Climate change may bring acidic oceans full of jellyfish

One often-neglected result of climate change is ocean acidification. If this process continues, we may start to see fewer fish and more jellyfish.

Jellyfish
PHILIPPE HUGUEN/AFP/Getty Images
  • Since the beginning of the industrial era, humanity has been pumping out unprecedented levels of CO2 into the atmosphere.
  • A significant portion of this CO2 is sucked back into the ocean, where it reacts with water to produce carbonic acid.
  • Most species fair poorly in the newly acidic ocean. Jellyfish, however, seem to resist ocean acidification more than others.

Human beings don't do well when they try to understand things past a certain scale. When you consider the 7.5 billion people on the planet, you don't think of them in the same way as, say, the people who you meet walking your dog or your extended family. People can't conceive of how small the Earth is in comparison with the Sun, and people can't conceive of how broad and ubiquitous climate change really is — which is why some folks scoff at the idea when the Northeast US experiences record snowfall.

Most of us limit our understanding of climate change to the impact that CO2 has on our atmosphere and the resulting warming of the planet. But climate change is a multifaceted phenomenon. As we change our planet's chemistry, all environments experience a subsequent change, not just through the air we breathe but also in the oceans. The oceans of the future won't just be bigger from melting sea ice; they will become acidic seas where the jellyfish reign supreme.

Why the ocean you know and love won’t exist in 50 years

How CO2 turns oceans acidic

CO2 released into the atmosphere traps heat, driving the bulk of climate change's obvious effects. But not all of that CO2 stays in the atmosphere. Since the beginning of the industrial age, the world's oceans have absorbed 525 billion tons of CO2. Today, oceans suck up about 22 million tons per day, roughly a quarter of all the man-made CO2 released into the atmosphere.

In a way, this is helpful. If more CO2 was retained in the atmosphere, the faster the planet would heat up from the greenhouse gas effect. There's no such thing as a free lunch, however. As CO2 mixes with the oceans' H2O, the two molecules combine to form carbonic acid (H2CO3), lowering the oceans' pH and increasing its acidity. Under normal circumstances, natural processes from the dissolved minerals deposited into the oceans by rivers help to keep the oceans' pH levels in balance, but the rate at which oceans are absorbing our CO2 means this process has not been sufficient.

Life under ocean acidification

PHILIPPE LOPEZ/AFP/Getty Images

Nearly all forms of life are extremely sensitive to pH levels. You can imagine how difficult it would be for humanity if all of our air was slightly acidic — such is the case in the oceans. But, like any environmental change, there are losers and winners.

The most obvious loser in this new environment are species that build shells, like oysters, clams, and corals. Any disruption to a food chain puts an ecosystem in danger, but the increased difficulty that corals face when building their shells is particularly worrisome. Corals are a foundation species, meaning that they create and maintain a habitat for other species. Without them, an estimated 4,000 species will be at risk.

While many species of shell-building animals and fish are negatively impacted by ocean acidification, jellyfish don't seem to struggle much at all. One of the ways scientists discovered this was by looking at places in the ocean where CO2 levels are naturally higher, such as nearby volcanic seeps in the Mediterranean. In these locations, jellyfish and other "nuisance" species like dangerous algae exist in much higher numbers than elsewhere. Additional research, too, has demonstrated that as pH levels drop in the ocean, jellyfish numbers rise.

It's unclear how jellyfish will fare as the oceans become even more acidic in the future. So far, it seems they are resistant to acidification, but not immune to it. Some researchers believe that the selectivity of this damage — that ocean acidification seems to affect other species more — is what's leading to the jellyfish's rise. As their competitors and prey becomes less fit, jellyfish capitalize by ramping up their consumption.

As an example, one study looked at how well copepods and jellyfish fared in tanks of normal ocean water and tanks of acidified ocean water. Copepods are small, abundant crustaceans that are critical to ocean ecology, serving as a food source for nearly every species. When box jellyfish were added to the copepod tanks that contained normal ocean water, the jellyfish consumed 37% of the copepods. When added to the acidified tanks, jellyfish ate 83% of the copepods. However, it's not clear whether this occurred because the copepods had been weakened by the acidification, whether the jellyfish became hungrier under the strain of acidification, or some combination of the two.

Jellyfish numbers appear to be on the rise, and it looks like ocean acidification is to blame. Unless we learn to curb our CO2 outputs, it may be that our future oceans may become more gelatinous than we'd like.

A landslide is imminent and so is its tsunami

An open letter predicts that a massive wall of rock is about to plunge into Barry Arm Fjord in Alaska.

Image source: Christian Zimmerman/USGS/Big Think
Surprising Science
  • A remote area visited by tourists and cruises, and home to fishing villages, is about to be visited by a devastating tsunami.
  • A wall of rock exposed by a receding glacier is about crash into the waters below.
  • Glaciers hold such areas together — and when they're gone, bad stuff can be left behind.

The Barry Glacier gives its name to Alaska's Barry Arm Fjord, and a new open letter forecasts trouble ahead.

Thanks to global warming, the glacier has been retreating, so far removing two-thirds of its support for a steep mile-long slope, or scarp, containing perhaps 500 million cubic meters of material. (Think the Hoover Dam times several hundred.) The slope has been moving slowly since 1957, but scientists say it's become an avalanche waiting to happen, maybe within the next year, and likely within 20. When it does come crashing down into the fjord, it could set in motion a frightening tsunami overwhelming the fjord's normally peaceful waters .

"It could happen anytime, but the risk just goes way up as this glacier recedes," says hydrologist Anna Liljedahl of Woods Hole, one of the signatories to the letter.

The Barry Arm Fjord

Camping on the fjord's Black Sand Beach

Image source: Matt Zimmerman

The Barry Arm Fjord is a stretch of water between the Harriman Fjord and the Port Wills Fjord, located at the northwest corner of the well-known Prince William Sound. It's a beautiful area, home to a few hundred people supporting the local fishing industry, and it's also a popular destination for tourists — its Black Sand Beach is one of Alaska's most scenic — and cruise ships.

Not Alaska’s first watery rodeo, but likely the biggest

Image source: whrc.org

There have been at least two similar events in the state's recent history, though not on such a massive scale. On July 9, 1958, an earthquake nearby caused 40 million cubic yards of rock to suddenly slide 2,000 feet down into Lituya Bay, producing a tsunami whose peak waves reportedly reached 1,720 feet in height. By the time the wall of water reached the mouth of the bay, it was still 75 feet high. At Taan Fjord in 2015, a landslide caused a tsunami that crested at 600 feet. Both of these events thankfully occurred in sparsely populated areas, so few fatalities occurred.

The Barry Arm event will be larger than either of these by far.

"This is an enormous slope — the mass that could fail weighs over a billion tonnes," said geologist Dave Petley, speaking to Earther. "The internal structure of that rock mass, which will determine whether it collapses, is very complex. At the moment we don't know enough about it to be able to forecast its future behavior."

Outside of Alaska, on the west coast of Greenland, a landslide-produced tsunami towered 300 feet high, obliterating a fishing village in its path.

What the letter predicts for Barry Arm Fjord

Moving slowly at first...

Image source: whrc.org

"The effects would be especially severe near where the landslide enters the water at the head of Barry Arm. Additionally, areas of shallow water, or low-lying land near the shore, would be in danger even further from the source. A minor failure may not produce significant impacts beyond the inner parts of the fiord, while a complete failure could be destructive throughout Barry Arm, Harriman Fiord, and parts of Port Wells. Our initial results show complex impacts further from the landslide than Barry Arm, with over 30 foot waves in some distant bays, including Whittier."

The discovery of the impeding landslide began with an observation by the sister of geologist Hig Higman of Ground Truth, an organization in Seldovia, Alaska. Artist Valisa Higman was vacationing in the area and sent her brother some photos of worrying fractures she noticed in the slope, taken while she was on a boat cruising the fjord.

Higman confirmed his sister's hunch via available satellite imagery and, digging deeper, found that between 2009 and 2015 the slope had moved 600 feet downhill, leaving a prominent scar.

Ohio State's Chunli Dai unearthed a connection between the movement and the receding of the Barry Glacier. Comparison of the Barry Arm slope with other similar areas, combined with computer modeling of the possible resulting tsunamis, led to the publication of the group's letter.

While the full group of signatories from 14 organizations and institutions has only been working on the situation for a month, the implications were immediately clear. The signers include experts from Ohio State University, the University of Southern California, and the Anchorage and Fairbanks campuses of the University of Alaska.

Once informed of the open letter's contents, the Alaska's Department of Natural Resources immediately released a warning that "an increasingly likely landslide could generate a wave with devastating effects on fishermen and recreationalists."

How do you prepare for something like this?

Image source: whrc.org

The obvious question is what can be done to prepare for the landslide and tsunami? For one thing, there's more to understand about the upcoming event, and the researchers lay out their plan in the letter:

"To inform and refine hazard mitigation efforts, we would like to pursue several lines of investigation: Detect changes in the slope that might forewarn of a landslide, better understand what could trigger a landslide, and refine tsunami model projections. By mapping the landslide and nearby terrain, both above and below sea level, we can more accurately determine the basic physical dimensions of the landslide. This can be paired with GPS and seismic measurements made over time to see how the slope responds to changes in the glacier and to events like rainstorms and earthquakes. Field and satellite data can support near-real time hazard monitoring, while computer models of landslide and tsunami scenarios can help identify specific places that are most at risk."

In the letter, the authors reached out to those living in and visiting the area, asking, "What specific questions are most important to you?" and "What could be done to reduce the danger to people who want to visit or work in Barry Arm?" They also invited locals to let them know about any changes, including even small rock-falls and landslides.

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