Environment & Energy
Related: About this forumOcean Oxygen Content Down Up To 40% In Past 50 Years In Some Tropical Areas; Global Average Down 2%
Escaping predators, digestion and other animal activitiesincluding those of humansrequire oxygen. But that essential ingredient is no longer so easy for marine life to obtain, several new studies reveal. In the past decade ocean oxygen levels have taken a divean alarming trend that is linked to climate change, says Andreas Oschlies, an oceanographer at the Helmholtz Center for Ocean Research Kiel in Germany, whose team tracks ocean oxygen levels worldwide. We were surprised by the intensity of the changes we saw, how rapidly oxygen is going down in the ocean and how large the effects on marine ecosystems are, he says.
It is no surprise to scientists that warming oceans are losing oxygen, but the scale of the dip calls for urgent attention, Oschlies says. Oxygen levels in some tropical regions have dropped by a startling 40 percent in the last 50 years, some recent studies reveal. Levels have dropped more subtly elsewhere, with an average loss of 2 percent globally.
Ocean animals large and small, however, respond to even slight changes in oxygen by seeking refuge in higher oxygen zones or by adjusting behavior, Oschlies and others in his field have found. These adjustments can expose animals to new predators or force them into food-scarce regions. Climate change already poses serious problems for marine life, such as ocean acidification, but deoxygenation is the most pressing issue facing sea animals today, Oschlies says. After all, he says, they all have to breathe.
A warming ocean loses oxygen for two reasons: First, the warmer a liquid becomes, the less gas it can hold. That is why carbonated beverages go flat faster when left in the sun, Oschlies says. Second, as polar sea ice melts, it forms a layer of buoyant water at the sea surface above colder, more saline waters. This process creates a sort of lid that can keep currents from mixing surface water down to deeper depths. And because all oxygen enters this habitat at the surfaceeither directly from the atmosphere or from surface-dwelling phytoplankton producing it during photosynthesisless mixing means less of it at depth. Some coastal regions around the equator naturally are low-oxygen hotspots because they contain nutrient-rich waters where bacterial blooms consume oxygen as they break down dead marine life. But shifts in ecosystems elsewhereincluding in the open ocean and around the polesespecially surprises and concerns Oschlies and others because these regions were not considered as vulnerable. Climate models projecting future change have also routinely underestimated the oxygen losses already observed around the worlds oceans, he and his colleagues reported in Nature last yearanother reason why this trend calls for more attention, he says.
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https://www.scientificamerican.com/article/the-ocean-is-running-out-of-breath-scientists-warn/
MLAA
(17,348 posts)We have really screwed up our planet. I think it is too late and the end will come sooner than expected.
I look at my daughter who is turning 3 next week and wonder what her life will be like when she is my age (i'm 42). I'd like to hope that I'm still here but given how I spent the latter half of my twenties; I'm pretty sure I removed a few years from my life. Anyway, my wife and I tried for years and had given up when she got pregnant (such a cliché I know). We are so grateful that she is in our lives but sometimes I fear for what her life will actually look like in the future.
MLAA
(17,348 posts)I am plant based so I feel like that is the single biggest thing I can do as an individual, though I think that and any other efforts are too late/too little. Beyond that, I am trying harder to enjoy every day and do things I enjoy. Enjoy your little ones childhood and make it the best you can for her full of wonderful memories!