HISTORY OF EXTINCTIONS

BY GOKUL B

JSGP 2014

INTRODUCTION

Climate is the underlying force which stimulates life on the planet.

From microorganisms to the largest existing animal the blue whale; climate is the force which triggers their functioning. Climatic change drastically impacts life, us the homo-sapiens are also programmed by nature to perform according to climate. A change in the climatic conditions of a region can only be for the worst. Being currently the dominant species on the planet and believing to command everything on the planet and understand nature, it is ironic that a minute variation in climate can threaten our dominion status. Are we being ignorant of other species? Are we taking mother Earth for granted? The inhuman human activities in the name of development and monetary benefits are leaving only one choice for our fellow beings and that is to just disappear forever. The paper studies about the climate changes which has happened during the past and relation with the present and the amount of effect it has brought about during the passage of time in the form of species’ extinctions and whether we are moving towards another possible 6th Extinction1 ? Beginning from the meaning of climate which comes from the Greek word klima meaning 'area', usually refers to a region's long-term weather patterns. This is measured in terms of average precipitation (i.e. the amount of annual rainfall, snow etc.), maximum and minimum temperatures throughout the seasons, sunshine hours, humidity, the frequency of extreme weather, and so on. Due to this prolonged nature it is important to study and understand exactly what to expect in the long run. This is where the subject of climate change comes relevant, climate change usually refers to global climate change, or long-term variations in the planet's average temperature. But it can also be used more generally to mean local and regional

1 With Reference to Elizabeth Kolbert’s Book ’ The Sixth Extinction’

changes in weather patterns. The global average temperature is influenced by many interacting systems which, together, we call the climate system. But, of course, global climate change also affects regional climates. Analyzing the reasons for these climatic changes leads us to the conclusion the changes are anthropogenic in origin. When global biodiversity is gradually being altered by human activities, species respond differently to such alterations in response to habitat destruction and habitation fragmentation either by adapting to it or by becoming extinct. WHY IS CLIMATE RELEVANT? Simply stating climate is as important to us as much as natural resources like fresh water, oxygen, trees etc. are. Climate acts as one of the stimulants for life. Climate regulates the activities of all the living organisms. Our agriculture is dependent on climate, our biological cycle is dependent on climate. We are wired to behave accordingly to the climate, if the climate cycle gets unbalanced, then from microbes to the humans, all will slowly die. In order to prevent such mass extinctions it is necessary to understand and protect our climate. ”God always forgives, man occasionally forgives but nature never forgives” -as quoted by Pope Francis. THE HISTORY OF CLIMATE CHANGE: Climate has been always subjected to changes, throughout the history of the planet

there is evidence that it has happened and affected the Earth throughout geologic

time. Evidence of past climate change comes from the geologic record of ancient

environments and glaciers, fossils of plant pollen, isotopes of elements such as

carbon and oxygen, tree rings, and fossil distributions. The age of these can be

determined by carbon dating. Then the question arises why we are alarmed about

it today? The answer is that we are accelerating the process of climate change to a

very unrecoverable position and the results are horrifying.

The following are the BIG FIVE extinctions, which are recorded proof of the harm

climate change can bring about in the ecosystem. By analyzing these past

occurrences we are able to understand what climate change is and how to tackle it.

1. The Ordovician Period

The Ordovician Period lasted almost 45 million years, during this period, the

area north of the tropics was almost entirely ocean, and most of the world's

land was collected into the southern supercontinent Gondwana. Throughout

the Ordovician, Gondwana shifted towards the South Pole and much of it was

submerged underwater.

The Ordovician is best known for its diverse marine invertebrates, plus red and

green algae, primitive fish, cephalopods, corals, crinoids, and gastropods.

From the Lower to Middle Ordovician, the Earth experienced a milder climate

— the weather was warm and the atmosphere contained a lot of moisture.

However, when Gondwana finally settled on the South Pole during the Upper

Ordovician, massive glaciers formed, causing shallow seas to drain and sea

levels to drop. This particularly affected the corals and bryozoans that were

living in shallow inland seas, which drained of water. Global cooling spelt

disaster for warm-adapted species that had nowhere to migrate This likely

caused the mass extinctions that characterize the end of the Ordovician in

which 60% of all marine invertebrate genera and 25% of all families went

extinct to.

A picture of the Ordovician sea.

2. Devonian Period

When the Devonian period dawned about 416 million years ago the planet

was changing its appearance. The great supercontinent of Gondwana was

headed steadily northward, away from the South Pole, and a second

supercontinent began to form that straddled the Equator. Known as

Euramerica, or Laurussia, it was created by the coming together of parts of

North America, northern Europe, Russia, and Greenland.

Red-colored sediments, generated when North America collided with Europe,

give the Devonian its name, as these distinguishing rocks were first studied in

Devon, England. 2

Climate

The Devonian was a relatively warm period, and probably lacked any glaciers.

The temperature gradient from the equator to the poles was not as large as it

today. The weather was also very arid, mostly along the equator where it was

the driest. Reconstruction of tropical sea surface temperature from condont

apatite implies an average value of 30 °C (86 °F) in the Early Devonian. CO2

levels dropped steeply throughout the Devonian period as the burial of the

newly evolved forests drew carbon out of the atmosphere into sediments; this

may be reflected by a Mid-Devonian cooling of around 5 °C (9 °F). The Late

Devonian warmed to levels equivalent to the Early Devonian; while there is no

corresponding increase in CO2 concentrations, continental weathering

increases (as predicted by warmer temperatures); further, a range of

evidence, such as plant distribution, points to Late Devonian warming. The

climate would have affected the dominant organisms in reefs; microbes would

have been the main reef-forming organisms in warm periods, with corals and

stromatoporoid sponges taking the dominant role in cooler times. The

warming at the end of the Devonian may even have contributed to the

extinction of the stromatoporoids.

2 Reference from National Geographic website

3. The Permian mass extinction

(Also nicknamed the great dying)

The Permian mass extinction (251.9 million years ago) 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. The event turns out

to have been complex, as there were at least two separate phases of extinction

spread over millions of years. Marine creatures were particularly badly

affected and insects suffered the only mass extinction of their history.3

Relation of this great dying with climate change

Due to gigantic volcanic eruptions and release of huge amount of lava covering

100000sq.ft in fire from the Siberian traps, the global temperature rose by a

staggering 5 degree Celsius making the entire planet inhospitable for life. The

volcanic activity released high volumes of CO2 gas into the atmosphere leading

to global warming at an enormous scale. The mass extinctions occurred in

three phases killing off land and marine life.

The release of methane gas from the sea beds due to increase in temperature

in the water further accelerated the global warming by an alarming 10

degrees.

The climate change thus caused killed of 96% of all life on planet Earth. The

unfortunate period very much holds relation to today

where increase in greenhouse gas emission are gradually paving the way

forward for a mass extinction.

3 Reference from Scientific America article dated 24-10-07

4. Triassic-Jurassic mass extinction

After the cataclysmic Late Permian mass extinction, it took 10-20 million years for life to recover its previous diversity. But it did recover, and in significant new ways. This was particularly true of vertebrates. Mammal-like reptiles flourished. Walrus-like reptiles, placodonts, appeared in the shallow seas. Sharks and fish diversified. And giant reptiles - the dolphin-like ichthyosaurs - became the top marine predators. One of the main beneficiaries of the Late Permian mass extinction may have been the dinosaurs. Their early ancestors emerged within about 5 million years of the event. While the first dinosaurs were only dog-size, by the end of the Triassic Period 6-metre-long giants had evolved. Then the good times came to an abrupt end as Earth was thrown into environmental chaos once again. Causes for the chaos This extinction is probably the least understood of the big five, because of the lack of accessible sediments for scientists to study. Most of the evidence suggests falling

sea levels were probably responsible for the longer-term extinction patterns. As the warm shallow seas decreased, reefs died and other marine organisms faced increased competition in less space. On land the lack of water would have led to more extreme temperatures and seasons. When deep water spread back over the continents it was low in oxygen, resulting in further marine extinctions. While the ultimate cause of this sea fall and rise isn’t certain, it appears to be associated with the start of a volcanic rift forming between the Americas and Africa and Europe. This would eventually produce the Atlantic Ocean. At the end of the Triassic, very large eruptions occurred along the rift zone (known as the Central Atlantic Magmatic Province) for about 500,000 years. The environmental changes these caused put further stress on life on Earth.4 Large quantities of methane gas created stress on the ecosystem adding to the global warming. Climatic changes finally ends up the cause.

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5. 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. Some groups had been in decline for several million years before the final event that destroyed them all. It's suggested that the decline was 4 Reference from Discovery channel 5From BBC Nature

due to flood basalt eruptions affecting the world's climate, combined with drastic falls in sea level. Then a huge asteroid or comet struck the seabed near the Yucatan Peninsula in Mexico and was the straw that broke the camel's back.

Climate

Earth’s geography was transforming radically. As the land separated into some of the continents we know today, ocean currents and climate were changing. Then, sea levels dropped significantly and rapidly, falling as much as 150 meters in less than 1 million years. But it reduced large inland seas such as the Western Interior Seaway of North America, with a knock-on impact on terrestrial habitats, including those important for dinosaurs. At the very end of the Cretaceous, intense volcanic activity rocked the planet. Ash and toxic gases poured into the atmosphere, sending temperatures plummeting and causing acid rain. As plants perished, herbivores and their predators would have starved. The intense volcanic eruptions would also have ejected vast amounts of carbon dioxide. Scientists speculate that this caused ocean acidification, poisoning the phytoplankton that larger marine animals relied on for food. Since these phytoplankton would normally remove carbon dioxide from the atmosphere (storing it as calcium carbonate in their skeletons), levels of this greenhouse gas were able to rise unchecked. Scientists estimate that temperatures may have increased by as much as 10°C, warming the oceans by up to 4°C and putting stress on species, particularly those already living in tropical areas. It seems the volcanic eruptions and meteor impact were probably the final straw for species already suffering from the effects of sea-level changes.

Conclusions drawn based on the events above:

1. From the analysis of the above cases we can easily say that climate was the underlying factor which determined the fate of the creatures (even the dominant ones). In some cases external factors like meteoroids did a play a part but it acted as a final nail on the coffin.

2. Temperature rise gave way for creation of inhospitable ecosystems. 3. Carbon and methane played a vital role in the mass extinction. 4. It can happen again.

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Are we heading for a 6th Extinction? We just crossed CO2 levels of 400ppm which is the highest levels found on earth in millions of years. As carbon dioxide is a greenhouse gas this means the temperatures are only set to rise unless we take necessary steps. We have already lost a considerable amount of flora and fauna. The concept of an ongoing sixth extinction is beautifully portrayed in Elizabeth Kolbert’s book The Sixth Extinction. Earth is losing its biodiversity fast due to human activities but the proof to whether it will lead to another mass extinction can only be verified by analyzing some of the cases.

1. The case of the declining amphibian population 6 2012 was marked as the hottest year in the 21st century, it resembles the geographical history.

Amphibians are particularly sensitive to changes in environment, amphibians have been described as a marker species or the equivalent of “canaries of the coal mines” meaning they provide an important signal to the health of biodiversity; when they are stressed and struggling, biodiversity may be under pressure. When they are doing well, biodiversity is probably healthy. Unfortunately, as has been feared for many years now, amphibian species are declining at an alarming rate. If current estimates of amphibian species in imminent danger of extinction are included in these calculations, then the current amphibian extinction rate may range from 25,039–45,474 times the background extinction rate for amphibians. At an alarming rate many of the varieties of amphibians like the panama golden frog have become extinct from being endangered.

7 It has been observed that the species could not adapt to the new world we had made, they lost their habitats and their resistance to fungal diseases dwindled and many died off (as in the case of Panama frogs).

1. Dwindling fish stock

The UN’s 3rd Global Biodiversity Outlook report, mentioned earlier, notes that, “About 80 percent of the world marine fish stocks for which assessment information is available are fully exploited or overexploited. Fish stocks assessed since 1977 have experienced an 11% decline in total biomass globally, with considerable regional variation. The average maximum size of fish caught declined by 22% since 1959

7The Golden Toad of Monteverde, Costa Rica was among the first casualties of amphibian declines. Formerly abundant, it was last seen in 1989. Source WIKIPEDIA

globally for all assessed communities. There is also an increasing trend of stock collapses over time, with 14% of assessed stocks collapsed in 2007.8” Increased fishing activities have led to the oceans being swiped clean of its stock of fisheries. IPS reports that fish catches are expected to decline dramatically in the world’s tropical regions because of climate change. Industrialized fishing methods have depleted the fish and it is feared it is irrecoverable. We must understand that each life form works together and only then can harmony be achieved, ocean ecosystems help in reducing carbon by absorbing it, helps in recycling sewage and helps in regulation of water cycle.

2. Declining ocean biodiversity due to acidification, oxygen loss and

temperature increase. 3. Rapid loss of forest cover.9

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These cases force us to believe that the ignorance with which we act could be leading us to a greater danger than we thought.

8 — Secretariat of the Convention on Biological Diversity (2010), Global Biodiversity Outlook 3, May, 2010, p.48

9 Alarming increase in loss of greenery

If we continue in this pattern we will face another mass extinction. In comparison to earlier mass extinctions which took place in millions of years the scenario today is fast approaching. The choices we have made as a species, educated or inadvertent, have created the following ecological stressors:

Rapidly changing atmospheric conditions

Warming above typical interglacial temperatures as CO2 levels continue to rise

Habitat fragmentation

Pollution

Overfishing and overhunting

Invasive species and pathogens (like chytrid fungus)

Expanding human biomass We are being mute witnesses to many of the extinctions going around us in our short life span which itself proves that it has become an accelerated process.

Why we cannot afford extinction?

We have no right to decline the right to live that our fellow beings (plants & animals) have; we are and never were dominant, we can only co-exist.

Due to mass extinction of our plant species we are fast losing forest cover, important for both rain water cycle and groundwater accumulation.

Disturbing Ecosystem Equilibria Ultimately it will end in utter turmoil, destabilization of the ecosystem can have devastating effects.

Measures Implemented and can be implemented: So far we have discussed about all the negative aspects of climate change and extinction. Now some of the measures implemented and can be implemented to prevent it are:

1. In order to prevent further destruction it is important to spread awareness among the general public. A similar approach is being done in India by NDTV by launching a massive awareness campaign to save the tigers. As a result of which they were able to keep in check poaching and illegal sales.

2. By resorting to clean energy and ditching fossil fuels.

3. By protecting endangered species legally and structurally by creating sanctuaries.

4. Controlling industrial fishing

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Conclusion Nature was never ours and it will never be also, the other 5 extinctions are examples to us, a nature’s way of warning us and we must heed to this warning or otherwise we will perish just as the other dominant species did.

10 WORLD WILD FUND FOR NATURE AIMS AT PROTECTING ENDANGERED SPECIES.