But it’s important to remember that life can also drastically impact the basic physical conditions of the Earth’s systems. Oxygen in the atmosphere is the result of plant photosynthesis, making the Earth habitable for the entire animal kingdom. And some interesting research is showing that the reflectivity of clouds — which radiates sunlight back into space, thereby serving as a planetary cooling system — is influenced by the metabolic process of tiny marine bacteria.
At the Society for Microbiology’s spring meeting in Edinburgh, Newcastle University postgraduate researcher Michael Maguire gained a lot of attention for his experiments simulating ocean acidification. The greater the acidity, the greater the die-off in an important type of bacteria known as the Marine Roseobacter clade.
The Marine Roseobacter breaks down a sulphur compound, dimethylsulfoniopropionate (DMSP) that’s produced by photosynthesizing phytoplankton. Much of that end product is used by other bacteria as a source of sulphur or breaks down further into dimethylsulfide (DMS), incidentally the chemical compound that’s responsible for the smell of the seaside.
When oxidized into the atmosphere, DMS turns into sulphur aerosol particles that make clouds reflect sunlight.
It’s a complicated process, but some have hypothesized that this system operates as a major feedback loop between the oceans and the Earth’s climate. So what happens when the metabolizing Marine Roseobacter can’t withstand the lower pH of ocean water?
How will the ocean food chain survive without the availability of sulphur? And will less sulphur in the air result in a drop in atmospheric reflectivity, thereby warming the climate further? The feedback of biological and physical processes flattens when just one building block falls down.