Global Warming
What is it?
Why is it happening?
Evidence that it is happening.
What are the consequences?
What can we do to stop it?
NASA Video
What is global warming?
• An increase of the average
temperature of the earth
• The earth’s average temperature
has increased 0.6oC or 10F increase
in temperature over the 20th
century
IPCC
Why is it happening?
• The natural greenhouse effect is being
increased by extra greenhouse gases
trapping more heat
• Greenhouse gases
– Water Vapor
– Carbon Dioxide
– Methane
– Smaller amounts of other gasses
Greenhouse gas: carbon dioxide
• 31% increase in carbon dioxide in recent years
– from fossil fuels combustion, open fires, also
increases when you cut down trees that previously
were absorbing this gas
What is the Greenhouse Effect?
Greenhouse effect video
Sunlight comes in and some reflects off of clouds back into space
Sunlight comes in and some is reflected off of the surface of the earth
Sunlight comes in and is absorbed as heat at the surface. Some heat is
then emitted from the earth and is released to space.
Some heat is emitted from the earth and is absorbed by greenhouse
gases. Some gets reflected back to the earth.
Global Warming
• Global warming occurs when there are too many
greenhouse gases in the atmosphere.
• Greenhouse gases (like CO2 and methane) trap
heat escaping to space and warm the planet more
than it should.
Evidence Global Warming is
happening
• The north and south pole are
showing signs of warming
before the rest of the earth
• Antarctic (south pole)
peninsula ice shelves calving
off
• 2.5oC recent warming on the
peninsula (50 year warming?)
• Larsen B ice shelf 2002
(opening scene in “The Day
After Tomorrow”)
• Video: Canadian Arctic
Jan 31 2002
17 Feb 2002
23 Feb 2002
05 March 2002
• “Arctic temperatures have increased in recent decades.
Compared to the past 50 years, average temperatures
from January through August, 2005 were 2 to 3 degrees
Celsius warmer than average across most of the Arctic
Ocean.”
-NSIDC
• “A record loss of sea ice in the Arctic this summer has
convinced scientists that the Arctic has now entered an
irreversible phase of warming which will accelerate the
loss of the polar sea ice that has helped to keep the
climate stable for thousands of years.”
- NSIDC fall 2005
Ice Albedo Feedback
Therefore this is
POSITIVE Feedback!
It reinforces the initial
heating.
Increase
Heat
Decrease amount
of ice and snow
Decrease albedo:
More area to absorb
sunlight rather than
reflect it
Cold to hot
Ice to no ice
Quelcaya Ice
cap, Peru
• Qori Kalis glacier
• 1963 -1978: retreat
rate of 4 m/yr
• by 1995: retreat rate
of 30 m/yr
•
(slide compliments Adina Racoviteanu)
Kilimanjaro,
East Africa
(5895 m)
Retreated by 87% from
1990s
(Thompson et al., 2002)
The challenge is this…
• Carbon dioxide stays in the atmosphere
for decades
– Even if we stopped emitting it today, our
extra carbon dioxide would continue to cause
problems for almost a century to come!
Why do we care about global
warming? Main reasons…
• Melting the ice caps will
increase sea level
enough to displace
millions of people
currently living on the
coast
• Growing food may
become increasingly
difficult due to
floods/droughts/salt
water entering our fresh
water supplies
Effects of rising sea levels in North
America and Europe
Global warming can cause an
Ice age!!!
•
•
•
•
•
Heat the earth
Melt the ice caps
Decrease the salinity at the poles
No deep water is formed
The global thermohaline ocean
circulation shuts down (500-1000
year cycle)
• The hot water stays at the equator
and the cold water stays at the poles
• Europe would be the first place to
notice the most significant difference
and have effects of an Ice Age.
• BUT…water is heavy, it has a lot of
momentum, so it will take a long
time for the oceans to just stop
moving! (in the movie it took about
a week, in reality...at least 10 years)
Another reason to care about global warming:
tropical diseases could come to new climates like
ours as we become warmer!
• According to the World Health Organization, each year nearly 500 million
people become infected with malaria, and nearly three million — mostly
children — die from it. Areas around the world facing the greatest risk,
shown in red, harbor some of the world's most impoverished people.
Local Effects of Climate Change
CANADA
• Polar ice caps melting
• Soil drying up
• Farmland changing
• Temperature increases (highest in the poles)
SOUTHERN ONTARIO
• smog is expected to intensify.
• Water levels will drop
• soil moisture in the region will decrease
• In other parts of the world, the effects of global
•
•
warming will be much more deadly.
Flooding in Bangladesh is expected to increase
by up to 40 per cent this century as global
temperatures rise.
The population of Bangladesh is greater than
150 million
What can we do to stop it?
• Change to renewable
•
energy sources that
do not produce
methane or carbon
dioxide
Suck greenhouse
gases out of the air
– Trees
– Algae
– Machines
Copenhagen Climate Agreement
• Deal signed in December, 2009 by most
•
•
•
countries
Agrees to making cuts, but is not binding.
Recommendations only
Still details to hammer out about specifics
Or we could let it happen
• We will pay the price!
– Money
– Food
– Human lives
– The comfort of our
North American living
will be gone
• Rick Mercer Video