California State University Long Beach 

The "Gerotol solution"

• Growth of phytoplankton is limited by the availability of all required nutrients
• "The weakest link in the chain" is the lowest concentration of a required nutrient
• The "iron hypothesis" suggested that iron is the limiting nutrient in:
• The equatorial Pacific Ocean
• Antarctic Ocean
• Gulf of Alaska
• Past times of global cooling (e.g., Ice Ages) are typically arid
• Dryer conditions = more dust
• More windblown dust to ocean may stimulate photosynthesis and the biological pump of CO₂
• Adding needed nutrients (iron) to oceans
• May increase photosynthesis by phytoplankton
• "Give me half a tanker of iron and I’ll give you an ice age!" - John Martin
• Tested in the open ocean, 1993 and 1995
• Dilute iron compound dissolved in a 25 square-mile patch of surface water
• Produced up to a 30-times increase in chlorophyll and an 85-times increase in diatoms!

Problems with geoengineering solutions

• Sovereignty
• Who has the right to deploy such global schemes?
• Equity
• How are costs and benefits distributed among nations, industries, and individuals?
• Liability
• What happens if there are unintended consequences?
• Would developers be blamed for natural climatic fluctuations?
• Security
• Could these schemes threaten some people or countries?

Can provide excuses for doing nothing now, put action off until later

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