Hungry Plankton Gobble CO2, Astound Scientists

Physorg
There is so much that scientists still do not know about Earth's climate, the oceans, the carbon cycle, and so much more. Recently, scientists were surprised to learn that plankton travel relatively long distances -- in terms of ocean depth -- to seek out both nutrients and CO2. Back to the drawing boards.

For almost three decades, oceanographers have been puzzled by the ability of microscopic algae to grow in mid-ocean areas where there is very little nitrate, an essential algal nutrient. In this week's issue of Nature, MBARI chemical oceanographer Ken Johnson, along with coauthors Stephen Riser at the University of Washington and David Karl at the University of Hawaii, show that mid-ocean algae obtain nitrate from deep water, as much as 250 meters below the surface. This finding will help scientists predict how open-ocean ecosystems could respond to global warming.

...Surface waters in this and other mid-ocean areas contain almost no nitrate or other plant nutrients. Yet each year, microscopic algae (phytoplankton) flourish in these vast, open-ocean areas. Although miniscule in size, these mid-ocean algae consume about one fifth of all the carbon dioxide taken up by plants and algae worldwide.
To solve this mystery, Johnson and his fellow researchers used a robotic drifter called an Apex float, which automatically moves from the sea surface down to 1,000 meters and then back again, collecting data as it goes. Researchers at the University of Washington outfitted this drifter with an oxygen sensor and a custom version of Johnson's In Situ Ultraviolet Spectrophotometer (ISUS), which measures nitrate concentrations in seawater.

...From January through October of each year, the instruments on the drifter showed a gradual increase in oxygen concentrations in the upper 100 meters of the ocean. At the same time, the float detected a gradual decrease in concentrations of nitrate in deeper waters, from 100 to 250 meters below the surface.
Johnson and his coauthors found that the amount of oxygen being produced near the surface through photosynthesis was directly proportional to the amount of nitrate that was being consumed in deeper water. _Physorg

Science is still relatively ignorant about the deep processes of life and climate on Earth. Certainly far too ignorant for humans to base the future of their civilisations upon half-baked computer models which leave out the most critical parameters -- and include too much uncertainty to reliably predict anything at all.

Science is just barely beginning to learn a few of the things it would need to know to predict a future climate. It is time for the rational humility of our present limitations to enter science at all levels once again -- particularly in the areas where science intersects with politics and public technological and economic policy.

There are a large number of ocean organisms that take CO2 out of the atmosphere on a semi-permanent basis -- as is obvious from observing geologic phenomena such as limestone and chalk. Fossil fuels are still being formed under the oceans, as well as the massive layers of fossil rock. All of that carbon was cycled through life forms -- including the lowly plankton.