As global temperatures rise, our oceans are heating up. Scientists recently found that warmer ocean temperatures are leading to stronger eddy currents — swirling currents that transport warm or cold water to and from the critical ecosystems of the deep, per The Conversation.
What's happening?
While satellites can only measure the temperature at the ocean's surface, researchers have been using long-term moorings (buoys that take measurements at depth) and Argo floats (robotic divers) to monitor temperatures in the twilight zone in the ocean — between 200 and 1,000 meters deep.
Using these two instruments, researchers gathered 2 million high-quality temperature readings — also known as "profiles" — across the world's oceans over a period of three decades.
Their analysis, published in Nature, shows that higher ocean temperatures are causing stronger eddy currents. In turn, these eddies are able to cause more severe ocean heatwaves and cold spells.
According to NASA, about 90% of heat trapped by planet-warming pollution has gone into the ocean, and "the last 10 years were the ocean's warmest decade since at least the 1800s."
Eddies can be hundreds of kilometers across and reach over 1,000 meters deep. They are massive and can even be seen on satellite images.
The scientists' research showed that eddies are playing a major role in instigating marine heatwaves and cold snaps.
Higher ocean temperatures are making the eddies stronger, and stronger eddy currents are more likely to trigger extreme temperatures in the deep, which can lower oxygen levels and decrease nutrients in the water.
"We will need to find out what threat these combined changes pose to life in the twilight," per The Conversation.
Why are eddy currents important?
The twilight zone in the ocean is home to the largest migration on Earth and the planet's most abundant vertebrate, the bristlemouth. This fish thrives in the twilight and is estimated to have a population in the quadrillions.
This area within ocean waters is where many important fish species and plankton thrive.
Extreme temperatures in the deep can cause these species to move or even die, which affects the overall health of ecosystems such as coral reefs. The damage can also negatively impact fishing industries.
What's being done to protect ocean wildlife?
Because eddy currents can be seen with satellites, researchers can predict when deep cold spells and marine heatwaves are likely to occur. Scientists can then monitor the species and ecosystems affected by the extreme temperatures and evaluate the damage caused.
Ocean conservation strategies, including developing new tech and effective government policies, are critical to maintaining healthy biodiversity and a safer future for us and our planet.
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