marine heatwave

A starfish to the rescue

June 3, 2025 By EarthWise Leave a Comment

Beginning in 2013, a mysterious disease associated with a marine heatwave decimated the population of sunflower sea stars. Those huge, colorful 24-armed starfish thrived along the Pacific Coast between Alaska and Baja California. But in fairly short order, nearly six billion of the creatures perished, amounting to 94% of the global population. California lost 99% of its sea stars to the wasting disease.

The result was an ecological disaster. Sunflower sea stars are carnivorous and purple urchins are the mainstay of their diet. Without sea stars to balance the food web, the urchin population exploded. Urchins devour kelp and over the past decade, 96% of the region’s kelp forests vanished. Kelp forests serve as shelter and food for a vast array of marine life and kelp sequesters carbon as much as 20 times more than terrestrial forests.

Researchers in California and Alaska are breeding sunflower sea stars in captivity to try to produce enough of the creatures to support reintroduction. The first successful spawning of sea stars took place last year at the Birch Aquarium at San Diego’s Scripps Institution of Oceanography. But all of these are siblings, which is not a desirable breeding stock for a new population. So, they are now working with the Alaska SeaLife Center, which has the largest collection of the animals in the world. The center will provide animals to introduce genetic diversity to the growing population in captivity.

The hope is to be able to reintroduce sea stars to the Pacific region within three to five years.

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A rare, giant starfish could hold the key to restoring kelp forests on the California coast

Photo, posted November 11, 2007, courtesy of Patrick Briggs via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

2023: A year of extreme climate

September 11, 2024 By EarthWise 1 Comment

There have already been all sorts of extreme weather this year in many parts of the world and undoubtedly there will be more to talk about in the coming months. But the American Meteorological Society has recently published its State of the Climate report for 2023 and it was a year for the record books.

In 2023, the Earth’s layers of heat-reflecting clouds had the lowest extent ever measured. That means that skies were clearer around the world than on average, a situation that amplifies the warming of the planet. Since 1980, clouds have decreased by more than half a percent per decade.

The most dramatic climate effect last year occurred in the world’s oceans. About 94% of all ocean surfaces experienced a marine heatwave during the year. The global average annual sea surface temperature anomaly was 0.13 degrees Celsius above the previous record set in 2016. This is a huge variation for the ocean. Ocean heatwave conditions stayed in place for at least 10 months in 2023 in vast reaches of the world’s oceans. Ocean heat was so remarkable that climate scientists are now using the term “super-marine heatwaves” to describe what is going on.

There were many other ways in which 2023 experienced weather extremes. July experienced a record-high 7.9% of the world’s land areas in severe drought conditions. During the year, most of the world experienced much warmer-than-average conditions, especially in the higher northern latitudes. These unprecedented changes to the climate are unlikely to be one-time occurrences; 2024 is likely to be another one for the record books.

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New Federal Report Details More of 2023’s Extreme Climate Conditions

Photo, posted May 27, 2021, courtesy of Wendy Cover/NOAA via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

The Collapse of Northern California Kelp Forests | Earth Wise

March 30, 2021 By EarthWise Leave a Comment

For thousands of years, thick canopies of kelp formed an underwater forest spanning the coast of Northern California. Kelp is the cornerstone of a rich subtidal community, providing food and habitat for all sorts of marine creatures. But in recent years, a shocking transformation has occurred. Satellite imagery reveals that the area covered by kelp forests off the coast of Northern California has declined by more than 95%. Only a few small, isolated patches remain.

In a new study, researchers at the University of California Santa Cruz found that the kelp forest decline was an abrupt collapse as opposed to a gradual decline.

According to the study, which was recently published in the journal Communications Biology, kelp forests north of San Francisco were resilient to warming events in the past, like El Niños and marine heatwaves. But the decline of a key sea urchin predator – the sunflower sea star – from sea star wasting disease caused the kelp forests’ resiliency to plummet. Sea urchins are voracious consumers of kelp.

But it was a series of events – not just the sea urchins – that combined to decimate the Northern California kelp forest. A marine heatwave that became known as “the blob” developed in 2014 and moved down the West Coast in 2015. Around the same time, a strong El Niño event developed and brought warmer water up the coast from the south. The warming ocean waters combined with the ravenous sea urchin population resulted in the dramatic decline of kelp.

According to researchers, the prospects for a Northern California kelp forest recovery remain poor unless sea urchin predators return to the ecosystem.

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The collapse of Northern California kelp forests will be hard to reverse

Photo, posted August 13, 2019, courtesy of Sara Hamilton of OSU College of Science via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.