We are Asphyxiating the Oceans
Situated as we are, in the midst of North America, it is easy to forget that two-thirds of the Earth’s surface is covered by water, which supports and sustains us. According to new studies in scientific journals that have not received much ink in the popular press, we are asphyxiating the oceans at a rapid rate as oxygen levels decline and corals die. The primary cause of this asphyxiation is the steady warming of the atmosphere that our ruling plutocracy insists does not exist.
A World-wide Trend
The decline in oxygen levels is a world-wide trend, as described by Denise Breitburg and colleagues in Science (2018). “This oxygen loss, or deoxygenation, is one of the most important changes occurring in oceans increasingly modified by human activities that have raised temperatures, carbon-diopxide levels, and nutrient inputs and have altered the abundances and distributions of marine species,” they write. In the open oceans, deoxygenation has been intensified by rising acidity provoked by carbon-dioxide absorption, as well as the injection of nutrients from agriculture and sewage that are predominant in Lake Eire around Toledo, well as other inland bodies of water.
The decline in oxygen levels has intensified since the 1950s, due nearly entirely to human activities, from increasing emissions of carbon dioxide and other greenhouse gases and overload of nitrogen-based fertilizers. All these activities combine along coastlines at the mouths of major rivers (such as the Mississippi in the United States and the Ganges in India and Bangladesh) to produce oxygen-starved “dead zones.”
“Oxygen is fundamental to biological and biogeochemical processes in the ocean,” wrote Breitburg and colleagues. “Its decline can cause major changes in ocean productivity, biodiversity, and biogeochemical cycles. Analyses of direct measurements at sites around the world indicate that oxygen-minimum zones in the open ocean have expanded by several million square kilometers and that hundreds of coastal sites now have oxygen concentrations low enough to limit the distribution and abundance of animal populations and alter the cycling of important nutrients.”
Corals: No Time to Recover
Coral Reefs, the richest source of food in the oceans, also are steadily becoming more vulnerable due to rising temperatures, which bleaches (kills) them. A study published in the same issue of Science that contained the work on ocean oxygen starvation described just how quickly the coral holocaust has developed. “Large-scale coral bleaching events, in which reefs become extremely fragile, were virtually unheard-of before the 1980s. But in the years since… the frequency of coral bleaching has increased to the point that reefs no longer have sufficient recovery time between severe episodes,” wrote Kendra Pierre-Louis and Brad Plummer in the New York Times.
When coral bleaches, they wrote, “Overheated seawater causes corals to part ways with symbiotic plantlike organisms called zooxanthella that live inside of them. In addition to giving coral reefs their bright colors, zooxanthella also provide corals with oxygen, waste filtration, and up to 90 percent of their energy. Absent zooxanthella, corals not only take on a ghostly pallor, hence the term bleaching, but they are also more susceptible to death.” Given enough time between bleaching events (10 to 15 years), corals can recover. The problem is that as ocean temperatures slowly rise, the intervals allowing recovery at sustainable temperatures are becoming shorter. World-wide bleaching conditions are usually associated with El Nino conditions (the most severe of which have occurred in 1982-1983, 1998, and 2015-2016). These cause ocean temperatures to rise suddenly in tropical ocean waters that contain most coral reefs.
A study by Terry P. Hughes and colleagues examined 100 reefs world-wide and found that rising temperatures have reduced recovery time for reefs 50 percent in less than 40 years (1980-2016), also increasing damage to reefs. “As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago,” they wrote. “Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.” The year 1980 was chosen to begin the study because before the major El Niño of 1982-83, mass bleaching’s were nearly unknown in the historical record.
“That year,” according to the Times report, “Reefs across the Tropical Eastern Pacific exposed to warm El Niño year waters bleached. Coral reefs in Costa Rica, Panama and Columbia experienced 70 to 90 percent mortality. Most reefs in the Galápagos Islands, the cradle of Darwin’s theory of evolution, experienced 95 percent mortality. While many mass bleaching’s were prompted by El Niño events, which tends to warm Pacific Ocean temperatures, the bleaching event that hit the Great Barrier Reef in 2017— he reef’s first back-to-back bleaching—occurred at the beginning of a La Niña event, when ocean waters should have been cooler. It’s a sign that global warming is steadily pushing up ocean temperatures even in cooler years.” By mid-century, given present trends, killing bleaching will be the norm in large parts of the world’s oceans.
REFERENCES
Breitburg, Denise, Lisa A. Levin, Andreas Oschlies, Marilaure Grégoire, Francisco P. Chavez, Daniel J. Conley, Véronique Garçon, Denis Gilbert, Dimitri Gutiérrez, Kirsten Isensee, Gil S. Jacinto, Karin E. Limburg, Ivonne Montes, S. W. A. Naqvi, Grant C. Pitcher, Nancy N. Rabalais, Michael R. Roman, Kenneth A. Rose, Brad A. Seibel, Maciej Telszewski, Moriaki Yasuhara, and Jing Zhang. “Declining Oxygen in the Global Ocean and Coastal Waters.” Science 359, January 5, 2018. DOI: 10.1126/science.aam7240. http://science.sciencemag.org/content/359/6371/eaam7240
Terry P. Hughes, Kristen D. Anderson, Sean R. Connolly, Scott F. Heron, James T. Kerry, Janice M. Lough, Andrew H. Baird, Julia K. Baum, Michael L. Berumen, Tom C. Bridge, Danielle C. Claar, C. Mark Eakin, James P. Gilmour, Nicholas A. J. Graham, Hugo Harrison, Jean-Paul A. Hobbs, Andrew S. Hoey, Mia Hoogenboom, Ryan J. Lowe, Malcolm T. McCulloch, John M. Pandolfi, Morgan Pratchett, Verena Schoepf, Gergely Torda, and Shaun K. Wilson. “Spatial and Temporal Patterns of Mass Bleaching of Corals in the Anthropocene.” Science 359(January 5, 2018):80-83.
Pierre-Louis, Kendra and Brad Plummer. “Global Warming’s Toll on Coral Reefs: As if They’re ‘Ravaged by War’.” New York Times, January 4, 2018. https://www.nytimes.com/2018/01/04/climate/coral-reefs-bleaching.html
Bruce E. Johansen, Frederick W. Kayser Professor at the University of Nebraska–Omaha, is author of Climate Change: An Encyclopedia of Science, Society, and Solutions (2017).
A World-wide Trend
The decline in oxygen levels is a world-wide trend, as described by Denise Breitburg and colleagues in Science (2018). “This oxygen loss, or deoxygenation, is one of the most important changes occurring in oceans increasingly modified by human activities that have raised temperatures, carbon-diopxide levels, and nutrient inputs and have altered the abundances and distributions of marine species,” they write. In the open oceans, deoxygenation has been intensified by rising acidity provoked by carbon-dioxide absorption, as well as the injection of nutrients from agriculture and sewage that are predominant in Lake Eire around Toledo, well as other inland bodies of water.
The decline in oxygen levels has intensified since the 1950s, due nearly entirely to human activities, from increasing emissions of carbon dioxide and other greenhouse gases and overload of nitrogen-based fertilizers. All these activities combine along coastlines at the mouths of major rivers (such as the Mississippi in the United States and the Ganges in India and Bangladesh) to produce oxygen-starved “dead zones.”
“Oxygen is fundamental to biological and biogeochemical processes in the ocean,” wrote Breitburg and colleagues. “Its decline can cause major changes in ocean productivity, biodiversity, and biogeochemical cycles. Analyses of direct measurements at sites around the world indicate that oxygen-minimum zones in the open ocean have expanded by several million square kilometers and that hundreds of coastal sites now have oxygen concentrations low enough to limit the distribution and abundance of animal populations and alter the cycling of important nutrients.”
Corals: No Time to Recover
Coral Reefs, the richest source of food in the oceans, also are steadily becoming more vulnerable due to rising temperatures, which bleaches (kills) them. A study published in the same issue of Science that contained the work on ocean oxygen starvation described just how quickly the coral holocaust has developed. “Large-scale coral bleaching events, in which reefs become extremely fragile, were virtually unheard-of before the 1980s. But in the years since… the frequency of coral bleaching has increased to the point that reefs no longer have sufficient recovery time between severe episodes,” wrote Kendra Pierre-Louis and Brad Plummer in the New York Times.
When coral bleaches, they wrote, “Overheated seawater causes corals to part ways with symbiotic plantlike organisms called zooxanthella that live inside of them. In addition to giving coral reefs their bright colors, zooxanthella also provide corals with oxygen, waste filtration, and up to 90 percent of their energy. Absent zooxanthella, corals not only take on a ghostly pallor, hence the term bleaching, but they are also more susceptible to death.” Given enough time between bleaching events (10 to 15 years), corals can recover. The problem is that as ocean temperatures slowly rise, the intervals allowing recovery at sustainable temperatures are becoming shorter. World-wide bleaching conditions are usually associated with El Nino conditions (the most severe of which have occurred in 1982-1983, 1998, and 2015-2016). These cause ocean temperatures to rise suddenly in tropical ocean waters that contain most coral reefs.
A study by Terry P. Hughes and colleagues examined 100 reefs world-wide and found that rising temperatures have reduced recovery time for reefs 50 percent in less than 40 years (1980-2016), also increasing damage to reefs. “As global warming has progressed, tropical sea surface temperatures are warmer now during current La Niña conditions than they were during El Niño events three decades ago,” they wrote. “Consequently, as we transition to the Anthropocene, coral bleaching is occurring more frequently in all El Niño–Southern Oscillation phases, increasing the likelihood of annual bleaching in the coming decades.” The year 1980 was chosen to begin the study because before the major El Niño of 1982-83, mass bleaching’s were nearly unknown in the historical record.
“That year,” according to the Times report, “Reefs across the Tropical Eastern Pacific exposed to warm El Niño year waters bleached. Coral reefs in Costa Rica, Panama and Columbia experienced 70 to 90 percent mortality. Most reefs in the Galápagos Islands, the cradle of Darwin’s theory of evolution, experienced 95 percent mortality. While many mass bleaching’s were prompted by El Niño events, which tends to warm Pacific Ocean temperatures, the bleaching event that hit the Great Barrier Reef in 2017— he reef’s first back-to-back bleaching—occurred at the beginning of a La Niña event, when ocean waters should have been cooler. It’s a sign that global warming is steadily pushing up ocean temperatures even in cooler years.” By mid-century, given present trends, killing bleaching will be the norm in large parts of the world’s oceans.
REFERENCES
Breitburg, Denise, Lisa A. Levin, Andreas Oschlies, Marilaure Grégoire, Francisco P. Chavez, Daniel J. Conley, Véronique Garçon, Denis Gilbert, Dimitri Gutiérrez, Kirsten Isensee, Gil S. Jacinto, Karin E. Limburg, Ivonne Montes, S. W. A. Naqvi, Grant C. Pitcher, Nancy N. Rabalais, Michael R. Roman, Kenneth A. Rose, Brad A. Seibel, Maciej Telszewski, Moriaki Yasuhara, and Jing Zhang. “Declining Oxygen in the Global Ocean and Coastal Waters.” Science 359, January 5, 2018. DOI: 10.1126/science.aam7240. http://science.sciencemag.org/content/359/6371/eaam7240
Terry P. Hughes, Kristen D. Anderson, Sean R. Connolly, Scott F. Heron, James T. Kerry, Janice M. Lough, Andrew H. Baird, Julia K. Baum, Michael L. Berumen, Tom C. Bridge, Danielle C. Claar, C. Mark Eakin, James P. Gilmour, Nicholas A. J. Graham, Hugo Harrison, Jean-Paul A. Hobbs, Andrew S. Hoey, Mia Hoogenboom, Ryan J. Lowe, Malcolm T. McCulloch, John M. Pandolfi, Morgan Pratchett, Verena Schoepf, Gergely Torda, and Shaun K. Wilson. “Spatial and Temporal Patterns of Mass Bleaching of Corals in the Anthropocene.” Science 359(January 5, 2018):80-83.
Pierre-Louis, Kendra and Brad Plummer. “Global Warming’s Toll on Coral Reefs: As if They’re ‘Ravaged by War’.” New York Times, January 4, 2018. https://www.nytimes.com/2018/01/04/climate/coral-reefs-bleaching.html
Bruce E. Johansen, Frederick W. Kayser Professor at the University of Nebraska–Omaha, is author of Climate Change: An Encyclopedia of Science, Society, and Solutions (2017).
