Segment II – Climate Change Power Point

heehawultraMécanique

22 févr. 2014 (il y a 3 années et 4 mois)

49 vue(s)

WHAT I S I T AND WHAT ARE SCI ENTI STS
DOI NG TO GATHER I NFORMATI ON ABOUT
I T?

Climate Change

Weather


What

is

it?


How

the

atmosphere

is

CURRENTLY

behaving
.


How

it

affects

humans

TODAY
.



Can

change

from

minute

to

minute,

day

to

day,

and

season

to

season
.


Components


Temperature


Humidity


Precipitation


Brightness


Visibility


Wind


Atmospheric

pressure



Different

kinds

of

weather


Sunny

or

Rainy


Clouds

and

wind


Hail,

snow,

or

sleet


Floods,

blizzards,

thunderstorms


Cold

front

or

heat

f
ront


Heat

wave


Climate


What is it?


LONG TERM
pattern of weather.


Average weather for an area.


Can be local or global.


Why is it important to study?


Keeping a record of the weather.


Deviations from the average could be an
indication of climate change in an area.



What contributes to the climate of an area?

Proximity to oceans and lakes:


Bodies of water absorb heat when it is
hot and release heat when it is cold,
contributing to the climate of an
area.


Heat exchanges between the ocean
and atmosphere cause wind.


Winds drive ocean currents.


Oceans absorb CO2, slowing global
warming.


Evaporation: Hot water from the
tropics evaporates and is carried by
trade winds to the north and south.


Storms often develop over warm
oceans before hitting land.





The ocean, land, and air are all
connected. Changes can have dramatic
effects in interconnected systems (e.g.,
El Nino).

External Forces of Climate Change


Long term climate cycles (measured in thousands of years) are
driven by astronomical forces.


Milankovitch

cycles: The Earth’s orbit, axial tilt, and other
movements go through long cycles of change which affect climate on
Earth.


Stretching of orbit


Elliptical obits cause interglacial periods


Circular orbits cause glacial periods


Occurs every 92,000 years


Tilt of axis


Affects polar sunlight


Changes by about 2 degrees every 41,000 years


Has great affects on
climate


Wobble of axis


Like a
top spinning

the axis of the Earth wobbles


Causes changes in the intensities of seasons


Occurs every 21,000 years


CLIMATE IS WHAT YOU EXPECT

WEATHER IS WHAT YOU GET

The Greenhouse Effect


Why do gardeners use
greenhouses?


Solar radiation is trapped
inside the glass or plastic
material.


Gases such as water, carbon
dioxide, methane, and nitrous
oxide absorb and emit the
radiation.

The Greenhouse Effect

Paleoclimatology


How do scientists know what the climate
was like thousands of year ago?


Sediments


Ice Cores


Tree Rings


Sediment Cores


Similar to ice cores


Taken from oceans or lakes


Sedimentation rate


Charcoal


Pollen


Diatoms
, foraminifera


Foraminifera

-
Also know as forams

-
Most are
benthic
: live on the bottom of the sea or lake

-
Some live in water column

-
Range in size from 1 mm to 200
mm




-
Important part of
food chain

-
Produce hard shells
made of calcium
carbonate

Foraminifera and Diatoms


The chemical makeup of their
environment depends on the
temperature of the water.


Oxygen has 3
isotopes.



In
warmer water, atoms with lighter
isotopes

evaporate faster than atoms
with heavy isotopes.


Isotope:
Natural variation in the number
of neutrons in the nucleus of an atom.


There are thousands
of different
species.


Each lives in a particular environment.


The chemical makeup of their shells depends on the chemical
makeup of their environment.


Many trees form annual growth rings.


The width, density, and isotopic composition of tree
rings is influenced by the environment.


Some trees are thousands of years old.


To extend chronologies from living trees, scientists
use
fossilized
wood or
wood from old
buildings.


Overlapping patterns found in tree rings allows us to
date tree rings back as far as 11,000 years ago.

Extending chronologies from living trees

http://www.ncdc.noaa.gov/paleo/slides/slideset/18/18_355_slide.html

Ice Cores


Collected from ice sheets in Greenland and Antarctica.


Can date as far back as 750,000 years ago.


Information That Can Be Obtained From Ice Cores


Annual snowfall


Substances found in snow


Dust, ash, gas, radioactive substances


Proxy for


Temperature


Precipitation


Composition of atmosphere


Volcanic eruptions


How Can Scientists Use Ice Cores To Determine
Past Climate Conditions?


They use isotopic ratios of water in cores to
determine temperature and precipitation.


Dust particles can determine atmospheric
circulations, volcanic eruptions, and wind speed.


Volcanic eruptions help scientists age ice cores
accurately.


Atmospheric composition is determined by air
bubbles compressed in the ice.



Vostok

Ice Core

Paleoclimatic

data

How has Florida’s Climate Changed?


Today, Florida has a subtropical climate


Approximately 130,000 years ago giant
ground sloths roamed the coasts of Florida


They are a tropical species, meaning the
climate was warmer and wetter at this time.


Mastodon fossils found off of the
coast of Florida indicate a colder
climate and lower sea levels.


Fossils found in Florida date back to
about
13,000 years ago, during the
last ice age.

Climate Change

Global Warming


The climate on Earth and
other planets is constantly
changing over large time
scales.


Abrupt climate change is
rare but possible.


Going from a warm period
to an ice age is considered
climate change.


Climate change occurs with
or without the presence of
humans, or life in general.



Caused by increases of
greenhouse gas
concentrations in the
atmosphere.


Occurs naturally due to
astrological phenomena.


Can occur by disrupting the
natural carbon dioxide
cycle.


The intensity of effects is
different in different parts
of the world.

Climate Change vs. Global Warming

Global Warming

Global Warming

Local Changes


Changes where you live many not reflect global
changes.


For example, the average yearly temperature of an
area can stay the same, while the seasons may
become more intense.


Warmer summers and colder winters

Armstrong & Miller
-
Climate Change

Video