FIGHTING CLIMATE CHANGE

BY ENGINEERING AIR POLLUTION

TO BRIGHTEN CLOUDS

LYNN M. RUSSELL SCRIPPS INSTITUTION OF OCEANOGRAPHY

HTTP://AEROSOLS.UCSD.EDU/

Earth’s “Energy Balance”

• Rudolf Clausius 1850

• William Thompson (Lord Kelvin) 1848

(Energy In = Energy Out + Sources – Sinks)

Earth Sun

FShort

• Josef Stefan 1874

• Ludwig Boltzmann 1884

• Max Planck 1901

CO2-enhanced greenhouse effect

Aerosol-enhanced albedo effect

FShort =S0(1- p)

Stefan-Boltzmann Law FLong= σTsurf

4

FLong

1st Law of Thermodynamics FShort = FLong

• Joseph Fourier 1824

• John Tyndall 1858

• Svante Arrhenius 1896

• Hilding Köhler 1936

• Sean Twomey 1974

S0(1- p) + Fghg= sTsurf4

Global Mean Temperature “Model” (N.B. Does Not Address Regional+Precipitation Changes)

Greenhouse Effect (Carbon Dioxide Removal – CDR)

Albedo Effect (Sunlight Reflection Methods – SRM)

25°C

15°C

5°C

25°C

15°C

5°C

S0(1- p) + Fghg= sTsurf4

Tsurf ≈ 15°C or 59°F

Carbon Dioxide Removal (CDR) vs. Solar Radiation Management (SRM)

SRM increases albedo components

CDR reduces greenhouse gases

Carbon Dioxide Removal (CDR) vs. Solar Radiation Management (SRM)

• INTRODUCTION TO AEROSOL EFFECTS ON CLOUDS AND HISTORICAL CONTEXT

• RECENT MODEL SIMULATIONS OF CLOUD BRIGHTENING

• NEW EXPERIMENTAL EVIDENCE OF CLOUD BRIGHTENING

• IMPLICATIONS FOR CLIMATE ENGINEERING

Cloud albedo effect: More droplets increased reflectance

more

scattering less

scattering

more

particles

RH>100%

P. Durkee, 1994

Effects of

Ship

Emissions

on Clouds

1950 1980

Historical Context: Combustion Emission Trends

• Fossil fuel usage and biomass burning have increased with human population, resulting in increased greenhouse gas and aerosol emissions

1950 1980

• However, in industrialized nations the emission of scattering aerosols has been Engineered to improve air quality.

2050

Historical Context: Combustion Emission Trends

• Fossil fuel usage and biomass burning have increased with human population, resulting in increased greenhouse gas and aerosol emissions

• INTRODUCTION TO AEROSOL EFFECTS ON CLIMATE AND HISTORICAL CONTEXT

• RECENT MODEL SIMULATIONS OF CLOUD BRIGHTENING

• NEW EXPERIMENTAL EVIDENCE OF CLOUD BRIGHTENING

• IMPLICATIONS FOR CLIMATE ENGINEERING

Proposed Cloud

“Seeding”

Rasch et al., 2009

20% increase shows some

cooling but no excessive

cooling; 70% shows

excessive cooling over

Pacific.

Predicted Changes in

Polar Sea Ice

Rasch et al., 2009

To offset most sea ice

reduction in Arctic, need

70% seeding.

But, how certain is this result?

Why is Response Nonlinear?

• In addition to adding new nuclei, particles change the rate at which water condenses, which changes the maximum cloud “supersaturation” (Relative Humidity – 100%)

Korhonen et al., 2010

Maximum Supersaturation

(RH-100)%

• INTRODUCTION TO AEROSOL EFFECTS ON CLIMATE AND HISTORICAL CONTEXT

• RECENT MODEL SIMULATIONS OF CLOUD BRIGHTENING

• NEW EXPERIMENTAL EVIDENCE OF CLOUD BRIGHTENING

• IMPLICATIONS FOR CLIMATE ENGINEERING

Lynn M. Russell1, Armin Sorooshian3,

John Seinfeld2, Bruce Albrecht5,

Athanasios Nenes4, Lars Ahlm1, Yi-Chun Chen2, Jill S Craven2, Matthew Coggon2,

Amanda Frossard1, Haf Jonsson6, Eunsil Jung5, Jack J Lin4, Andrew R

Metcalf2, Robin Modini1, J. Muelmenstaedt1,

Greg Roberts1, Taylor Shingler3, Siwon Song5,

Zhen Wang3, Anna Wonaschuetz3

1.Scripps/UCSD,

2.Caltech, 3.Univ.Arizona, 4.GeorgiaTech, 5.Univ.Miami,

6.CIRPAS.

Eastern Pacific Emitted Aerosol Cloud Experiment (E-PEACE) 2011

No

Data 0% 10% 20% 40% 30%

Daytime Stratocumulus

Cloud Amount

Where is highest Sc probability?

Prior Use of Paraffin Oil Smoke for Plume Dispersion Studies

R/V Point Sur Smoke Operations

R/V Point Sur Smoke Operations

CIRPAS Twin Otter Measurements of Smoke from R/V Pt Sur

Three Parts of Engineering Clouds

• Did we produce enough smoke particles?

• Do smoke particles make cloud droplets?

• Do the droplets change albedo?

[cm-3]

Differential

Mobility Sizing

Scanning

DMA

Optical Sizing

OPS

PCASP

Aerodynamic

Sizing

APS

Lognormal Fit

Sum of Modes

Clean

Marine

Polluted

Marine

dN

d logDp

R/V Point

Sur Stack

Generated

Smoke

Giant

Salt

Cargo

Ship

Overall

Chemical

Composition

Organic

Functional

Group

Composition

Organic Hydroxyl

Amine

Carboxylic Acid

Other Carbonyl

Alkane

Particle

Number

Concentration

.11

Organic

Nitrate

Sulfate

Ammonium

Sea Salt

dN

d logDp

C Clean Marine

A Smoke Generator B Cargo Ship

D Clean Marine

[cm-3]

dN

d logDp

[cm-3]

Organic

Nitrate

Sulfate

Ammonium

Sea Salt

in c

loud

in c

loud

Do Smoke Particles

Act as Cloud

Droplets?

45

40

-130 -140 -120

35

365

-122

355

-123

Estimated location of

smoke emitted at 0625

Estimated location of

smoke emitted at 1230

R/V Point Sur

location at 0625

R/V Point Sur

location at 1230

0630 1230 0930

Three Parts of Engineering Clouds

• Did we produce enough smoke particles?

– Yes.

• Do smoke particles make cloud droplets?

– Yes.

• Do the droplets change albedo?

– Sometimes. How often?

Why Did So Few Tracks Form?

Tracks Observed

Clear or Scattered

Multi-Layered1

High or Raining2

July 1-31 (2011) in region 22 days 0 days NK NK

July 12-23 (2011) in region 4 days variable NK NK

July 12-23 (2011) at ship 1 day 2 days 7 days 2 days

The region near the ship had multi-layered clouds 7 out of 12 days; particles don’t mix up to the top layer so tracks don’t form on these days. How important is this effect globally for cloud albedo forcing?

Multi-Layered Cloud Frequency Reduces Cloud Albedo Effects

• Seeding clouds doesn’t “work” if there are other clouds above them

Frequency of Multi-Layered

Low Clouds

Muelmenstaedt et al., in prep.

• INTRODUCTION TO AEROSOL EFFECTS ON CLIMATE AND HISTORICAL CONTEXT

• RECENT MODEL SIMULATIONS OF CLOUD BRIGHTENING

• NEW EXPERIMENTAL EVIDENCE OF CLOUD BRIGHTENING

• IMPLICATIONS FOR CLIMATE ENGINEERING

This was not a geoengineering experiment, but it is worth noting that…

Two man-made technologies have demonstrated an observable cooling

• Cargo ships – Price: $100k/dy – 100k gal bunker/dy burned

• 1 nK warming from CO2

• 2 nK cooling from CDN

– Cooling/Warming ~ 2 (±1)

• R/V Pt Sur with smoke generators – Price: $15k/dy – 500 gal diesel/dy burned

• 0.008 nK warming from CO2

– 200 gal oil/dy • 0.4 nK cooling from CDN

– Cooling/Warming ~ 50 (±20)

Assumptions: 100-yr time horizon, scaled to climate sensitivity of IPCC [2007] median value (i.e. 3K per 280 ppmv); 15% increase in reflectivity for track on 16 July; assume track persists in daylight for 6 hr normalized by 100 years.

Brightening clouds “works”

(to offset some warming)

• Organic particles are effective nuclei for cloud droplets1

• Increased droplet numbers increases albedo

• Technology for seeding exists at low CO2 cost (~20x)2

• Observations show competing, nonlinear effects.

But it’s complicated

(so scale up is uncertain)

• Ecosystem impacts of smoke have not been investigated3

• Frequency less than predicted by climatology

– Multi-layered clouds4

• GCMs do not have key processes and variability

• Experiments are needed to provide scale-up testing.

1Shingler et al., 2012, Atmo. Chem. Phys. 2Russell et al., 2012, Bull.Am.Met.Soc.

3Russell et al., 2012, AMBIO 4Muelmenstaedt et al., 2012, in prep

CIRPAS Twin Otter Measurements of Smoke from R/V Pt Sur

FIGHTING CLIMATE CHANGE

BY ENGINEERING AIR POLLUTION

TO BRIGHTEN CLOUDS

LYNN M. RUSSELL SCRIPPS INSTITUTION OF OCEANOGRAPHY

HTTP://AEROSOLS.UCSD.EDU/