It’s not just us: Ocean heatwaves are changing the landscape beneath the waves.


For those who know what to look for, the world around us is on the move. Every ecosystem on the planet exists where it does because of the abiotic environmental factors that exist in any given location. Temperature, rainfall, prevailing winds, proximity to water sources – all of these things govern what lives where. The temperature is changing now. It’s changing more in some places than in others, but it is changing across the entire surface of this planet.

And so ecosystems are changing too. Range shift was one of the most predictable responses to a warming world. Plants die out at one edge of their range and expand at another, moving like giant, slow amoebas toward cooler temperatures, or more reliable water sources. Animals, not rooted in place, simply relocate. As the 21st century continues, we’ll see more reports of animals showing up where they never did before, and with them will come a variety of problems, not least being new diseases like the one behind the COVID-19 pandemic. For a while, my job involved keeping track of research into range shifts like this, particularly in the New England region of the United States. It’s been happening on both land and sea.

When it comes to the oceans, however, it’s a little harder to track what’s happening, and a lot of the news has focused on things like coral reefs, that see a lot of human activity, and make for dramatic pictures. High temperatures have been linked to coral bleaching and plankton decline, but I have to confess that I never really thought about “marine weather” as having things like heat waves. It makes perfect sense that such events would exist, of course, I just never thought about it in those terms.

Just as heat waves can cause a great deal of damage, and long-term change here on dry land, it seems they can also cause a great deal of change down where it’s wetter:

Changing Temperatures Highlight Management Questions

For example, a 2012 marine heatwave in the northwest Atlantic pushed commercial species such as squid and flounder hundreds of miles northward. At the same time it contributed to a lobster boom that led to record landings and a collapse in price.

“Given the complex political geography of the United States’ Eastern Seaboard, this event highlighted management questions introduced by marine heatwave-driven shifts across state and national lines,” the scientists wrote.

“While these management issues are often discussed in the context of climate change, they are upon us now,” the scientists wrote. “Modern day marine heatwaves can induce thermal displacements comparable to those from century-scale warming trends, and while these temperature shifts do not solely dictate species distributions, they do convey the scale of potential habitat disruption.”

A 2014-2015 Pacific marine heatwave known as “the Blob,” shifted surface temperatures more than 700 kilometers, or more than 400 miles, along the West Coast of the United States and in the Gulf of Alaska. That moved the prey of California sea lions farther from their rookeries in the Channel Islands off Southern California. This left hundreds of starving sea lion pups to strand on beaches.

Across the world’s oceans, the average long-term temperature shift associated with ocean warming has been estimated at just over 20 kilometers, about 13 miles, per decade. By comparison, marine heatwaves have displaced temperatures an average of approximately 200 kilometers, roughly 120 miles, in a matter of months. In effect, marine heatwaves are shifting ocean temperatures at similar scales to what is anticipated with climate change — but in much shorter time frames.

As the article states, this is going to have a lot of implications in the coming decades. According to the World Wildlife Fund, something like 3 billion people currently get a sizable portion of their protein from wild-caught seafood. As the ocean warms, traditional fisheries – already strained by over-fishing – are likely to collapse. This is something we should be preparing for. It may be that increasing the farming of fish will be a viable option, if we can work to reduce the environmental impact of doing so, and it’s probably a good idea to look into things like algae and insect farming to create new sources of protein to take pressure off both fisheries and to make it easier to scale back energy-intensive livestock farming.

As always, there’s a lot of work to do, and not much time in which to do it.


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