using global climate models to evaluate environmental problems and potential solutions

Using global climate models to evaluate environmental

problems and potential solutions

Ken CaldeiraDept. of Global Ecology

Carnegie Institution for ScienceStanford CA 94305 USA

[email protected]

PIK21 May 2012

Exercises in undisciplined science



[email protected]

PIK21 May 2012

Factual statements

Prescriptive and normative

statements

Values, moralityScience

internationalv

Caldeira, Cao, and Bala, submitted

Where did carbon come out of the ground to supply Germany’s CO2 emissions?

Germany

Russia

Norway

Rest ofworld


Where was CO2 emitted to support consumption in Germany?

Germany

China

Rest ofworld


Where was the carbon extracted to supply consumption in Germany?

Germany

Russia

Norway

Rest ofworld

What is the international trade in carbon that is extracted from the ground in one country and emitted in another?

Davis, Peters, and Caldeira, PNAS 2011

Extraction Production

Where was CO2 released in one country to produce products that were consumed in a different country ?


Production Consumption

What is the international trade in real or “embodied” carbon from the country of extraction to country of consumption?


Extraction Consumption

Infrastructural commitment to future climate change

How much climate change are we committed to from existing CO2-

emitting devices?

Steven J. Davis, lead co-conspirator

Assuming normal device lifetime


Approach

Analyze existing stock of power plants, automobiles, etc, and estimate future emissions

from these devices

Apply emissions in a climate models

Project future temperature change


Davis, S. J., K. Caldeira, and H. D. Matthews (2010) Future CO2 emissions and climate change from existing energy infrastructure, Science



A1G-FI

A2

B1

Climate consequences of energy system transitions

What the climate effects be of specific energy system transitions, taking into account energy-system

life-cycle analysis data?

Nathan Myhrvold, lead co-conspirator

Climate consequences of energy system transitions

Approach

Develop simple low-dimensional climate model-- radiative forcing from greenhouse gases-- time evolution of GHG concentrations

-- thermal inertia of ocean-- radiative fluxes to space

Represent GHG emissions during plant construction and operation

Simulate energy system transitions

Climate consequences of 40 year transition of 1 TW coal system to alternative technologies

Climate consequences of afforestation / deforestation

What are the combined biophysical and biogeochemical responses t

large-scale afforestation or deforestation?

Govindasamy Bala, lead co-conspirator

Climate consequences of afforestation / deforestation

LLNL coupled ocean-atmosphere carbon-climate model

(NCAR PCM2, IBIS, modified OCMIP)

Govindasamy Bala, lead co-conspirator

With deforestation, CO2 is much higher but temperatures are slightly cooler

A2

Atmospheric CO2 TemperatureAdditional contribution from loss of CO2-fertilization of forests

Effect of loss of carbon from forests

Global deforestation experiment: net temperature change (CO2 +

biophysical)

A2

Temperature change predicted in latitude-band deforestation simulations

Boreal

Temperate

Tropical

Predicted role of forestsTropical forests cool the planetTemperate (mid-latitude) forests do littleBoreal forests warm the planet

Does evaporating water cool global climate?

George Ban-Weiss, lead co-conspirator

Does evaporating water cool global climate?

For each Joule of evaporated water, about ½ Joule additional

gets to space

1 W/m2 of evaporation leads to about ½ K cooling

Geophysical limits on wind power

How much power could civilization get out of winds, considering only

geophysical limits?

Kate Marvel, lead co-conspirator


Approach

Perform simulations using NCAR’s CAM3.5 atmosphere model coupled to mixed-layer

ocean with specified heat transport.

2⁰ lat x 2.5⁰ lon , 26 horizontal layers

100 year simulations, 60 years used


Simulations

Drag added to (i.e., momentum removed from)SL: bottom two Surface Layers

WA: Whole Atmosphere

Effective drag area from 1 to 104 m2 km-3

Geophysical limits on wind powerAdisk = Disk area

η = Fraction of kinetic energy (momentum) removed from flow

Geophysical limits on wind powerAdisk = Disk area

η = Fraction of kinetic energy (momentum) removed from flow

Effective areaAeff = η Adisk

Amount effective drag area and kinetic energy extracted

Amount effective drag area and kinetic energy extracted

Global power demand

Climate effects: Temperature change

Suggests civilization-scale zonal mean temperature changes of ~0.1 K

Climate effects: Precipitation change

Suggests civilization-scale zonal mean precipitation changes of ~1 %

429 TW

428 TW

Atmospheric kinetic energy

Atmospheric kinetic energyproduction (loss)

Slope = 0.8

Atmospheric polewardheat transport

Conclusions: wind powerGeophysical limits to global wind power greatly exceed global power demand.

Global power demand ~ 18 TWNear surface winds > 429 TWWhole atmosphere > 1873 TW

Climate effects of uniformly distributed wind turbines appear to be minor at civilization scale (0.1 K temperature , 1% precipitation)

Distribution of corals andocean acidification

Long Cao, lead co-conspirator

0 1 2 3 4 5

Corrosive OptimalΩAragonite

Carbon dioxide level,

Coral reef distribution

,

and chemical

conditions helping

drive reef formation

Cao and Caldeira, 2008

0 1 2 3 4 5

Corrosive OptimalΩAragoniteCao and Caldeira, 2008

Carbon dioxide level,

Coral reef distribution

,

and chemical

conditions helping

drive reef formation

One Tree Reef, Queensland, Australia

Kenny Schneider, lead co-conspirator

Study area at One Tree Reef

About 4 km x 2 km

Water ponds at different levels in different lagoons at low tide.

Some flow over sills.

One Tree Island Research Station

Our study area

Depth transect along experimental site

Observed reductions in

alkalinity concentrations as water flows over reef and

reef builds CaCO3 skeleton

If added alkalinity was taken up by reef, we should have seen a decrease in alkalinity-to-dye ratio as water flowed over reef.

We did not detect any increase in calcification as a result of alkalinity addition.

Time scale of response?

We did not control for formation (dissolution) of Mg(OH)2.



[email protected]

Post-doc positions available for brilliant, creative, and productive scientists

who have recently completed or will soon complete their PhD.

If you fit this category and the kind of stuff in this talk interests you, please email your CV to me with “post-doc application” in the header line.

Ocean chemical consequences of ocean iron fertilization

Can ocean fertilization help with the ocean acidification problem, as has sometimes been claimed?


Consequences of CO2 removal from the atmosphere

What is the relationship between CO2 removal from the atmosphere,

atmospheric CO2 concentrations, and temperature?



Approach

Remove all CO2 from the atmosphere of a carbon-climate model and see what happens.

(Uvic model)


Cao, L., and K. Caldeira. Atmospheric carbon dioxide removal: long-term consequences and commitment. 2010, Environmental Research Letters. doi: 10.1088/1748-9326/5/2/024011


Approach

Take the extreme case where we assume that ocean iron fertilization is able to cause all ocean mixed-layer

phosphate to be utilized.

Perform simulations in the UVic carbon-climate model and see what happens.

Cao, L., and K. Caldeira. 2010. Can ocean iron fertilization mitigate ocean acidification? Climatic Change, 99. DOI: 10.1007/s10584-010-9799-4


No iron fertilization(A2 CO2 emissions)

Fertilize ocean to mitigate atmosphere CO2

8.18

7.74

7.80

7.74

3.53

1.54

1.71

1.52

pH Aragonite saturation

Year

210

0

Fertilize ocean to generate carbon credit

Without human interference

Solar Geoengineering

Julia Pongratz, lead co-conspirator

Temperature effects of doubled CO2

ΔTemperature Statistical significance

Caldeira and Wood, 2008



ΔTemperature Statistical significance


with a uniform deflection of 1.84% of sunlight

Precipitation effects of doubled CO2




with a uniform deflection of 1.84% of sunlight


Deflecting 1.8% of sunlight reduces but does not eliminate simulated temperature and precipitation change caused by a doubling of atmospheric CO2 content

But what about the effect ofdecreased sunlight food?

Probability of 2080-2100 summer being hotter than hottest on record

Maize yield in a high-CO2 world without and with

deflection of sunlight

Benefit of CO2-fertilization without the

costs of higher temperatures

Pongratz et al 2012

From Pongratz, Lobell, Cao &-Caldeira, Nature Climate Change, 2012.

Crop yields in a high-CO2 world without and with deflection of sunlight

Benefit of CO2-fertilization without thecosts of higher temperatures

92From Pongratz, Lobell, Cao &-Caldeira, Nature Climate Change, 2012.


93


Pongratz et al 2012

94From Pongratz, Lobell, Cao &-Caldeira, Nature Climate Change, 2012.

% increase in crop yields in a high-CO2 world

without and with deflection of sunlight2xCO2 minus pre-industrial

2xCO2 + geo minus pre-industrial

2xCO2 + geo minus 2xCO2

Maize -3 11 14Wheat 6 26 21

Rice 19 28 8

using global climate models to evaluate environmental problems and potential solutions

Documents

future climate change

future climate changeapproach

future climate changehow

future climate changedavis

climate effects

future emissions

future co2 emissions

global climate models