Climate Change In The Past by Tristan P.

this slideshow tells you about climate change that is caused by things from space such as meteors

1. Brought to you by
Tristan, Shaheen, and
Dannish from 8A
climate
change in
the past

2. Climate is the long-term pattern of temperatures, wind and rainfall on Earth. The Earth's climate has been very different in the past
compared to the climate today. Model-simulated global temperature anomalies for the Last Glacial Maximum (21,000 years ago),
the mid-Holocene (6,000 years ago), and projection for 2071–2095, under RCP8.5
About 2 billion years ago, the Earth
experienced the first ice age that we know
about. Since then, the Earth has cycled
between relatively warm periods and
relatively cold ones. In the warm periods,
there was no ice at all, even at the poles. In
the colder periods, called ice ages, there was
ice at the poles.
The Holocene is the current geological
epoch, beginning approximately 11,700 years
ago. It follows the Last Glacial Period, which
concluded with the Holocene glacial retreat.
The Holocene Climatic Optimum (HCO) was
a period of warming throughout the globe
but was not globally synchronous and
uniform. Following the HCO, the global
climate entered a broad trend of very
gradual cooling known as Neoglaciation,
which lasted from the end of the HCO to
before the Industrial Revolution.
Earth’s climate is now changing faster than
at any point in the known history of the
climate, primarily as a result of human
activities. There is scientific consensus that
unmitigated carbon emissions will lead to
global warming of at least several degrees
Celsius by 2100, resulting in high-impacts of
local, regional and global.

3. On at least one occasion, perhaps about 650
million years ago, the whole Earth was
covered with ice and snow. Scientists call
this 'snowball Earth', or sometimes
'slushball Earth', because they are not sure
whether everything was completely frozen.
(Slush is melting ice.) Scientists still do not
completely understand what caused this to
happen.
This is what the Earth may have looked like,
650 million years ago. At that time, the
continents were not in the same positions
as now.

4. Asteroids Colliding
with each other
Around 470 million years ago,
scientists think that two asteroids
collided with one another when they
were in space, somewhere in-between
Earth and Mars.
The collision produced huge quantities
of dust. The dust reduced the amount
of light and heat from the Sun reaching
the Earth's surface. This triggered an
ice age. The Earth became much colder
– the ice caps spread much further
from the poles and sea level fell.

5. Asteroids Colliding
with earth
Around 67 million years ago, an asteroid
collided with Earth. Researchers have
identified an area on the coast of Mexico
where the asteroid impact took place.
There was huge devastation close to
where the asteroid fell. It would have been
like a massive bomb exploding, with
shock waves and very high temperatures
spreading out from the crater.
But the collision affected the whole
planet, not just the surrounding area,
because it threw huge quantities of rock
and dust into the air. It would also have
created a massive tsunami (a huge sea
wave), which could have spread across all
of the Earth's oceans.

6. The dust in the air meant that less light reached the Earth's surface.
Plants could not photosynthesise, so animals had less food. As well
as the disruption to food chains, the Earth became much colder,
because less heat from the Sun could reach the surface.

7. Most scientists think that these changes in
climate, caused by the asteroid impact, explain
why dinosaurs became extinct around this time.
Not only the dinosaurs, but also many other
species on Earth, were destroyed as a result
of the climate change following the asteroid
collision. The asteroid caused a mass
extinction. Up to three-quarters (75%) of all
the species on Earth that were alive at that
time are thought to have become extinct
because of the asteroid collision.

8. There are about 175 known asteroid impact craters around the world. The crater shown in the
picture is in the Arizona, USA. The crater is more than 1 km wide and 170 m deep. It is
estimated that the asteroid collision that formed this crater happened 50000 years ago.

9. Brought to you by
Tristan, Shaheen, and
Dannish from 8A
climate
change in
the past
Thank you for listening.