Editor's Note: Today we welcome Jeanne Roberts to the writing team. Jeanne hails from Minneapolis, Minnesota, and kicks off her Celsias tenure with an interesting post on what not to do with our oceans.
 Coccolithophore |
I’m always less than overwhelmed when scientists make a discovery that purports to solve a worldwide problem. Genetically modified foods were one such discovery, and their consequences (plant DNA destabilization, increased use of pesticides, severe allergic reactions) are only now appearing on the average person’s radar. The idea that algae may save the planet from widespread warming is another. Some scientists have pinned their hopes on coccolithophores, one-celled marine plants that occupy the bottom of the oceanic food chain and live in the upper layers of ocean water. They make up half the ocean’s biosphere, and use photosynthesis to convert water and carbon dioxide into carbohydrates (for food) and oxygen. They feed zooplankton, which in turn feed krill, which are then eaten by crabs, fish and whales.
Each coccolithophore wears its own armor, a calcite shield that uses one part carbon, one part calcium, and three parts oxygen. As these tiny marine creatures build, and then shed, their armor, they produce an abundance of calcite, or limestone, which settles to the ocean floor, sequestering the carbon component. For every ton of limestone deposited, 320 pounds of carbon is captured forever. Along the way, a certain percentage of carbon dioxide is also produced. The problem is, scientists don’t know how much. Initial experiments to determine this failed, because the researchers simply dumped dissolved carbon dioxide into water, killing the coccolithophores, which ultimately disintegrated without performing their magic.
Later experiments, which involved pumping oxygen mixed with carbon dioxide gas into a vat filled with coccolithophores, produced more reliable results and reportedly supported field observations, which suggest that, over the past two millennia, coccolith deposits on the ocean floor have increased 40 percent. In other words, coccolithophores are responding to global warming and atmospheric concentrations of carbon dioxide. They may even be able to double their rate of carbon sequestration (from 380 to 760 parts per million, for example). If so, they may be handy to have around in this era of rising global temperatures.
The problem is, the experiments only focused on one species and didn’t account for a vast range of variables in ocean conditions – some of which (like reduction through grazing) may have escaped scientific observation. Otherwise, the experiment does suggest that Nature has its own method of dealing with global warming. After all, the earth has been through warming before, even if man hasn’t. Coccolithophores, which appeared in the early Jurassic and died back by about two-thirds in the Late Cretaceous, are one of Nature’s coping mechanisms. The tiny creatures solve warming by “blooming”, a process which leads them to consume dissolved carbon dioxide, nitrate, and phosphate while producing oxygen, ammonia, and dimethyl sulfide, or DMS. This DMS, released into the atmosphere, creates clouds which block sunlight. This prevents photosynthesis, and the coccolithophores die off, taking their burden of carbon to the ocean floors with them.
Then the cycle begins again. Some see this as a natural, Earth thermostat. Others say that coccolith blooms prevent the ocean from absorbing heat from sunlight, thus cooling the water and possibly interfering with ocean currents that regulate global temperatures. These currents, collectively known as the Ocean Conveyor, distribute heat around the planet. Encouraging blooms in an effort to sequester carbon dioxide could lead to rapid and devastating climate change on an order not anticipated under current warming scenarios. In any case, there’s no sense in waiting for Nature to come to our rescue, if indeed She can. We need to move immediately to reduce carbon dioxide emissions from all sources, particularly transportation and energy generation. Having polluted most of the air, water, and soil, our approach to oceans - whose regulatory effects on earth’s climate are largely unknown – should be reverent rather than reckless. Anything else spells disaster, and is about as dangerously uninformed as the recent proposal to seed the ocean with iron-enriched fertilizer to encourage these phytoplankton.
Science has brought humanity many improvements. It also has a bad habit of getting the cart before the horse by failing to consider the eventual ramifications of its assault on Nature – which it commonly refers to as progress. Interfering with the oceans may be one cart that, when tipped, also tips the ecological balance beyond redemption. Further Reading:
