Transcript What We Know About Climate Change and How We Know It

Question 1
a) Two Cornell Trustees
b) Professional Engineering
College Grad Students
c) The Mythbusters
d) David Skorton and Hunter
Rawlings
Who are these guys???
Question 2
What does this have to
do with State of the
Planet ??
Answer…..
Today’s Lecture:
Infamous Climate Change Myths
BUSTED!
Or…..
How to dazzle your climate change
skeptic friends with science
Myth 1
There’s not enough
Carbon Dioxide in the
atmosphere to matter.
The Truth
Argon
Oxygen
CO2
Nitrogen
But….Size doesn’t matter!
Carbon Dioxide
Carbon Dioxide
4.3 µm
Carbon Dioxide
Carbon Dioxide
15 µm
Water Vapor
Water Vapor
Absorbed Energy is Trapped
Without an Atmosphere
4. Remaining “heat”
lost to space
Earth receives 240
Wm-2 from sun.
Earth must lose
240 Wm-2 to space.
E = sT4
240 = 5.7x10-8 T4
2. Earth absorbs
sunlight and
2.
Radiates it as
“heat”
T = -18ºC
= 0°F
With an Atmosphere
4. Remaining “heat”
lost to space
Earth receives 168
Wm-2 from sun.
Earth also receives 222 Wm-2
from the atmosphere.
E = sT4
168 + 222 = 5.7x10-8 T4
2. Earth absorbs
sunlight and
2.
Radiates it as
“heat”
T = 15ºC
= 59°F
Doubling Carbon Dioxide
Less loss
Atmosphere absorbs 4 Wm-2
more radiation
Changes:
1) Amount of radiation
received from atmosphere
2) Temperature
Little
Effect
More
absorbed and
2. Earth absorbs
sunlight and returned
2.
Radiates
it as
“heat”
Temperature increase
Can Compute:
 DT = 0.3DF + feedbacks
1.2°C = 0.3 x 4 Wm-2
Myth 2
Water vapor is a more
important GHG than Carbon
Dioxide
The Earth’s Climate System
Components of the System
Interact
CO2 increases
Earth warms
Atmospheric
Water Vapor
Increases
Positive Feedback
Evaporation
Increases
Components of the System
Interact
CO2 increases
Earth warms
Less Solar Energy
Reflected (more
than 240 W m-2
received)
Ice Melts
Positive Feedback
Components of the System
Interact
CO2 increases
Earth warms
Clouds Trap
Terrestrial
Radiation
Positive Feedback
More Clouds
Clouds
Reflect Solar
Radiation
Earth Cools
More Evaporation
Negative Feedback
Myth 3
Carbon Dioxide will be
removed from the
atmosphere naturally
Carbon Cycle
7
100
100
90
0.1
2
Climate Carbon Feedback
Feedbacks Drive Ice Ages
Slight Orbital Changes
Decrease Solar Received
N.H. Cools
Earth Cools
CO2 Declines
More Ice
N.H. Cools more
Why does CO2 decline when
it’s cold?
Which drink is flat?
a)
b)
Myth 1 Revisited
Ice Age
Not an Ice Age
Or a Different movie
Dinosaurs
No Dinosaurs
Myth 5
Climate models are
inaccurate
A.K.A.
You can’t get tomorrow’s weather
right, you expect me to believe your
prediction for 100 years from now?
WEATHER
≠
CLIMATE
Typical Climate Model
Scale Matters
Model Validation & Attribution
A Question
Choose the best day to swim in
Cayuga Lake
a) Memorial Day 5/31 Air Temperature 85°
b) Labor Day 9/4 Air Temperature 85°
Features of the Climate
System
 Different
components have different
response times
• More on this later
 Internal
Forcings
• Things like El Nino
Myth 6
There is time to avoid
negative global warming
impacts
Magnitude of Response
Current Impacts will persist
for centuries
Emisssions
100 years
1000 years
Myth 7
Ah…but what about
Ithaca
and all those other
stations Michael
Crichton showed us
Ithaca Summer Temperature
86
84
82
80
78
76
74
+1.5°F
-2.8°F
72
70
1920
1930
1940
1950
1960
1970
1980
1990
2000
2010
What are the chances?
124 years
1/124
0.8% chance for a
record
What are the chances?
8 years (1997-2004) 8x0.008 = 6.4%
Chance of a record
What are the chances?
All 12 months
0.6412 = 0.00000000000047%
Myth 8
The problem is so big, it
doesn’t matter what we do
Wedges
Wedges

Increased efficiency
• Electric, Transportation, Heating (3 possible wedges)
• 1 wedge = 60 mpg cars

Switch from coal to natural gas (2 possible wedges, heat
and electric)
• 1 wedge = 1,400 large coal plant to gas

Carbon capture and storage
2 possible wedges, electric
and hydrogen)



1 wedge = 800 coal plants
1 wedge = 3500 million tons/year stored
Nuclear or hydrogen
(2 possible wedges, electric or
hydrogen)

1 wedge = doubling of reactors
Wedges

Wind or hydrogen



(1 wedge)
1 wedge = NJ size area
Biofuels (1 wedge)


1 wedge = area the size of Germany 2 million
windmills
Solar electricity

(2 wedges electric or hydrogen)
1 wedge = 1/6 of present cropland
Natural sinks (1 wedge)

Halt deforestation and double rate of forest planting
Myth 9
Adaptation will not be
required if we choose to
mitigate climate change