12340 Global Warming Science Geoengineering

Dan Cziczo Thursday May 10 2012

httpwwwtechnologyreviewcomenergy24157

This image has been removed due to copyright restrictions Please see the firstimage on page httpwwwtechnologyreviewcomfeaturedstory416801the-geoengineering-gambit

1

ONLINE SUBJECT EVALUATIONS

ARE NOW OPEN

httpwebmitedusubjectevaluation bull You have until Monday May 21 at 9 AM bull Please evaluate all subjects in your list bull Write comments

Your feedback is read and valued 2

ldquoGeoengineeringrdquo History Weather modification - The changing of natural weather phenomena by technical means for example through the microscale of condensation and freezing nuclei Terraforming - transform (a planet) so as to resemble the earth especially so that it can support human life (Oxford Dictionaries normally attributed to Jack Williamson Collision Orbitrdquo (1942) although many similarities to HG Wells ldquoThe War of the Worldsrdquo (1898)) Geoengineering - the deliberate large-scale manipulation of an environmental process that affects the earthrsquos climate in an attempt to counteract the effects of global warming (Oxford Dictionaries) Generally attributed to Paul Crutzen (2006) but several earlier works

This image has been removed due to copyright restrictions Please see the firstimage on page httpwwwerbzinecommag14marsterrjpg

httpwwwerbzinecommag14marsterrjpg3

Weather Modification History

Initial attempts at weather modification were of limited successhellip

This image has been removed due to copyright restrictions Please see the secondimage on httpwwwdesertusacommag07janimagesinstonehtml

4

Hail Cannon (1901)

Cloud Seeding

Lest you think this was a long time agohellip

This image has been removed due to copyright restrictions Please see thefirst image on page httpwwwsacreddestinationscomfranceanzy-le-duc-church

This image has been removed due to copyright restrictions Please see thefirst image on page httpwwwabsurdintellectualcom20090622all-hail-the-hail-cannons

5

Lest you think this was a long time agohellip

This image has been removed due to copyright restrictions Pleasesee the image on page httpwwwhailcannoncompictureshtml

6

The lsquoModernrsquo Age of Weather Mod Mid-1940rsquos Generally considered to have grown out of the WWII contrail research The pioneers Vincent Shaefer Irving Langmuir and Bernie Vonnegut at GE Showed that particles with water-ice structure could effectively nucleate ice at temperature near 0deg C

This image (published on the Journal of Meteorology by the AmericanMeteorological Society) is copyright copy AMS and used with permission

103

102

101

100

102

103

104

105

106

Temperature (C)Fr

eezi

ng n

ucle

i per

gra

m P

bO

01m NH4 I

PbO

PbO + 01m NH4 I

PbI2

Freezing nucleus activity of the preparations as a function of temperature

-30-25-20-15-10-50

PbO + 001m NH4 I

10-1

Free

zing

nuc

lei p

er c

m3

Image by MIT OpenCourseWare

7

National Academy of Science 2003 Last comprehensive report on weather modification

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnapeducatalogphprecord_id=10829

8

National Academy of Science 2003 Last comprehensive report on weather modification

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnapeducatalogphprecord_id=10829

8

The lsquoModernrsquo Age of Weather Mod

Early ldquodemonstrationsrdquo with clouds were mixed increased glaciation was observed but little or no enhanced precipitations (clouds contained too little water) ldquoNeed for impartial assessmentrdquo recognized as early as 1957 ldquoDouble blindrdquo studies suggested 1957 1963 (ldquohellipit has not been demonstrated that precipitation hellip can be increased significantly by seedinghelliprdquo) 1973 (ldquoice-nuclei seeding can sometimes lead to more precipitation can sometimes lead to less precipitation and at other times hellip have no effecthelliprdquo) 2003 (ldquohellipour Committee finds little reason to differ from these findingshelliprdquo) Point Theory itself does not show if a technique works when multiple steps are involved (in this case initiation not growth and precipitation) Further the scale of the experiment (lab versus isolated cloud versus system) often leads to different results

9

ldquoBy far the preferred way to resolve the policy makersrsquo dilemma is to lower the emissions of the greenhouse gasesrdquo ldquoTherefore although by far not the best solution the usefulness of artificially enhancing earthrsquos albedo and thereby cooling climate by adding sunlight reflecting aerosol in the stratosphere (Budyko 1977 NAS 1992) might again be explored and debatedhelliprdquo ldquoFinally I repeat the very best would be if emissions of the greenhouse gases could be reduced so much that the stratospheric sulfur release experiment would not need to take place Currently this looks like a pious wishrdquo

10

Budyko M I 1977 lsquoClimatic Changes American Geophysical Societyrsquo Washington DC 244 pp Bodansky D 1996 lsquoMay we engineer the climatersquo Clim Change 33 309ndash321 Dickinson R E 1996 lsquoClimate Engineering A review of aerosol approaches to changing the global energy balancersquo Clim Change 33 279ndash290 Jamieson D 1996 lsquoEthics and intentional climate changersquo Clim Change 33 323 336 Schneider S H 1996 lsquoGeoengineering Could-or-Should-we do itrsquo Clim Change 33 291ndash302 Keith D W 2000 lsquoGeoengineering the climate History and prospectrsquo Annu Rev Energy Environ 25 245ndash284 National Academy of Sciences (NAS) 1992 Policy Implications of Greenhouse Warming Mitigation Adaptation and the Science Base Panel on Policy Implications of Greenhouse Warming Committee on Science Engineering and Public Policy National Academy Press Washington DC 918 pp

Early Referenceshellip

11

ldquoThe climatic changes that may be produced by the increased CO2 content could be

deleterious from the point of view of human beings The possibilities of deliberately bringing about countervailing climatic

changes therefore need to be thoroughly explored A change in the radiation balance

in the opposite direction to that which might result from the increase of

atmospheric CO2 could be produced by raising the albedo or reflectivity of the earth Such a change in albedo could be

brought about for example by spreading very small reflecting particles over large

oceanic areasrdquo

hellipBut Not The Earliest

12

Source New Scientist

Reduction of Solar Radiation Higher Albedo

Carbon Capture

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnextnaturenet201002nine-geoengineering-strategies

13

ldquoBy far the preferred way to resolve the policy makersrsquo dilemma is to lower the emissions of the greenhouse gasesrdquo ldquoTherefore although by far not the best solution the usefulness of artificially enhancing earthrsquos albedo and thereby cooling climate by adding sunlight reflecting aerosol in the stratosphere (Budyko 1977 NAS 1992) might again be explored and debatedhelliprdquo ldquoFinally I repeat the very best would be if emissions of the greenhouse gases could be reduced so much that the stratospheric sulfur release experiment would not need to take place Currently this looks like a pious wishrdquo

10

Budyko M I 1977 lsquoClimatic Changes American Geophysical Societyrsquo Washington DC 244 pp Bodansky D 1996 lsquoMay we engineer the climatersquo Clim Change 33 309ndash321 Dickinson R E 1996 lsquoClimate Engineering A review of aerosol approaches to changing the global energy balancersquo Clim Change 33 279ndash290 Jamieson D 1996 lsquoEthics and intentional climate changersquo Clim Change 33 323 336 Schneider S H 1996 lsquoGeoengineering Could-or-Should-we do itrsquo Clim Change 33 291ndash302 Keith D W 2000 lsquoGeoengineering the climate History and prospectrsquo Annu Rev Energy Environ 25 245ndash284 National Academy of Sciences (NAS) 1992 Policy Implications of Greenhouse Warming Mitigation Adaptation and the Science Base Panel on Policy Implications of Greenhouse Warming Committee on Science Engineering and Public Policy National Academy Press Washington DC 918 pp

Early Referenceshellip

11

ldquoThe climatic changes that may be produced by the increased CO2 content could be

deleterious from the point of view of human beings The possibilities of deliberately bringing about countervailing climatic

changes therefore need to be thoroughly explored A change in the radiation balance

in the opposite direction to that which might result from the increase of

atmospheric CO2 could be produced by raising the albedo or reflectivity of the earth Such a change in albedo could be

brought about for example by spreading very small reflecting particles over large

oceanic areasrdquo

hellipBut Not The Earliest

12

Source New Scientist

Reduction of Solar Radiation Higher Albedo

Carbon Capture

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnextnaturenet201002nine-geoengineering-strategies

13

Budyko M I 1977 lsquoClimatic Changes American Geophysical Societyrsquo Washington DC 244 pp Bodansky D 1996 lsquoMay we engineer the climatersquo Clim Change 33 309ndash321 Dickinson R E 1996 lsquoClimate Engineering A review of aerosol approaches to changing the global energy balancersquo Clim Change 33 279ndash290 Jamieson D 1996 lsquoEthics and intentional climate changersquo Clim Change 33 323 336 Schneider S H 1996 lsquoGeoengineering Could-or-Should-we do itrsquo Clim Change 33 291ndash302 Keith D W 2000 lsquoGeoengineering the climate History and prospectrsquo Annu Rev Energy Environ 25 245ndash284 National Academy of Sciences (NAS) 1992 Policy Implications of Greenhouse Warming Mitigation Adaptation and the Science Base Panel on Policy Implications of Greenhouse Warming Committee on Science Engineering and Public Policy National Academy Press Washington DC 918 pp

Early Referenceshellip

11

ldquoThe climatic changes that may be produced by the increased CO2 content could be

deleterious from the point of view of human beings The possibilities of deliberately bringing about countervailing climatic

changes therefore need to be thoroughly explored A change in the radiation balance

in the opposite direction to that which might result from the increase of

atmospheric CO2 could be produced by raising the albedo or reflectivity of the earth Such a change in albedo could be

brought about for example by spreading very small reflecting particles over large

oceanic areasrdquo

hellipBut Not The Earliest

12

Source New Scientist

Reduction of Solar Radiation Higher Albedo

Carbon Capture

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnextnaturenet201002nine-geoengineering-strategies

13

ldquoThe climatic changes that may be produced by the increased CO2 content could be

deleterious from the point of view of human beings The possibilities of deliberately bringing about countervailing climatic

changes therefore need to be thoroughly explored A change in the radiation balance

in the opposite direction to that which might result from the increase of

atmospheric CO2 could be produced by raising the albedo or reflectivity of the earth Such a change in albedo could be

brought about for example by spreading very small reflecting particles over large

oceanic areasrdquo

hellipBut Not The Earliest

12

Source New Scientist

Reduction of Solar Radiation Higher Albedo

Carbon Capture

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnextnaturenet201002nine-geoengineering-strategies

13

Source New Scientist

Reduction of Solar Radiation Higher Albedo

Carbon Capture

This image has been removed due to copyright restrictions Please see theimage on page httpwwwnextnaturenet201002nine-geoengineering-strategies

13

Albedo Increase Solar Mitigation

Archer 2007

(1 - α)lsolar

4

Earth

Boundary to space

lup atmosphere

ldown atmospherelup ground

Image by MIT OpenCourseWare

14

This image has been removed due to copyright restrictionsPlease see the image on page httpscommonswikimediaorgwikiFileAlbedo-e_hgsvg

Simple Albedo Increase

Courtesy Jimmy Gasore Haider et al 1997

Necessary square footage gtgt available square footage

Image courtesy of nycgov

15

Murphy et al JGR 2009

Naturersquos Examples Direct Effect

This image has been removed due to copyright restrictions Please seeFigure 6 on page httponlinelibrarywileycomdoi1010292009JD012105full

16

Murphy et al JGR 2009

Naturersquos Examples Direct Effect

This image has been removed due to copyright restrictions Please seeFigure 6 on page httponlinelibrarywileycomdoi1010292009JD012105full

16

Climate Model Response

IPCC 2007 Models

Climate Change 2007 The Physical Science Basis Working Group I Contribution to the Fourth Assessment Reportof the Intergovernmental Panel on Climate Change Figure 95 Cambridge University Press Used with permission

17

Pinatubo ~15 Tg SO2 into the stratosphere

Natural Version of the Direct Effect Method

Robock 1998

Image courtesy of USGS

Image courtesy of NASA

18

Global temperatures dropped by 04-06degC after

Pinatubo Particle layer persisted for 3

years (e-folding ~1 year)

IPCC 2001 Houghton J TY Ding D J Griggs M Noguer P J van der Linden X Dai K Maskell andC A Johnson (eds) Climate Change 2001 The Scientific Basis Contribution of WorkingGroup I to the Third Assessment Report of the Intergovernmental Panel on ClimateChange Cambridge UK Cambridge University Press Used with permission

Wm

2

El ChichonMt Pinatubo

540

520

500

480

460

440

420

400

380

360

34001978

1978

1980 1982

1982

1984 1986 1988 1990

1991

1992 1994 1996 1998

Image by MIT OpenCourseWare

19

The Direct Effect Method

httpwwwtechnologyreviewcomenergy24157

Say we want to ldquooffsetrdquo current ~075deg C warming Pinatubo was ~15 Tg SO2 injection Some variation of initial injection of ~20 Tg sulfuric acid and then an increasing yearly amount of 10+ Tg Aircraft balloon and other lsquodesignsrsquo (25km tethered hose) proposed

This image has been removed due to copyright restrictionsPlease see the third image on page httpwwwtechnologyreviewcomenergy24157

20

Pinatubo ~15 Tg SO2 into the stratosphere

Natural Version of the Direct Effect Method

Robock 1998

Image courtesy of USGS

Image courtesy of NASA

18

Global temperatures dropped by 04-06degC after

Pinatubo Particle layer persisted for 3

years (e-folding ~1 year)

IPCC 2001 Houghton J TY Ding D J Griggs M Noguer P J van der Linden X Dai K Maskell andC A Johnson (eds) Climate Change 2001 The Scientific Basis Contribution of WorkingGroup I to the Third Assessment Report of the Intergovernmental Panel on ClimateChange Cambridge UK Cambridge University Press Used with permission

Wm

2

El ChichonMt Pinatubo

540

520

500

480

460

440

420

400

380

360

34001978

1978

1980 1982

1982

1984 1986 1988 1990

1991

1992 1994 1996 1998

Image by MIT OpenCourseWare

19

The Direct Effect Method

httpwwwtechnologyreviewcomenergy24157

Say we want to ldquooffsetrdquo current ~075deg C warming Pinatubo was ~15 Tg SO2 injection Some variation of initial injection of ~20 Tg sulfuric acid and then an increasing yearly amount of 10+ Tg Aircraft balloon and other lsquodesignsrsquo (25km tethered hose) proposed

This image has been removed due to copyright restrictionsPlease see the third image on page httpwwwtechnologyreviewcomenergy24157

20

Global temperatures dropped by 04-06degC after

Pinatubo Particle layer persisted for 3

years (e-folding ~1 year)

IPCC 2001 Houghton J TY Ding D J Griggs M Noguer P J van der Linden X Dai K Maskell andC A Johnson (eds) Climate Change 2001 The Scientific Basis Contribution of WorkingGroup I to the Third Assessment Report of the Intergovernmental Panel on ClimateChange Cambridge UK Cambridge University Press Used with permission

Wm

2

El ChichonMt Pinatubo

540

520

500

480

460

440

420

400

380

360

34001978

1978

1980 1982

1982

1984 1986 1988 1990

1991

1992 1994 1996 1998

Image by MIT OpenCourseWare

19

The Direct Effect Method

httpwwwtechnologyreviewcomenergy24157

Say we want to ldquooffsetrdquo current ~075deg C warming Pinatubo was ~15 Tg SO2 injection Some variation of initial injection of ~20 Tg sulfuric acid and then an increasing yearly amount of 10+ Tg Aircraft balloon and other lsquodesignsrsquo (25km tethered hose) proposed

This image has been removed due to copyright restrictionsPlease see the third image on page httpwwwtechnologyreviewcomenergy24157

20

The Direct Effect Method

httpwwwtechnologyreviewcomenergy24157

Say we want to ldquooffsetrdquo current ~075deg C warming Pinatubo was ~15 Tg SO2 injection Some variation of initial injection of ~20 Tg sulfuric acid and then an increasing yearly amount of 10+ Tg Aircraft balloon and other lsquodesignsrsquo (25km tethered hose) proposed

This image has been removed due to copyright restrictionsPlease see the third image on page httpwwwtechnologyreviewcomenergy24157

20

The Indirect Effect Method

IPCC 2007

Climate Change 2007 The Physical Science Basis Working Group I Contribution to the Fourth Assessment Reportof the Intergovernmental Panel on Climate Change Figure 210 Cambridge University Press Used with permission

21

Murphy et al JGR 2009

Anthropogenic Example

This image has been removed due to copyright restrictions Please see Figure 6on page httponlinelibrarywileycomdoi1010292009JD012105full

22

Murphy et al JGR 2009

Anthropogenic Example

This image has been removed due to copyright restrictions Please see Figure 6on page httponlinelibrarywileycomdoi1010292009JD012105full

22

NASA January 27 2003 Atlantic France Spain

from D Rosenfeld Image courtesy of Danniel Rosenfeld Used with permission

Image courtesy of NASA

23

Stephen Salterrsquos design

US Navy

Unpublished results use of particle production in Marine Boundary Layer (MBL) with cloud formation ~1 in 10 times

Image courtesy of US Navy

This image has been removed due to copyright restrictionsPlease see the image on page httpphysicsworldcomcwsarticlenews356931cloud

24

Stephen Salterrsquos design

US Navy

Unpublished results use of particle production in Marine Boundary Layer (MBL) with cloud formation ~1 in 10 times

Image courtesy of US Navy

This image has been removed due to copyright restrictionsPlease see the image on page httpphysicsworldcomcwsarticlenews356931cloud

24

Reward Risk 1 Cool planet 1 Regional droughts 2 Reduce or reverse ice loss 2 Continued ocean acidification 3 Reduce or reverse sea level rise 3 Ozone depletion 4 Increase plant productivity 4 Diffuse radiation effect on plants 5 Nice sunsets 5 Acid deposition 6 Better precipitation control 6 Cirrus effects

7 White skies 8 Lower solar power margins 9 Environmental side effects 10 Cannot stop effects quickly (1-3 years or more) 11 Rapid warming if stopped (all effects back in 1-3 years) 12 Human error 13 Undermining mitigation efforts 14 Cost 15 Who controls Commercialization 16 Military use 17 Whose hand on the thermostat 18 Conflict with treaties 19 ldquoUnknown unknownsrdquo

Robock 2008

What would you propose as a method 1 Model all results first

2 Small scale tests For direct effect method how do you do this 3 Are there effects that canrsquot be accepted

Risk vs Reward

25

As with the example of cheaper natural gas the ldquostop gaprdquo makes a possible ldquolong term solutionrdquo much less likely

Sunlight measured at Mauna Loa The reduction in direct sunlight and increase in diffuse sunlight following the eruption of Mt Pinatuboin 1991 are readily apparent The reduction in total sunlight was much smaller

500

400

300

200

100

1990 1992 1994 1996 19980

Direct

Total

Year

Mau

na L

oa S

olar

Rad

iatio

n (W

m-1

)

100 700

600

500

400

300

200

100

80

60

40

20

0

Annual solar output

Summer on-peak capacity

1990 1992 1994 1996 1998

Year

SEG

S O

n-Pe

ak S

umm

er

Cap

acity

(

)

SEG

S G

ross

Sol

ar

Out

put

(CW

h)

Output of the solar electric generating systems (SEGS) solar thermalpower plants in California (data are from ref 9) The SEGS plants had significant reductions in on-peak capacity and total output following the eruption of Mt Pinatubo

Diffuse

A

B

Image by MIT OpenCourseWare

Effect of Stratospheric Aerosols on Direct Sunlight and Implications for Concentrating Solar Power

DANIEL M MURPHYEarth system research laboratory Chemical sciences division National oceanic and atmospheric administration 325 Broadway Boulder Colorado 80305

Image by MIT OpenCourseWare

26

Summer sea ice

goes away with a

doubling of CO2

Ice returns with

geoengineering

(but not

homogeneously)

It is possible to

overdo the effect

Rasch et al 2009

This image has been removed due to copyright restrictionsPlease see Figure 2 in httpiopscienceioporg1748-932644045112fulltext

27

As with the example of cheaper natural gas the ldquostop gaprdquo makes a possible ldquolong term solutionrdquo much less likely

Sunlight measured at Mauna Loa The reduction in direct sunlight and increase in diffuse sunlight following the eruption of Mt Pinatuboin 1991 are readily apparent The reduction in total sunlight was much smaller

500

400

300

200

100

1990 1992 1994 1996 19980

Direct

Total

Year

Mau

na L

oa S

olar

Rad

iatio

n (W

m-1

)

100 700

600

500

400

300

200

100

80

60

40

20

0

Annual solar output

Summer on-peak capacity

1990 1992 1994 1996 1998

Year

SEG

S O

n-Pe

ak S

umm

er

Cap

acity

(

)

SEG

S G

ross

Sol

ar

Out

put

(CW

h)

Output of the solar electric generating systems (SEGS) solar thermalpower plants in California (data are from ref 9) The SEGS plants had significant reductions in on-peak capacity and total output following the eruption of Mt Pinatubo

Diffuse

A

B

Image by MIT OpenCourseWare

Effect of Stratospheric Aerosols on Direct Sunlight and Implications for Concentrating Solar Power

DANIEL M MURPHYEarth system research laboratory Chemical sciences division National oceanic and atmospheric administration 325 Broadway Boulder Colorado 80305

Image by MIT OpenCourseWare

26

Summer sea ice

goes away with a

doubling of CO2

Ice returns with

geoengineering

(but not

homogeneously)

It is possible to

overdo the effect

Rasch et al 2009

This image has been removed due to copyright restrictionsPlease see Figure 2 in httpiopscienceioporg1748-932644045112fulltext

27

Summer sea ice

goes away with a

doubling of CO2

Ice returns with

geoengineering

(but not

homogeneously)

It is possible to

overdo the effect

Rasch et al 2009

This image has been removed due to copyright restrictionsPlease see Figure 2 in httpiopscienceioporg1748-932644045112fulltext

27

Model 2 (NASA GISS)

Model 1 (Hadley)

Jones et al 2010

Precipitation change from stratospheric sulfate

This image has been removed due to copyright restrictions Please see Figure 4in httpwwwatmos-chem-physnet1059992010acp-10-5999-2010pdf

28

Precipitation change from marine cloud seeding

Jones et al 2009

This image has been removed due to copyright restrictions Please see Figure4 in httponlinelibrarywileycomdoi1010292008JD011450full

29

The Ozone Effect

Image courtesy of NOAA

30

The Ozone Effect

Image courtesy of NOAA

This image (published on the Journal of AtmosphericSciences by the American Meteorological Society) iscopyright copy AMS and used with permission

31

Baseline With Geoengineering

Rasch et al 2008

Ethics in research when do you decide to stop researching a topic because the result is too negative When does ldquowe should know more about it in case we try itrdquo conflict with ldquothis is not a good ideardquo

This image has been removed due to copyright restrictions Please seeFigure 8 in httpclimateenvscirutgersedupdfRaschPhilTranspdf

32

The Ozone Effect

Image courtesy of NOAA

This image (published on the Journal of AtmosphericSciences by the American Meteorological Society) iscopyright copy AMS and used with permission

31

Baseline With Geoengineering

Rasch et al 2008

Ethics in research when do you decide to stop researching a topic because the result is too negative When does ldquowe should know more about it in case we try itrdquo conflict with ldquothis is not a good ideardquo

This image has been removed due to copyright restrictions Please seeFigure 8 in httpclimateenvscirutgersedupdfRaschPhilTranspdf

32

Baseline With Geoengineering

Rasch et al 2008

Ethics in research when do you decide to stop researching a topic because the result is too negative When does ldquowe should know more about it in case we try itrdquo conflict with ldquothis is not a good ideardquo

This image has been removed due to copyright restrictions Please seeFigure 8 in httpclimateenvscirutgersedupdfRaschPhilTranspdf

32

ldquoConvention on the Prohibition of Military or Any Other Hostile Use of Environmental Modification Techniquesrdquo (ENMOD) prohibits the use of the environment as a weapon A result of opposition to Agent Orange and weather modification during Vietnam Adopted by the UN General Assembly on 10 December 1976 and opened for signature on 18 May 1977 ENMOD entered into force when Laos the twentieth State Party deposited its instrument of ratification on 5 October 1978

Map wikipedia 33

This image has been removed due to copyright restrictions Please see theimage on page httpenwikipediaorgwikiFileENMOD_Participationsvg

For you to consider

1 Have we shown that the ldquocurerdquo is better than the ldquodiseaserdquo 2 Is this really the same as what wersquove already done (ldquoinadvertentrdquo

climate modification) 3 If this is a ldquolast resortrdquo are we certain it is going to work

httpwwwtechnologyreviewcomenergy24157

This image has been removed due to copyright restrictions Please see the second image onpage httpwwwtechnologyreviewcomfeaturedstory416801the-geoengineering-gambit

34

MIT OpenCourseWarehttpocwmitedu

12340 Global Warming ScienceSpring 2012 For information about citing these materials or our Terms of Use visit httpocwmiteduterms