“Give me half a tanker of iron, and I’ll give you an ice age” is an often quoted remark made by the late John Martin in 1988. It may have been said in jest, but it was based upon serious science looking at the possible role of iron in the ocean in regulating the greenhouse gas, carbon dioxide (CO2). Iron plays a special role in marine food chains, as it is an essential ingredient for the growth of all marine algae (single celled plants). A little iron goes a long way to assist algae in converting CO2 into organic carbon during photosynthesis. Some fraction of this carbon is transported to the deep sea via the “biological pump”, where it remains for centuries to millennia, thus reducing CO2 in the atmosphere which would impact climate.
Already, we can thank the oceans for the removal of about one third of the man-made (anthropogenic) emissions of CO2. By several estimates, an additional 0.25 to 0.75 billion tons of carbon could be removed each year by adding iron to high nutrient low chlorophyll (HNLC) areas, such as the waters surrounding Antarctica where naturally low iron levels in seawater limit algae growth. Even more CO2 removal is possible if iron has effects in low nutrient waters, such as the central Pacific gyre.
However, the ocean iron and carbon cycle is much more complicated than adding a tanker of iron. Despite thirteen small-scale experiments that deliberately added iron to the ocean and studied the responses, many questions remain. Thus far, the science is relatively certain that adding iron to low iron ocean regions will increase the growth of marine algae, and hence the removal of CO2 in the atmosphere. However we still do not know the effectiveness of this process (how much added iron would result in how much CO2 removal?), nor do we understand the intended and unintended ecological impacts (will changes do more good than harm?). Issues of scaling are critical, and longer and larger experiments and improved modeling would help us resolve many of these key unknowns.
The genie is out of the bottle, and we contend that attempts to alter the ocean and climate by adding iron to the ocean will take place with or without good science. The ISIS Consortium and its members agree that it is better to resolve the unknowns with coordinated international research experiments. We need to be able to predict the consequences before we can support, suggest regulations or rule out ocean iron fertilization as a carbon removal tool.
The ocean is changing already. This can be seen by its higher temperatures, elevated sea levels, unsustainable fisheries, coastal pollution and the global increase in ocean acidity which can have serious impacts to corals, shellfish and other ecosystems that rely on them. Without the best science we may end up making the wrong choices, or take no action because of a lack of options.
On this page you will find links to several studies and resources regarding the role of iron in regulating ocean productivity and C sequestration. Additional pages of this ISIS web site provide a variety of resources geared to the public, scientists, policy makers and legal issue that arise with any attempt to alter the ocean’s common.