The Ocean Is Running Out of Oxygen, Largest Study of Its Kind Finds
The International Union for Conservation of Nature (IUCN) report combined the work of 67 scientists from 17 countries to conclude that oxygen levels in the ocean had declined around two percent since the mid-20th century, and the volume of waters entirely deprived of oxygen had increased four-fold since the 1960s. The report was released Saturday at the COP25 UN Climate Change Conference in Madrid, CBS News reported, in hopes of persuading world leaders to protect the oceans from future oxygen loss.
"Urgent global action to overcome and reverse the effects of ocean deoxygenation is needed," IUCN Global Marine and Polar Programme director Minna Epps said, as CBS News reported. "Decisions taken at the ongoing climate conference will determine whether our ocean continues to sustain a rich variety of life, or whether habitable, oxygen-rich marine areas are increasingly, progressively and irrevocably lost."
Ocean deoxygenation comes from two major causes: nutrient pollution and the climate crisis.
Nutrient pollution has long been understood as a threat to ocean oxygen levels. Run-off from sewage and agriculture, as well as nitrogen from fossil fuel emissions, encourages the excessive growth of algae, which depletes oxygen. This process is relatively fast and easy to fix.
But in recent years scientists have come to understand how rising ocean temperatures are also lowering oxygen levels. Warmer water can't hold as much oxygen, and it is also more buoyant, which means it mixes less with deeper, less-oxygenated water, reducing oxygen circulation overall. Rising temperatures are likely responsible for around 50 percent of the oxygen loss in the top 1,000 meters (approximately 3,281 feet) of the ocean, which are also the most abundant in biodiversity. Climate-change-related oxygen loss is difficult or impossible to reverse.
"This is one of the newer classes of impacts to rise into the public awareness," Kim Cobb, a Georgia Tech climate scientist who was not involved with the study, told The New York Times.
While a two percent decrease in overall oxygen levels might not sound like a lot, there are environments where a small change in oxygen can make a huge difference, report editor Dan Laffoley explained to The New York Times.
"[I]f we were to try and go up Mount Everest without oxygen, there would come a point where a 2 percent loss of oxygen in our surroundings would become very significant," he said.
He also said the oxygen loss was not evenly distributed. Some waters in the tropics had seen a 40 to 50 percent decrease in oxygen. The number of oxygen-deprived areas has also increased, from 45 before the 1960s to 700 in 2011, according to the report.
This oxygen loss is especially threatening to larger fish species like marlin, tuna and sharks, who require more energy, BBC News reported. These species are already moving closer to the surface for oxygen, which puts them at greater risk from overfishing. Cobb also pointed to the mass die-offs of fish along the coast of California as another symptom of falling oxygen levels.
Climate change and nutrient pollution are driving oxygen out of the ocean and coastal waters, threatening marine li… https://t.co/k4yms0MFQB— IUCN (@IUCN)1575876622.0
Loss of oxygen could also impact Earth systems that extend beyond the ocean, such as the nitrogen and phosphorus cycles.
"If we run out of oxygen it will mean habitat loss and biodiversity loss and a slippery slope down to slime and more jellyfish," Epps said, according to CBS and BBC News. "It will also change the energy and the biochemical cycling in the oceans and we don't know what these biological and chemical shifts in the oceans can actually do."
The report warned that if nations continue to emit greenhouse gases at business-as-usual levels, the ocean will lose three to four percent of its oxygen by century's end.
"To stop the worrying expansion of oxygen-poor areas, we need to decisively curb greenhouse gas emissions as well as nutrient pollution from agriculture and other sources," Laffoley said, according to BBC News.
At first glance, you wouldn't think avocados and almonds could harm bees; but a closer look at how these popular crops are produced reveals their potentially detrimental effect on pollinators.
Migratory beekeeping involves trucking millions of bees across the U.S. to pollinate different crops, including avocados and almonds. Timothy Paule II / Pexels / CC0<p>According to <a href="https://www.fromthegrapevine.com/israeli-kitchen/beekeeping-how-to-keep-bees" target="_blank">From the Grapevine</a>, American avocados also fully depend on bees' pollination to produce fruit, so farmers have turned to migratory beekeeping as well to fill the void left by wild populations.</p><p>U.S. farmers have become reliant upon the practice, but migratory beekeeping has been called exploitative and harmful to bees. <a href="https://www.cnn.com/2019/05/10/health/avocado-almond-vegan-partner/index.html" target="_blank">CNN</a> reported that commercial beekeeping may injure or kill bees and that transporting them to pollinate crops appears to negatively affect their health and lifespan. Because the honeybees are forced to gather pollen and nectar from a single, monoculture crop — the one they've been brought in to pollinate — they are deprived of their normal diet, which is more diverse and nourishing as it's comprised of a variety of pollens and nectars, Scientific American reported.</p><p>Scientific American added how getting shuttled from crop to crop and field to field across the country boomerangs the bees between feast and famine, especially once the blooms they were brought in to fertilize end.</p><p>Plus, the artificial mass influx of bees guarantees spreading viruses, mites and fungi between the insects as they collide in midair and crawl over each other in their hives, Scientific American reported. According to CNN, some researchers argue that this explains why so many bees die each winter, and even why entire hives suddenly die off in a phenomenon called colony collapse disorder.</p>
Avocado and almond crops depend on bees for proper pollination. FRANK MERIÑO / Pexels / CC0<p>Salazar and other Columbian beekeepers described "scooping up piles of dead bees" year after year since the avocado and citrus booms began, according to Phys.org. Many have opted to salvage what partial colonies survive and move away from agricultural areas.</p><p>The future of pollinators and the crops they help create is uncertain. According to the United Nations, nearly half of insect pollinators, particularly bees and butterflies, risk global extinction, Phys.org reported. Their decline already has cascading consequences for the economy and beyond. Roughly 1.4 billion jobs and three-quarters of all crops around the world depend on bees and other pollinators for free fertilization services worth billions of dollars, Phys.org noted. Losing wild and native bees could <a href="https://www.ecowatch.com/wild-bees-crop-shortage-2646849232.html" target="_self">trigger food security issues</a>.</p><p>Salazar, the beekeeper, warned Phys.org, "The bee is a bioindicator. If bees are dying, what other insects beneficial to the environment... are dying?"</p>
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