Is This Our Warning to Change While We Can?

The Atlantic has an article "Climate Change Is Going to Be Gross." It's about the Sea of Marmara, near Istanbul, and the mysterious appearance of something called "sea snot."

Marmara is an inland sea entirely within Turkey that connects the Black Sea with the Aegean.

A few months ago reports surfaced about the appearance of nasty sea snot accumulating on the surface of the Marmara Sea.

The mean surface temperature of the Marmara, like that of many seas, is rising due to climate change, but the Marmara’s has increased by 2.5 degrees Celsius—1.5 degrees more than the global average, making it a leading indicator for seas around the world.

This intense warming, along with decades of abuse from pollution and overfishing, sent the Marmara into a state of maritime shock. At the end of 2020, increased concentrations of phosphorus and nitrogen led to a boom in phytoplankton, single-celled organisms whose name means “plant drifter” in Greek. The Marmara’s warming surface temperature also caused its waters to stratify, slowing the currents that would normally help disrupt algae growth.

Meanwhile, the bacteria in the mucilage degraded, releasing enough gas to inflate small surface bubbles, ballooning the mucilage into conglomerates that scientists call “clouds.” With the clouds acting as sails, Turkey’s fierce westerly lodos pushed the mucilage around the Marmara. Some flocs—as loosely clumped masses of mucilage are called—sailed all the way to Greece, raising concerns about the international spread of bacteria and viruses (none of my sources was aware of any reports of illness directly attributed to the mucilage).

Eventually, the phytoplankton began to run out of nutrients, causing the cells of some species to exude a sticky substance. As these cells died, they collided and stuck together, aggregating into globs that hovered in the warmest layer of the stratified water. With time and exposure, the globs turned into a submerged mat of mucus that trapped nearly everything around it—bacteria, fish larvae, dead cells, debris. Bacteria thrived on the dead phytoplankton, adding to the mat’s mass. “At that point, it takes on a life of its own,” Mustafa Yucel, a marine-science professor at Middle East Technical University’s Institute of Marine Science, told me. With increasing water temperatures, he said, we should prepare to see more extreme reactions in our seas—including invasive-species outbreaks and massive algal and seaweed blooms.

...As the mucilage drifted below the surface, it started to rot, beginning a nasty metamorphosis. The decay was spurred by viruses and bacteria that multiplied in the mucus and ruptured the dead phytoplankton cells, causing them to release more mucus and gas. As the gas inflated the mucilage, it began to rise. In May, it broke the surface of the Marmara, making its grand entrance into the public eye. It pooled in the shallow bays near Gebze, haunted the harbors around Erdek, and flourished on the shores of Istanbul’s tony Princes’ Islands. Kadıköy smelled like rotten eggs. Headlines about the sea-snot outbreak went viral, and the world recoiled in disgust.

A warming sea, stratifying waters, slowing currents and gas, smelling like rotten eggs, bubbling at the surface. These things brought to mind of a book I bought years ago by University of Washington paleontologist, Peter Ward, "Under a Green Sky."  Written in 2007 it's more relevant and much more urgent than ever.

Ward had researched Earth's six great mass extinctions. One of them resulted from an asteroid hit, the one that killed off the dinosaurs. The others, all five of them, were what Ward called "greenhouse extinctions."  Somehow professor Ward managed to sum up the entire process in one paragraph:

First, the world warms over short intervals of time because of a sudden increase of carbon dioxide and methane... The warmer world affects the ocean circulation systems and disrupts the position of the conveyor currents. Bottom waters begin to have warm, low-oxygen water dumped into them. Warming continues, and the decrease of equator-to-pole temperature differences reduces ocean winds and surface currents to a near standstill. Mixing of oxygenated surface waters with the deeper, and volumetrically increasing, low-oxygen bottom waters decreases, causing ever-shallower water to change from oxygenated to anoxic. Finally, the bottom water is at depths were light can penetrate, the combination of low oxygen and light allows green sulfur bacteria to expand in numbers and fill the low-oxygen shallows. They live amid other bacteria that produce toxic amounts of hydrogen sulfide, and the flux of this gas into the atmosphere is as much as 2,000 times what it is today. The gas rises into the high atmosphere, where it breaks down the ozone layer, and the subsequent increase in ultraviolet radiation from the sun kills much of the photosynthetic green plant phytoplankton. On its way up into the sky, the hydrogen sulfide also kills some plant and animal life, and the combination of high heat and hydrogen sulfide creates a mass extinction on land. These are the greenhouse extinctions.

Ward was writing about a mass failure of the Earth's oceans.  Marmara is, of course, an inland sea which is, by comparison, something akin to an oceanic Petri dish. Could the Sea of Marmara be our canary in the coal mine?  In the days ahead I'll see if I can track down Peter Ward for his opinion.