How Wide Is the ScienceAction Gap

1
How Wide Is the Science-Action Gap?
Stephen W. Pacala Director Princeton
Environmental Institute
Princeton University
2
Surface Air Warming (F)
2xCO2 Climate
6o
12o
4xCO2 Climate
GFDL Model
3
Monsters Behind the Door

• Ocean Circulation
• Hurricanes
• Ice Sheets
• Sahel Drought

4
At What Maximum Level Should We Stabilize
Atmospheric CO2?

• 550 PPM ?
• 500 PPM ?
• 450 PPM ?
• 400 PPM ?

5
Past Emissions
Billion of Tons of Carbon Emitted per Year
14
Historical emissions
7
1.9 ?
0
2106
2056
2006
1956
6
The Stabilization Triangle
Billion of Tons of Carbon Emitted per Year
14
Currently projected path ramp
Stabilization Triangle
Interim Goal
O
Historical emissions
7
Flat path
1.9 ?
0
2106
2056
2006
1956
7
The Stabilization Triangle Beat doubling or
accept tripling (details)
(380)
(850)

Values in parentheses are ppm. Note the identity
(a fact about the size of the Earths
atmosphere) 1 ppm 2.1 GtC.
8
Wedges
Billion of Tons of Carbon Emitted per Year
14
14 GtC/y
Currently projected path
Seven wedges
O
Historical emissions
7 GtC/y
7
Flat path
1.9 ?
0
2106
2056
2006
1956
9
At What Maximum Level Should We Stabilize
Atmospheric CO2?

• 550 PPM 3 wedges
• 500 PPM 7 wedges
• 450 PPM 11 wedges
• 400 PPM gt 15 wedges

10
15 Different Technologies Already in the
Marketplace at Industrial Scale
Coal to Gas
11
Efficiency in Transport
Effort needed for 1 wedge 2 billion gasoline and
diesel cars (10,000 miles/car-yr) at 60 mpg
instead of 30 mpg (500 million cars now).
Photos courtesy of Ford, WMATA, Washington State
Ridesharing Organization
12
Electricity
Nuclear
Effort needed by 2056 for 1 wedge Add twice
current capacity (displacing coal).
Graphic courtesy of NRC
13
US Share
14
Delay of D Years
14GT/Y

350 50-D GT/y
7 GT/y
175 GT
175 GT
7GT/Y
0GT/Y
2004
2054
2004
2054
Every delay of 5 years makes the size of the 2054
fossil energy system smaller by 1 GT/Y. Because
the US must decarbonize in any case, the extra
mitigation must occur primarily in poor countries.

15
The Gap Between Science and Action
Billion of Tons of Carbon Emitted per Year
14
Currently projected path ramp
The GAP
Historical emissions
7
Flat path
1.9 ?
0
2106
2056
2006
1956