The impact of climate change on marine ecosystems is increasingly alarming, with rising ocean temperatures not being the only cause for concern. Recent research has unveiled that extremely cold upwelling events are also triggering mass die-offs in marine life. Moreover, the same pollution responsible for global warming could be contributing to these lethal phenomena at opposite temperature extremes.
In the past year, the world’s oceans have experienced unprecedented heat, leading to significant distress for marine organisms. Billions of crabs have vanished in the North Pacific, sea lions and dolphins are falling ill, and iconic coral reefs are enduring widespread bleaching.
While ocean temperatures are on the rise, the frequency and intensity of extremely cold upwelling events, which are generated by strong winds and ocean currents bringing cold water to the surface, have also been increasing. This poses a significant threat to marine life, as highlighted in a study published in the journal Nature Climate Change by Nicolas Lubitz, a researcher at James Cook University in Queensland, Australia.
Lubitz emphasizes that climate change is a multifaceted issue, impacting the functioning of oceans in various ways. Research into marine animal deaths, such as sharks, manta rays, and squid found deceased on the southeastern coast of South Africa in March 2021, spurred investigations into these extreme events.
The study analyzed the impact of these deadly cold upwelling events in the Indian Ocean Agulhas Current and the Australian Eastern Current using 41 years of sea surface temperature data and 33 years of wind records. The findings point to a concerning trend where the lethality of a cold event is increasingly linked to the speed at which the temperature drops, potentially leading to hypothermia and physiological failure in marine animals if the cold persists over several days.
Not only does this have implications for biodiversity, but it also affects local fishing communities as the health of fish stocks could be compromised. To gain a better understanding of these phenomena, Lubitz has tagged bull sharks with electronic devices to track their movements and monitor water temperatures at various depths, revealing that sharks avoid cold upwelling water by staying close to the surface.
This study sheds light on a lesser-known aspect of the climate crisis, highlighting its dual impact on oceans through extreme hot and cold events. The results underline the urgency of taking action to safeguard our oceans and the marine life dependent on them. Understanding and addressing all phenomena affecting our ecosystems is crucial to ensuring a sustainable future for our planet.
For more in-depth analysis and related articles, you can follow these links:
1. How Climate Change Could Be Driving Killer Cold Outbreaks in Oceans