelerated, particularly in the past 150 years during which time the rising population has doubled the area of arable land in use on the Earth’s surface.

The extent of ecosystem loss and alteration is closely related to population density, which is very uneven across the planet. Today, one half of the human population lives on less than 10 percent of the Earth’s land, and three quarters on only 20 percent.

For much of human history, the most heavily populated regions of the planet, and the most ecologically disturbed, have been Europe and South and East Asia – and that remains the case. The population densities of the Americas and Africa have only now risen to those achieved in Europe and India by 1750. In India today, population density is more than 300 people per square kilometer, seven times the global average; little land is unused by humans; and almost 80 percent of the original forest cover has been lost

Land affected by human activity can be divided into areas transformed – notably by agriculture, which in some parts of the world such as the North American prairies is characterized by low population density but high ecosystem loss – and areas degraded and fragmented by pollution, sporadic human activity including hunting and tourism, or infrastructure development such as highways and pipelines.

Overall, at least half of the world’s forests have disappeared at the hand of humankind – three quarters of these in the past 300 years and the majority within the past century.

Their survival is lowest where population density is highest. The Asia/Pacific region has lost 76 percent of its original forest cover, mostly to agricultural development but also to urbanization and mineral exploitation. Losses in Europe (excluding Russia) average 75 percent, in Russia 24 percent, in Africa 68 percent, and in the Americas 35 percent, but with much higher rates in more densely populated areas such as the coastal regions and Central America


The link between population density and environmental damage is also disrupted when prosperous or powerful communities, either deliberately or accidentally, buy local ecological conservation at the expense of damage to other areas. Such transference has a long history. The ancient city of Rome turned North Africa into a grain-growing “breadbasket” to supply its million-plus population, until most African soils were exhausted. The grain, meanwhile, was transported across the Mediterranean aboard a fleet of a thousand ships made of wood cut from the Levant.

Koi fish Endangered in West Bengal, India

A research team from Calcutta University have found that Sumidon – 40, an organophosphate pesticide, excessively used in paddy fields of West Bengal hampers the reproductive performance of Koi (Anabus testudenius) fish, which prefers to breed in shallow water-logged paddy field during rainy season.

The adverse effects of the pesticide went to the extent that this fish was dubbed as endangered species, the study reveals. The reproductive performance of the fish significantly deteriorated with increase of the period of the exposure of pesticide. The team found that the hatchlings died instantly due to pesticide exposure. Scanning electron microscope showed that the pesticide affected the outer thick layer of mature eggs.

Irrawaddy Dolphins Endangered in India

Exposure to organochlorine pesticides and persistent organic pollutants put Irrawaddy dolphins at risk of extinction in Chilika Lake of Orissa claims an international research team. For the first time, concentrations of organochlorine pesticides (OC), polychlorinated biphenyls (PCBs), and polybrominated diphenyl ethers have been found in tissues of Irrawady dolphins collected from Chilika Lake.

DDT and its metabolites (DDTs) were the predominant contaminants found in Irrawaddy dolphins; the highest concentration found was 10,000-nanogram/g lipid weight in blubber. Hexachlorocyclohexanes (HCHs) were the second most prevalent contaminants in dolphin tissues.

How Alien Species Wipe Out Natives

Below I discuss three major impacts of alien species with examples

Predation - The introduction of a predator that organisms have not previously been exposed to can profoundly affect food chains. Most obvious in the Great Lakes-St. Lawrence system was the introduction of the sea lamprey (Petromyzon marinus) which, combined with overharvesting, caused lake trout to be wiped out from the upper Great Lakes in the mid-1900s. Though, right now, lake trout is making recovery with conservation efforts by humans.

Disease and Parasites - Pest species accidentally introduced to an area provide the most dramatic example of the damage that exotics can pose to native species. For instance, an exotic beetle was the vector for Dutch elm disease, which has devastated elm trees in North America.

Accidental Species Introduction - Species introductions can occur accidentally, when organisms “hitchhike” into new systems on other animals or objects. For instance, zebra mussels are thought to have been brought into the Great Lakes in the ballast water of tankers that traveled up the St. Lawrence Seaway.

Alien Species Can Wreak Havoc

Humans are the most mobile of species and can live anywhere on earth. When they travel from place to place they often transport other species along with them, resulting in alien introductions. While the most drastic devastation occurs on small islands, large landmasses have also felt the impact of imported species that have no natural control to their numbers.

Prior to the arrival of humans, Hawaii had thousands of species of birds, and invertebrates, and plants found no where else on earth. Since the introduction of mongoose, rats, pigs and dogs and – as well as many species of plants, -- over half the bird species and countless species of snail have gone extinct. The introduction of rabbits into Australia, Asian fish species into Florida, Africanized bees into Brazil, plants such as Kudzu, melaleuca, and Brazilian pepper throughout the US, and rhododendrons into England are obvious examples of introduced species that outcompete and exterminate the native animals and plants.

Green crabs, zebra mussels, the African tulip tree and the brown tree snake are just a few of the ecological offenders named invasive alien species. Biological invasion by alien species, second only to habitat loss as a threat to biodiversity, severely disrupts freshwater and marine ecosystems, tropical, boreal and temperate forests, urban areas, islands, grasslands and deserts. This in turn impacts global and local economies. Introductions of alien species can happen deliberately or unintentionally, for example, by organisms “hitch-hiking” in containers, ships, cars or soil.

We Lose 137 Species Each Day

Worldwide, 5 to 80 million species of plants and animals comprise the "biodiversity" of planet Earth. Tropical rain forests-covering only 7% of the total dry surface of the Earth-hold over half of all these species. Of the tens of millions of species believed to be on Earth, scientists have only given names to about 1.5 million of them, and even fewer of the species have been studied in depth.

Many of the rain forest plants and animals can only be found in small areas, because they require a special habitat in which to live. This makes them very vulnerable to deforestation. If their habitat is destroyed, they may become extinct. Every day, species are disappearing from the tropical rain forests as they are cleared. We do not know the exact rate of extinction, but estimates indicate that up to 137 species disappear worldwide each day.

India’s Deforestation

Forest in India covers about 76.2 m ha (million hectare), which constitute 23 per cent of the total geographical area (328 m ha) as against 33.3 per cent envisaged in the National Forest Policy of 1988. The most significant revelation is that the country is losing about 1.3 m ha of forest cover every year due to extension of cultivation, mining and establishment of wood based industries leading to indiscriminate felling of trees.

The annual rate of deforestation in India is one per cent, an extremely high rate of deforestation. During the last 30 years, around 24 lakh hectares of forest land has been diverted to agricultural purpose for meeting the increased demand of the growing population.

The observations reflect that India having just 2.5 per cent total geographical forest resources is sustaining around 16.1 per cent of the human and 18 per cent of the livestock populations of the World. India ranks low in terms of per capita availability (0.07 ha) as against World average of 0.8 ha per capita forest area.

Forest in India is under unbearable biotic pressure. Over-grazing and uncontrolled illicit felling for firewood and timber, interfere with regeneration operations and depleted the growing stock and nearly 37 m ha or 49 per cent are degraded.

Rate of Tropical Deforestation

The Food and Agriculture Organization (FAO) estimates that 53,000 square miles of tropical forests (rain forest and other) were destroyed each year during the 1980s. Of this, they estimate that 21,000 square miles were deforested annually in South America, most of this in the Amazon Basin. Based on these estimates, an area of tropical forest large enough to cover North Carolina is deforested each year.

The rate of deforestation varies from region to region. Recent research results showed that in the Brazilian Amazon, the rate of deforestation was around 6200 square miles per year from 1978-1986, but fell to 4800 square miles per year from 1986-1993. By 1988, 6 per cent of the Brazilian Amazon had been cut down (90,000 square miles, an area the size of New England).

The much smaller region of Southeast Asia (Cambodia, Indonesia, Laos, Malaysia, Myanmar, Thailand, and Vietnam) lost nearly as much forest per year as the Brazilian Amazon from the mid-1970s to the mid-1980s, with 4800 square miles per year converted to agriculture or cut for timber.

Deforestation Increases CO2 Emission

Deforestation increases the amount of carbon dioxide (CO2) and other trace gases in the atmosphere. The plants and soil of tropical forests hold 460-575 billion metric tons of carbon worldwide with each acre of tropical forest storing about 180 metric tons of carbon. When a forest is cut and burned to establish cropland and pastures, the carbon that was stored in the tree trunks (wood is about 50 per cent carbon) joins with oxygen and is released into the atmosphere as CO2.

The loss of forests has a profound effect on the global carbon cycle. From 1850 to 1990, deforestation worldwide (including the United States) released 122 billion metric tons of carbon into the atmosphere, with the current rate being approximately 1.6 billion metric tons per year. In comparison, fossil fuel burning (coal, oil, and gas) releases about 6 billion metric tons per year, so it is clear that deforestation makes a significant contribution to the increasing CO2 in the atmosphere.

Global Warming Leads to Coral bleaching

Warmer sea surface temperatures are blamed for an increase in a phenomenon called coral bleaching. It is a whitening of coral caused when the coral expels a single-celled, symbiotic alga called zooxanthellae. This alga usually lives within the tissues of the corals and, among other things, gives them its spectacular range of colours.

Zooxanthellae are expelled when the coral is under stress from environmental factors such as abnormally high water temperatures or pollution. Since the zooxanthellae help coral in nutrient production, their loss can affect coral growth and make coral more vulnerable to disease. Major bleaching events took place on the Great Barrier Reef in 1998 and 2002, causing a significant die-off of corals in some locations.

Global Warming: Fallout of Human Impact

Greenhouse gases (CO2, CH4, and N2O) that trigger global warming are spewed into the atmosphere by agricultural lands, fossil fuel and wood burning, and livestocks like cows (methane produced by bacteria in their guts).

It has been concluded that global mean temperature of the planet is likely to rise in the range of 1.4 to 5.8° C by 2100, in relation to 1990. Such rise in temperature can have devastating effects. The ice sheet covering Greenland is most vulnerable to climate warming and any warming above 2-5° C would make this gigantic ice sheet disappear. An 8° C warming would cause 6-metre rise in a few hundred years. Given such increase, West Antarctic ice sheet could disappear in 600 years.

Major changes will be brought about in water distribution. Water streams located in high latitudes and South-east Asia will increase while; it will decrease in Central Asia, Southern Africa, Australia, Mediterranean. Small glaciers will disappear while most glaciers will shrink.

Monsoons will become more intense causing flooding. In the coastal areas, flooding will increase and land erosion will accelerate. Seawater will contaminate fresh water. Coral reefs will be affected. Coral reefs, which make up small areas of the oceans, contain 25 per cent of fish species. An increase of 1º C. in water temperature will destroy an entire reef and the fish therein.

Human Impacts – Threats to Ecological Balance


About five million years ago, an upright animal emerged on African plains. Gradually, these animals grew smarter and made tools for hunting. They discovered how to set fire and cook food. Even they began to talk, carved jewelry, and rendered wonderful cave paintings. About twenty millennia ago, they were beginning to look and behave like us. Yes, they were modern Homo sapiens.

About ten thousand years ago, the last ice age drew to a close. And those humans made another leap. They invented agriculture paving the way for sedentary life. Driven by pursuing own material goals, modern humans began to plunder natural resources. Gradually, stone ages gave way to metal ages culminating in industrial revolution. Since then humans’ growth and development are unprecedented till the moment I write this article on a word processor. But, this pay-off comes at a huge cost. Human activities drove many animals and plants to extinction. Our needs and greed are depleting pristine forest at an alarming rate. It turns out that human activities may usher in sixth extinction unlike the natural ones that happened millions of years ago. Let’s explore how human activities are conjuring up doomsday scenario.

Human activities like agriculture, urbanisation, and industrialisation destroy biodiversity. And unabated population growth adds to the woes. Mindless consumption and development lead to deforestation, increasing threat of global warming, species extinction and a host of other environmental hazards.


This is the introductory part of a recent invited lecture delivered by me at a seminar on Attack on Ecological Balance-Impact on Mankind held on 15th September, 2006 at Bose Institute, Kolkata, India.

In the forthcoming posts, I will elaborate on this issue at length, so keep an eye on my blog.