Iron Isotopes as Tools in Oceanic Geoengineering

It has been widely agreed upon that oceans act as the largest carbon sinks of the world, engulfing vast amounts of carbon dioxide each year. The water in itself does not draw in carbon dioxide (CO2) – the main greenhouse gas that causes global warming. Rather, tiny organisms known collectively as the phytoplankton, which reside in most waters around the globe, do. These creatures are the very bottom of the food chain, and are consumed for food by nearly every larger marine creature. However, they play a fundamental role in delaying climate change.

The way they do this is through the same process that allows trees to 'breathe' in carbon and release oxygen in return, namely photosynthesis. During this process, CO2 and sunlight are converted into energy and oxygen. In the case of phytoplankton, this ability is crucial. While alive and near the surface of the ocean, they absorb vast amounts of carbon from the atmosphere through their sheer numbers. As they die, their carcasses sink to the ocean floor, carrying the stored carbon with them. The dangerous substance then gets trapped in sediments, and safely tucked away from the atmosphere.

There are, however, two main problems with this system. For starters, it cannot go on forever, as in the phytoplankton's ability to capture and store the billions of tons of CO2 humankind puts out each year will soon be overrun, if it hasn't been already. When this happens, the gas buildup in the atmosphere will accelerate significantly, and global warming will get worse every year. The second issue is that smaller numbers of phytoplankton are generated each year. Apparently, they lack iron oxide.

This chemical, alongside phosphate, nitrate and silicate – which can be found in the seawater in abundance – is the main source of food for the tiny organisms, and, at this point, they are short on it. That is why geoengineers have proposed using airplanes to drop vast amounts of the fine particles on the surface of the water, in an attempt to boost phytoplankton production. The idea is still being discussed at the highest levels, but critics believe that insufficient studies have been conducted in order to assess its probable outcome, and the dangers it could pose on the marine ecosystem, AlphaGalileo reports.