Download Present - Princeton University

Climate Change:
A Scientist’s Perspective
Taplin Lecture
Princeton Environmental Institute
April 7, 2011
Ralph J. Cicerone, President
National Academy of Sciences
Science and Climate Change
What is Happening?
Is There an Explanation?
Is There An Alternate Explanation?
What Can Be Predicted?
OUTLINE
Earth’s Energy Balance
The Greenhouse Effect
Observed Changes
Temperatures of Air and Water
Sea-Level Rise
Ice Losses from Greenland & Antarctica
Future Fossil-Fuel Usage
Over Earth’s history, climate has changed many times
(global sea level, ice amounts, windiness, rain amounts).
What forces control or influence climate?
How can humans affect our planet’s climate?
Earth receives visible light from hot Sun
and Earth radiates to space as a
blackbody at infrared wavelengths
239
341
102
68
H2O, CO2, O3
390
327
169
90
16
Calculating the Surface
Temperatures of Planets
Visible
S(1 - a) = sTe
4
Infrared
for Earth, S = 341 W/m2, a = 0.3, so we calculate
Te = - 18 ºC (or - 32 ºF)
WRONG !
Greenhouse effect & clouds are needed
for Mars
Te = - 28 ºC (± 5 ºC) (large day/night swings) OK !
Greenhouse effect is very small, low pressure
for Venus
WRONG !
Actual Te = 450 ºC
Greenhouse effect and clouds, high pressure
[Hanel et al. (1972)]
Energy in the Climate System
Averaged over the whole Earth
All Human Energy Usage
0.025 watts/meter2
Extra Heat Trapped by
Greenhouse gases (2007)
2.6 watts/meter2
Energy Absorbed from Sunlight
239 watts/meter2
www.scrippsco2.ucsd.edu
http://agage.eas.gatech.edu
[Hansen and Sato (2004)]
CO2 Increase is from Human Activities:
Approximate Fractions
• 85% from fossil fuels
• 15% from deforestation
12 Jan 2011
http://data.giss.nasa.gov/gistemp/graphs
12 Jan 2011
http://data.giss.nasa.gov/gistemp/graphs
http://data.giss.nasa.gov/gistemp/graphs/
Time series of yearly ocean heat content (1022J) for the 0–700 m layer from this
study (solid) and from Levitus et al. [2005a] (dashed). Each yearly estimate is
plotted at the midpoint of the year. Reference period is 1957–1990.
Levitus et. al. (2009)
Relative Sea Level (cm)
1882-2005 sea level rise based on Permanent Service for Mean Sea Level
(PSMSL) tide gauge data from 23 sites selected by Douglas (1997)
This figure was prepared by Robert A. Rohde
http://www.globalwarmingart.com/wiki/Image:Recent_Sea_Level_Rise.png
Source : University of Colorado, Boulder
http://sealevel.colorado.edu
Greenland Mass Loss – From Gravity Satellite
Greenland Ice mass loss from GRACE
Trend Apr 2002-Sep 2010:
-240±33 Gt/yr (= 0.7 mm/yr sea level rise)
ACCELERATION: -17 ±8 Gt/yr2
Velicogna (2009 GRL), updated by Velicogna (2011)
Antarctica Ice mass loss from GRACE
Trend Apr 2002-Sep 2010:
-143 Gt/yr (= 0.4 mm/yr sea level rise)
ACCELERATION: -17 Gt/yr2
Velicogna (2009 GRL), updated by Velicogna (2011)
ALL
Global annual mean
surface temperature
anomalies, observed
and calculated.
NATURAL
From Stott et. al. (2006)
Physical Principles
Explain the Warming Since
the late 1970’s through the
Greenhouse Effect
12 Jan 2011
http://data.giss.nasa.gov/gistemp/graphs
Solar irradiance through September 2008.
Reference: Fröhlich, C. and J. Lean, Astron.
Astrophys. Rev., 12, pp. 273--320, 2004. http://www.pmodwrc.ch/pmod.php?topic=tsi/composite/SolarConstant
Global Fossil-Fuel Carbon Dioxide Emissions, 1751 to 2007
Includes Cement Manufacturing
9000
8000
7000
6000
5000
4000
3000
2000
1000
0
2007
1992
1976
1960
1944
1928
1912
1896
1880
1864
1848
1832
1816
1800
1784
1767
1751
Total Emissions
All emissions estimates are expressed in million metric tons of carbon
Boden & Marland (2009)
cdiac.ornl.gov
World marketed energy consumption, 1990-2035
(quadrillion Btu)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
Shares of world energy consumption in the United States,
China, and India, 1990-2035 (percent of world total)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
Coal consumption in selected world regions, 1990-2035
(quadrillion Btu)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
Global Carbon Cycle Management
Anthropogenic
Emission
7.2 GtC / y
ex: 2.4-2.8℃ rise from PI
Dangerous Level 425～440ppm
2ppm/y
How to control
the tap
to avoid risk
Present
380ppm
industrialization
280ppm
Pre-Industrial
Feedback
CO2 in Atmosphere
Absorption
3.1 GtC/ y
Ocean 2.2
Land 0.9
Adapted from Nishioka, NIES, Japan
In future climate:
Global temperatures ?
Sea-level rise ?
Precipitation amounts in each region and season?
Frequencies of extreme events?
How to limit CO2 emissions from fossil-fuel burning?
Oceans acidifying as well as warming
pH history and “business as usual” projection
Red line is global annual
average; blue lines show
ocean-to-ocean and
seasonal variation.
Surface ocean pH has already
fallen by 0.1 pH unit. Projected
additional changes are likely to
have large impacts on corals and
other ocean organisms that make
skeletons/ shells from calcium
carbonate.
Article 2, UN Framework Convention on
Climate Change (1992)
“The Ultimate objective of this Convention and any related
legal instruments that the Conference of the Parties may
adopt is to achieve, in accordance with the relevant
provisions of the Convention, stabilization of greenhouse
gas concentrations in the atmosphere at a level that would
prevent dangerous anthropogenic interference with the
climate system. Such a level should be achieved within a
time-frame sufficient to allow ecosystems to adapt
naturally to climate change sufficient to allow ecosystems
to adapt naturally to climate change, to ensure that food
production is not threatened and to enable economic
development to proceed in a sustainable in a sustainable
manner.”
Who Should Define "Dangerous" ?
scientists?
elected leaders?
____________ ?
Global Methane Release Rates
Gas Production
45 Tg/yr (8.3%)
Coal Mining
35 Tg/yr (6.5%)
Enteric Fermentation
80 Tg/yr (14.8%)
Clathrate Decomposition
5? Tg/yr (0.9%)
Landfills
40 Tg/yr (7.4%)
Termites
40 Tg/yr (7.4%)
Freshwaters
5 Tg/yr (0.9%)
Biomass Burning
55 Tg/yr (10.2%)
Wetlands
115 Tg/yr (21.3%)
Boreal: 20 – 60 Tg/yr
Rice Paddies
110 Tg/yr (18.5%)
Total = 540 Tg/yr
Oceans
10 Tg/yr (1.9%)
Cicerone & Oremland, 1988
Immediate action with multiple benefits.
Energy efficiency would:
 decrease our dependency on foreign oil
 improve our national security
 decrease our trade deficit
 decrease local air pollution
 increase our national competitiveness
 encourage development of new products for
global markets
 decrease household energy costs while also
slowing the increases of CO2 and CH4 !
Evidence
• Time history of CO2 increase and that of fossil-fuel usage
• Amounts of atmospheric CO2 increase
(0.6 x fossil-fuel emissions)
• Contemporary atmospheric amounts exceed those of
previous four glacial cycles
• Geographical patterns of atmospheric CO2
• Isotopic contents of CO2
• Ice-core data show that CH4 and N2O amounts are
also unprecedented
Extreme heat waves in Europe, already 2X more frequent because of
global warming, will be “normal” in mid-range scenario by 2050
Black lines are
observed
temps,
smoothed &
unsmoothed;
red, blue, &
green lines are
Hadley Centre
simulations w
natural &
anthropogenic
forcing; yellow
is natural only.
Asterisk and
inset show 2003
heat wave that
killed 35,000.
Stott et al., Nature 432: 610-613 (2004)
World electricity generation by fuel, 2007-2035
(trillion kilowatthours)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
Renewable electricity generation in China by energy
source, 2007-2035 (billion kilowatthours)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
World liquids consumption by region and country group,
2007 and 2035 (million barrels per day)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
World liquids consumption by sector, 2007-2035
(million barrels per day)
EIA, International Energy Statistics database (as of November 2009),
web site www.eia.gov/emeu/international. Projections: EIA, World Energy Projection System Plus (2010).
The challenge of scale
• Stabilizing at 500 ppmv CO2-e means global CO2
emissions must be ~7 GtC/yr below BAU in 2050.
• Avoiding 1 GtC/yr requires…
- energy use in buildings cut 20-25% below BAU in 2050, or
- fuel economy of 2 billion cars ~60 mpg instead of 30, or
- carbon capture & storage for 800 1-GWe coal-burning
power plants, or
- 700 1-GWe nuclear plants replacing coal plants, or
- 1 million 2-MWe(peak) wind turbines replacing coal power
plants or
- 2,000 1-GWe(peak) photovoltaic power plants replacing
coal power plants
Socolow & Pacala, 2004