Earlier this week, the news cycle in the USA heated up with stories about multiple extreme heatwaves washing across North America–especially in the normally cool Pacific Northwest region where triple-digit temperatures were literally off the charts. The result: the hottest temperatures ever (as in ever_) recorded.
Did you know that similar types of marine heatwaves are also wreaking havoc across the world’s oceans?
As a leading climate scientist, Dr. Michael Mann, and notable science communicator, Susan Hassol described in the New York Times, heatwaves now occur 3X more often as they did in the 1960s. They’ve also become larger, affecting 25 percent more area on land–and 25% more ocean area–in the Northern Hemisphere than they did in 1980.
"The science is clear on how human-caused climate change is already affecting heatwaves: Global warming has caused them to be hotter, larger, longer and more frequent. What were once very rare events are becoming more common."
While heatwaves on land seem to come and go relatively rapidly (think a week or less ), the lingering and long-term effects of prolonged marine heatwaves (months and even years) are having a lasting impact–including the loss of entire coastal ecosystems like kelp forests and coral reefs.
To find out why and how this is happening, and what we can do about it, take a deep dive with our own Chief Scientist, Kevin Whilden, a Geologist by training; who also loves to have "heated" discussions about the finer points of edge-surfboard designs (but that's a different blog post entirely_).
So Kevin, why is the global ocean heating up, and what are marine heatwaves doing to coastal ecosystems?
It's pretty simple really, the ocean has already absorbed over 93% of the excess heat from human-caused global warming within the last 50 years. And thankfully the ocean was there to do that, because otherwise, as the film Chasing Coral notes, the "average" temperature on the planet would be about 122 degrees Fahrenheit/50 degrees celsius. For context, the global average surface temperature right now on Earth is about 59°F.
So relatively speaking, we've turned the ocean into a bit of a "hot tub", as you can see in this graph (Kevin loves graphs) from a recent science report, which shows that warming in the ocean has seen a steady continuous rise since 1985, with ocean heat content hitting a record high in 2020.
"The Blob" - an anomalous mass of warm water in the Pacific Ocean
The reason that most people don't know more about the impact of marine heatwaves is that they usually occur out of sight, so it's out of mind for most of us. But the interconnected global world has been changing that, and the story of the vanishing kelp forests and coral reefs have been grabbing people's attention, in a way that a graph or a spreadsheet full of data never will.
The Blob and Coral Bleaching
In California, starting in 2012, a years-long heat wave called "The Blob" triggered the collapse of kelp forests in Northern California. Causing over 95% of bull kelp forests to disappear within a decade. National Geographic caught up with us and others to find out what could be done and highlighted the potential that our SeaTrees program can have towards solving this issue.
A warming ocean also affects coral reefs worldwide. In Australia, the Great Barrier Reef has experienced three mass-bleaching events in the last five years. This has raised international concern about the short & long-term survival of the collective reef ecosystem and films like Chasing Coral have been able to put this issue in front of Millions of people, right in their own homes.
It's not just ecosystems that are threatened by a warming ocean. There are many societal impacts. Hurricanes and other storms that travel over the sea become supercharged. Warmer water expansion increases sea level rise, causing coastal flooding. Especially during the aforementioned supercharged storms.
However, the most harmful impact of a warming ocean is “ocean stratification”, where the surface warms more quickly than the deeper ocean layers. This inhibits ocean mixing and the distribution of dissolved oxygen and nutrients, which disrupts the oceanic food chain and has been identified as the primary cause of mass extinctions in the geologic past.
The rate and scale of these impacts is unprecedented in geologic history. If we want future generations to have a healthy planet, we need to act with urgency.
Let's talk about the Arctic
The Arctic region is warming three times faster than the rest of the planet, through a process called "Arctic amplification". It recently hit 100 degrees for the first time ever.
Unfortunately, Arctic amplification is the primary cause of the heatwaves and other extreme weather mentioned above. Dr. Michael Mann published a 2018 paper in Science describing this process, by which a warming Arctic slows down the jetstream and increases the severity of extreme weather.
A warming Arctic also matters because thinning sea ice and melting permafrost are some of the most significant warming feedbacks in the carbon cycle. Read more on the danger of climate feedback loops in our blog post from last year.
So What's the Good News?
We recently wrote about some good news from Dr. Michael Mann, who like us, believes that there's still a clear pathway to solving these problems.
Furthermore, the ocean has the capacity to sequester excess CO2 from the atmosphere. It already contains 90% of the carbon in the carbon cycle. We just need to give it a helping hand–by protecting and restoring blue-carbon coastal ecosystems. You know, planting and protecting mangrove forests, restoring kelp forests, and protecting and enhancing ridge to reef watersheds.