Imagine, for a moment, that you’re standing on a pier by the sea, grabbing a bowling ball, inexplicably. Suddenly, you lose your grip and it falls into the wave below with a decisive blow. Now imagine that the bowling ball is made of gas…carbon dioxide, namely compressed down to that familiar size and weight. That’s roughly your share, on a per capita basis, of the human-caused portion carbon emissions absorbed by the sea every day: Your bowling ball has extra CO2, plus 8 billion or so from others. Since the Industrial Revolution, the oceans have sucked up 30% of that additional gas.
The reason so much CO2 ends up in the oceans because that molecule is extremely hydrophilic. It likes to react with water — much more than other gases in the atmosphere, like oxygen. The first product of that reaction is a compound called carbonic acid, which soon removes its hydrogen ion. It’s a recipe for a caustic solution. The more hydrogen ions a solution has, the more acidic the solution is, that’s why when CO2 in the Earth’s atmosphere has increased, its water has also become more acidic. By the end of this century, models predict the oceans will reach unprecedented levels of acidity seen for millions of years. Previous periods of acidification and warming have been linked to the mass death of some aquatic species and the extinction of others. Scientists believe this round of acidification happens much faster.
Nina Bednaršek, a researcher at the National Institute of Biology of Slovenia, said that change was most dramatic and rapid in the planet’s northernmost waters, where the effects of acidification have been severe. She studies arthropods, tiny sea snails known as “sea butterflies” because of their translucent, shimmering shells that resemble an exotic pair of wings. But catching those snails from arctic waters, and taking a closer look at their exoskeletons reveals a worse reality. In more corrosive aquatic environments, once pristine crusts become flaky and pitted – a sign of early death. Those creatures are “coal-mine canaries,” as Bednaršek puts it — an important part of the food chain that supports larger fish, crabs and mammals, and a sign that many species will crashed as the oceans became more caustic.
Wei-Jun Cai, an oceanographer at the University of Delaware, says the icy waters of the Arctic are a special case for a number of reasons. One is melting ice. It normally acts as a lid on the water below it, preventing the exchange of gases between the atmosphere and the ocean. When it runs out, the water will absorb more CO .2 in the air above it. Plus, that melt water dilutes compounds that can neutralize acids. And then it usually just lays there, not mixing much with the deep water below. That results in a puddle near the surface that is more acidic. In a study recently published in the journal Science, Cai’s team looked at data from Arctic sea voyages between 1994 and 2020 and concluded that acidification is occurring at three to four times the rate of other ocean basins. “The acidification is going to be rapid, we know. But we don’t know how Cai said. The culprit, they surmised, was the rapid decline in summer ice extent during those years. From 1979 to 2021, the end of summer ice shrinks an average of 13 percent per decade.
However, it is difficult to give specific numbers on the rate of acidification across the entire Arctic seascape. In some places, the water is shallow and heavily mixed with melt and fresh water from the surrounding continents. Elsewhere, it is deeper and is currently frozen all year. Ideally, researchers want a window into everything: consistent data from year to year, covering a wide range of territories and different seasons, capturing churn that sometimes spans decades. decade of ocean currents. The short-term duration is also extremely important, as local conditions can change dramatically on a weekly basis depending on factors such as phytoplankton activity, which can bloom rapidly in an area during the summer. and suddenly suck up some CO2. But it’s hard to get the data there. Acidification scientists, like Cai, are observing through a narrow periscope — in his case, based on summer voyages through a relatively small part of the sea, where most of the time like it’s still locked.
But there are other ways to decipher the larger trends. James Orr, a senior scientist at France’s Atomic Energy Commission, uses global climate models to track trends in ocean salinity, temperature, and the movement of biological forces. learning in water, such as algae. His team was then able to make predictions about the location of the acidification. In a study that recently appeared in Nature, Orr and his co-authors have found that those models suggest that by the end of the century, the seasonal pattern of conventional ocean acidity could be improved. Algae blooms often reduce acidity in the summer. But as the ice melts and shrinks a few weeks earlier than it did a few weeks before, instead of offering a rebound, summer is poised to become the most acidic period of the year. For Orr, it was a startling conclusion. “We thought it was going to be pretty boring, maybe up to a month of model changes,” he said. “But it could be up to six months.”
