The climate chain reaction that threatens the heart of the Pacific
Lined up along the side of their boat, the fishermen hauled a huge, heavy net up from swelling waves. At first, a few small jellyfish emerged, then a piece of plastic. Then net, and more net. Finally, all the way at the bottom: a small thrashing mass of silvery salmon.
It was just after dawn at the height of the autumn fishing season, but something was wrong.
“When are the fish coming?” boat captain Teruhiko Miura asked himself.
The salmon catch is collapsing off Japan’s northern coast, plummeting by about 70 percent in the past 15 years. The disappearance of the fish coincides with another striking development: the loss of a unique blanket of sea ice that dips far below the Arctic to reach this shore.
The twin impacts — less ice, fewer salmon — are the products of rapid warming in the Sea of Okhotsk, wedged between Siberia and Japan. The area has warmed in some places by as much as 5.4 degrees Fahrenheit since preindustrial times, making it one of the fastest-warming spots in the world, according to a Washington Post analysis of data from the nonprofit organization Berkeley Earth.
That increase far outstrips the global average and exceeds the limit policymakers set in Paris in 2015 when they aimed to keep Earth’s average temperature rise “well below” 3.6 degrees Fahrenheit.
The rising temperatures are starting to shut down the single most dynamic sea ice factory on Earth. The intensity of ice generation in the northwestern Sea of Okhotsk exceeds that of any single place in the Arctic Ocean or Antarctica, and the sea ice reaches a lower latitude than anywhere else on the planet. Its decline has a cascade of consequences well beyond Japan as climate dominoes begin to fall.
When sea ice forms here, it expels huge amounts of salt into the frigid water below the surface, creating some of the densest ocean water on Earth. That water then sinks and travels east, carrying oxygen, iron and other key nutrients out into the northern Pacific Ocean, where marine life depends on it.
As the ice retreats, that nutrient-rich current is weakening, endangering the biological health of the vast northern Pacific — one of the most startling, and least discussed, effects of climate change so far observed. [Continue reading…]