Ocean Acidification

La acidificación en los océanos se da por un conjunto de reacciones químicas entre el agua y el CO₂, que al estar ambos en contacto provoca la liberación de iones de hidrógeno, lo que lleva a un incremento de la acidez del agua, afectando no sólo a los océanos sino también a los estuarios costeros y canales. La acidificación del océano disminuye la concentración de iones carbonatos, que son indispensables para algunos organismos (esponjas, corales de aguas profundas y superficiales, pepinos de mar) que forman sus conchas o esqueletos de carbonato del calcio, haciendo que sea más difícil para ellos mantener o crear estas estructuras. De esta manera, altera la diversidad funcional del ecosistema, incluidos los hábitats biogénicos costeros, lo que resulta en la homogeneización y simplificación del ecosistema. 

Entre más CO₂ encontremos, habrá más acidificación en los océanos. Tengamos en cuenta que los niveles de este gas han aumentado desde la Revolución Industrial a causa de la quema de combustibles fósiles, dando lugar a una disminución en el pH del agua superficial del 0.1 que representa un aumento del 30% en la acidez de los océanos en comparación con los niveles pre-industriales. Es importante disminuir el CO₂ al menos a 350 ppm (partes por millón), ya que en la actualidad hemos llegado a las 400 ppm.

El problema del aumento de los GEI está afectando gravemente a nuestros océanos, dando paso a una bomba de tiempo que acabará no sólo con éstos, sino también con los seres humanos, pues no debemos olvidar que al aumentar la temperatura también es posible liberar el metano que ha quedado atrapado por tanto tiempo en el fondo marino y en el permafrost (suelo permanentemente congelado), lo que ayudaría a un ascenso de temperatura más rápido y sin retorno, algo parecido a lo que ocurrió hace 56 millones de años en el llamado Máximo Térmico Paleoceno-Eoceno.

…

Ocean-based climate solutions have a key role in keeping the goal to limit temperature rise to 1.5 degrees Celsius within reach and improving global climate resilience.  On the occasion of the “Oceans and Coastal Zones” thematic day at COP27, the United States highlights the following ocean-climate action.

…

Developing a National Ocean Acidification Action Plan: The United States announced the commencement of a process to create/develop the United States’ Ocean Acidification Action Plan (OA-AP), with a goal of finalizing it by COP28.  The OA-AP aims to 1) identify U.S. actions that address the root causes of ocean acidification, 2) highlight U.S. leadership and priorities on ocean acidification, 3) illustrate the coordinated approach to OA across U.S. federal, state, and local agencies, 4) identify gaps and opportunities for further action, and 5) serve as a mechanism to promote greater international collaboration among members of the OA Alliance.  The OA-AP will be closely tied to the United States’ Ocean Climate Action Plan, which will guide significant ocean-based climate mitigation and adaptation actions, including on green shipping, ocean-based renewable energy, ocean acidification, and other ocean-related solutions.  Drafting and releasing the U.S. national action plan will provide a model for other members seeking to integrate OA research, monitoring, and adaptation efforts across their governments.

…

The West African Canary Current extends along the north-west African coast, from the northern Atlantic coast of Morocco to Guinea-Bissau. It’s a hotspot for changes in the oceans driven by climate change. These include rising temperatures, ocean acidification and ocean deoxygenation. All affect marine life on multiple levels.

The current is one of the world’s most productive ocean ecosystems, a consequence of the upwelling of cold and nutrient-rich waters. Ecosystems like this provide around 20% of global fish catches and support livelihoods in coastal communities.

From 2016 -2019, we worked with an international team to draw attention to the impacts of climate change on the West African Canary Current. In a recent publication, we described the limited economic and institutional capacity to monitor and respond to climate variability and change in the countries bordering the West African Canary Current and the urgent need to build scientific capacity in the region in order address this shortcoming.

…

Image: Cold-water coral habitat off the west coast of Scotland taken during the JC073 Changing Oceans research cruise in 2012.

Dr Helen Findlay, Biological Oceanographer at PML, led a team of internationally recognised scientists to bring together the Marine Climate Change Impacts Partnership (MCCIP) Topic Review Update on Ocean Acidification.

Published during the 1st week of COP27 at the Marine Alliance for Science and Technology for Scotland Annual Science Meeting, these MCCIP Topic Review Updates are a comprehensive exploration of the current science on the topics of aquaculture, coastal flooding and stratification as well as ocean acidification.

The MCCIP Ocean Acidification Topic Review Update summary:

• Atmospheric carbon dioxide (CO₂) exceeded 414 ppm in 2021 and has continued to increase by approximately 2.4 ppm per year over the last decade. The global ocean absorbs approximately a quarter of this anthropogenic CO₂ emissions annually.
• The North Atlantic Ocean contains more anthropogenic CO₂ than any other ocean basin and surface waters are experiencing a decline in pH (increased acidity).
• Some species are already showing effects from ocean acidification when exposed to short-term fluctuations and could be used as indicator species for long-term impacts on marine ecosystems.
• Models project that the pH of the average continental shelf seawater will continue to decline at similar rates as today until 2050, when rates will then increase in the second half of the century, depending on the emissions scenario used in the model run.
• The rate of pH decline in coastal areas is projected to be faster in some areas (e.g. Bristol Channel) than others (e.g. Celtic Seas).
• Under high-emission scenarios, it is projected that waters at the bottom of the north-west European shelf seas will become corrosive to more-soluble forms of calcium carbonate (aragonite), which organisms such as cold-water corals and molluscs use to build their skeletons and shells, and this is projected to begin by 2030.
• By 2100, up to 90% of the north-west European shelf seas may become corrosive to some species for at least one month of each year.
• High variability in coastal carbonate chemistry may mean that some species have a higher adaptative capacity than others. However, all species will be at an increased risk from extreme exposure episodes.

Dr Helen Findlay commented: “The science around the chemistry of ocean acidification is very well established and we have a high level of confidence that atmospheric CO₂ is increasing the acidity of the ocean.”

…

PHOTOGRAPH: ALEXANDER SEMENOV/SCIENCE SOURCE

Imagine, for a moment, that you are standing on a pier by the sea, grasping, somewhat inexplicably, a bowling ball. Suddenly you lose your grip and it tumbles down into the waves below with a decisive plonk. Now imagine that the bowling ball is made of gas—carbon dioxide, to be specific, compressed down into that familiar size and weight. That’s approximately your share, on a rough per capita basis, of the human-caused carbon emissions that are absorbed by the sea every day: Your bowling ball’s worth of extra CO₂, plus the 8 billion or so from everyone else. Since the Industrial Revolution, the oceans have sucked up 30 percent of that extra gas.

The reason so much CO₂ ends up in the oceans is because that molecule is extremely hydrophilic. It loves to react with water—much more than other atmospheric gasses, like oxygen. The first product of that reaction is a compound called carbonic acid, which soon gives up its hydrogen ion. That’s a recipe for a caustic solution. The more hydrogen ions a solution has, the more acidic it is, which is why as the CO₂ in Earth’s atmosphere has increased, its water has gotten more acidic too. By the end of the century, models predict the oceans will reach a level of acidity that hasn’t been seen in millions of years. Prior periods of acidification and warming have been linked with mass die-offs of some aquatic species, and caused others to go extinct. Scientists believe this round of acidification is happening much faster.

That change is striking hardest and fastest in the planet’s northernmost waters, where the effects of acidification are already acute, says Nina Bednaršek, a researcher at Slovenia’s National Institute of Biology. She studies pteropods, tiny sea snails that are also known as “sea butterflies” due to their translucent, shimmering shells that look uncannily like wings. But scoop those snails from Arctic waters, and a close look at their exoskeletons reveals a duller reality. In more corrosive water, the once-pristine shells become flaked and pock-marked—a harbinger of an early death. Those critters are “the canary in the coal mine,” as Bednaršek puts it—a critical part of the food chain that supports bigger fish, crabs, and mammals, and a sign of coming distress for more species as the oceans become more caustic.

…

Massive die-offs of Dungeness crab have been documented off the Pacific Northwest Coast. Once dead, the aquatic crabs often wash up on beaches, such as the ones photographed on Kalaloch Beach on June 14, 2022. Photo: Jenny Waddell/NOAA

Dungeness crab is an iconic and valuable fishery resource that is culturally and economically important to West Coast communities. Off the coast of Oregon and Washington, tribal, commercial, and recreational fishers pull up crab pots, expecting a haul of Dungeness crabs. Too often lately, what they find are pots filled with dead crabs, suffocated from a lack of oxygen near the seafloor.

Hypoxia—dangerously low oxygen levels—is killing Dungeness crabs off the Pacific Northwest Coast, predominantly during the summer and early fall. Marine animals don’t breathe air, but they still need oxygen, which they absorb from the water. If sufficient oxygen is missing from the water column, the animals may perish.

In addition, blooms of harmful algae have led to the closure of entire Dungeness crab fisheries on the West Coast in past years. Harmful algal blooms are the rapid growth of algae that can produce toxins dangerous to animals and habitats, with potential risk to humans who eat contaminated shellfish.

Multiple Stressors

Hypoxia and harmful algal blooms are considered stressors to the health of Dungeness crabs. Other stressors include ocean acidification, rising ocean temperatures, and marine heatwaves. Each of these stressors is known to harm marine species and ecosystems independently, but scientists are only beginning to unravel the ways in which environmental stressors may interact, and whether there may be unprecedented consequences.

…

NOAA has awarded $967,505 of an anticipated four-year, $4.2 million project to support research on multi-stressor impacts on marine ecosystems under climate change. The newly funded project, led by Oregon State University and NOAA’s Pacific Marine Environmental Laboratory, will occur off the coasts of northern California, Oregon, and Washington, including NOAA’s Olympic Coast National Marine Sanctuary, and will focus on climate impacts to Dungeness crab, an iconic and valuable fishery resource that is culturally and economically important to the region’s coastal communities.

Dungeness crab outreach aboard a vessel in Washington. Credit: Olympic Coast National Marine Sanctuary.

Ocean acidification (OA), hypoxia, increasing temperatures, and harmful algal blooms (HABs) have emerged as leading environmental stressors in the northern California Current Ecosystem, impacting ecosystems, fisheries, and Indigenous and other coastal communities. Climate change is already making existing marine environmental stressors worse through changes to temperature, precipitation, seasonal cycles, and ocean chemistry. For the Dungeness crab fishery, the U.S. West Coast’s most valuable fishery, hypoxia has resulted in mass mortality of crabs in commercial pots, and HAB events have led to substantial fishing curtailment including season-scale closures. The continued intensification of this suite of multi-stressors poses substantial challenges for the management of ocean resources, ecosystems, and protected species. For marine protected areas and Tribal treaty fishing areas that have fixed boundaries, uncertainties in the expression and impacts of multi-stressors (OA, hypoxia, increasing temperatures, and HABs) threaten to undercut the ability of area-based tools to safeguard marine resources.

The goal of the proposed work is to help resource managers and tribes of the northern California Current Ecosystem prepare for the anticipated impacts of climate change, by increasing their understanding of how multiple stressors are likely to impact these ecosystems in the future. Also, this work will help determine the biological sensitivity of Dungeness crabs (Metacarcinus magister) and krill (Euphausia pacifica) to OA, hypoxia, HABs, and increasing temperatures.

…

Credit: Pixabay/CC0 Public Domain

The Pacific blue mussel (Mytilus trossulus) is a foundational and beneficial species in the intertidal environments of the northern Pacific Ocean. Comparative physiologists have recently studied how two aspects of climate change—warming temperatures and increasingly acidic waters—may affect this ecologically important species. The scientists present their findings this week at the American Physiological Society (APS) Intersociety Meeting in Comparative Physiology: From Organism to Omics in an Uncertain World conference in San Diego.

As a foundational species, Pacific blue mussels create habitat and maintain ecosystem function, much as corals do in a coral reef. They are also of growing economic value in Alaska, with about 8 million mussels cultivated each year on aquatic farms.

For marine life that relies on calcium for their outer shells—such as mussels—climate change is a double whammy. It means not only warming temperatures but also changes in the pH of their habitat. That change in pH can make calcium more scarce.

As carbon increases in the atmosphere, an increasing amount of carbon is absorbed by seawater, setting off a chemical reaction that makes the ocean more acidic. This is called ocean acidification. According to the National Oceanic and Atmospheric Administration, surface ocean waters have already become approximately 30% more acidic. Mussels, like other calcifying shellfish, rely on calcium carbonate to make their shells. But calcium carbonate dissolves in acidic environments. In fact, it is even used in common antacids, such as Tums.

For this study, the research team used tide pools in Sitka, Alaska, to simulate different aspects of climate change. Some tide pools were artificially warmed, some artificially acidified, and others were both warmed and acidified. They monitored the mussels for six months, testing shell strength and thickness at three time intervals.

…

Acetabularia jalakanyakae, also known as the mermaid’s wineglass, is a species of algae found around the Andaman and Nicobar Islands. Photograph: Courtesy of Felix Bast.

Growing between the tides around the Andaman and Nicobar Islands, in the tropical waters of the Indian Ocean, are clusters of what look like tiny, green mushrooms. In fact, this is a type of seaweed, or algae – each one made from a single, gigantic cell.

In 2021, scientists named them Acetabularia jalakanyakae, also known as the “mermaid’s wineglass”, because of its umbrella-shaped cap.

…

Mermaid’s wineglass algae might grow in the relatively unpolluted waters of the Andaman and Nicobar Islands, but they face a global threat. The ocean is absorbing more anthropogenic carbon from the atmosphere and consequently becoming more acidic, which puts species like the mermaid’s wineglass algae at risk. As Bast explains, more than half of the dry weight of this algae is calcium carbonate, which melts in acidified seawater.

“Any organism, be it animal or a plant, with calcium carbonate is highly prone to ocean acidification,” says Bast. “So, that will be having a tremendous impact on species like Acetabularia because the calcium carbonate will simply dissolve into the acid.”

Scientists stand beside a new carbon capture test unit at Longanet power station on May 29, 2009 in Longanet, Scotland. The technology being tested at the coal fired power station removes carbon dioxide using chemicals and turns it into a liquid which is stored underground. Jeff J Mitchell—Getty Images.

In the late 1800s, before the Wright Brothers took off, earth’s annual average temperature was about 13.7 degrees Celsius. But since the Industrial Revolution, the global temperature has gone up by about 1 degree Celsius because greenhouse gas emissions (such as carbon dioxide) in the atmosphere trap heat like a blanket. Science says a hotter globe triggers extreme weather events: more fires, bigger floods, stronger hurricanes.

Without drastic measures, researchers say, the climate consequences will be much, much worse. So what’s the plan? The Paris Agreement wants to make sure earth absolutely does not get 2 degrees Celsius hotter than pre-industrial levels—and ideally no more than 1.5 degrees. This goal requires countries to act now (or, more accurately, yesterday) by reducing emissions to net-zero by 2050. Net-zero means greenhouse gases removed from the atmosphere cancel out greenhouse gases emitted from fossil fuels and industrial processes.

Will it be enough to avert a climate disaster? Some say no. Every year about 51 billion tons of greenhouse gases get released into the air, with carbon dioxide being the main culprit, making up 76% of the mix. In 2021, the global average level of carbon dioxide set a new record high at 414.72 parts per million. With so much carbon in the air, reducing emissions is critical, but not enough to meet climate goals. This is where using carbon removal technology—vacuuming CO2 straight out of the atmosphere for safe storage—comes in. If you follow the money, investors are betting big that carbon removal technology will be the way forward.

…

Based in Canada, Planetary Technologies is taking a more liquid approach. Its technology is based on the fact that the atmosphere and the ocean are constantly communicating. Too much CO2 in the air leads to too much CO2 in the oceans, which over time leads to dangerous ocean acidification, says Mike Kelland, CEO of Planetary Technologies.

“What if we reverse that?” Kelland says. “What if we put antacid into seawater, then what does that do? Research says it starts to rebalance and the ocean pulls CO2 out of the atmosphere, safely storing it for hundreds of thousands of years.”

The antacid (magnesium hydroxide) works like TUMS or baking soda, lowering the pH balance of seawater to make it less acidic. The idea is that by adding antacid to outflows from wastewater treatment facilities—which already are permitted and monitored to ensure the safety of treated water before it goes into the ocean—it will combine with dissolved CO2 in the surface oceans to form carbonates and bicarbonates that remain in the seawater for a long, long time. This, in turn, would allow more CO2 from the atmosphere to be captured and stored in the ocean.

…

Corals are especially vulnerable to damage from ocean acidification, and rising CO2 levels jeopardize the future of coral reefs globally. However, a new study by researchers at the University of Pennsylvania and the University of Queensland report that certain corals may do better than others at withstanding ocean acidification.

The U.S. National Science Foundation-supported study was published in Proceedings of the Royal Society B. Using samples from the Great Barrier Reef, the researchers studied how coral from environments with greater CO2 variability respond to increasing acidification.

Ocean acidification threatens coral because it breaks down the rocky, calcified skeletons that give coral its distinctive structure, says Katie Barott of Penn, senior author of the study. When water CO2 levels surge, corals can no longer grow or maintain their skeletons.

…