海洋告急：关键洋流濒临崩溃

A crucial ocean current is at risk of shutting down. How close is this disaster and what happens next, asks Alec Luhn On a sunny evening in July, a research ship called the Sir David Attenborough was working near the Sorgenfri glacier in south-eastern Greenland when a kilometre-long wall of craggy, bulging ice collapsed into the fjord. The scientists on deck watched in stunned silence as an estimated 18 million tonnes of ice slowly flipped over, sending up vast plumes of spray. Iceberg calving on this scale was once relatively rare – but it has become commonplace in recent years as Earth warms. And that acceleration could have catastrophic impacts that extend far beyond Greenland. …