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1. By sujith bhaskar R
OUT OF THIN AIR

2. http://blog.centreetech.com/
PETER D WARD:
A professor of biology and earth and space studies.
Professor of astronomy at the university of Washington.
Co-founder of the institute for astrobiology at the university
of Washington.
Principal investigator of the university of Washington node
of NASA Astrobiology institute.
His famous books are: The End of Evolution, Life as We Do
Not Know.

3. OUT OF THIN AIR
Deals with the history of oxygen level and their effects on
extinction from deep time to the modern world.
Reason for the disappearance of dinosaurs from earth.
Relation between the dinosaurs and birds.

4. Dinosaurs came to dominate the planet – during eras when
oxygen levels fell to unprecedentedly low levels and
extinguished thousands of species in other forms, including
mammals.
Over the past 500 million years, life on Earth has been
punctuated by 15 waves of mass deaths, during which huge
numbers of plants and animals quickly went extinct.
Out of the 15 waves ,5 were the biggest and were the prime
culprits in leading earth to low oxygen level.

5. Amount of oxygen
 78 percent nitrogen
21 percent oxygen and
1 percent that’s a variety of gases from carbon dioxide to
water vapor.
•5 million years ago, oxygen levels were as high as 28 percent
•544 million years ago oxygen levels were about 13
percent(Cambrian Explosion).
•300 million years ago, it topped out at 35 percent(the
Carboniferous/early Permian ).
•Then it was down to 12 percent or lower(Triassic).

6. PERMIAN EXTINCTION
250 million years ago, nearly four times as old as the
Cretaceous Extinction.
Known as Dinosaurs’ swan song.
At least 90 percent of all species were wiped out in the
Permian Extinction.
This is most speeder than cretaceous extinction so the
results were unknown.
End of the Permian, the world turned hot and desert-
like.

7. There was no ice at the poles, and great fields of dunes
on land.
 Harsh, hot winds blew across them and there was little
plant life.
The largest animals were no bigger than a lamb; they
were inactive and stayed close to sea level, and very few
species lived in the ocean as well.
Even insects were rare. The air reeked of rotten eggs.

8. CRETACEOUS EXTINCTION
known as the K/T extinction event.
This event was clearly sparked by an asteroid strike.
extinctions from the K/T event were selective
 most dinosaurs and photosynthesizing organisms
suffered heavy losses, omnivores, insectivores, and
carrion-eaters didn’t do too badly.

9. CAMBRIAN EXPLOSION
Just before the Cambrian Explosion, land consisted of not
much more than bare rock with little vegetation: no soil, no
trees, no plants, no flowers, no bugs, no amphibians, no fish.
The sun and moon were dimmer but the moon was also much
closer, so there were huge tides.
oxygen levels were low.
The only life to speak of were bits of moss and red and brown
algae on the rocks, although the oceans had photosynthesizing
bacteria, sponges, jellyfish, anemone-like creatures, and
worm-like forms on the bottom.

10. THE UPCOMING CHANGES
The northern land masses will move out of the high latitudes and
Antarctica will shift from the south to converge in another
supercontinent.
As part of that change, the Mediterranean will disappear and a
mountain range will spring up to reach from what we know as
Europe to the Persian Gulf.
Australia will close with Papua New Guinea and Indonesia.
Baja will shift north along the Pacific Coast of the U.S.
Mountain building will continue in the Appalachians and along the
east coast of South America.
Sea levels will rise.
Antarctic and Greenland ice will melt, and ocean levels will climb
about 300 feet, but Antarctica and Australia will remain separated
from the supercontinent by an inland sea.

11. CONCLUSION
According to the view of Peter D Ward the main reason
for these major extinctions, explosions, etc. are due to
the climate change especially greatest drop in Oxygen
and jump in Carbon Dioxide. This means that if there is
a 10 percentage drop in atmospheric oxygen it will lead
a total change in the world.