Earthweek: a diary of the planet

Weakening current

The long-feared weakening of the massive Atlantic Ocean circulation due to climate change appears to be underway. The Atlantic Meridional Overturning Circulation (AMOC) carries warmth to high latitudes and makes Northern Europe far more temperate than it otherwise would be. It’s also crucial for fisheries off the coasts of New England and the Canadian Maritime Provinces. But scientists from the Potsdam Institute for Climate Impact Research write in the journal Nature that the AMOC has declined in strength by 15 percent since the mid-20th century, reaching a new record low. Changes in ocean salinity, brought on by melting glaciers and ice sheets, are blamed for the slowdown.

Antarctic melt

Antarctica’s Larsen C ice shelf now melts in the dead of winter when the average temperature on the adjacent Antarctic peninsula is only 5 degrees Fahrenheit. It’s been known for a while that Antarctic ice shelves are thinning and

retreating, mainly because warmer currents below are melting them. But new remote sensors have found that downslope winds also can cause them to thin. These “foehn winds” blowing off Antarctica’s mountains can cause air temperatures to rise several degrees, sometimes to above freezing. The phenomenon had earlier been observed in summer, but it’s now happening in the depth of winter.

Plastic eaters

Mutant plastic-dissolving enzymes could help curb the increasing global plastic pollution that threatens marine life and

even the humans who eat it. Researchers from the University of Portsmouth, in Portsmouth, England, were studying a bacterium discovered at a Japanese dump in 2016 that had naturally evolved to eat plastic. While using ultra-intense beams of X-rays to examine the structure of the key enzyme produced by the bacterium, they accidentally improved the enzyme’s ability to break down the kind of plastic used to make beverage bottles.

Coral shield

Australian scientists have developed a "sun shield" that they hope can save the Great Barrier Reef from the coral bleaching that has ravaged the reef since 2016. The shield is an ultra-thin biodegradable film that floats on the ocean’s surface. The shield contains calcium carbonate — the same compound corals use to make their hard skeletons. Though it would be impractical to deploy the film over the entire 135,000-squaremile reef, the scientists say it could be selectively placed to protect the most precious or high-risk areas.

Eruption migration

Heavy ash and hazardous fumes from an active volcano on Vanuatu’s Ambae Island have prompted officials to permanently resettle most of the island’s 11,000 residents by the end of May.

Kenyan fractures

A second massive crack has ripped through the Kenyan landscape, but geologists assure nervous residents that neither means their country will break apart any time soon. They say both fissures were caused by heavy rains that soaked the area, causing the volcanic soil beneath to give way. The latest fault line, near the town of Naivasha, is more than a mile long and has destroyed crops and forced at least 16 families to move to safer ground. The earlier fissure, about 20 miles to the southeast, severed a road and forced other people to flee in late March. Scientists say a growing split in the African tectonic plate will eventually cause a slice of Africa to break away.

Earthquakes

Eastern parts of Japan’s Hokkaido Island were briefly jolted by a strong offshore earthquake. Tremors also were felt in western Quebec, central Nebraska, western Montana and western Oregon.