Oxygen & Ocean
Did you know that most of the oxygen you breathe comes from organisms in the ocean?
That’s right—more than half of the oxygen you breathe comes from marine photosynthesizers, like phytoplankton and seaweed. Both use carbon dioxide, water and energy from the sun to make food for themselves, releasing oxygen in the process. In other words, they photosynthesize. And this is done in the ocean.
However, some scientists suggested that the phytoplankton in the oceans have reduced in abundance globally by 40% since 1950, or a decline of about 1% per year.
The scientists found that long-term phytoplankton declines were negatively correlated with rising sea surface temperatures and changing oceanographic conditions have led to this decline.
How is oxygen from the ocean created?
Photosynthesizers have been in the ocean for a long time. Land plants first appeared in the fossil record 470 million years ago, long before dinosaurs roamed the earth. But the ocean was producing oxygen for billions of years before that. The oldest known fossil is from a marine cyanobacterium, a tiny-blue green photosynthesizer that was releasing oxygen 3.5 billion years ago.
In a way, we owe to the ocean for all of the oxygen that comes from land plants as well, since land plants evolved from green marine algae.
But the ocean’s long history of photosynthesis would matter little to us if not for the photosynthesizers that live in it today. Cyanobacterium called Prochlorococcus is the most impressive one. It is estimated to be more abundant than any other photosynthesizer on the planet, and to be responsible for producing 20 percent of the oxygen in the atmosphere.
One in every five breaths you take, you owe to this marine plankton.
There are more than 7,000 different species of algae. Most live in the oceans, but they also live in freshwater and even on land. Also, algae produce about 330 billion tons of oxygen each year.
There is some discussion going on that, climate change and extreme currents in the ocean can disrupt this tiny creatures. Also, severe water pollution can possibly kill them. But there is still not concrete reports about it.
This research combines new observations and modelling to determine what controls the exchange of these gases and how they are linked to and interact with the climate system. This video explains how the deep ocean connects with the atmosphere and the role of this deep breathing in climate change.
What is Ocean Deoxygenation?
Ocean deoxygenation refers to the loss of oxygen from the oceans due to climate change. Long-term ocean monitoring shows that oxygen concentrations in the ocean have declined during the 20th century, and a new report predicts that they will decrease by 3-6% during the 21st century in response to surface warming.
We see many studies are consistently identifying the decreasing concentration of dissolved oxygen in ocean waters. At the same time, ocean waters are acidifying at the fastest rate in over 300 million years. According to The State of the Ocean Report (2013), written by an international panel of marine scientists, an increase in human CO2 emissions and warming of the oceans are creating conditions similar to those of the great Permian extinction 300 million years ago.
The processes in the ocean are slow to change, so the effects of deoxygenation the oceans will continue. Even if all CO2 emissions stopped today, the effects in the oceans will be felt for another 50 years. What is happening now can represent the first stages of a global marine catastrophe – if CO2 emissions are not rapidly reduced.
‘In the past decade ocean oxygen levels have taken a dive—an 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.
Many scientists are not surprised the warming effects of climate change are causing the oceans to lose oxygen, but the scale of the dip calls for urgent attention. 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.
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. 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 surface—either directly from the atmosphere or from surface-dwelling phytoplankton producing it during photosynthesis—less mixing means less of it at depth.
Direct measurements show the amount of oxygen in the global oceans has decreased by around 2% over the past 50 years.
Climate change is thought to be a principal cause of this “deoxygenation”, affecting how much oxygen seawater can hold and the circulation patterns that carry oxygen-rich water to the deeper ocean.
Marine Animals
Rising global temperatures on ocean oxygen levels, poses a huge threat to marine life.
Deoxygenation can be catastrophic to the ocean’s ecosystems. Hypoxic water (water that is low in oxygen) is already killing marine species in the Pacific Northwest.
Ocean animals large and small, however, respond to even slight changes in oxygen by seeking refuge in higher oxygen zones or by adjusting behavior, scientists 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, since “they all have to breathe.”
As we mentioned above, phytoplankton are decreasing at an alarming pace. Not only they are responsible for producing oxygen, they are also part of very complex marine ecosystem. They are the food source for many sea animals, so you can imagine that if this tiny creatures disappear, the food chain will break.
Dead Zones
Dead zones are areas of large bodies of water—typically in the ocean or even lakes and rivers—that do not have enough oxygen to support marine life. What is causing such “hypoxic” (lacking oxygen) conditions is usually eutrophication, an increase in chemical nutrients in the water, leading to excessive blooms of algae that deplete underwater oxygen levels. Nitrogen and phosphorus from agricultural runoff are the primary culprits, but sewage, vehicular and industrial emissions play a role in the development of dead zones.Also, said above climate change affects ocean as well. Warming surface waters make it harder for oxygen to reach the ocean interior. Furthermore, as the ocean gets a whole warmer, it holds less oxygen.
Andreas Oschlies, GEOMAR Helmholtz Centre for Ocean Research Kiel, Germany. From: The Expansion of Low Oxygen Zones in the Global Ocean and Coastal Waters (symposium), 2019-02-21.
One report on dead zones, reviewed evidence on low-oxygen zones collected around the world, and found that these deadly swathes of water in the open ocean have quadrupled in number since the 1950s, expanding by millions of square kilometers. And that's a much bigger problem than most people recognise.
Dead zones occur in many areas of the country, particularly along the East Coast, the Gulf of Mexico, and the Great Lakes, but there is no part of the country or the world that is immune. There are over 400 dead zones worldwide. The Baltic Sea has the largest dead zone. The second largest dead zone in the world is located in the U.S., in the northern Gulf of Mexico. It’s the size of 5 million soccer fields.
Ocean expert Nancy Rabalais tracks the ominously named "dead zone" in the Gulf of Mexico -- where there isn't enough oxygen in the water to support life. The Gulf has the second largest dead zone in the world; on top of killing fish and crustaceans, it's also killing fisheries in these waters. Rabalais tells us about what's causing it -- and how we can reverse its harmful effects and restore one of America's natural treasures.
A brief environmental video essay that looks at the Dead Zone in the Gulf Mexico and the effect of industrial agriculture, fertilizer, and manure on America's waterways. Specifically, I trace the oxygen deprivation caused by algal blooms in the Dead Zone back to overuse of fertilizers and runoff from conventional farms near the Mississippi.
Ocean acidification is another way oceans are affected nowadays. It is created when carbon dioxide from the the atmosphere finds its way into the ocean. When carbon dioxide dissolves in seawater, the water becomes more acidic and the ocean’s pH drops. Since the industrial revolution, the average pH of the ocean has been found to have fallen from 8.2 to 8.1, which may seem small but corresponds to an increase in acidity of about 26%.
As we keep pumping carbon dioxide into the atmosphere, more of it is dissolving in the oceans, leading to drastic changes in the water's chemistry. Triona McGrath researches this process, known as ocean acidification, and in this talk she takes us for a dive into an oceanographer's world. Learn more about how the "evil twin of climate change" is impacting the ocean -- and the life that depends on it.
What Can be Done?
Need for Attention by Policy-Makers
Since climate change is the driving cause of ocean deoxygenation, reducing carbon dioxide (CO2) emissions is the only real solution. However, certain other actions can help to ameliorate the problem especially at a local level. As mentioned on the climate change articles, governments should create strict regulations on these dangerous emissions.
What’s more, decreasing or banning anthropogenic stressors such as nutrient pollution and overfishing may improve the resilience capacity of marine communities. Pollution from agriculture pesticides is causing severe damages to the water.
Education
Nevertheless, raising awareness through campaigns and advocacy can significantly address such situations from happening in the first place. It can simply be done through an educative process that helps people realize the causes and effects of ocean detoxification. In any case, people contribute to air pollution in multiple ways without even knowing. By raising awareness, we can help minimize these causes.
Today's environmental problems are so big they can seem overwhelming, but there are steps each individual can can take to help reverse dead zones.
Avoid chemical based household products. Every bit of water you flush away eventually returns to the watershed, bringing man-made pollutants with it.
Avoid using fertilizers. Seed companies have developed strains of crops that require less nitrogen and phosphorus, and if you're uncomfortable with genetically modified plants, you can rotate garden crops to naturally replenish soil. Also,by organic products you support farmers that haven’t used any pesticides or fertilizers.
Be mindful of air pollution. Burning wood or using fossil fuels releases nitrogen into the air which will make its way into the water. The biggest steps most individuals can take are driving less and reducing power consumption in the home.
Be aware of legislation that can either worsen or improve the situation. Vote, and if you see a problem, raise your voice and become part of the solution.
What can you do to help reduce ocean deoxygenation? By tagging us with #theconsciouschallenge you can share your ideas!
Want to contribute to our Ecological Footprint Bible? Submit us your scientific articles! Mail us at info@theconsciouschallenge.org
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