Introduction to Geoengineering for Ecologists

Ken CaldeiraCarnegie Institution Dept of Global Ecology

kcaldeira@carnegie.stanford.edu

Ecosystem Impacts of Geoengineering WorkshopScripps, 31 Jan 2011

Reuters: David Gray

Reuters: David Gray

www.sit.ac.nz

SolarRadiation

Management options

CarbonDioxide

Removal options

Desire for

improvedwell-being Demand

for goods and

services

Demand for

energy

Impacts on

humans and

Climate change &

ocean

CO2 emission

s

CO2 in

ecosystems

acidification

atmosphere

Conservation

Efficiency

Low-carbonenergy

Carbon dioxide removal

Adaptation

Climateengineering

Temperatures continue to increase throughout this

century in every plausible emissions scenario

IPCC TAR

There is no practical way for emissions reduction to reduce

temperatures this century

Volcanoes caused global cooling by putting dust in the

stratosphere

Soden et al., 2002

Mt.

Pin

atu

bo

Temperature effects of doubled CO2

ΔTemperature Statistical significance

Caldeira and Wood, 2008

Temperature effects of doubled CO2

ΔTemperature Statistical significance

Caldeira and Wood, 2008

with a uniform deflection of 1.84% of sunlight

Precipitation effects of doubled CO2

Caldeira and Wood, 2008

Temperature effects of doubled CO2

Caldeira and Wood, 2008

with a uniform deflection of 1.84% of sunlight

Zonal average precipitation and temperature

Caldeira and Wood, 2008

Cao et al, in prep.

In HadCM3L, a coarse-resolution atmosphere-ocean GCM,perform outer product of (27) simulations starting from

-- 3 different initial conditions (1xCO2, 2xCO2, 4xCO2)

-- 3 different CO2 levels (1xCO2, 2xCO2, 4xCO2)

-- 3 different solar intensity levels (-2CO2eq, normal, +2CO2eq)

Perform linear regressions to separate dependencies on -- global mean temperature,

-- CO2-concentration, and

-- solar intensity.

C – response per CO2-doublingS – response per equiv. solar increaseT – response per C warming

Cao et al, in prep.

C – response per CO2-doublingS – response per equiv. solar increaseT – response per C warming

Cao et al, in prep.

C – response per CO2-doublingS – response per equiv. solar increaseT – response per C warming

Cao et al, in prep.

Main effects- High CO2

- Lower temperature

Secondary effects- Changes in PAR- Changes in precip/evap

Not considered- Changes in UV- Diffuse radiation- Everything else

Trees Crops

Grasses

C4

Positive down

Mt. Pinatubo and global ozone

Mt. Pinatubo

Concluding suggestions• Consider consequences if people are

deploying measures thoughtfully

• Compare “geoengineered” state to both “natural” state of the system and the perturbed state in the absence of “geoengineering”