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Geoengineering: Climate Change by Design

A survey of the science behind some of the leading proposals for climate engineering, and some thoughts about governance and implementation.

Jon Lawhead

on 30 January 2018

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Transcript of Geoengineering: Climate Change by Design

Climate Change By Design

Climate Strategies
Solar Radiation Management
Carbon Capture and Sequestration
Stop climate change before it starts (or before it goes any further)
Reduce the negative impact of climate change
For the purposes of our discussion, geoengineering:
Stratospheric Aerosol Injection
Probably the most popular idea in the scientific literature
Aerosol Challenges
Mt. Pinatubo, June 1991
Albedo Management
Would need a forcing of about -4 watts per square meter to offset a CO2 doubling
Albedo Challenges
Incredibly, ridiculously expensive (several trillion dollars per year to approach effectiveness for some approaches)
Oceanic Fertilization
Fertilization Challenges
How many of those 100,000 carbon atoms actually STAY locked up?
Chemical CCS
"Enhanced weathering" on land
Jon Lawhead, PhD
University of Southern California

Chemical CCS Challenges
Aerosol Injection
Ocean Fertilization
Albedo Management
My questions for you:
Usually involves intervening on human behavior or institutions
Examples include:
Carbon tax
Cap & trade
Alternative energy R&D
Gold standard of climate change response
Pretty Pictures
Summary Charts
Royal Society Report (2009)
What's the right regulatory model here?
How might we go about building an international consensus on what technique to employ?
How can we prevent or discourage unilateral action by state or non-state actors?
Often given an economic basis
Changes to human or natural systems
Examples include:
Emigration/immigration plans
Levee construction
Agricultural land use changes
Is deliberately pursued as a response to climate change, and not an unintended side-effect of another activity.
Is designed to produce an effect that is global in scope and capable of impacting the climate on timescales of (at least) years.
Primarily involves interventions in the functioning of geosystems rather than human institutions or behavior.

~2% decrease in insolation offsets a CO2 doubling
Hydrogen sulfide or sulfur dioxide
5-7 Tg every year!
Global mean temperature drop of 0.5 degrees C, but also....
Trenberth & Dai (2007)
But that's not all! We can also expect:
Ozone damage; recovery delay by ~70 years
Increased atmospheric water vapor (so increased greenhouse effect)
Continued ocean acidification
Relatively cheap
Responsive (quick start/stop)
Extant natural models
Significant side-effects
Only impacts temperature
Potentially "addictive"
Impacts temperature and ocean acidification
Moderately effective
Potentially disastrous side effects
Not well understood
Relatively slow
High potential for unilateral action (pro or con?)
That means increasing the global surface albedo by about 0.02 (from 0.15 to 0.17)
This could take the form of urban albedo increases, agricultural changes, or desert reflectors
We can't do much with the ocean, so we'd really need a land surface albedo change of 0.08
Ecosystem disruption
Changes in local atmospheric circulation
Land use conflicts
Not easily (or cheaply) reversible
Limited by nutrient availability
C:N:P:Fe ~= 106:16:1:0.001
One atom of Fe theoretically locks up 100,000 atoms of C
As is almost always the case, things are more complex than that
Downstream nutrient robbing
Ecosystem feedbacks
Algae blooms
Not easily reversible
Only impacts temperature
Difficult to scale up to effective levels
Deployable right now
Unlikely to break down
Potentially helpful when used in tandem with mitigation or adaptation
Sarmiento & Gruber (2002)
CaSiO + CO CaCO + SiO
Or, in the ocean:
Ca(OH) +2CO Ca + 2HCO
This can be at the source, or from ambient air (the later is much more expensive for thermodynamic reasons)
Manipulation of the natural carbon cycle
Resource intensive
Mining the minerals, getting them to the right place, processing them in the right way, &c.
Ocean PH (even if we do it on land)
Policy Portfolios
Most of these evaluations are based on considering CE solutions in isolation (even though most everyone agrees that CE would never work as a solo solution)
This raises an important question:
How might CE scenarios interact with other climate policies to change the utility of policies when taken as a portfolio?
How can we plan for portfolio interactions?
High potential for unilateral action (pro or con?)
"The future cannot be predicted, but futures can be invented"
-Dennis Gabor
"We are generalists. You can't draw neat lines around planet-wide problems. Planetology is a cut-and-fit science."
- Frank Herbert,
You are here
This is only slightly less ridiculous than a Bond villain plot.
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