Record high ocean temperatures off southern California raise fears of prolonged marine heatwave | US news
For more than a century, shoreline stations have been Scripps Institution of Oceanography We measured water temperatures along the California coast. This year they are raising a warning sign.
Over the past three months, many stations have consistently recorded record-breaking daily high temperatures. La Jolla station At one point last month temperatures were recorded 10F above the historical average.
Southern California’s waters have historically warmed every few years as tropical currents move northward, a phenomenon known as El Niño. However, the marine heat wave that began last fall was not caused by tropical currents. Instead, a high-pressure atmospheric system (think calm, sunny days) has perched over southern California, warming both the air and sea above historic levels. On land, the same event helped fuel the severe California heat wave.
The expanding ocean warming has led to comparisons with the “Blob,” a three-year marine heat wave caused by similar prolonged high-pressure conditions a decade ago. devastated marine life. Scientists say the next few weeks will determine whether this marine heatwave fades or turns into something more like the Blob.
“The biggest concern is how the year will go,” said Andrew Leising, an oceanographer with the National Oceanic and Atmospheric Administration. “If the weather remains warm and is followed by a strong El Niño, we could face much larger impacts next fall and winter.”
It is typical for atmospheric conditions to change in the spring, producing northwesterly winds that push warm surface water back into the open ocean and allow cooler water from below to rise to the surface; This situation is called escalation. Upwelling brings nutrient-rich water from the depths to the surface, nourishing phytoplankton that plays an important role in supporting much of California’s marine life.
High water temperatures have cooled slightly in the past few days, raising the possibility that the heat wave may already be dissipating. But it will take more time to make sure the heat dissipates.
“The expectation right now is that even the waters as far as Southern California will start to cool down a bit next month, but that’s not a guarantee,” Leising said. “The concern is the order of events and how they unfold.”
Prolonged ocean temperatures have a devastating effect on phytoplankton and can lead to harmful algal blooms. These changes can harm many marine life, from sea lions to dolphins, from shorebirds to marine creatures. halibut. The Blob years led to one of the worst Dungeness crab seasons in recent history, said Melissa Carter, a researcher at UC-San Diego Scripps Institution of Oceanography.
Such heat waves are becoming more common and last longer, partly because oceans are slowly warming due to the climate crisis and partly because of atmospheric changes that scientists still struggle to understand.
“The question is: What is causing us to have these extremely high temperatures?” Carter said. “What are the drivers? That’s what we’re trying to find out.”
What concerns Carter is that when these high-pressure systems settle in an area, they create a “feedback loop” that reinforces warm, calm conditions, making them less likely to escalate, he said.
“If these systems become this strong and persistent where they come in year after year, they could have the potential to stop the rise,” Carter said. “Everything we think has to do with the health of west coast ecosystems could change forever.”
Continued ocean warmth offers some benefits, although they pale in comparison to the costs. Warm water temperatures bring tuna much closer to shore, making them easier to catch. Surfers and swimmers also enjoyed warmer water throughout the winter.
“I enjoy being on the water when there is a marine heat wave,” Carter said. “But our ocean shouldn’t be a swimming pool. Nothing can live in a swimming pool. That’s not what we want.”
