Predicting Past Climates
Huzaifa and Shajee
We will talk about:

Predicting Past Climates:

Ice Cores


Dentrochronology


Record temperature data by trapping gases such
as oxygen, carbon dioxide, methane, and nitrous
oxide
Tree rings and coral reefs grow annual layers in
proportion to how favourable climate is.
Rocks, Oceans, and Caves

Sediment may contain evidence such as fossils
and plant pollen, of past climates.
Studying Clues to Past
Climates:




Scientist have recorded temperature, rainfall, and other data over
the last 200 years
Before people kept climate records in:
 Journals
 Paintings
 Farming Records
 Oral Histories
People who study past climates are called Paleoclimatologists.
Proxy record: stores of information in tree rings, ice cores, and
fossils that can be measured to give clues on what the weather was
like in the past.
Ice Cores
What are Ice Cores:



A core sample from the build up of snow and ice
They have recrystallized and have trapped air bubbles
from previous time periods
They Contain:






Ice
Snow
Wind blown dust
Ash
Bubbles of atmospheric gas
Radioactive substances
What are Ice Cores:


Typical ice cores are removed from ice sheets
Most commonly from the polar ice caps of Antarctica,
Greenland, and from high mountain glaciers.
Structure:





Mostly formed from snow
It is a firm grainy material with texture
similar to sugar.
Age depends of thickness
Portions of Antarctica are said to be
covered with ice for more than 20 million
years
Scientists don’t to retrieve cores more
than one million years old.
What do Ice Cores do:





Ice cores increase the levels of CO2 in the
atmosphere
The concentration continuously has been going up
and down through out the millenniums.
Ice cores also change the temperature
The temperature has been changing more constantly
today, than it was 400 million years ago.
Give information on weather, precipitation, and
volcanic eruptions.
Dentrochronology
What is Dentrochronology:

Study of:

Tree Rings



Wider in good growing years
Narrower in bad growing years
Coral Reefs


Grow near the surface of the ocean
Layers of coral grow at different in warm and
cold weather
Tree Rings:





Trees crate one growth ring per year
In warm conditions, they produce a thick ring
In cold conditions, a narrow ring
Some trees live for thousands of years
They are:





Bristle cone pine
California Redwood
Clues are assembled from both dead and living trees
They collect records going as far back as 10,000 years
In Ontario, trees have provided proxy climate data for
the past 2767 years.
Bristlecone
Pine
California
Redwood
Narrower
Thicker
Coral Reefs:

Records are also preserved in coral reefs

Corals add a layer of growth each season

Scientist study them by drilling cylinders of
coral and studying their layers

Information from corals, helps determine the
water temperature.
Rocks, Oceans, and Caves
Rocks:


Layers of soil and rock build up on the earths surface over time.
Each layer may contain clues such as:





Plant Pollen
Fossils
Fossils of pollen grains can be used to identify the plants that grew
thousand of years previously.
Palynologists: Scientist who study Pollen.
They use the:



Size
Shape
Presence of:



Pores
Furrows
Air sacs
to Identify the species of the plants
Oceans:






Layers of sediment drift to the ocean floor and form
layers of rock
Scientist drill cores of sediment from the ocean floor
Fossils of marine plants and animals are found
sometimes
Sometimes they are found in colder water than they
lived in
This is evidence that the layer containing these fossil
fuels formed during a warmer climate
This has allowed scientist to build a picture of the
earth's climate thousand years past.
Caves:




Rock formations grow as the minerals that are
dissolved in dripping water solidify into rock.
Scientists can measure and date layers from
these rocks
Rock formations grow faster in rainy water
Analysis of the layers determine how much
precipitation occurred at specific times in the
past.
Quiz Time
1.) What are Proxy Records?
a)
b)
c)
d)
Stores of information in tree rings and
ice cores
Stores of information in tree rings and
ice cores, and fossils
Stores of information in rocks
Stores of information in
Dentrochronology
2.)In Ontario, trees have provided proxy
climate data for the past
a)
2267
b)
2676
c)
2767
d)
10,000
_____ Years
3.)Tree rings are wider in good
growing Years:
a)
True
b)
False
4.) Which tree can live for
thousands of years?
a)
Pine
b)
Bristlecone Pine
c)
Maple
d)
Mahogany
5.) Scientists who study pollen
are called ________.
a)
b)
c)
d)
Palynologists
Balneologists
Pollen Scientists
Apologists
The End