तूफान के निशान

देश ने समुद्री लहरों का सबसे भयानक कोप दिसंबर 2004 में देखा, जब सुनामी ने

दक्षिण भारत के साथ-साथ श्रीलंका और इंडोनेशिया पर भी कहर बरपाया था।

प्राकृतिक आपदा को रोका नहीं जा सकता। पर उसके कहर को कम जरूर किया जा सकता है, और जाहिर है, यह निर्णायक रूप से पूर्व-सूचना तथा पूर्व-तैयारी पर निर्भर करता है। ‘वरदा’ तूफान से, पूर्व के अनुभवों की तुलना में, जान-माल का कम नुकसान हुआ, तो इसका बड़ा कारण चेतावनी प्रणाली का विकास है। तूफान के आने की सूचना समय से लोगों तक पहुंचा दी गई थी और सरकारों ने भी अपनी तैयारी कर ली थी। सोमवार को दोपहर बाद जब वरदा नामक समुद्री तूफान तमिलनाडु के तट से टकराया, उसके पहले राज्य सरकार ने कोई दस हजार लोगों को तटीय क्षेत्र से हटा कर सुरक्षित स्थानों पर पहुंचा दिया था। इसी तरह आंध्र प्रदेश की सरकार ने भी हजारों लोगों को तटीय क्षेत्र से दूर पहुंचा दिया था। मछुआरों समेत तटीय इलाकों में रहने वाले सारे लोगों को तूफान के बारे में आगाह कर दिया गया था। केंद्रीय आपदा रक्षक बल के कई दस्तों और सेना की कई टुकड़ियों को आपात-सहायता के लिए पहले ही बुला लिया गया था। अभी तक तमिलनाडु और आंध्र प्रदेश में तूफान के चलते कुल मिलाकर दस लोगों के मारे जाने की खबर है। क्या पता यह तादाद कहीं ज्यादा होती, अगर वरदा से निपटने की पूर्व-तैयारी न हो पाती।

हाल के इतिहास में जिस सबसे भयंकर चक्रवात की याद लोगों को है वह 1999 में ओड़िशा में आया था। जब वह चक्रवात जगतसिंहपुर जिले के पारादीप बंदरगाह से टकराया तो उसकी गति करीब ढाई सौ किलोमीटर प्रतिघंटा थी। उस तूफान ने भयावह तबाही मचाई थी। हजारों लोग मारे गए और लाखोें घर उजड़ गए थे। उसके मुकाबले वरदा की रफ्तार काफी कम थी, सवा सौ से डेढ़ सौ किलोमीटर के बीच। पर जान-माल का नुकसान अपेक्षया कम हुआ तो इसकी वजह तूफान की गति कम होने के अलावा बरती गई सतर्कता भी थी। ओड़िशा के चक्रवाती तूफान के बाद देश ने समुद्री लहरों का सबसे भयानक कोप दिसंबर 2004 में देखा, जब सुनामी ने दक्षिण भारत के साथ-साथ श्रीलंका और इंडोनेशिया पर भी कहर बरपाया था। उसी के बाद चेतावनी प्रणाली विकसित करने पर तेजी से काम चला। फिर, अंतरिक्ष कार्यक्रम में हुई प्रगति से इसमें और मदद मिली। अब मौसम संबंधी भविष्यवाणियां पहले से ज्यादा प्रामाणिक होने लगी हैं। चक्रवाती तूफान के साथ अक्सर भारी बारिश भी होती है। तूफान, तेज हवाओं और भारी बारिश ने चेन्नई तथा चित्तूर समेत तमिलनाडु और आंध्र के कई तटीय जिलों में बहुत सारे पेड़ और मकान ढहा दिए हैं।

यों चेन्नई हवाई अड्डे से विमानों के उड़ान भरने का क्रम फिर से चालू हो गया है, और गिरे हुए पेड़ हटा कर कई प्रमुख रास्ते फिर से आवागमन के लिए खोल दिए गए हैं। पर कई रास्ते अब भी बंद हैं और कुछ इलाकों में बिजली की आपूर्ति फिलहाल ठप है। सामान्य स्थिति बहाल होने में अभी वक्त लग सकता है। वरदा की पूर्व सूचना मिल जाने और बचाव की पूर्व तैयारी हो जाने पर लोगों ने राहत की सांस ली है। पर तूफान की मारकता और कम हो सकती थी अगर समुद्रतटीय वनों को नष्ट नहीं किया गया होता। सुनामी के समय यह देखा गया था कि जहां मैंग्रोव वन थे वहां कम तबाही हुई। लेकिन विडंबना यह है कि सुनामी के भीषण अनुभव के बाद भी मैंग्रोव वनों को बचाने का कोई खास प्रयास शुरू नहीं हो पाया, और यह कोताही अब भी जारी है।

Permian Period: Climate, Animals & Plants

The Permian Period was the final period of the Paleozoic Era. Lasting from 299 million to 251 million years ago, it followed the Carboniferous Period and preceded the Triassic Period. By the early Permian, the two great continents of the Paleozoic, Gondwana and Euramerica, had collided to form the supercontinent Pangaea. Pangaea was shaped like a thickened letter “C.” The top curve of the “C” consisted of landmasses that would later become modern Europe and Asia. North and South America formed the curved back of the “C” with Africa inside the curve. India, Australia and Antarctica made up the low curve. Inside the “C” was the Tethys Ocean, and most of the rest of Earth was the Panthalassic Ocean. Because Pangaea was so immense, the interior portions of the continent had a much cooler, drier climate than had existed in the Carboniferous.

Marine life

Little is known about the huge Panthalassic Ocean, as there is little exposed fossil evidence available. Fossils of the shallower coastal waters around the Pangaea continental shelf indicate that reefs were large and diverse ecosystems with numerous sponge and coral species. Ammonites, similar to the modern nautilus, were common, as were brachiopods. The lobe-finned and spiny fishes that gave rise to the amphibians of the Carboniferous were being replaced by true bony fish. Sharks and rays continued in abundance.

Plants

On land, the giant swamp forests of the Carboniferous began to dry out. The mossy plants that depended on spores for reproduction were being replaced by the first seed-bearing plants, the gymnosperms. Gymnosperms are vascular plants, able to transport water internally. Gymnosperms have exposed seeds that develop on the scales of cones and are fertilized when pollen sifts down and lands directly on the seed. Today’s conifers are gymnosperms, as are the short palm like cycads and the gingko.

Insects

Arthropods continued to diversify during the Permian Period to fill the niches opened up by the more variable climate. True bugs, with mouthparts modified for piercing and sucking plant materials, evolved during the Permian. Other new groups included the cicadas and beetles.

Land animals

Two important groups of animals dominated the Permian landscape: Synapsids and Sauropsids. Synapsids had skulls with a single temporal opening and are thought to be the lineage that eventually led to mammals. Sauropsids had two skull openings and were the ancestors of the reptiles, including dinosaurs and birds. 

In the early Permian, it appeared that the Synapsids were to be the dominant group of land animals. The group was highly diversified. The earliest, most primitive Synapsids were the Pelycosaurs, which included an apex predator, a genus known as Dimetrodon. This animal had a lizard-like body and a large bony “sail” fin on its back that was probably used for thermoregulation. Despite its lizard-like appearance, recent discoveries have concluded that Dimetrodon skulls, jaws and teeth are closer to mammal skulls than to reptiles. Another genus of Synapsids, Lystrosaurus, was a small herbivore — about 3 feet long (almost 1 meter) — that looked something like a cross between a lizard and a hippopotamus. It had a flat face with two tusks and the typical reptilian stance with legs angled away from the body.

In the late Permian, Pelycosaurs were succeeded by a new lineage known as Therapsids. These animals were much closer to mammals. Their legs were under their bodies, giving them the more upright stance typical of quadruped mammals. They had more powerful jaws and more tooth differentiation. Fossil skulls show evidence of whiskers, which indicates that some species had fur and were endothermic. The Cynodont (“dog-toothed”) group included species that hunted in organized packs. Cynodonts are considered to be the ancestors of all modern mammals.

At the end of the Permian, the largest Synapsids became extinct, leaving many ecological niches open. The second group of land animals, the Sauropsid group, weathered the Permian Extinction more successfully and rapidly diversified to fill them. The Sauropsid lineage gave rise to the dinosaurs that would dominate the Mesozoic Era.

The Great Dying

The Permian Period ended with the greatest mass extinction event in Earth’s history. In a blink of Geologic Time — in as little as 100,000 years — the majority of living species on the planet were wiped out of existence.  Scientists estimate that more than 95 percent of marine species became extinct and more than 70 percent of land animals. Fossil beds in the Italian Alps show that plants were hit just as hard as animal species. Fossils from the late Permian show that huge conifer forests blanketed the region. These strata are followed by early Triassic fossils that show few signs of plants being present but instead are filled with fossil remnants of fungi that probably proliferated on a glut of decaying trees.

Scientists are unclear about what caused the mass extinction. Some point to evidence of catastrophic volcanic activity in Siberia and China (areas in the northern part of the “C” shaped Pangaea). This series of massive eruptions would have initially caused a rapid cooling of global temperatures leading to increased glaciations. This “nuclear winter” would have led to the demise of photosynthetic organisms, the basis of most food chains. Lowered sea levels and volcanic fallout would account for the evidence of much higher levels of carbon dioxide in the oceans, which may have led to the collapse of marine ecosystems. Other scientists point to indications of a massive asteroid impacting the southernmost tip of the “C” in what is now Australia. Whatever the cause, the Great Dying closed the Paleozoic Era.

Tetrapods: Natural Antacid Helped Early Land Creatures Breathe

The earliest creatures to crawl out of the water onto land may have concocted antacids out of their own bones, a clever innovation that would’ve let the animals breathe, researchers now find.

The earliest tetrapods, or four-limbed creatures, made their first evolutionary forays onto land about 370 million years ago. Breathing air came with challenges, though. A major one was getting rid of the air’s carbon dioxide, which, when it builds up, reacts with water in the body and forms an acid.

Now, growing evidence in modern reptiles suggests that bones that grew within the skin of early tetrapods may have acted as a natural antacid by releasing their neutralizing chemicals into the bloodstream. The result would have bought the creatures time to spend on land before they had to head back to the water to rid themselves of excess carbon dioxide.

The skeleton of Eryops, one of the earliest land-walking tetrapods.

Credit: © Christine M. Janis

 “Now we know that dermal bone can do this and it’s something we didn’t know before, that gives us a basis that maybe this is why tetrapods had this feature, which previously we didn’t have a good explanation for,” study researcher Christine Janis, a paleontologist at Brown University, told LiveScience. “It’s the discovery of this new feature of the physiology of these living animals that lets us go back [in time].”

First on land

So let’s rewind the clock: The first tetrapods evolved from fish in the Devonian period, which spanned from about 416 million years ago to 359 million years ago. These early tetrapods had broad faces, not unlike frogs, and rather immobile ribcages. That means they wouldn’t have been able to get rid of extra carbon dioxide by breathing quickly, as humans and other mammals do with their longer snouts and flexible ribcages. Nor were the tetrapods small enough to exchange carbon dioxide and oxygen via their skin, as modern amphibians do.

What tetrapods did have was complex “dermal bone,” or bone that forms from connective tissue in the skin instead of from cartilage like the long bones of the arm or leg.The concept of skin bone may seem strange, but it’s very common: The human skull, for example, is a dermal bone.

Early tetrapod bone showed many pits and furrows, indicating lots of blood supply, Janis said. Her colleagues, including paper co-author and biologist Daniel Warren of Saint Louis University, had found another piece of the puzzle: In modern turtles and alligators, this dermal bone helps the reptiles tolerate carbon dioxide buildup when they’re under water, unable to breathe.

Bone breathing

Tetrapods would have the opposite problem, Janis realized: They’d be able to release carbon dioxide through their skin while in the water, since their skin was more permeable than an alligator’s tough hide. But out on land, they’d need another means of release. It seemed very possible that tetrapods could have used their complex dermal bones as a storage unit for calcium and other acid-neutralizing minerals, releasing them as needed when body acid levels got too high, Janis said.

To test the idea, the researchers analyzed the skeletons of tetrapods. As you might expect, the tetrapods known by the skeletons to spend more time out of the water had the most complex dermal bones. The evolutionary history of the animal supports the hypothesis, as well.

“When [the dermal bone] gets lost, it gets lost in the lineage leading to modern reptiles when they start getting more mobile ribs,” Janis said.

She and her colleagues reported their work Tuesday (April 24) in the journal Proceedings of the Royal Society B.

End of the early tetrapods

While the evidence is consistent with Janis’ theory, there’s no proof yet that tetrapods really used their bones in this way. The next step, Janis said, will be to look for chemical or other clues in modern reptiles who use their bones as antacid. If any telltale signs are established, researchers can then hunt for the same signals in ancient tetrapods.

The terrestrial tetrapods studied by Janis and her colleagues went extinct during the Permian period 299 million to 251 million years ago. It was a changing world, Janis said, and atmospheric carbon dioxide was increasing. It’s possible that tetrapods’ bone-dependent breathing wasn’t as effective in this new atmosphere.

“Who knows?” Janis asked. “I think the point to make is that this was probably a perfectly good way to live for awhile — millions of years — but in the end, there were things that had figured out better ways of how to get rid of carbon dioxide.”

MASS EXTINCTION

Major extinction events

Although the Cretaceous-Tertiary (or K-T) extinction event is the most well-known because it wiped out the dinosaurs, a series of other mass extinction events has occurred throughout the history of the Earth, some even more devastating than K-T. Mass extinctions are periods in Earth's history when abnormally large numbers of species die out simultaneously or within a limited time frame. The most severe occurred at the end of the Permian period when 96% of all species perished. This along with K-T are two of the Big Five mass extinctions, each of which wiped out at least half of all species. Many smaller scale mass extinctions have occurred, indeed the disappearance of many animals and plants at the hands of man in prehistoric, historic and modern times will eventually show up in the fossil record as mass extinctions.

Ordovician-Silurian mass extinction

The third largest extinction in Earth's history, the Ordovician-Silurian mass extinction had two peak dying times separated by hundreds of thousands of years. During the Ordovician, most life was in the sea, so it was sea creatures such as trilobites, brachiopods and graptolites that were drastically reduced in number.

Late Devonian mass extinction

Three quarters of all species on Earth died out in the Late Devonian mass extinction, though it may have been a series of extinctions over several million years, rather than a single event. Life in the shallow seas were the worst affected, and reefs took a hammering, not returning to their former glory until new types of coral evolved over 100 million years later.

Permian mass extinction

The Permian mass extinction has been nicknamed The Great Dying, since a staggering 96% of species died out. All life on Earth today is descended from the 4% of species that survived.

Triassic-Jurassic mass extinction

During the final 18 million years of the Triassic period, there were two or three phases of extinction whose combined effects created the Triassic-Jurassic mass extinction event. Climate change, flood basalt eruptions and an asteroid impact have all been blamed for this loss of life.

Cretaceous-Tertiary mass extinction

The Cretaceous-Tertiary mass extinction - also known as the K/T extinction - is famed for the death of the dinosaurs. However, many other organisms perished at the end of the Cretaceous including the ammonites, many flowering plants and the last of the pterosaurs.

Importance of mass Extinction events in Evolution

Mass extinctions have sometimes accelerated the evolution of life on Earth. When dominance of particular ecological niches passes from one group of organisms to another, it is rarely because the new dominant group is "superior" to the old and usually because an extinction event eliminates the old dominant group and makes way for the new one.

For example mammaliformes ("almost mammals") and then mammals existed throughout the reign of the dinosaurs, but could not compete for the large terrestrial vertebrate niches which dinosaurs monopolized. The end-Cretaceous mass extinction removed the non-avian dinosaurs and made it possible for mammals to expand into the large terrestrial vertebrate niches. Ironically, the dinosaurs themselves had been beneficiaries of a previous mass extinction, the end-Triassic, which eliminated most of their chief rivals, the crurotarsans.

Causes of particular mass extinctions

Flood basalt events: Eleven occurrences, all associated with significant extinctions. Only five of the major extinctions coincided with flood basalt eruptions and that the main phase of extinctions started before the eruptions.

Basaltic eruptions can have series of interrelated effects. A basaltic eruption could have

1.     produced dust and particulate aerosols which inhibited photosynthesis and thus caused food chains to collapse both on land and at sea

2.     emitted sulfur oxides which were precipitated as acid rain and poisoned many organisms, contributing further to the collapse of food chains

3.     emitted carbon dioxide and thus possibly causing sustained global warming once the dust and particulate aerosols dissipated.

Flood basalt events occur as pulses of activity punctuated by dormant periods. As a result they are likely to cause the climate to oscillate between cooling and warming, but with an overall trend towards warming as the carbon dioxide they emit can stay in the atmosphere for hundreds of years.

It is speculated that massive volcanism caused or contributed to the End-Permian, End-Triassic and End-Cretaceous extinctions.

2. Sea-level falls

Sea-level falls could reduce the continental shelf area (the most productive part of the oceans) sufficiently to cause a marine mass extinction, and could disrupt weather patterns enough to cause extinctions on land. But sea-level falls are very probably the result of other events, such as sustained global cooling or the sinking of the mid-ocean ridges.Sea-level falls are associated with most of the mass extinctions, including all of the "Big Five"—End-Ordovician, Late Devonian, End-Permian, End-Triassic, and End-Cretaceous.

3. Impact events

The impact of a sufficiently large asteroid or comet could have caused food chains to collapse both on land and at sea by producing dust and particulate aerosols and thus inhibiting photosynthesis. Impacts on sulfur-rich rocks could have emitted sulfur oxides precipitating as poisonous acid rain, contributing further to the collapse of food chains. Such impacts could also have caused megatsunamis and/or global forest fires.

The Shiva hypothesis proposes that periodic gravitational disturbances cause comets from the Oort cloud to bombard earth every 26 to 30 million years.

4. Ocean asteroid impact

Carbon Dioxide (CO2) is soluble in sea water and is present in very large quantities. It mostly reports as the bicarbonate radical (−HCO3) which is only stable at temperatures below 50°C.Sea surface temperatures are normally below 50°C, but can easily exceed that temperature when an asteroid strikes the ocean thereby inducing a large thermal shock. Under those circumstances very large quantities of CO2 erupt from the ocean. As a heavy gas, the CO2 can quickly spread around the world in concentrations sufficient to suffocate air breathing fauna, selectively at low altitudes.Asteroid impacts with the ocean may not leave obvious signs, but these impacts have the potential to be far more devastating to life on earth than impacts with land.

5. Sustained and significant global cooling

Sustained global cooling could

·      kill many polar and temperate species and force others to migrate towards the equator;

·      reduce the area available for tropical species;

·      often make the Earth's climate more arid on average, mainly by locking up more of the planet's water in ice and snow.

The glaciation cycles of the current ice age are believed to have had only a very mild impact on biodiversity, so the mere existence of a significant cooling is not sufficient on its own to explain a mass extinction.

It has been suggested that global cooling caused or contributed to the End-Ordovician, Permian-Triassic, Late Devonian extinctions, and possibly others. Sustained global cooling is distinguished from the temporary climatic effects of flood basalt events or impacts.

6.Sustained and significant global warming

This would have the opposite effects:

·      expand the area available for tropical species;

·      kill temperate species or force them to migrate towards the poles;

·      possibly cause severe extinctions of polar species;

·      often make the Earth's climate wetter on average, mainly by melting ice and snow and thus increasing the volume of the water cycle.

It might also cause anoxic events in the oceans.

Global warming as a cause of mass extinction is supported by several recent studies.The most dramatic example of sustained warming is the Paleocene-Eocene Thermal Maximum, which was associated with one of the smaller mass extinctions. It has also been suggested to cause the Triassic-Jurassic extinction event, during which 20% of all marine families went extinct. Furthermore, the Permian–Triassic extinction event has been suggested to have been caused by warming. Human-caused global warming is contributing to extinctions today.

7.Clathrate gun methane eruptions

Clathrates are composites in which a lattice of one substance forms a cage around another. Methane clathrates (in which water molecules are the cage) form on continental shelves. These clathrates are likely to break up rapidly and release the methane if the temperature rises quickly or the pressure on them drops quickly—for example in response to sudden global warming or a sudden drop in sea level or even earthquakes. Methane is a much more powerful greenhouse gas than carbon dioxide, so a methane eruption ("clathrate gun") could cause rapid global warming or make it much more severe if the eruption was itself caused by global warming.

It has been suggested that "clathrate gun" methane eruptions were involved in the end-Permian extinction and in the Paleocene–Eocene Thermal Maximum, which was associated with one of the smaller mass extinctions.

8. Anoxic events

Anoxic events are situations in which the middle and even the upper layers of the ocean become deficient or totally lacking in oxygen. Their causes are complex and controversial, but all known instances are associated with severe and sustained global warming, mostly caused by sustained massive volcanism.

It has been suggested that anoxic events caused or contributed to the Ordovician–Silurian, late Devonian, Permian–Triassic and Triassic–Jurassic extinctions, as well as a number of lesser extinctions. On the other hand, there are widespread black shale beds from the mid-Cretaceous, which indicate anoxic events but are not associated with mass extinctions.

9. Hydrogen sulfide emissions from the seas

During the Permian–Triassic extinction event the warming also upset the oceanic balance between photosynthesising plankton and deep-water sulphate-reducing bacteria, causing massive emissions of hydrogen sulphide which poisoned life on both land and sea and severely weakened the ozone layer, exposing much of the life that still remained to fatal levels of UV radiation.

10. Oceanic overturn

Oceanic overturn is a disruption of thermohaline circulation which lets surface water (which is more saline than deep water because of evaporation) sink straight down, bringing anoxic deep water to the surface and therefore killing most of the oxygen-breathing organisms which inhabit the surface and middle depths. It may occur either at the beginning or the end of a glaciation, although an overturn at the start of a glaciation is more dangerous because the preceding warm period will have created a larger volume of anoxic water

It has been suggested that oceanic overturn caused or contributed to the late Devonian and Permian–Triassic extinctions.

11. A nearby nova, supernova or gamma ray burst

A nearby gamma ray burst at the End-Ordovician extinction would be powerful enough to destroy the Earth's ozone layer, leaving organisms vulnerable to ultraviolet radiation from the sun. Gamma ray bursts are fairly rare, occurring only a few times in a given galaxy per million years.

12. Geomagnetic reversal

Increased geomagnetic reversals will weaken Earth's magnetic field destroy magnetosphere, long enough to expose the atmosphere to the solar winds, causing oxygen ions to escape the atmosphere, resulting in a disastrous drop on oxygen. Additionally, Magnetosphere destruction will cause the earth to be bombarded with Alpha, beta, gamma and X rays, wiping out lives.

13. Plate tectonics

Movement of the continents into some configurations can cause or contribute to extinctions in several ways:

·      by initiating or ending ice ages;

·      by changing ocean and wind currents and thus altering climate;

·      by opening seaways or land bridges which expose previously isolated species to competition for which they are poorly adapted (for example, the extinction of most of South America's native ungulates and all of its large metatherians after the creation of a land bridge between North and South America).

Occasionally plate tectonics creates a super-continent which includes the vast majority of Earth's land area, which is likely to reduce the total area of continental shelf (the most species-rich part of the ocean) and produce a vast, arid continental interior which may have extreme seasonal variations.

ASTEROIDAL IMPACT ON EARTH

Some asteroids have orbits that cross the orbit of the Earth. That means that the Earth will be hit sometime. Recent studies have shown that the Earth has been hit an alarmingly large number of times in the past. One large impact is now thought to have contributed to the quick demise of the dinosaurs about 65 million years ago.

Thermonuclear warhead Effect

The largest yield of a thermonuclear warhead is around 50--100 megatons. The kinetic energy of the falling object is converted to the explosion when it hits. The 10-kilometer object produces an explosion of 6 × 107 megatons of TNT (equivalent to an earthquake of magnitude 12.4 on the Richter scale).

Hole in the atmosphere

On its way to the impact, the asteroid pushes aside the air in front of it creating a hole in the atmosphere. The atmosphere above the impact site is removed for several tens of seconds. Before the surrounding air can rush back in to fill the gap, material from the impact: vaporized asteroid, crustal material, and ocean water (if it lands in the ocean), escapes through the hole and follows a ballistic flight back down. Within two minutes after impact, about 105 cubic kilometers of ejecta (1013 tons) is lofted to about 100 kilometers.

Steam  explosions

If the asteroid hits the ocean, the surrounding water returning over the hot crater floor is vaporized, sending more water vapor into the air as well as causing huge steam explosions.

Tsunami

The oceans cover about 75% of the Earth's surface, so it is likely the asteroid will hit an ocean. The asteroid will push the water aside and hit the ocean floor to create a large crater. The water pushed aside will form a tsunami, a megatsunami.

The steam blasts from the water at the crater site rushing back over the hot crater floor will also produce tsunamis following the initial impact.

Global Firestorm

The material ejected from the impact through the hole in the atmosphere will re-enter all over the globe and heat up from the friction with the atmosphere. The chunks of material will be hot enough to produce a lot of infrared light. The heat from the glowing material will start fires around the globe.

Acid Rain

The heat from the shock wave of the entering asteroid and reprocessing of the air close to the impact produces nitric and nitrous acids over the next few months to one year.

Atmospheric NO2 is converted to nitric and nitrous acids when it is mixed with water.These are really nasty acids. They will wash out of the air when it rains---a worldwide deluge of acid rain with damaging effects:

1.     destruction or damage of foliage;

2.     great amounts of weathering of continental rocks;

3.     the upper ocean organisms are killed. These organisms are responsible for locking up carbon dioxide in their shells (calcium carbonate) that would eventually become limestone. However, the shells will dissolve in the acid water. That along with the "impact winter" kills off about 90% of all marine nanoplankton species..

4.     The ozone layer is destroyed by O3 reacting with NO. The amount of ultraviolet light hitting the surface increases, killing small organisms and plants (key parts of the food chain). The NO2 causes respiratory damage in larger animals. Harmful elements like Beryllium, Mercury, Thallium, etc. are let loose.

Temperature Effects (impact winter)

All of the dust in the air from the impact and soot from the fires will block the Sun. The dramatic decrease of sunlight reaching the surface produces a drastic short-term global reduction in temperature, called impact winter. Plant photosynthesis stops and the food chain collapses.

The cooling is followed by a much more prolonged period of increased temperature due to a large increase in the greenhouse effect. The greenhouse effect is increased because of the increase of the carbon dioxide and water vapour in the air. The carbon dioxide level rises because the plants are burned and most of the plankton are wiped out. Also, water vapor in the air from the impact stays aloft for a while. The temperatures are too warm for comfort for a while.

Beneficial Asteroid Impacts

The near-Earth asteroids are the most worrisome ones for possible impacts but they could also be potentially very beneficial to Earth if we could mine them for rare metals and use the asteroids as convenient stepping stones to manned exploration of the solar system, especially traveling to Mars.

The near-Earth asteroids are relatively abundant in heavy metals like iron and nickel and the platinum-group metals (platinum, palladium, rhodium, ruthenium, osmium, and iridium) used in modern technology.

In fact, all of the heavy metals in the Earth's crust came from asteroid impacts after the Earth differentiated

The water from the asteroids could also be broken down into oxygen and hydrogen to be used as rocket fuel.

AIR POLLUTION

Issue-1. Air Quality Standards

Question: What are the issues concerning Air Quality Standards? And why Indian Air Quality standards are not considered safe?

1.      Air quality is not being monitored in real time

Central Pollution Control Board gets real-time air quality data from only two or three monitoring stations in most cities. This gives a skewed picture of air quality status and compromises policy-making. Most cities depend on manual monitoring stations, which use obsolete technology, and data is released just twice a week.

2.      The sources of air pollution are not very well known

A study by IIT Kanpur for Delhi revealed that the contribution of each source of pollution-vehicles, waste burning, construction dust-changes with the seasons, but most cities don't have this information. Bengaluru's emissions inventory was conducted in 2010 and Chennai's by IIT Madras in 2011, while Kanpur, Mumbai and Pune released their reports in 2010. 2008 was when data on pollution sources was last collected in cities

3.      Governments fail to enforce

But no city administration seems worried about getting off that list. Delhi, for instance, is still short of 5,000 buses; it hasn't implemented SC directions on prohibiting waste burning or ensuring construction projects don't pollute. Data for most cities makes it obvious that air pollution is not high on any government's priority list. 94 cities don't meet national air quality standards.

4.      health risks are Ignored

While air pollution is hurting the country's exchequer, it's also associated with certain cancers, lower birth weight of babies, premature birth, strokes a respiratory disease. Across the country, air pollution is linked to 6.7 lakh premature deaths

5.      People’s participation not forthright

The Deonar landfill fire drew attention to Mumbai's waste problem, while Delhi's three landfills are constantly on fire exposing lakhs to carcinogenic emissions. This is a common problem in all cities. If people segregated garbage at home, there would be no burning of waste. People can also choose public transport, or pick electric and CNG vehicles 

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Floodplain: Issues associated with it

What is a floodplain?

That portion of a river valley, adjacent to the river, that is built up of alluvium deposited during the present disposition of the stream flow. It is covered with water when the river overflows during flood periods. Meandering streams are typical features of floodplains. During the process of lateral erosion, the form of a meandering stream is altered by reduction, trimming, and cutting through, until all that remains is a crescentic mark, a floodplain meander scar, indicating the former position of a river meander on a floodplain. The beginnings of a floodplain are represented by lunate or sinuous strips of coarse alluvium along the inner bank of a stream meander. These are called point bars.

Floodplain is the area adjacent to a river that is not always under water, but is prone to flooding. It is an extension of the riverbed. In the case of the Yamuna in Delhi, the area that is likely to get submerged at least once in a 25-year period has been classified as its floodplain. The floodplains are not separate from the river. They are an integral part of any river-system, and are an ecologically sensitive area.

Why was Yamina Floodplains in news?

The biggest ever festival of music and dance organized by The Art of Living saw 3.5 million people attending to it. A huge 7-acre stage apparently the world’s largest ever, was erected. Several tents have been put up, pontoon bridges are being laid, dirt tracks were being laid, and heavy equipment have been deployed. Vegetation has been cut to make way for the temporary constructions. A major portion of the area has been flattened.

Environment  impacts on Flood plain.

1. One of the important functions of the floodplains is groundwater recharge. In the process of flattening, the surface is to be hardened, and that can severely impact its groundwater recharge capability.
2. Such works can also change the natural gradient of the floodplain, which can diminish its flood-carrying capacity.
3. Small water bodies and wetlands are filled up which absorb rainwater.
4. Some vegetation necessarily gets cleared up which has a role in either diverting the water flow and or increasing the biodiversity.

But what did the committee say?

A committee appointed by the NGT did make a site visit, and recorded its observations in a report to the court. But it was based on just a three-hour inspection, and not a proper scientific assessment.

In his observations, one of the members of the committee, said that

q  the site had been cleared of all natural vegetation, raised with the help of JCBs

q  huge amount of debris and construction waste had been dumped into the main channel of the Yamuna

q  The  activity was in no way benign and would have a permanent footprint on the floodplain.

It recommended that the organisers restrict the area of their operation to the bare minimum, and pay for the entire cost of the restoration. It said that a strong message should be sent to the DDA so that such violations are not repeated, and a restoration plan is prepared and its implementation monitored strictly.

An assessment

The area be restored to its original condition with not too much amount of difficulty. The clearing of debris can be done comparatively easily. Some other works can take several years. However, the problem in this case is that the authorities don’t even know what the original condition was. No study or assessment was done before the Art of Living Foundation was allowed to make changes to the floodplain for the event. In the absence of a baseline scenario, there is no way to assess whether the original condition has been restored.

Depending on what the impacts are, the monetary costs of restoration can be very high. The NGT-appointed committee had estimated that between Rs 100 and Rs 120 crore might be required for the restoration. It had recommended that the organisers be asked to deposit this amount in a separate account ahead of the event.

But the Akshardham temple and Commonwealth Games Village too stand on the Yamuna floodplains. They also caused damage. On both occasions, activists and citizens petitioned the courts, and the matter reached the Supreme Court. On both occasions, the apex court finally cleared the construction. In the CWG Village case, the court ruled that the site did not constitute the floodplains of the river.

In scale and size, these two are several times bigger than the Art of Living Foundation’s event. Activists and experts say the two gigantic, permanent structures have caused irreparable and irreversible damage to the river. But again, no scientific assessment has ever been made of the precise impact.

Why India needs a strong Navy

1.      Oceans are a large buffer zone inviting control and management for want of which the buffer can be replaced by a direct face off.

2.      India has along coastline of 7516 kms with many littoral islands, which requires to be defended monitored and to undergo surveillance. Only a strong navy will be able to do it.

3.      India has to make necessarily concentrate on Indian Ocean

·         If China were to gain the upper hand in the Indian Ocean region, it will mark the end of India’s great-power ambitions.

·         India’s tactical and strategic disadvantages along its land frontiers are more than compensated by its immense geographic advantage in the Indian Ocean. Such is peninsular India’s vantage location in the Indian Ocean — the world’s premier energy and trade seaway — that the country is positioned dominantly astride vital sea lanes of communication (SLOCs), including China’s emergent Maritime Silk Road.

·         The Indian Ocean promises to shape the wider geopolitics and balance of power in Asia and beyond.

·         To conter The Silk Road of China with the use of aid, investment and other leverage to pull littoral states closer to its orbit, including through the construction of seaports, railroads and highways. Such construction may provide a counterpoint to China’s military assertiveness. Yet it is integral to a strategy that fuses soft and hard tactics to bind countries to China’s economy and security and to convince them that it is in their interest to accept China as Asia’s alpha power.

·         To prevent Chinese military encirclement, India needs to significantly accelerate naval modernization. It must build sufficient naval prowess to potentially interdict Chinese SLOCs in the Indian Ocean and hold the Chinese economy hostage if a Himalayan war were thrust upon it again.

·         The Chinese military keeps Indian ground forces busy in peacetime by staging Himalayan border incursions and other flare-ups, the oil and liquefied gas flowing from the Gulf and Africa to China pass through the Indian Ocean unmolested and unimpeded. Over 80% of China’s oil imports pass through the Malacca Strait chokepoint. Boosting SLOC interdiction capability would allow the Indian Navy to dominate key maritime routes and help improve the Chinese military’s behaviour along the Himalayas.

4.      As India expands its regional influence through trade and commerce, it needs a Navy to protect and defend its interests. Trade with African countries is improving. India is involved in several projects in Africa and a Naval presence is required in the Arabian Sea and the Indian Ocean to deter the Chinese. Despite superior numbers, the Chinese have a distinct disadvantage in the fact that their Navy has no actual war experience. India, thus is improving its Naval presence there.

5.      The US is friendly, for now. But they have the same Anglo Saxon mentality of their ancestors, the British. They mistake friendliness for weakness. They will always try to ensure their supremacy in the world by making other nations fight among themselves, providing arms to all sides of the conflict. An expanded presence in our own backyard will help us to protect ourselves in cases of National threats coming from outside. Indigenous production in this case becomes more vital. The Soviets protected us from the Americans in the 1971 war against Pakistan. The USSR exists no more. So we need to be stronger to prevent such events from recurring.

6.      India imports 70% of its crude oil from abroad. This passes through the strategically important Strait of Hormuz. The US has its 5th fleet stationed there.

7.      The Chinese are building a port with a nuclear submarine pen in the city of Gwadar in Pakistan. The port will be connected to China via a highway from Gwadar through Pakistan Occupied Kashmir and into China. This will save them the 6000 mile long journey to take the oil through the Sea. India is countering this by building the port in Chabahar in Iran. The actual work was delayed thus far due to sanctions against Iran. Now that they are lifted, the work will hopefully resume. The port will serve 2 purposes:

·         It will outflank the Chinese Pakistani project.

·         It will provide access to the sea for land locked Afghanistan.

India also plans to source raw materials and minerals from Afghanistan through this project.

Challenges to rise of Indian naval power

Naval power had always been technology intensive and most innovative like aerospace power. Waves of technology revolutions have rendered obsolescent the concepts, doctrines, operations and the hardware of the past era.

Four cardinal challenges stand out for India.

1.      The pace of platform buildup outpaces by the platform ageing of the current inventory-therefore the order of battle of the fleet is constantly under flux with falling numbers. Although considerable service-life-extension-programs have gone into the platforms with hybridization of technology, these platforms are now coming to an end of their immensely useful operational life. The imperatives for newer platforms on emerging technology templates require urgency. However, the addition of platforms to the ratio of retirement has- not been sufficient in numbers.

2.      Secondly, the complexity and diversity of missions have been increasing stressing the existing fleets into missions often beyond their capacity.

3.      Thirdly, the pace of Revolution in Military Affairs or even specifically the Revolution in Naval Affairs produces new synergies in technology, doctrines and operations resulting in new templates of naval platforms, organizational and operational complexity.

4.      The operational reputation of a navy is often intact unless challenged by a rising challenger or a new wave of technology and weaponry that may reduce the robustness of an established navy be inflicting a shocking defeat.

5.      The pace of the plan modernization and the strategic alliances that it is building with Pakistan, Bangladesh, Myanmar, and Sri Lanka for access and basing engages the Navy into inevitable regional overdrive to sustain and leverage its power and domain. It demands the Indian Navy the buildup of capacities in organizational, order of battle and operational wherewithal that would be able to develop a strong forward presence in the Strait of Malacca-South China Sea all the way to the East Pacific as a counterpoise to the Chinese maritime access building