Produced by: Mohsin Shaikh
Satellite images revealed eerie green slicks in the Baltic—turns out, they’re made of pine pollen, not algae or oil, changing how we think about ocean surface phenomena.
Pine pollen, carried by wind and rain, clustered on the sea's surface—creating huge swirling slicks visible from space and tracked by satellites over two decades.
What looked like algal blooms in Sentinel-2 images baffled scientists—until spectral analysis confirmed it was dry land pine pollen masquerading as a marine event.
Credit: NASA Earth Observatory
These slicks aren’t just pretty—they carry loads of organic carbon into the sea, feeding microbes and fueling food webs in a way similar to leaf litter in rivers.
Credit: NASA Earth Observatory
Unlike harmful algal blooms, pollen slicks don't poison fish—but they do spike carbon and nutrient levels, possibly altering marine food chains in subtle ways.
Credit: NASA Earth Observatory
With pollen seasons growing longer and more intense due to climate change, scientists suspect these slicks may become more frequent—and more impactful—in coming decades.
Credit: NASA Earth Observatory
The European Sentinel-2 satellite spotted the slicks thanks to its multispectral eye, capturing the unique greenish tone that pinpoints airborne pollen deposits at sea.
Tracking pollen slicks could help map ocean currents, monitor environmental changes, and even offer insights into nutrient hotspots important for fish and plankton.
This discovery blurs the line between land and ocean systems—proving that what trees drop in spring can ripple far beyond forests, into the heart of marine ecosystems.