Rise of the DMS: from Phytoplankton-Bloomed Sea Clouds to Extra-terrestrial Life

By Vera Hsiang

Each spring, microscopic algae known as phytoplankton bloom into an army. When sun rays reflect off of their chlorophyll pigments, we see a sea of green, brown, or red. NASA scientists say that these massive blooms can be seen from space (Ramsayer & McNamee, 2023). Blooms can produce toxins and cause harm, but most of them are beneficial to their surrounding environments.

Phytoplankton serve as food for sea creatures and produce oxygen for us to breathe. These soldiers also fight global warming, creating clouds that keep our planet cool. However, phytoplankton did not evolve to produce clouds; they just wanted to survive.

Since phytoplankton float with the currents, they need protection. One of their most important arsenals is dimethylsulfoniopropionate, or DMSP. Per Smithsonian Ocean, this agent protects against ultraviolet radiation, keeps away predators, and serves as antifreeze when temperatures drop (Hall, 2018). While DMSP works hard when stored in phytoplankton cells, it plays another vital role when released.

Remember that spring bloom? As phytoplankton multiply, zooplankton begin a feeding frenzy. Phytoplankton cells get chewed up and all that DMSP spills out. Then, nearby cyanobacteria join the feast, breaking down DMSP into the gas dimethyl sulfide, or DMS, which rises from the water’s surface to fill the sky. Blooms can increase atmospheric DMS up to 100 times the usual daily amount (Hall, 2018).

Once airborne, DMS is quickly broken down by the sun into microscopic particles in the atmosphere. According to the Los Alamos National Laboratory, these “aerosol particles act as cloud condensation nuclei” because they are small sticky molecules that attract water (Wang et. al, 2018). As water droplets cling onto these seed particles, clouds are born.

So why do we care about clouds? Clouds serve as shields for our planet. They reflect sun heat and radiation back into space, and decrease the amount that reaches our lands and oceans. Clouds keep us cool and safe.

Understanding nature’s air conditioning system is just the beginning as scientists follow the DMS trail. Given how this molecule originates from phytoplankton life on Earth, it may also represent a biosignature outside our solar system. Using the James Webb Space Telescope, astronomers from the University of Cambridge have detected DMS “in the atmosphere of the exoplanet K2-18b, which orbits its star in the habitable zone,” suggesting phytoplankton life in space (Collins, 2025).
 
Though the DMS fingerprint may suggest life, scientists want more evidence. Proving that the signal is real will take independent teams of scientists. Asa Stahl, Science Editor of The Planetary Society, reminds us that prior sightings of another biosignature on Venus were not reproducible (Stahl, 2025). Furthermore, even if the DMS signal persists, a nonliving chemical process could explain its presence.

While only time will tell if DMS truly proves the existence of extra-terrestrial life, excitement on Earth still fills the air alongside the DMSP-DMS pipeline. As we continue to learn more about their significance in the cycle of life, the endless possibilities are putting scientists on cloud nine!

References
1. Collins, S. (2025). Strongest hints yet of biological activity outside the solar system. University of Cambridge. https://www.cam.ac.uk/stories/strongest-hints-of-biological-activity
2. Hall, D. (2018). The Cloud Factories that Live in the Sea. Smithsonian Ocean.
3. Leonard, D. (2023). Plankton Generate a Cloudy Shield over the Antarctic. Scientific American. https://www.scientificamerican.com/article/plankton-generate-a-cloudy-shield-over-the-antarctic/
4. Ramsayer, K.D., McNamee, E. (2023). NASA Wants to Identify Phytoplankton Species from Space. Here’s Why. NASA Explore. https://www.nasa.gov/centers-and-facilities/goddard/nasa-wants-to-identify-phytoplankton-species-from-space-heres-why/
5. Stahl, A. (2025). A possible sign of life on K2-18b? Here’s what it means — and why it's just the beginning. The Planetary Society. https://www.planetary.org/articles/possible-sign-of-life-k2-18-b
6. Wang, S., Maltrud, M.E., Burrows, S.M., Elliott, S.M., Cameron-Smith, P. (2018). “Impacts of Shifts in Phytoplankton Community on Clouds and Climate via the Sulfur Cycle.” Global Biogeochemical Cycles, 10 June 2018.