CREATE Summer School Tim Canty - CANDACSources: IPCC 2007 WG2 Figure SPM.2; Six Degrees: Our Future on a Hotter Planet by Mark Lynas; Chris Barnet presentations on Global Warming

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Tim Canty

Geo-engineering of climate

Lecture C

27 July 2012

CREATE Summer School

Today:

• Climate change

• Geo-engineering of climate

• How this may affect the polar regions

• Will it really work?

Is the climate warming?

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Monthly, global temperature anomaly


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Monthly, land temperature anomaly


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So, the Earth is getting warmer.

What’s the big deal?

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Consequences of Climate Change as a

Function of Future Rise in Globally Averaged T 1°C

– Increased damage from flooding & storms

– Coral bleaching

2°C: – Severe damage to Arctic, alpine, and coral ecosystems

– Freshwater resources stressed, leading to widespread crop shortages

3°C: – ~30% of global coastal wetlands lost

– Terrestrial biomass could become net carbon source due to drought,

accelerating rise in atmospheric CO2

4°C:

– Widespread coral mortality

– Melting of Ronne and Ross Ice Sheets

5°C:

– Permanent loss of ice sheets at both poles

– Loss of ocean clathrates, accelerating rise in atmospheric CH4

Sources: IPCC 2007 WG2 Figure SPM.2; Six Degrees: Our Future on a Hotter Planet by Mark Lynas;

Chris Barnet presentations on Global Warming

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Consequences of Climate Change as a

Function of Future Rise in Globally Averaged T 1°C

– Increased damage from flooding & storms

– Coral bleaching

2°C: – Severe damage to Arctic, alpine, and coral ecosystems

– Freshwater resources stressed, leading to widespread crop shortages

3°C: – ~30% of global coastal wetlands lost

– Terrestrial biomass could become net carbon source due to drought,

accelerating rise in atmospheric CO2

4°C:

– Widespread coral mortality

– Melting of Ronne and Ross Ice Sheets

5°C:

– Permanent loss of ice sheets at both poles

– Loss of ocean clathrates, accelerating rise in atmospheric CH4

Sources: IPCC 2007 WG2 Figure SPM.2; Six Degrees: Our Future on a Hotter Planet by Mark Lynas;

Chris Barnet presentations on Global Warming

So, the Earth is getting warmer.

What’s the big deal?

Hmm… OK, what can we do about this?

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Atmospheric Radiation

Panel (a): Curves of black-body energy versus

wavelength for 5750 K (Sun’s approximate

temperature) and for 245 K (Earth’s mean

temperature). The curves are drawn with equal area

since, integrated over the entire Earth at the top of

the atmosphere, the solar (downwelling) and

terrestrial (upwelling) fluxes must be equal.

Panel (b): absorption by atmospheric gases for a

clear vertical column of the atmosphere (1.0

represents complete absorption).

From Houghton, Physics of Atmospheres, 1991

• Solar irradiance (downwelling) at top of atmosphere occurs at wavelengths

between ~200 and 2000 nm (~5750 K “black body” temperature)

• Thermal irradiance (upwelling) at top of the atmosphere occurs at wavelengths

between ~5 and 50 m (~245 K “black body” temperature)

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Atmospheric Radiation

Panel (a): Curves of black-body energy versus

wavelength for 5750 K (Sun’s approximate

temperature) and for 245 K (Earth’s mean

temperature). The curves are drawn with equal area

since, integrated over the entire Earth at the top of

the atmosphere, the solar (downwelling) and

terrestrial (upwelling) fluxes must be equal.

Panel (b): absorption by atmospheric gases for a

clear vertical column of the atmosphere (1.0

represents complete absorption).

From Houghton, Physics of Atmospheres, 1991

• Solar irradiance (downwelling) at top of atmosphere occurs at wavelengths

between ~200 and 2000 nm (~5750 K “black body” temperature)

• Thermal irradiance (upwelling) at top of the atmosphere occurs at wavelengths

between ~5 and 50 m (~245 K “black body” temperature)

CFC’s absorb in the clearest region of the

“Atmospheric Window”

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GWP weighted emissions of CO2

GWP weighted emissions of CFCs,

without early aerosol propellant ban

(i.e., no ban on CFCs)

GWP weighted emissions of CFCs,

without Montreal Protocol

Velders et al., PNAS, 2007

ODS

Actual

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Geo-engineering of weather & climate has a long history:

• 1945: John von Neumann and other leading scientists meet at Princeton and agreed

that modifying weather deliberately might be possible (motivation was “next great war”)

• 1958: US Congress funded expanded rainmaking research (Irving Langmuir, GE)

• Cold War: U.S. military agencies devoted significant funds to research on what

came to be called "climatological warfare”

one aim was to make the Arctic Ocean navigable by eliminating the ice pack

extensive cloud-seeding conducted over Ho Chi Minh Trail during Vietnam war,

to increase rainfall and bog down the North Vietnamese Army's supply line in mud

• 1975: Mikhail Budyko calculated that if global warming ever became a serious threat,

we could counter with just a few airplane flights a day in the stratosphere, burning

sulfur to make aerosols that would reflect sunlight away

• 1977: N.A.S. report looked at a variety of schemes to reduce global warming, should it

ever become dangerous, and concluded a turn to renewable energy was a more practical

solution than geo-engineering of climate

Source: S. Weart, The Discovery of Global Warming, Harvard University Press, 2003

http://www.aip.org/history/climate/

http://www.aip.org/history/climate/

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Geo-engineering of climate garnered renewed attention

with the publication, in August 2006, of an article entitled:

Albedo Enhancement by Stratospheric Sulfur Injections: A Contribution

to Resolved a Policy Dilemma?

by Paul J. Crutzen : Climatic Change, 77, 211-219, 2006


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(1995)

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(1995)

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(1995)

“…major volcanic eruptions can thus cause a drop in global mean

surface temperature of about half a degree Celsius that can last for

months and even years”. IPCC 2007

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Geo-engineering of climate garnered lots of renewed attention





According to model calculations … complete improvement in air quality

could lead to a decadal global average surface air temperature increase by

0.8 K on most continents and 4 K in the Arctic. Further studies indicate that

global average climate warming during this century may even surpass the

highest values in the projected IPCC global warming range of 1.4–5.8ºC

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According to model calculations … complete improvement in air quality

could lead to a decadal global average surface air temperature increase by

0.8 K on most continents and 4 K in the Arctic. Further studies indicate that

global average climate warming during this century may even surpass the

highest values in the projected IPCC global warming range of 1.4–5.8ºC

What aspect of air quality improvement

might lead to a large increase

in surface air temperature?

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Atmospheric Response to Mt. Pinatubo

Soden et al.,

Science, 2002

Agung El Chichón

Santa María

Pinatubo

Agung El Chichón

Santa María

Pinatubo

Mt Pinatubo erupted in June 1991,

depositing 6 Tg of sulfur into the stratosphere

The Microwave Sounding Unit (MSU) reported global avg’d cooling of ~0.5°C

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• Requires 5.3 Tg perturbation to stratospheric S to counter

requires continuous injection of 2.65 to 5.3 Tg S per year (due to 2 or 1 yr τ STRATOSPHERE)

estimated cost $70 to 140 billion per year ($70 to 140 per capita of affluent world)

for comparison: annual military expenditures $1000 billion per year

advocates manufacture & surface release of a special gas (insoluble, non-toxic,

un-reactive with OH, and zero GWP) that is processed photochemically only

in the stratosphere to yield sulfate aerosols (he’s an atmospheric chemist!)

• Ozone depletion

Global column O3 declined by ~2.5% following eruption of Mt. Pinatubo

Compensating for CO2 doubling would lead to less ozone loss than followed Pinatubo

Stratospheric chlorine is declining, so enhanced O3 loss less worrisome in the future

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• Requires 5.3 Tg perturbation to stratospheric S to counter

requires continuous injection of 2.65 to 5.3 Tg S per year (due to 2 or 1 yr τ STRATOSPHERE)

estimated cost $70 to 140 billion per year ($70 to 140 per capita of affluent world)

for comparison: annual military expenditures $1000 billion per year

advocates manufacture & surface release of a special gas (insoluble, non-toxic,

un-reactive with OH, and zero GWP) that is processed photochemically only

in the stratosphere to yield sulfate aerosols (he’s an atmospheric chemist!)

• Ozone depletion

Global column O3 declined by ~2.5% following eruption of Mt. Pinatubo



Will the response of polar ozone to stratospheric sulfur injection be as modest

as suggested by the response of global ozone to Mt. Pinatubo aerosol?

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Arctic Ozone Loss vs PSC Exposure

PSCs polar stratospheric clouds: provide surfaces for heterogeneous

conversion of HCl and ClNO3 to ClO

update to Rex et al., 2006

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Stratospheric Optical Depth

• Chlorine activation reactions occur on cold aerosols

• Chlorine activation depends on T as well as Surface Area

• Volcanoes provide more reactive surface area than PSCs !

Tabazadeh et al., PNAS, 99, 2609, 2002

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Effect of Geo-Engineering on Arctic O3 Loss

Tilmes et al., Science, 2008

Enhancement of stratospheric aerosols due to geo-engineering risks:

a) future Arctic Ozone Hole in “cold” winters

b) 30 to 70 year delay in the recovery of the Antarctic ozone hole

Cold Winter Moderately Cold Winter

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• Ozone depletion

Global column O3 ↓ 2.5% following eruption of Mt. Pinatubo



▪ National Academy of Sciences:

For the injection of sulfate aerosols, an additional concern exists: the potential for

increased concentrations of stratospheric aerosols to enhance the ability of residual

chlorine, left from the legacy of chlorofluorocarbon use, to damage the ozone layer,

especially in the early spring months at high latitudes. A sudden increase in stratospheric

sulfate aerosol could strongly enhance chemical loss of stratospheric polar

ozone for several decades, especially in the Arctic (Tilmes et al., 2008: 89 citations)

There’s something else to consider…

Analysis of Surface Temperature

30 Canty et al., ACPD submitted 20 July, 2012

Weighted Multiple Linear Regression


TMDL i = (1+ γ) (GHG RF i ) + (NAA RF i)

+ Co + C1SOD i−6 + C2TSI i + C3ENSO i

+ C4AMO i + C5PDO i + C6IOD i

QOCEAN i

Anthropogenic forcing term: accounts for greenhouse gas (GHG)

radiative forcing and net anthropogenic aerosol (NAA) radiative forcing






QOCEAN i

Multiple linear regression: determines the contribution to temperature

record from various climate proxies.






QOCEAN i

Export of energy into the ocean


34 Lean and Rind, GRL, 2008 Canty et al., ACPD submitted 20 July, 2012



Our model includes a climate sensitivity

parameter that accounts for feedbacks due

to water vapor, clouds, albedo, etc..

Also, accounts for energy flow to the ocean



Our model includes a climate sensitivity

parameter that accounts for feedbacks due

to water vapor, clouds, albedo, etc..

Also, accounts for energy flow to the ocean

We can include other climate proxies in our

regression analysis, such as the Pacific

Decadal Oscillation (PDO), Indian Ocean

Dipole (IOD), and the Atlantic Multidecadal

Oscillation (AMO)

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Atlantic Meridional Overturning Circulation (AMOC)

http://science.nasa.gov/science-news/science-at-nasa/2004/05mar_arctic








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Atlantic Multidecadal Oscillation (AMO)

The Atlantic multidecadal oscillation occurs

on a 60-70 year cycle (Schelsinger and

Ramunkutty, 1994). Different theories as to

what drive this behavior:

May be due to the interplay between AMOC

and the export of sea ice through the Fram

Strait (Dima and Lohmann, 2007).

Dima and Lohmann, 2007

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Atlantic Multidecadal Oscillation (AMO)

The Atlantic multidecadal oscillation occurs

on a 60-70 year cycle (Schelsinger and

Ramunkutty, 1994). Different theories as to

what drive this behavior:

May be due to the interplay between AMOC

and the export of sea ice through the Fram

Strait (Dima and Lohmann, 2007).

Could be due to forcing from anthropogenic

aerosols (Booth et al., 2012).

Booth et al., 2012

Atlantic Multidecadal Oscillation










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SOD vs AMO

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T vs SOD

Analysis of Atmospheric Temperature








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SOD GISS TPINATUBO

Surface

Temperature

Record

NO AMO Had3 SST Had3 LIN Had3 AF

CRU4, global 0.33 0.27 0.15 0.15

GISS, global 0.37 0.32 0.22 0.22

NCDC, global 0.27 0.23 0.15 0.15

CRU4, land 0.55 0.44 0.29 0.35

GISS, land 0.40 0.38 0.30 0.32

NCDC, land 0.50 0.40 0.25 0.28

BEG, land 0.56 0.41 0.25 0.30

Lower Atmos.

Temperature

Record

MSU, global –0.41 –0.39 –0.33 –0.31

MSU, land –0.50 –0.46 –0.37 –0.36

Canty et al., ACPD submitted 20 July, 2012

Overall Implications for Geo-engineering

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Temperature records indicate atmosphere cooled after major eruptions:

The timing of stratospheric optical depth (SOD) and North Atlantic SST

anomalies suggest changes in ocean circulation preceded the four major

volcanic eruptions that have occurred since 1900.

Data record suggests ocean circulation has affected prior estimates of

volcanic cooling

Geo-engineering schemes based on input of sulfate aerosols into the

stratosphere must be “re-calibrated”

0.5° cooling from Pinatubo based on Atmospheric temperature record

not Surface temperature record



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volcanic cooling






If geo-engineering via anthropogenic release of sulfate aerosols is

still “on the table”… the question remains….

Who controls the thermostat?


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volcanic cooling






If geo-engineering via anthropogenic release of sulfate aerosols is

still “on the table”… the question remains….

Who controls the thermostat?

Documents

CREATE Summer School Tim Canty - CANDACSources: IPCC 2007 WG2 Figure SPM.2; Six Degrees: Our Future on a Hotter Planet by Mark Lynas; Chris Barnet presentations on Global Warming