Transcript The Carbon Cycle and Climate Change

The Carbon Cycle and
Climate Change
What’s the Connection?
The Carbon Cycle

Carbon cycles throughout the
biosphere, atmosphere, hydrosphere
and geosphere continuously.
http://www.co2logic.com/home.aspx/en/our+climate/the+carbon+cycle
Global Warming
Global warming, or the enhanced
greenhouse effect, is due to an increase
in greenhouse gases in our atmosphere,
most notably carbon dioxide.
 Atmospheric carbon dioxide
concentrations have increased by 30%
during the past 200 years. The
concentration today is almost 370 parts
per million (0.037%). Human activities
such as burning of fossil fuels and
deforestation are thought to be
responsible for the rapid increase in
carbon dioxide concentrations.

http://www.dar.csiro.au/publications/greenhouse_2000d.htm
The global carbon cycle.
Numbers represent
the mass of carbon,
in gigatonnes of carbon
(Gt C).
(A gigatonne is a
thousand million tonnes.)
Source: Wheeling Jesuit
University/NASA (2000)
How Does Ocean Water Carbon
Exchange Affect Climate?
 As
ocean water warms up, its
molecules move faster and CO2 can
be released to the atmosphere.
 The more CO2 there is in the
atmosphere, the warmer the
climate becomes, because CO2 is a
greenhouse gas and absorbs
infrared radiation (heat) from the
sun.
 AND, VICE VERSA (see next page)
How Does Ocean Water Carbon
Exchange Affect Climate?
Cold ocean water absorbs more carbon
dioxide (CO2) from the atmosphere than
warm ocean water (the molecules are
moving slower).
 As water cools down it absorbs more
and more CO2.
 The less CO2 there is in the atmosphere,
the cooler the atmosphere becomes.
Eventually, an ice age can form.
 Cool, huh! Brrrrr…….

Earth’s Climate History
Earth’s climate
changes drastically
depending on the
amount of CO2 in
the atmosphere. The
oceans play a huge
role in regulating
this amount of
change in climate.
The dashed line in
each graph is the
Mean Global
Temperature
Relative to Present
Day.
Ice Ages &
Warming Trends (Interglacial periods)
There have been many ice ages in
Earth’s past. The average surface
temperature has ranged from 10oC
warmer to 6oC cooler than today’s
average climate.
 Plate tectonics and Continental Drift
have played huge roles in creating ice
ages and warming trends.
 There have been times when the entire
planet was covered in ice; this
condition is called “Snowball Earth.”

How Does Earth Come Out of an
Ice Age and Enter an Interglacial
Period?
Volcanic activity spews massive
amounts of CO2 gas into the
atmosphere eventually warming the
Earth and atmosphere. An Interglacial
Period begins.
 “Inter” means “between”. “Glacier”
means “ice”. Interglacial means a
time between ice ages (a warming
trend).

Tilt of Earth’s Axis & Eccentricity of
Earth’s Orbit Affect Global Climate
The more Earth’s axis is
tilted, the more variable
the climate, with
certain areas of Earth
receiving
more or less of the Sun’s
radiation.
The Milankovitch Theory
states that “The closer
Earth is to the Sun in its
elliptical orbit, the
warmer the
Earth becomes. This orbit
takes about 100,000
years.”
http://aa.usno.navy.mil/faq/docs/seasons_orbit.html
Some researchers still have doubts
about the association between the
100,000-year climate cycle and
orbital variations. Thus, many
questions remain about long-term
climate variations and their
relationship, if any, to astronomical
causes.