Growing up in Pittsburgh, Pennsylvania, where coal-fueled fires powered the steel industry, Brenda Ekwurzel received an early education in air and water pollution.

“We’d see barges of coal being sent down the river for the mills to burn. When my brother and I went canoeing on that river with our parents,” she says, “they’d tell us to try not to touch the water or even let it splash on us. Back then, it was so polluted, there weren’t any fish.”

Today, as director of climate science at the Union of Concerned Scientists, Ekwurzel is focusing on the consequences of burning fossil fuels on a much larger scale: the impact on the world’s oceans.

“So far, people are not paying nearly enough attention to one of the most significant and direct effects of carbon emissions in our atmosphere,” she says. “Globally, our oceans aren’t just warming. They’re also acidifying. And this has serious consequences for marine life and food chains worldwide.”

While some emissions from burning fossil fuels are taken up by plants and animals on land, some linger in the atmosphere, contributing to the blanketing “greenhouse” effect that warms the earth. The world’s oceans absorb the rest, which nudges its chemistry along the pH scale from basic toward acidic. Surface waters are now nearly 30 percent more acidic than they were in 1850. And ocean acidification is happening at a faster rate today than at any point in the last 66 million years. Projections show that if we do not reduce our carbon emissions, ocean surface waters could be more than twice as acidic in 2100 as they were in 2000.

Ekwurzel isn’t just studying the process of acidification, however. She and her team are examining who is responsible, and to what extent.

In the decades since she left Pittsburgh, one of its major steel companies has been repeatedly held liable for air and water pollution, paying out large settlements for cleanup and to affected residents. The company’s fingerprints on the damage were clear.

As it turns out, it’s also possible to prove who is responsible for the destructive effects of climate change, including ocean acidification. Ekwurzel is in the forefront of scientific research showing that such effects are, to a large extent, the result of the practices and policies of the fossil fuel industry.

Attribution and Accountability

Ekwurzel and her team have been working for several years to attribute specific effects of climate change to the largest industrial producers of carbon emissions, including ExxonMobil and Chevron. With Ekwurzel as lead author, the team published a paper in the peer-reviewed journal Climatic Change debuting a scientific formula that assigns responsibility for hotter temperatures and rising seas to 90 private, majority state-owned and national companies.

The team concluded that emissions traced to those producers from 1854 to 2010 were responsible for 42 to 50 percent of the rise in global average surface temperatures, and 26 to 32 percent of global sea level rise. That paper was the journal’s most widely read article in 2018, with nearly 1,000 shares and 70,000 downloads.

“We calculated the increase of carbon dioxide in the atmosphere that can be traced back to the extraction, production, and sale of oil, gas, and coal, as well as cement production,” Ekwurzel says, noting that the work relied on these companies’ own detailed records.

Now the team, led by Ekwurzel and UCS Senior Climate Scientist Rachel Licker, has applied the same formula to attribute documented changes in ocean pH to specific companies. As Catalyst went to press, the new analysis was under consideration for publication in a peer-reviewed scientific journal.

Ekwurzel says the process for attributing ocean acidification to the fossil fuel industry is more straightforward than her team’s previous research. One reason: the world’s oceans absorb carbon dioxide swiftly compared with the lengthier processes that lead to rising temperatures and seas.

“Based on the amount of carbon we’ve emitted, we haven’t yet felt the full expression of sea level rise or warming,” says Ekwurzel. “It takes time to melt huge ice sheets. It takes time to warm large bodies of water. But the atmosphere is in direct contact with the ocean’s surface, and we can measure that absorption happening every day.”

Acidic Oceans Erode Coastal Economies

Dr. Brenda Ekwurzel (left) talks to an attendee of the Maine Fisherman’s Forum about UCS and our work.

As Northeast regional advocacy director for UCS, Roger Stephenson works with scientists such as Brenda Ekwurzel to connect their research with people who can use it. In March, Stephenson brought Ekwurzel’s new work on ocean acidification to the Maine Fishermen’s Forum, a three-day trade show for fishermen, academics, government agencies, and other people interested in the Gulf of Maine’s fishing industry.

“We wanted to build awareness and share the science attributing ocean acidification to specific fossil fuel companies,” says Stephenson. “This research dovetails very closely with the ‘polluters pay’ principle: namely, that those who cause the pollution should pay the costs of dealing with it.”

From large-scale fishing operations to individual subsistence fishers, ocean warming and acidification pose an existential threat to the millions of people worldwide who depend on healthy oceans for their survival. The science of attribution can help many of the people facing the most immediate impacts take steps toward economic restoration. This is especially true in acidification “hot spots” including the South Pacific’s Coral Triangle, the Gulf of Alaska, the Arctic, the California current (which spans the coastal Pacific Northwest), and the Peru current (which runs along the western coast of South America) that are all acidifying more rapidly than other regions. In the Coral Triangle alone, where the region’s marine biodiversity supports more than 100 million people, $6 billion in annual fisheries exports and tourism are at risk.

Ekwurzel and her team’s research includes some quantification of the risk to lives and livelihoods for each of these hot spots—such as the number of jobs that could be lost—along with specific changes to oceanwater pH.

“If people at risk use our work in conjunction with regional studies dedicated to acidification, we have confidence that they could tie the harmful changes occurring in their specific location back to the fossil fuel producers,” she says.

Ocean acidification is such a rapid process, Ekwurzel says, that her team can track shifts in acidity in direct proportion to atmospheric carbon dioxide, just a year after its emission. And the bright side to these quick changes in our oceans’ chemistry, she adds, is that we can reverse the damage much more easily than we can with warming or rising seas.

“If you think about the order of magnitude and immediacy of the impacts of climate change,” she says, “ocean acidification is at the top of the list, then warming, then sea level rise. Over this century, we’ll experience the biggest improvements from emissions reductions in the same order of the impacts. For ocean acidification especially, cutting our emissions now will make a noticeable difference in protecting our oceans.”

But as Ekwurzel emphasizes, given the stakes involved, we don’t have long to act.

The Biological Risks of Ocean Acidification

The consequences of acidification are disastrous to marine life, and pose at least as much of a threat to humans as other global warming impacts such as extreme weather and sea level rise.

As carbon dioxide dissolves into the ocean, chemical reactions deprive shell-forming marine organisms such as shellfish, corals, and foraminifera of the carbonate ions they need to build their protective shells. Acidifying waters eat away at the bottom of the world’s food chain: the marine life that depends on the current chemistry of the ocean to survive. Without them, our global food chain is at risk—to say nothing of the millions of people worldwide who make their livings from, or subsist on, seafood

Warming and acidification are a one-two punch for marine life, says Ekwurzel, pointing to corals as an example. A coral reef bleached by warming waters will be less able to rebuild itself in acidic waters.

“It’s a double whammy,” she says.

Perhaps most importantly, Ekwurzel warns there is a point beyond which the consequences of acidification can be devastating. “We’re fast approaching the threshold where particular organisms can’t form shells and deep-water corals can’t bounce back, within the next decades,” she says.

Searching for Solutions

The solution to ocean acidification is also the solution to global warming and sea level rise: rapid, drastic, widespread cuts to carbon emissions. Ekwurzel stresses the potential for damage prevention.

“The swift reduction in carbon we need would most directly slow down the pace of ocean acidification,” she says.

She also points to the possibilities of carbon sequestration (the removal and storage of atmospheric carbon) through new, undiscovered technologies, and/or the deployment of so-called blue carbon—coastal ecosystems that trap and store carbon naturally, such as seagrasses and tidal marshes.

“We could build carbon ‘credits’ for restoring mangroves and wetlands, and making sure seagrasses are healthy,” she says. “There are other, larger-scale ideas for carbon sequestration, too, but for now they are costly and energy-intensive. I’m in favor of innovation and research into every method that’s out there. There’s no one silver bullet—there’s silver buckshot. And we need every pellet.”

The work of Ekwurzel and her team is part of that spray of buckshot. By laying the groundwork of scientific evidence for attributing increased acidity in the world’s oceans to the major producers of fossil fuels, this work offers another potential legal recourse to those suffering the consequences—a way to demand restoration and an end to unchecked carbon emissions (see the sidebar). People in particular locales and with particular livelihoods will face greater impacts than others, but many of the impacts are urgent and universal.

“Everyone on Earth has a stake in the health of our oceans and should care about ocean acidification,” Ekwurzel says, “especially those who eat any type of marine protein. If we act fast, we can really make a difference in reducing this threat.”

Learn more about ocean acidification and the fossil fuel industry’s responsibility, here.