Climate Change: A Scientist’s Perspective
description
Transcript of Climate Change: A Scientist’s Perspective
Climate Change: A Scientist’s Perspective
Taplin Lecture Princeton Environmental Institute
April 7, 2011
Ralph J. Cicerone, President
National Academy of Sciences
What is Happening?
Is There an Explanation?
Is There An Alternate Explanation?
What Can Be Predicted?
Science and Climate Change
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
OUTLINE
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?
239
102
341
68
169
390
327 90
16
H2O, CO2, O3
Earth receives visible light from hot Sun and Earth radiates to space as a
blackbody at infrared wavelengths
Calculating the Surface Temperatures of Planets
for Venus
Actual Te = 450 ºC Greenhouse effect and clouds, high pressure
S(1 - e
for Earth, S = 341 W/m2, = 0.3, so we calculate
Te = - 18 ºC (or - 32 ºF)
Greenhouse effect & clouds are needed
WRONG !
WRONG !
for Mars
Te = - 28 ºC (± 5 ºC) (large day/night swings)
Greenhouse effect is very small, low pressure
OK !
Infrared
Visible
[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
http://data.giss.nasa.gov/gistemp/graphs12 Jan 2011
http://data.giss.nasa.gov/gistemp/graphs12 Jan 2011
http://data.giss.nasa.gov/gistemp/graphs/
Levitus et. al. (2009)
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.
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. Rohdehttp://www.globalwarmingart.com/wiki/Image:Recent_Sea_Level_Rise.png
Rel
ativ
e S
ea L
evel
(cm
)
Source : University of Colorado, Boulder http://sealevel.colorado.edu
Greenland Mass Loss – From Gravity Satellite
Velicogna (2009 GRL), updated by Velicogna (2011)
Trend Apr 2002-Sep 2010: -240±33 Gt/yr (= 0.7 mm/yr sea level rise)
ACCELERATION: -17 ±8 Gt/yr2
Greenland Ice mass loss from GRACE
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)
Global annual mean surface temperature anomalies, observed
and calculated.
From Stott et. al. (2006)
ALL
NATURAL
Physical Principles Explain the Warming Since the late 1970’s through the
Greenhouse Effect
http://data.giss.nasa.gov/gistemp/graphs12 Jan 2011
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
Boden & Marland (2009) cdiac.ornl.gov
0
10002000
3000
40005000
6000
70008000
900017
51
1767
1784
1800
1816
1832
1848
1864
1880
1896
1912
1928
1944
1960
1976
1992
2007
Total Emissions
Global Fossil-Fuel Carbon Dioxide Emissions, 1751 to 2007Includes Cement Manufacturing
All emissions estimates are expressed in million metric tons of carbon
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 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)
Pre-Industrial 280ppm
380ppm
425 ~ 440ppm
Present
Dangerous Level
Global Carbon Cycle Management
Anthropogenic Emission 7.2 GtC / y
Absorption3.1 GtC/ y
How to control the tap
to avoid risk
industrialization
CO2 in Atmosphere
Ocean 2.2 Land 0.9
2ppm/y
ex: 2.4-2.8 rise from PI℃
Feedback
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 warmingpH 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?
____________ ?
Clathrate Decomposition 5? Tg/yr (0.9%)
Termites40 Tg/yr (7.4%)
Freshwaters5 Tg/yr (0.9%)
Wetlands115 Tg/yr (21.3%)Boreal: 20 – 60 Tg/yr
Oceans10 Tg/yr (1.9%)
Rice Paddies110 Tg/yr (18.5%)
Biomass Burning55 Tg/yr (10.2%)
Landfills40 Tg/yr (7.4%)
Global Methane Release Rates
Coal Mining35 Tg/yr (6.5%)
Gas Production45 Tg/yr (8.3%) Enteric Fermentation
80 Tg/yr (14.8%)
Cicerone & Oremland, 1988Total = 540 Tg/yr
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)
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 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)
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