A jumble of syllables akin to a complicated wizarding spell, the term is actually the name for an extremely important chemical that has global impacts. Scientists don’t bat an eye at such a tongue-twister, but for those not in-the-know some explanation is needed. For Karen Romano Young, artist and science lover, a few simple cartoons are the key to conveying complicated topics that are nevertheless exciting and important. Her most recent project, the Antarctic Log, delves into the world of plankton, microbes and dimethylsulfoniopropionate (which, thankfully, scientists have abbreviated to DMSP)
Chasing down the story of DMSP has kept scientists busy for over a decade. Off the coast of Antarctica in the surface waters of the ocean, microscopic algae, including one called Phaeocystis, have the power to change the weather. The key to their weather-controlling abilities lies in the production of DMSP, its breakdown to dimethyl sulfide (DMS) – another complicated but important name—and the release of DMS from the ocean into the atmosphere. It is that last step that contributes to the formation of clouds. But cloud making was never the intent of the tiny plankton. For them, it is a matter of life or death.
Phytoplankton spend their lives at the mercy of ocean currents. Unlike larger mobile animals, these microscopic algae cannot avoid a harmful experience such as an oncoming predator or a patch of bad weather and instead must fortify themselves against whatever comes their way. This is where DMSP plays a role. Scientists believe that it is one of many protective chemicals in the tiny algae’s arsenal to help them survive in an unpredictable environment. In this manner, a freezing spell can be combatted by the production of an antifreeze and the onslaught of a voracious predator can be deterred by the release of a distasteful chemical. The exact function of DMSP is still a mystery to scientists—they believe it could aid in deterring predators, avoiding viral infection, protecting against ultraviolet radiation, or preventing cells from freezing when the temperature drops.
Left alone, the algae lock away the DMSP within the borders of their cells to do its work. Come spring, however, sunshine and warming waters cause a bloom of phytoplankton, which in turn feeds a young and hungry crowd of zooplankton. In the feeding frenzy, algae cells are chewed and ripped apart, spilling the DMSP into the open ocean. The spilled innards of the algae create a microscopic feast for bacteria, who are able to break down the DMSP using special enzymes. This feasting tends to have gassy consequences, and as the bacteria digest the DMSP they produce the gas DMS, which rises to the surface and enters the atmosphere. A Phaeocystis bloom can cause a 10 to 100 time increase of atmospheric DMS compared to a day without a bloom.
All that gas provides a key ingredient in the recipe for making clouds. For a cloud to form, water droplets need bits of floating particles like salt, dust, fire soot, volcanic ash to cling to. DMS can also serve the same purpose. Once in the atmosphere, DMS is quickly altered by sunlight into small, sticky molecules that water droplets glom onto. When large amounts of DMS from a phytoplankton bloom float from the ocean up into the atmosphere and hitch up with water vapor, a cloud can be born.
A single cloud may seem like nothing more than a blip in the sky, but all together clouds act as major regulators of the Earth’s climate. When the sun’s solar radiation hits a cloud, it bounces back up into space rather than being absorbed by the land or ocean. More clouds mean a cooler planet, which suggests that Phaeocystis (and other DMSP-producing phytoplankton) act as part of a global thermostat regulator. It also means they may play a part in climate change, but the details are still being sorted out. With algae growth tightly linked to sunlight (which decreases in a cloudier world) it is tough to say whether Phaeocystis will thrive in a warmer climate or whether it will be overshadowed by the very clouds it helped make.
In the end, our global climate is impacted by algae no bigger than half the tip of a needle. It’s a complicated cycle, and therefore no surprise that the gas involved has a complicated name to match.