The rising threat of upwelling: marine life in crisis

The climate crisis has various faces and its effects continue to alarm the scientific community. The subject of a new study is the upwelling of deep water, a phenomenon responsible for a massacre of marine animals in South Africa

Climate change spares nothing and no one. It has dramatic impacts on wildlife and flora across the globe, and off the coast of South Africa, it has caused a massive die-off involving 81 different marine species.

Scores of sharks, rays, and other specimens perished in the year 2021, and researchers can now explain exactly what happened to the marine megafauna in these waters. The details emerge from a new scientific study published in the journal Nature Climate Change.

A team of scientists analyzed this terrible mass mortality event that occurred in 2021 and discovered that the climate crisis is responsible for an increase in the upwelling of deep waters, leaving no escape for sea inhabitants.

The phenomenon, known as upwelling, is a process that occurs due to the action of the wind which, by “pushing away” the surface water, favors the rise of deeper, colder, and nutrient-rich ocean waters.

It’s a trap that can prove lethal for marine fauna. Many marine animals have died in these upwelling currents, with no possibility of escape. Their carcasses were recovered on African beaches.

Documented in detail

Researchers have documented the event in detail, initially monitoring a bull shark, Carcharhinus leucas, and subsequently other sharks. The study’s findings indicate that the intensity and frequency of the upwelling of deep ocean waters have locally increased between 1981 and 2022.

The data is disturbing, according to researchers, as it highlights further pressures on an already extremely fragile biodiversity. These are consequences upon consequences, a fearsome chain reaction, where everything is traceable back to the climate crisis.

This underscores the potential impacts of the increase in cold events and also the complexity of climate changes on marine ecosystems as oceans are generally warming, but climate change can simultaneously shift currents and winds to produce brief but intense cold spells,” explained Dr. Lubitz, the lead author of the study.

We know, in fact, that climate change and the abnormal temperatures of the waters push subtropical species to explore new regions, expanding their range of distribution. But it is precisely in these territories that they can fall victim to mass mortality events due to upwelling.

Unlike other phenomena, the effects of these “cold waves” are still understudied. Researchers are sounding the alarm.

Source: Nature Climate Change