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Crossing planetary boundaries (PB), a concept that defines nine potential ecological “tipping points”, could mean catastrophe for Earth’s ecosystems and the future of humanity.
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Of these PBs, humans have already crossed six of the nine thresholds.
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Now, scientists argue there may be an unrecognized 10th boundary: a global underwater oxygen depletion in lakes, reservoirs, oceans and other bodies of water.
“Climate Change“Climate change” is a scary umbrella term for all the anthropogenic degradation that humans are causing to the Earth. One Of the many threats facing the planet.
First introduced in 2009 Planetary boundaries The (PB) concept identifies nine unique limits that, if crossed, could lead to catastrophe. Climate change is one of the nine limits, but the list also includes: Biosphere Atmospheric integrity, ozone depletion, ocean acidification, changes in freshwater, etc. (Of course, what we think of as climate change exacerbates all of these issues, so in some sense it’s still public enemy No. 1).
In a new study, scientists argue that a tenth boundary could be added to this list: underwater oxygen deficiency. Black SeaWaters of the Pacific Ocean (such as the Gulf of Mexico, the Baltic Sea, and various fjords) are naturally anoxic, meaning they contain little or no oxygen. However, widespread oxygen depletion is different and affects previously oxygenated waters to different degrees around the world.
Over the past 45 years, oxygen levels in lakes and reservoirs have declined by 5.5% and 18.6%, respectively, while the oceans have declined by 2% – staggering figures, the researchers found. oxygen Considering the breadth of the ocean, one of the most dramatic examples of oxygen depletion is in the intermediate waters off the coast of California, where oxygen levels have fallen by 40 percent since 1960. The findings are published in the journal Nature. Natural Ecology and Evolution.
Study co-author Andreas Oschries, professor of marine biogeochemical modelling at the GEOMAR Helmholtz Centre for Ocean Research in Kiel, Germany, provides a detailed explanation: In a press release Methodology Temperature rise Land (mis)use can cause such rapid oxygen depletion.
Loss of oxygen in water is caused by global warming due to greenhouse gas emissions and nutrient inputs from land use. Increasing water temperatures reduce the solubility of oxygen in water. In addition, global warming promotes stratification of the water column, as less dense, warmer, less saline water overlies the colder, more saline, deeper waters below. This prevents the exchange of oxygen between the oxygen-poor deep layers and the oxygen-rich surface layers. waterAdditionally, the influx of nutrients from land encourages algal blooms, causing more organic matter to sink and be broken down by microorganisms deep inside, consuming more oxygen.
Animals living in the ocean need oxygenated water to survive, so oxygen-poor water can have a major impact on fish, mussels and crustaceans. This then has ripples up the food chain, threatening the collapse of ecosystems. And as if that wasn’t enough, oxygen-poor water can also: Produce Nitrous oxide and methane, two notorious Greenhouse gasesIn other words, the loss of oxygen from Earth’s waters could lead to a plethora of potentially catastrophic climate disasters.
“Dissolved oxygen regulates the function of the ocean and marine ecosystems. Freshwater “In regulating the Earth’s climate, improving oxygen levels depends on addressing underlying causes, such as climate warming and runoff from developed land,” Kevin Rose, a professor at Rensselaer Polytechnic Institute in New York and lead author of the study, said in a press statement. “Unaddressed oxygen deficiencies in water will ultimately have consequences not only for ecosystems, but also for economic activity and global society.”
Humanity has already Six of the nine boundaries were crossed. Enumerated in the original PB concept, now the 10th boundary could soon join that notorious club. Luckily, there is a solution, and it’s It’s been with us for over a century—Eliminate emissions and save the planet.
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