Iron Salt Aerosol

ISA could provide major commercial benefits for industries such as insurance, shipping, tourism, energy, fishing, mining, chemicals and agriculture, through reducing the business impact of climate change and reducing the damage these industries cause to the climate.

No.  A range of hypothetical risks could arise from adding iron to the ocean, relating to plankton blooms, oxygen levels and permanence of carbon removal, but our calculation, to be validated by field testing, is that ISA will not cause any harm. The low iron concentration of ISA is expected to generate phytoplankton growth that will increase biological activity up the entire food chain, delivering major benefits for biodiversity and cooling. The field trials will measure phytoplankton properties to provide clear information on actual effects.

Jellyfish booms result from human impacts including overfishing and warmer seas. ISA can counteract these problems by increasing the overall biomass in the ocean food chain, benefiting predators and competitors of jellyfish such as tuna and sardines. ISA could further reduce jellyfish numbers by cooling the ocean surface.

Positive effects would far outweigh any localized adverse changes.  ISA will increase primary productivity at the base of the ocean food chain, increasing quantity and diversity of all kinds of fish and ocean life. As a result, the location where some nitrate, silicate and phosphate nutrients in surface water are consumed by plankton will change, mainly increasing but possibly also decreasing in some locations. The scale and effect of these changes are expected to have major benefits for biodiversity, and will require monitoring and modeling as part of the ISA field test process, with scientific confirmation of benefits an important factor in decision to scale up ISA.

The world oceans have abundant phosphate and nitrate nutrients in deep water, but at the surface, the nutrient level is mostly less.  In large regions, more than sixty million square kilometres or 20% of the world ocean surface, lack of iron creates ocean deserts with low biological activity – High Nutrient Low Chlorophyll or HNLC regions. ISA will result in mixing water from different ocean levels, increasing total biomass and primary productivity. 

Contributing factors to ocean mixing include activation of brine production by enhanced winter ice freezing, less stratification of ocean water by reduced ice cap melting, and increased krill swarms due to greater volume of phytoplankton. 

Huge swarms of krill move up and down hundreds of meters every day, eating plankton on the surface at night and resting in the deep water in the day. The krill move through a barrier called the thermocline, in and out of the higher nutrient deep ocean water. This daily movement helps to fertilize the surface water. By increasing plankton growth, ISA will increase krill population, thereby increasing the daily transport of deep water into the top layer.  This will help replace nutrient removed by phytoplankton growth, reducing change to downstream nutrient levels.

ISA is the only available way to fertilize oceanic plankton at low and even dosage. By cooling the ocean surface through multiple effects, ISA enables the ocean to absorb more oxygen. Further, ISA protects against low oxygen (anoxia) by promoting increased vertical cycling of the ocean water.

The main issues for upper limits are theorised with far higher iron concentration than delivered by ISA, and include downstream depletion and anoxia. Using all the available nutrients in one region with added iron would constitute the upper limit, but ISA is well below these levels, and ISA nutrient uptake is counteracted by causing krill to bring up deep ocean water nutrients. While adding to the total productivity and biodiversity, specific impacts of iron limits in sensitive locations indicate the need for careful measurement. Similarly, depletion of ocean oxygen levels from concentrated plankton blooms constitute a limiting factor, as seen in dead zones caused by agricultural runoff from rivers. The concentrations of iron from ISA are well below the level where these effects occur. At ISA level these factors are outweighed by the broad benefit for biodiversity of increasing overall uptake of otherwise unused nutrients.

Research is planned to determine how iron delivered with ISA can activate microbes that consume and degrade marine micro plastics, helping to remove a significant source of ocean pollution.

No. The ISA plume only acts within the first kilometre above the ocean, where its chlorine is expected to deplete ozone that causes warming, as well as chlorofluorocarbons. The ozone layer that stops UV radiation is twenty kilometres high, in the stratosphere. ISA chlorine will be completely removed in the lower atmosphere by reaction with methane and other gasses, and will never rise to the stratosphere.

A primary blockage for ISA is the widespread false belief among advocates of action on climate change that reducing emissions is the only way to stop global warming.  This belief ignores the potential low cost and high impact of carbon dioxide removal technologies such as ISA, seeing research on carbon removal as detracting from the political focus on emission reduction. 

Another widespread false assumption is that the settled science of climate change means political strategies to restore the climate are equally settled.  This is wrong, because the Paris Accord plans to only remove 10% of planned emissions, and has no effective strategy to hold warming below four degrees. Achieving climate restoration must remove embedded warming from past emissions, through carbon dioxide removal methods such as ISA. 

Due to the political nature of UN climate forums, we will need to contest their guidelines to fully deploy ISA in the event that our coastal trials are successful.