Ocean Geoengineering

Lecture 13: 6/19/2014

CO2 direct injection

• How much CO2 can ocean sequester?– Based on physical chemistry, it can exceed the

estimated available fossil energy resources• Effect on ocean– 1300 GtC (~200 years of current emissions) would

decrease average ocean pH by 0.3 units– Average global ocean pH drop since industrial

revolution 0.1 unit

Methods(from Herzog et al.)

• Droplet plume – liquid CO2 injected below 1000m

• Dense plume – dense CO2-water mixture created between 500-1000 m (sinks to bottom)

• Dry ice – released at ocean surface from a ship

• Towed pipe – liquid CO2 injection below 1000 m from moving ship

• CO2 Lake – liquid CO2 introduced to a sea floor depression, forming stable “deep lake” (e.g. 4000 m)

Effects?

Ocean Fertilization … see former CEO of Planktos

Why add Fe to the ocean?

• In High Nutrient Low Chlorophyll (regions) the phytoplankton (hence primary and new production) are typically limited by dissolved iron availability

Estimated annual dust fluxes to the

surface of the Earth

(Ginoux et al. 2001, J. Geophys. Res.

106: 20,255-20,273)

Main global HNLC areas:• Ocean Area:

– 361 million square kilometers• HNLC areas ~1/3 of ocean

– Subarctic Pacific: 4.6 million square kilometers

– Southern Ocean (south of 60° S): <9 million square kilometers

– Equatorial Pacific (just Wrytki box 10°S-10°N, 90°W-180°):~27.4 million square kilometers • Almost 10% of ocean!• Continental area (~149 million square km)

– Asia (43.8), Africa (30.4), N. America (24.5), S. America (17.8), Antarctica (13.7), Europe (10.2), Australia (9)

The Science Behind Fertilization

De Baar et al. 2005. Synthesis of Fe Enrichments

You get a bloom, but you cannot control where it goes …

De Baar et al. 2005. Synthesis of Fe Enrichments

Big diatoms typically bloom with +Fe

De Baar et al. 2005. Synthesis of Fe Enrichments

Depth of wind-mixed layer (WML) matters for biological response

De Baar et al. 2005. Synthesis of Fe Enrichments

Drawdown in DIC (i.e. CO2) not directly coupled to enhanced export

De Baar et al. 2005. Synthesis of Fe Enrichments

The first to verify deep export …But with extensive caveats

• Proponents claim that ocean fertilization is: • easily controlled – NO, oceans are fluid and turbulent … beyond our

control!• verifiable process that mimics nature – NO, these methods rapidly

accelerate natural fertilization, addition of artificial chelater to keep Fe in solution (different from natural sources)

• environmentally benign – NO, this is inconsistent with almost everything we know about aquatic ecosystems (e.g. change in O2, successional patterns, radical shifts in food webs)

• long-term solution to atmospheric CO2 accumulation – NO, this only gets it into the ocean interior (e.g. 1000 years), not likely to be preserved in sediments– Two different CO2 cycles:

• 1) Volcanic outgassing of CO2 coupled to metamorphic weathering of silicate rocks• 2) Biological reduction of CO2 to organic matter and oxidation by respiration (small fraction

incorporated into lithosphere … basis for fossil fuels, and transfers from the fast cycle, Biology, to the slow cycle, Geology)

Wave pumps (Fertilization meets Surface Cooling)

Angelique White et al. 2010

Angelique White et al. 2010

Pumps (issues)• Logistical

– these things break and move (why? Because they require waves!)– From White et al. 2010:

• significant reengineering of existing wave pump technology is necessary for open ocean applications• the difficulties inherent in tracking a biochemically evolving mass of water are significant and cannot

be underestimated

• Ecosystem shifts – Shift phytoplankton and deep sea benthos which is fueled by the rain of particulate organic

matter– All new organic matter will result in increased respiration (i.e. O2 removal)– Potential for cascading and transforming ocean ecosystems (THIS IS BOTH AN

ENVIRONMENTAL AND ETHICAL ISSUE)• “we believe that any proposed strategy to intentionally perturb marine ecosystems using artificial

upwelling is premature and should be avoided until the sign and magnitude of potential outcome scenarios can be verified for a given habitat” (White et al. 2010)

• Quantifying carbon capture– This only works if you put the carbon into “slow” cycle (i.e. Volcanic)

Wave Energy Extraction (review)

• Not a trivial amount of energy:• A “big wave” Example:

– Deep water wave, H = 2m, T = 10 s– L = 156 m (deep water), c = 15.6 m/s (deep water)– Energy = 5000 J/m2

– Power = 1.6x1010 W = 16 GW (16,000,000 kW)• Average annual US Household electricity consumption per year?

11000 kWh or 1.25 kW• This one wave could power 12,800,000 households for a year• Equivalent gallons needed for this much energy?

– Gasoline: 456,000 gallons– Natural gas: 2,267,000 pounds

Wave parks (Oregon Coast, high energy)

Toleak Point, Washington State Peninsula CoastOlympic National Park

What main physical driver structures this amazing system?

Environmental Issues?

Cloud Brightening• An actual publication

https://www.youtube.com/watch?v=fg7J8P-uXqM

Geoengineering … (not talking Fe here)

Geoengineering … (not talking Fe here)

Geoengineering … (not talking Fe here)

“A city of the equatorial region where sunlight is plentiful and the impact of typhoons is minimal.”

“An area rising 700-1,000m above the equator. Here you find an energy-conserving compact city that is pleasant and peaceful, with no strong winds and a temperature of about 26-28°C year-round.” Any environmental issues?

You be the judge

Take Home Points (Proceed with Caution!)

• 1) Messing with the ocean requires understanding of consequences– We need study of these potential

consequences• 2) There is only one ocean, drawing

down nutrients in one place messes with something “down stream” (Sarmiento et al. 2004)

• 3) Organisms have evolved for specific niches, rapid changes (in the geological record) can result in mass extinction– Is this something we understand or

are even prepared for?