Transcript The Facts and Fiction of Climate Change

The Facts and Fiction of Climate Change
Kim Cobb
Paideia School
April 15, 2008
Which of the following are scientific statements?
1) Slowing global warming costs too much money.
2) Hurricane Katrina was caused by global warming.
3) The Earth was warmer than today 60 million years ago.
Which of the following are scientific statements?
1) Slowing global warming costs too much money.
2) Hurricane Katrina was caused by global warming.
3) The Earth was warmer than today 60 million years ago.
Some definitions
What is CLIMATE?
how the weather acts over many years
What is WEATHER?
temperature, rainfall, wind changes over days
Why Study Climate?
CLIMATE is our best guess at what temperature
and rainfall patterns will be
- next year
- next ten years
- next century
CLIMATE is changing, and we need to prepare for
the future
- crops need enough water to grow
- we need water to drink (but not too much)
- ice is melting, sea level is rising (very slowly)
What is CO2 (carbon dioxide)?
- represents less than 1% of the atmospheric gases
- animals breathe CO2 out, plants “breathe” CO2 in
- burning fossil fuels (gasoline, oil) dumps CO2 into the atmosphere
- more atmospheric CO2 warms the atmosphere
Average Global Temperature
0.5
Atmospheric CO2 (ppm)
0.0
360
340
Atmospheric CO2
320
300
280
1860
1880
1900
1920
1940
1960
1980
2000
Temperature (°C)
1.0
greenhouse gases in the
atmosphere trap heat at
the Earth’s surface and
prevent it from escaping.
without greenhouse gases
average temp of Earth
would be -18ºC instead of
15ºC
4
1
So the greenhouse effect is
a good thing!
we are increasing the
greenhouse effect by
adding CO2 to the
atmosphere
3
2
The consequences of climate change
in 100 years….
average global temperatures will rise by 2-14F
sea level will rise by 7-22 inches
rainfall patterns will change
Why is there so much uncertainty in future climate?
One uncertainty comes from unknown future CO2
Will we join international plans to reduce CO2?
Will we ignore the problem?
What will other countries like China and India do?
Decisions made NOW will effect your grandchildren!
Another uncertainty comes from imperfect climate models
Over 20 models are used, because we don’t know which
one is right.
Tools to study Paleoclimates -- “ancient” climates
“the past is the key to understanding the present”
Corals
Tree Rings
- oceanic, tropical
- 100’s yrs long
- continents
-1000’s yrs long
Sediments
Ice Cores
- along coastlines
- 10,000’s yrs long
- Ice Ages
- North, South poles
- 10,000’s yrs long
- Ice Ages
Studying Climate with Corals
What is a CORAL?
a tiny animal in the shallow tropical ocean that lives
colonially and grows a hard rock skeleton
corals can live for hundreds of years
My Research: Studying Climate with Corals
Goal: to compare past tropical Pacific climate with present-day climate
Palmyra Island
Palmyra Island
How it works:
1) coral skeletons record
temperature changes
2) we can count back 1000
years to read temperature
Corals provide long records of past climate that can be
compared to present climate (is it different? how?)
Science can be fun!
Global warming is very real, but the exact
consequences are uncertain.
Example:
Driving in a car is dangerous, but you don’t know when you
might have an accident.
Do you wear a seatbelt? YES!
We must begin to act to reduce global warming BEFORE
we know the exact consequences.
The good news: humans are VERY smart!
Three strategies to reduce CO2:
1)use less energy
- drive less, drive smaller cars
- conserve electricity
CO2
cost
- 50%
+ $$
2) make “clean” energy
- solar power, wind power, nuclear energy- 50%
- $$
3) take CO2 out of the sky (more difficult)
What can YOU do?
Bug your parents to buy flourescent light bulbs!
When you starting driving, don’t drive an SUV.
Save electricity wherever you can.
Think about a job in science and engineering
or politics, or education.
Can you think of three things you
can do to start saving the planet?
A climate scientist’s plea to the next generation:
seek out information, ask questions, get the facts, and then VOTE
distinguish the science of global warming from the politics/economics
of global warming
recognize uncertainties, but don’t be paralyzed by them
[buy flourescent light bulbs, don’t drive SUV’s, eat your broccoli]
THANK YOU
[email protected]
Google ‘Kim Cobb’ for web-site
Studying Climate with Corals
What is a CORAL?
a tiny animal in the shallow tropical ocean that lives
colonially and grows a hard rock skeleton
corals can live for hundreds of years
My Research: Studying Climate with Corals
Goal: to compare past tropical Pacific climate with present-day climate
Palmyra Island
Palmyra Island
How it works:
1) coral skeletons record
temperature changes
2) we can count back 1000
years to read temperature
Summary
We need to understand more about how climate is changing.
Corals provide long records of past climate that can be
compared to present climate (is it different? how?)
Science can be fun!