Scientists have finally identified the surprising origin of the strange oceanic blobs that seem to circle the surface of the Baltic Sea: tree pollen.
Mystery spots are more visible in a corrected color satellite image (opens in a new tab) captured off the coast of Gdansk in Poland on May 16, 2018, but have turned up several times on satellite images in recent years.
The researchers knew that the eddy patterns were caused by currents driven by wind and waves moving the blobs on the ocean’s surface, but they weren’t sure exactly what they were made of. Experts initially suspected that they were algae blooms or “sea snot,” a slimy substance produced by some plankton.
However, in a study published in January in the journal Remote Sensing of the Environment (opens in a new tab)The researchers analyzed the reflective properties of the mysterious substance and found that it was more like pine pollen (wild pine). The appearance of the spots and direct observations by local scientists later confirmed that this is what the spots were made of, the researchers wrote.
Related: 10 stunning shots of Earth from space in 2022
Pine trees are the most common tree in Poland and account for more than 55% of the country’s forests, which in turn cover just under 30% of the country’s land area, according to state forests Poland (opens in a new tab). However, pollen from the trees was not previously known to have been washed so far offshore.
After identifying the pollen, the researchers looked at historical satellite images and noted that similar spots appeared 14 times between 2000 and 2021. The amount of pollen in the spots increased year by year, and the spots also began to appear earlier in the year. they found.
Changes in pollen counts during the study period reflect a global trend of increasing pollen counts caused by climate change.
In February 2021, a study published in the journal Environmental Sciences (opens in a new tab) revealed that in North America, pollen counts increased by 21% between 1990 and 2018, with the pollen season lasting about 20 days longer on average.
According to NASA earth observatory (opens in a new tab)these changes are the result of extra carbon dioxide in the atmosphere, allowing plants to produce more pollen.
Due to the high organic carbon content of the pollen, the team believes that follow-up studies are needed to fully assess the role it plays in ocean ecosystems.
“If we can track pollen aggregation in different locations, this may provide useful data for fisheries studies,” the study’s lead author. chuan min hu (opens in a new tab), optical oceanographer from the University of South Florida, to the Earth Observatory. The data could also complement ground-based pollen detectors in tracking long-term trends that might affect people with allergies, he added.