Untersuchungen zeigen, dass der vom Menschen verursachte Klimawandel in den letzten vier Jahrzehnten zu jeder globalen Korallenbleiche geführt hat. Die Forscher fanden heraus, dass Treibhausgasemissionen die Ozeane so stark erwärmt haben, dass El Niño nun hauptsächlich als Auslöser und nicht als Grundursache fungiert.

Every morning, as the Indian Ocean retreats from the reef off Zanzibar’s Jambiani village, Chiku Chande steps into the knee-deep lagoon carrying bundles of seaweed seedlings. Years of farming these waters have taught her about every channel and coral outcrop. But lately, the corals that once glowed in brown and gold have become chalky white.

“You don’t need anyone to tell you these changes,” Chande tells IPS. “We see it with our own eyes. The coral has lost its colour.”

Like many families in Jambiani, the 48-year-old grandmother depends on the reef. It shelters her seaweed farm from crashing Indian Ocean waves, supports fish stocks and brings tourists to the village. As the corals bleach and slowly die, she worries about the future.

Chande has watched the reef change year after year. Scientists say her observations mirror what is happening across the world’s tropical oceans.

Scientists long regarded El Niño – the natural warming of parts of the Pacific Ocean that disrupts weather patterns globally – as the main driver of mass coral bleaching

A new study led by Climate Central and published in Oceanography concludes that human-induced climate change has driven every global coral bleaching event over the past four decades. The researchers found greenhouse gas emissions have warmed the oceans so much that El Niño now acts mainly as a trigger rather than the root cause.

“Our study shows that without climate change, coral bleaching would be a rare and isolated event, and global mass coral bleaching simply would not occur,” says Andrew Pershing, Climate Central’s chief programme officer and the study’s lead author.

https://tos.org/oceanography/article/quantifying-the-role-of-climate-change-in-driving-mass-coral-bleaching