In July 2021, my family stood on our local beach in Vancouver toting towels and sunscreen, wondering why the shorefront looked a little odd. It dawned on us slowly. At low tide, all the mussels were open, lifeless shells that crunched ominously underfoot, cooked by the extreme heat wave that had gripped British Columbia the week before. Soon it was in papers around the world: One researcher guessed that the record-breaking heat must have killed more than a billion creatures along British Columbia’s shores.
Climate change has felt increasingly real and powerful over the past few years. Its impacts on the ocean have been heartbreaking for me, someone who grew up going to that same beach and who studied oceanography at university before becoming a journalist. Ocean surface waters have warmed about a degree Celsius since pre-industrial times, and that’s speeding up: This April, average global ocean surface waters hit 21.1 degrees Celsius for the first time in recorded history.
This June 8, on World Ocean Day, I’ll be standing on that beach trying hard to peer into the ocean’s future.
As anyone who has waited for their backyard pool to heat up in the sun knows, it takes a long time for water to warm. While our vast oceans have soaked up about 90 percent of the heat from climate change so far, their surface average temperature has increased less than the air. There’s a lot of warming left to go. By 2100, the top 2,000 meters of the ocean are expected to see two to six times the warming felt so far. Our waters are expected to keep heating up through 2300, even if we clamp down hard on emissions.
The ocean, like land, suffers from occasional heat waves that leave creatures sweltering; as the ocean warms, the extreme temperatures that accompany marine heat waves are going up too, cranking up the heat stress that wilts or kills marine life, including corals. The first-ever global coral bleaching event happened during a marine heat wave in 1998, as hot corals far and wide spewed out the marine microalgae they need to thrive. There have been two more global bleachings since then, and one coral expert has told me that another global coral catastrophe looks set to happen later this year. The longer-term forecast is that 70 percent to 90 percent of tropical coral reefs will disappear if global warming hits a landmark 1.5 degrees Celsius above pre-industrial times — which it’s expected to do in the early 2030s. That’s just a decade away.
The impacts of marine heat waves can be complex and unexpected. From 2013 to 2016, a patch of hot water nicknamed the Blob hit the west coast of North America. It drove whales closer to shore in search of food and spurred a harmful algal bloom that delayed the crab fishery — a confluence of events that pushed whales and crabs closer together in time and space, causing a record number of whale entanglements in nets. Right now, another blob is lurking offshore.
Meanwhile, the acidity of the oceans is rising as it absorbs skyrocketing levels of carbon dioxide. Ocean waters are now about 25 percent more acidic than in pre-industrial times. In 2012, the year my daughter was born, researchers reported that the shells of swimming snails in the Southern Ocean were dissolving. Creatures from mussels in the Pacific Northwest to pink maerl seaweeds in the Mediterranean are feeling the bite.
Warmer water can hold less dissolved gas (as you might know, a warm soda is flatter than a cold one), so the oceans are losing oxygen — from 1960 to 2010 oxygen levels went down about 2 percent, and that figure is likely to reach 7 percent by 2100. Like mountaineers gasping for breath on a high peak, many fish species are sent scurrying for higher-oxygen waters. Rockfish in California have migrated upward in the water column to catch a breath, and North Atlantic tuna have been squished into territory 15 percent smaller than usual by declining oxygen.
Heat. Acid. Deoxygenation. None are good. The resulting hot soup of an ocean will mainly be more hospitable to gelatinous creatures like jellyfish than to usual restaurant menu items like salmon. Fish will flee the tropics in search of cooler waters, leaving many island nations that rely on them for food facing empty nets. In the species that survive overfishing and climate change, individuals will likely be small and stunted by harsh conditions.
Then there are a host of other human impacts on our seas, from pollution with plastics and fertilizer runoff, to noise pollution that buffets and confuses echolocating dolphins and whales, to the terrifying idea of mining the seafloor for rare elements needed to make rechargeable batteries, scouring out ecosystems in the process.
So far, humanity has used the ocean as a dumping ground for heat and pollution. But there are signs that we might start to care for it better and harness its powers to heal. Several First Nations groups in my neck of the woods are exploring better ways to sustainably fish, harvest and steward our waters. A growing interest in farming kelp and restoring seagrass promises to help feed the planet, reduce water acidity, soak up carbon and provide refuges for fish. Electricity-generating kites flying from barges could help to ease the burden on land for wind farms, boosting clean energy supplies. And while the shipping industry expands, many of the new ships will be quieter, powered by innovative wind systems (like rotating poles, rather than sails, that are better at capturing wind), or by friendlier fuels like green ammonia.
Earlier this year, delegates to the United Nations finally bashed out a high seas treaty — a structure for international rules governing the vast expanses of ocean previously considered lawless pirate territory. Importantly, it sets out a feasible path for designating marine protected areas out in the open ocean, so we can have parks and sanctuaries for marine life in the high seas.
Recently, standing on that same beach, my kids and I saw a sea otter — an animal that was once nearly wiped out from these shores by the fur trade. Much effort has gone into bringing them back, and it has worked. The voracious otters feast on abalone and urchins, giving kelp forests a reprieve from these grazers, in turn bringing back underwater landscapes full of color and life. Sometimes, we humans can get some things right.
