Due to people's emissions, oceans are getting hotter. Oceans take up heat from the atmosphere, causing loss of habitat loss for marine species, leading to their extinction. Oceans also take up carbon dioxide (CO₂) from the atmosphere, causing acidification of the water. Organisms in oceans through photosynthesis split CO₂ into carbon and oxygen, which helps replenish the oxygen we breathe
In the early days of Earth, the Sun was about 30% dimmer than it is now. Air temperatures were elevated by relatively high levels of greenhouse gases in the atmosphere, resulting from volcano eruptions and further seismic events such as earthquakes and tectonic plate movements.
Andrew Glikson suggests that, in order to have oceans with water above freezing point, the atmosphere would have needed CO₂ levels some 100–1000 times the present atmospheric level.
Initially, Earth didn't have oceans and the atmosphere didn't have oxygen. When Earth formed, some 4.6 billion years ago, hydrogen and oxygen were present, but only in the form of water vapor in the atmosphere, rather than in the form of free oxygen and oceans.
Over many years, weathering kept converting atmospheric CO₂ to calcium carbonate. As a result, atmospheric CO₂ levels declined, thus reducing the greenhouse effect and thus bringing down the temperature of Earth's lower atmosphere.
Life emerges
Between 3.5 and 4 billion years ago, oceans formed as water kept falling down as rain. Simple life forms started to appear in the oceans, i.e. single-cell organisms such as bacteria and algae.
More than two billion years after Earth formed, free oxygen started to get released by organisms in oceans that used photosynthesis to split CO₂ into carbon and oxygen. Eventually, plants could grow on land once enough oxygen had accumulated in the atmosphere for the ozone layer to form. Plants growing on land further helped to take CO₂ out of the atmosphere. The first animals appeared on land some 1.2 billion years ago.
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| Biomass |
High greenhouse gas levels caused by people result in higher temperatures. Much heat goes into oceans. One danger is that the capacity of oceans to act as sinks for surplus heat and carbon dioxide will decrease. High levels of CO₂ are causing acidification in oceans. Furthermore, there are the problems of stratification of the water of oceans and of loss of oxygen.
Acidification, stratification and oxygen depletion
As said, more CO₂ in oceans causes acidification. Diatoms are single-celled algae that use dissolved silica to build the walls of their cells. These are dense, glass-like structures, making diatoms sink more quickly than other phytoplankton, and thus sequestering more carbon at the sea floor where it may remain stored for millennia. A recent study found many of the species were highly sensitive to increased acidity, reducing their individual silicification rates by 35-80%.
Next to acidification, there is stratification. As the water heats up, it tends to form a layer at the surface that does not mix well with colder, nutrient-rich water below, depriving phytoplankton of essential nutrients. Stratification causes depletion of nutrients and makes phytoplankton less able to take up CO₂ from the atmosphere, so more CO₂ will remain in the atmosphere.
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| Phytoplankton are most abundant (yellow, high chlorophyll) in high latitudes and in upwelling zones along the equator and near coastlines. They are scarce in remote oceans (dark blue), where nutrient levels are low. This map shows the average chlorophyll concentration in the global oceans from July 2002–May 2010. (NASA image by Jesse Allen & Robert Simmon, based on MODIS data from the GSFC Ocean Color team.) |
The word 'phytoplankton' comes from the Greek phyto (i.e. plant) and plankton (i.e. made to wander or drift). Phytoplankton is formed by microscopic (single-celled), free-floating, non-swimming plants that drift in the water. The chlorophyll in phytoplankton captures sunlight through photosynthesis, enabling decomposition of CO₂ into carbon and oxygen. The oxygen is then released.
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| 1 Gigatonne (Gt) = 1 billion tonnes = 1 Petagram (Pg).
1 PgC = 3.664 Gt of CO₂. Oceans have absorbed some 40% of CO₂ emissions since the start of the industrial era. Recent annual CO₂ take up by oceans is about 26% (annual global average over 2006 - 2015). From an earlier post. |
So, next to the temperature rise of oceans, further problems are acidification and stratification, and depletion of oxygen in oceans.
Hot water holds less oxygen than cold water, and oxygen depletion makes it harder for many lifeforms to exist. To obtain oxygen, fish take water into their mouth, passing the gills just behind its head on each side. Diatoms are the predominant forms of phytoplankton. Diatoms produce as much as 50% of the air we breathe. Together, phytoplankton in oceans, algae, kelp and seaweed produce some two-thirds of the planet’s total atmospheric oxygen, as well as the oxygen that remains in ocean.
Dead zones growing in oceans reflect hypoxia, i.e. depletion of oxygen in the water. Dead zones in oceans are caused by blooms of hazardous algae that cause oxygen in the water underneath the surface to be depleted. Ocean currents slowing down and stratification can further contribute to oxygen depletion as they result in less mixing and thus less oxygen and nutrients getting provided to organisms in the water.
Stratification occurs as water masses with different properties, primarily temperature and salinity, become layered, with lower density water on top of higher density water. The larger the differences in the properties between layers, the less mixing occurs between the layers.
Oxygen depletion was discussed in an earlier post. A study by Boyce et al. found a decrease of about 1% per year of phytoplankton in oceans globally. There are indications that, at a 5°C rise in ocean temperature, phytoplankton would start consuming, rather than producing oxygen. One study warns that this “would result in the depletion of atmospheric oxygen on a global scale. This would likely result in the mass mortality of animals and humans.”
Temperature rise of the North Atlantic
The image below shows that the North Atlantic sea surface temperature was 23.3°C on June 21, 2023 (on the black line), 0.9°C higher than the 22.4°C on June 21, 2022 (on the orange line). A record high of 24.9°C was reached on September 4, 2022, even while La Niña at the time was suppressing the temperature, whereas there now is an El Niño, so the outlook is grim.
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| [ from earlier post ] |
Therefore, the following points should be taken into consideration:
- The narrowing temperature difference between the Arctic and the Tropics is slowing down the flow of air from the Tropics to the Arctic, deforming the Jet Stream, which can strongly prolong and amplify extreme weather events in the Northern Hemisphere, and result in stronger heating up of the North Atlantic.
- This is also slowing down AMOC, resulting in more hot water to accumulate in the North Atlantic and to reach the Arctic Ocean, resulting in strong melting of sea ice from below and thus strong thinning.
- Additionally, increased stratification further raises surface water temperatures.
- As the North Atlantic Ocean heats up and as cold air from the Arctic can more deeply descend over North America (Jet Stream deformation), the temperature difference between land and oceans widens, especially during the Northern Winter, and this can result in storms abruptly pushing strong wind along the path of the Gulf Stream, pushing ocean heat into the Arctic Ocean, with stronger evaporation occurring over the North Atlantic and with stronger precipitation (rain, snow, etc.) occurring further down the path of the Gulf Stream. The evaporation cools the surface of the North Atlantic.
- This cooling, together with cooling from increased meltwater, has until now covered up the full extent of the rise in ocean heat in the North Atlantic, but - as illustrated by the above image - the continued rise in ocean heat now is overwhelming this surface cooling.
- This cooling, together with cooling from increased meltwater, also results in formation of a cold freshwater lid on top of the North Atlantic, also because freshwater is less dense than saltwater.
- This lid on top of the North Atlantic enables more hot water to flow underneath this lid into the Arctic Ocean, with the danger that more heat will reach sediments at the seafloor of the Arctic Ocean and destabilize hydrates, resulting in eruption of huge amounts of methane.
Outlook is grim
As temperatures keep rising, life on Earth looks set to go extinct, and most life will likely disappear with a 5°C rise, as discussed in this post and this post, and as also illustrated by the image below.
What can be done to improve the situation?
Furthermore, it is important to look for ways to increase the presence of diatoms in oceans. Diatoms are good types of algae, both producing oxygen and reducing carbon levels in oceans, thus also tackling acidification. More oxygen in the water will also help microbes that can break down methane in the water as it gets released from the seafloor. Thus, it is important to look at ways to help diatoms grow. The exoskeleton of diatoms is made of silica, so it's important to make that there is enough silica in the water. This can be achieved by enhanced weathering of olivine, which will also provide further necessary nutrients.
Roelof Schuiling once imagined creating a lagoon along the beach, by surrounding a piece of the sea in front of this beach by a dam. Construct a connection through this dam, Roelof Schuiling continues, through which water can flow into the lagoon at high tide, and flow out of the lagoon at ebb tide. Cover the beach with half a meter thick layer of olivine grains between the high tide line and the low tide line. The beach will alternatively be wetted and drained, by which the silica-rich water will flow into the lagoon, and feed the diatoms.
Another way to counter acidification is to use electrolysis in oceans to produce hydrogen and to consume CO₂, as also described in an earlier post.
Around 50% of soil-available phosphorus comes from mineral fertilisers in agricultural systems worldwide
https://www.eurekalert.org/news-releases/975848
Half of global agricultural soil phosphorus fertility derived from anthropogenic sources - by Joséphine Demay et al.
https://www.nature.com/articles/s41561-022-01092-0
A lot of phosphorus is flushed away with urban sewage and runoff from agricultural land. This reduces the phosphorus in the soil and it also causes blooms (eutrophication) of blue green algae (Cyanobacteria) that in turn cause depletion of oxygen (hypoxia) in local waters and in oceans. Additionally, global warming is causing oxygen depletion in oceans. See:
https://www.epa.gov/caddis-vol2/dissolved-oxygen
A 2015 study calculates that an increase in the water temperature of the world's oceans of around six degrees Celsius -- which some scientists predict could occur as soon as 2100 -- could stop oxygen production by phytoplankton by disrupting the process of photosynthesis. About two-thirds of the planet's total atmospheric oxygen is produced by ocean phytoplankton - and therefore cessation would result in the depletion of atmospheric oxygen on a global scale. This would likely result in the mass mortality of animals and humans.
https://www.eurekalert.org/news-releases/652115
It therefore makes sense to add iron and other trace metals/micro nutrients to the water in an effort to stimulate growth of a specific type of phytoplankton called diatom algae, which through photosynthesis absorb carbon dioxide in the water and add oxygen. The oxygen is then also used by methanotroph bacteria to oxidize methane that may be escaping from the seafloor.
https://arctic-news.blogspot.com/p/oxygenating-arctic.html
Additionally, it makes sense for most biowaste (including kitchen and garden waste, and sewage) to be turned into biochar that is added to the soil, as discussed at 'Transforming Society', at:
https://arctic-news.blogspot.com/2022/10/transforming-society.html
Links
• Habitat loss and extinction of species
https://arctic-news.blogspot.com/p/habitat-loss.html
• Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene - by Andrew Glikson et al.
http://www.springer.com/gp/book/9783319225111
• Aqua Facts
https://www.oceanicinstitute.org/aboutoceans/aquafacts.html
• Diatoms
https://diatoms.org/what-are-diatoms
• Global warming disaster could suffocate life on planet Earth, research shows
https://www.eurekalert.org/news-releases/652115
• Oxygenating the Arctic
• Accelerating growth in CO₂ levels in the atmosphere
• Cold freshwater lid on North Atlantic
https://arctic-news.blogspot.com/p/cold-freshwater-lid-on-north-atlantic.html
• Arctic sea ice under threat - update 4
• Accelerating growth in CO₂ levels in the atmosphere
https://arctic-news.blogspot.com/2017/02/accelerating-growth-in-co2-levels-in-the-atmosphere.html
• Monthly CO₂ not under 400 ppm in 2016
https://arctic-news.blogspot.com/2016/11/monthly-co-not-under-400-ppm-in-2016.html
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
As temperatures keep rising, life on Earth looks set to go extinct, and most life will likely disappear with a 5°C rise, as discussed in this post and this post, and as also illustrated by the image below.
 |
| [ from an earlier post ] |
What can be done to improve the situation?
Rising temperatures cause stratification in oceans and thus oxygen depletion in oceans, so it's important to take action to combat the temperature rise. Managing runoff from land is also important, because it comes with emission of greenhouse gases and also because it contributes to ocean stratification, as the water in the runoff has lower salinity of the water than seawater and due to nutrient contained in the runoff, i.e. fertilizers and other nutrients that feed hazardous algae blooms resulting in oxygen depletion in oceans.
Nutrients including phosphorus are flushed away with urban sewage and runoff from agricultural land, to end up in oceans. This reduces the phosphorus in the soil and it also causes blooms (eutrophication) of blue green algae (Cyanobacteria) that in turn cause depletion of oxygen (hypoxia) in local waters and in oceans.
Nutrient-rich runoff from land, combined with nutrients contained in sewage, cause blooms of cyanobacteria and other harmful algae. Such blooms can spread on top of the water and result in dead zones and loss of phytoplankton underneath such blooms. Ways to combat this are described in the post Transforming Society.
Nutrients including phosphorus are flushed away with urban sewage and runoff from agricultural land, to end up in oceans. This reduces the phosphorus in the soil and it also causes blooms (eutrophication) of blue green algae (Cyanobacteria) that in turn cause depletion of oxygen (hypoxia) in local waters and in oceans.
Nutrient-rich runoff from land, combined with nutrients contained in sewage, cause blooms of cyanobacteria and other harmful algae. Such blooms can spread on top of the water and result in dead zones and loss of phytoplankton underneath such blooms. Ways to combat this are described in the post Transforming Society.
Furthermore, it is important to look for ways to increase the presence of diatoms in oceans. Diatoms are good types of algae, both producing oxygen and reducing carbon levels in oceans, thus also tackling acidification. More oxygen in the water will also help microbes that can break down methane in the water as it gets released from the seafloor. Thus, it is important to look at ways to help diatoms grow. The exoskeleton of diatoms is made of silica, so it's important to make that there is enough silica in the water. This can be achieved by enhanced weathering of olivine, which will also provide further necessary nutrients.
Roelof Schuiling once imagined creating a lagoon along the beach, by surrounding a piece of the sea in front of this beach by a dam. Construct a connection through this dam, Roelof Schuiling continues, through which water can flow into the lagoon at high tide, and flow out of the lagoon at ebb tide. Cover the beach with half a meter thick layer of olivine grains between the high tide line and the low tide line. The beach will alternatively be wetted and drained, by which the silica-rich water will flow into the lagoon, and feed the diatoms.
The olivine will take CO₂ out of the atmosphere and out of the water. The lagoon can also receive input from rivers that contain run-off from farms with high levels of fertilizers.
Diatom production in the lagoon can be boosted by installing an underwater LED-lighting, enabling photosynthesis of diatoms to continue through the night. Dead diatoms can be left to flow deeper in the ocean to sequester carbon. Bags, made from seaweed or other organic material, can also be used to help harvest the diatoms and be brought onto land to be pyrolyzed together with other biomass to create biochar to be added to soil.
Another way to counter acidification is to use electrolysis in oceans to produce hydrogen and to consume CO₂, as also described in an earlier post.
Around 50% of soil-available phosphorus comes from mineral fertilisers in agricultural systems worldwide
https://www.eurekalert.org/news-releases/975848
Half of global agricultural soil phosphorus fertility derived from anthropogenic sources - by Joséphine Demay et al.
https://www.nature.com/articles/s41561-022-01092-0
A lot of phosphorus is flushed away with urban sewage and runoff from agricultural land. This reduces the phosphorus in the soil and it also causes blooms (eutrophication) of blue green algae (Cyanobacteria) that in turn cause depletion of oxygen (hypoxia) in local waters and in oceans. Additionally, global warming is causing oxygen depletion in oceans. See:
https://www.epa.gov/caddis-vol2/dissolved-oxygen
A 2015 study calculates that an increase in the water temperature of the world's oceans of around six degrees Celsius -- which some scientists predict could occur as soon as 2100 -- could stop oxygen production by phytoplankton by disrupting the process of photosynthesis. About two-thirds of the planet's total atmospheric oxygen is produced by ocean phytoplankton - and therefore cessation would result in the depletion of atmospheric oxygen on a global scale. This would likely result in the mass mortality of animals and humans.
https://www.eurekalert.org/news-releases/652115
It therefore makes sense to add iron and other trace metals/micro nutrients to the water in an effort to stimulate growth of a specific type of phytoplankton called diatom algae, which through photosynthesis absorb carbon dioxide in the water and add oxygen. The oxygen is then also used by methanotroph bacteria to oxidize methane that may be escaping from the seafloor.
https://arctic-news.blogspot.com/p/oxygenating-arctic.html
Additionally, it makes sense for most biowaste (including kitchen and garden waste, and sewage) to be turned into biochar that is added to the soil, as discussed at 'Transforming Society', at:
https://arctic-news.blogspot.com/2022/10/transforming-society.html
Links
• Habitat loss and extinction of species
https://arctic-news.blogspot.com/p/habitat-loss.html
• Climate, Fire and Human Evolution: The Deep Time Dimensions of the Anthropocene - by Andrew Glikson et al.
http://www.springer.com/gp/book/9783319225111
• Aqua Facts
https://www.oceanicinstitute.org/aboutoceans/aquafacts.html
• Diatoms
https://diatoms.org/what-are-diatoms
• Global warming disaster could suffocate life on planet Earth, research shows
https://www.eurekalert.org/news-releases/652115
• Oxygenating the Arctic
• Accelerating growth in CO₂ levels in the atmosphere
https://arctic-news.blogspot.com/2017/02/accelerating-growth-in-co2-levels-in-the-atmosphere.html
• Most Important Message Ever
http://arctic-news.blogspot.com/2019/07/most-important-message-ever.html
• What the IPCC Impact Report is hiding
https://arctic-news.blogspot.com/2022/02/what-the-ipcc-impacts-report-is-hiding.html
• Earthrise: The 45th Anniversary
https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4129
• What are Phytoplankton?
https://earthobservatory.nasa.gov/features/Phytoplankton
• Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change - by Yadigar Sekerci and Sergei Petrovskii
https://link.springer.com/article/10.1007%2Fs11538-015-0126-0
• News Release: Global warming disaster could suffocate life on planet Earth, research shows
https://www2.le.ac.uk/offices/press/press-releases/2015/december/global-warming-disaster-could-suffocate-life-on-planet-earth-research-shows
• July 2019 Hottest Month On Record
https://arctic-news.blogspot.com/2019/08/july-2019-hottest-month-on-record.html
• Acid oceans are shrinking plankton, fuelling faster climate change - by Katherina Petrou and Daniel Nielsen
https://theconversation.com/acid-oceans-are-shrinking-plankton-fuelling-faster-climate-change-121443
• Study Acidification diminishes diatom silica production in the Southern Ocean - by Katherina Petrou et al.
https://www.nature.com/articles/s41558-019-0557-y
• Will there be Arctic sea ice left in September 2023?
• Recent increase in oceanic carbon uptake driven by weaker upper-ocean overturning
• Most Important Message Ever
http://arctic-news.blogspot.com/2019/07/most-important-message-ever.html
• What the IPCC Impact Report is hiding
https://arctic-news.blogspot.com/2022/02/what-the-ipcc-impacts-report-is-hiding.html
• Earthrise: The 45th Anniversary
https://svs.gsfc.nasa.gov/cgi-bin/details.cgi?aid=4129
• What are Phytoplankton?
https://earthobservatory.nasa.gov/features/Phytoplankton
• Mathematical Modelling of Plankton–Oxygen Dynamics Under the Climate Change - by Yadigar Sekerci and Sergei Petrovskii
https://link.springer.com/article/10.1007%2Fs11538-015-0126-0
• News Release: Global warming disaster could suffocate life on planet Earth, research shows
https://www2.le.ac.uk/offices/press/press-releases/2015/december/global-warming-disaster-could-suffocate-life-on-planet-earth-research-shows
• July 2019 Hottest Month On Record
https://arctic-news.blogspot.com/2019/08/july-2019-hottest-month-on-record.html
• Acid oceans are shrinking plankton, fuelling faster climate change - by Katherina Petrou and Daniel Nielsen
https://theconversation.com/acid-oceans-are-shrinking-plankton-fuelling-faster-climate-change-121443
• Study Acidification diminishes diatom silica production in the Southern Ocean - by Katherina Petrou et al.
https://www.nature.com/articles/s41558-019-0557-y
• Will there be Arctic sea ice left in September 2023?
https://arctic-news.blogspot.com/2023/05/will-there-be-arctic-sea-ice-left-in-september-2023.html
• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html
• Jet Stream
https://arctic-news.blogspot.com/p/jet-stream.html
• Cold freshwater lid on North Atlantic
https://arctic-news.blogspot.com/p/cold-freshwater-lid-on-north-atlantic.html
• Arctic sea ice under threat - update 4
https://arctic-news.blogspot.com/2017/02/accelerating-growth-in-co2-levels-in-the-atmosphere.html
• Monthly CO₂ not under 400 ppm in 2016
https://arctic-news.blogspot.com/2016/11/monthly-co-not-under-400-ppm-in-2016.html
• Transforming Society
https://arctic-news.blogspot.com/2022/10/transforming-society.html
• Olivine weathering to capture CO2 and counter climate change
https://arctic-news.blogspot.com/2016/07/olivine-weathering-to-capture-co2-and-counter-climate-change.html
• Negative-CO2-emissions ocean thermal energy conversion, by Greg Rau and Jim Baird
https://arctic-news.blogspot.com/2016/07/olivine-weathering-to-capture-co2-and-counter-climate-change.html
• Negative-CO2-emissions ocean thermal energy conversion, by Greg Rau and Jim Baird
https://www.sciencedirect.com/science/article/pii/S136403211830532X
• 'Electrogeochemistry' captures carbon, produces fuel, offsets ocean acidification
https://arctic-news.blogspot.com/2018/06/electrogeochemistry-captures-carbon-produces-fuel-offsets-ocean-acidification.html
• 'Electrogeochemistry' captures carbon, produces fuel, offsets ocean acidification
https://arctic-news.blogspot.com/2018/06/electrogeochemistry-captures-carbon-produces-fuel-offsets-ocean-acidification.html
