A beautiful, potentially toxic event is 'carpeting' the Baltic Sea

This striking green-blue image isn’t a lost work of Van Gogh — it’s a giant, growing bloom of microscopic plants and animals in the Baltic Sea, which NASA photographed from space on August 11.

But don’t let its beauty fool you.

NASA suggests the bloom might contain cyanobacteria. The marine bacteria are big oxygen producers but can threaten wildlife and even humans if they grow out of control. Some species can also be toxic. What’s more, cruise ships full of summer tourists might be inadvertently feeding the blooms.

Keep scrolling to see some incredible views of the bloom, including ships cutting through the biological “carpet” that’s coating a popular vacation spot.

NASA's Landsat 8 satellite constantly photographs the Earth. On August 11, 2015, it captured this section of the Baltic Sea.

Researchers saw what they think is a beautiful bloom of phytoplankton, made mostly of microscopic plants.

NASA Earth Observatory

It stretches for hundreds of miles across the sea.

'We steamed through 'carpets' of it the entire day,' one scientist on a research ship told NASA.

The researchers suspect the bloom is full of cyanobacteria, also called blue-green algae, which absorb sunlight like a plant.

But sometimes the beauty of blooms can be deceiving.

NASA Earth Observatory

Too many algae can overload waters: As they die, other bacteria eat them and use up oxygen in the water. This can create oxygen-depleted dead zones where 'organisms cannot survive.'

Other species of algae produce toxins that can sneak into fishes and shellfish, threatening the food supply.

Blooms of harmful algae are suspected in mass die-offs of other animals, including a recent killing of dozens of whales near Alaska.

Dr. Bree Witteveen/Alaska Sea Grant Marine Advisory Program


Meanwhile, cruise ships are reportedly still dumping sewage into the Baltic Sea. Along with fertilisers in agricultural runoff, this fuels bloom growth.

The Helsinki Convention of 1974 banded countries together to curb Baltic Sea pollution, but it may not be enough.

A Baltic Sea bloom in July 2014.


Climate change is draining more freshwater into the Baltic, which further encourages blooms to grow. So giant blooms appear somewhat regularly during the summer.



Addressing the problem will likely take the whole planet working together to reduce greenhouse emissions, slow climate change, and curb its disruption.

Earth from space as seen by Apollo 8 astronauts.


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