GLOBAL WARMING AND THE SEA
giant jellyfish off Japan
maybe connected to global warming Global warming is causing ocean temperatures as well as air temperatures to rise. A 2005 report by a team headed by Tim Barett of Scripps Institution of Oceanography found that between 1955 and 2000, the oceans warmed by 0.7 degrees F. Because the oceans are so vast the energy needed to warm them even smalls amount is huge.
Scientist have been surprised how even water at great depths is warming up. Water surface temperatures in the tropical Northern Hemisphere have increased at ten times the rate of global warming in the air since 1984. Increases of .5 degree to 1 degree F have occurred in the major hurricane and typhoon breeding areas in the Atlantic and Pacific Oceans since 1906.
Carbon dioxide moves freely between the air and sea in a process known as molecular diffusion and tend to go where concentrations are the lowest. When carbon dioxide of levels are high in the air it flows into the sea. It is thought that carbon dioxide used moved from the seas to the air but now the situation is reserved and its flowing from the air to the seas. Some people have proposed pumping excess carbon dioxide into the deep sea but these plans were dropped when it was discovered that large doses of carbon dioxide kill marine life immediately
A number of Earth-orbiting satellites routinely provides updates on sea surface temperatures, sea level changes and ocean winds. Some have asked is it possible for heat from inside the Earth to heat up the seas, If that was happening the seas would heat up from the bottom up. There is no indication that that is happening. Most of the warming occurs at the surface.
Environmental Impact of Hotter Oceans
According to research by the National Center for Atmospheric Research in Colorado warmer ocean waters are helping to increase the intensity of storms, hurricanes and extreme rainfall, which in turn are exacerbating the risks of severe flooding. Heated ocean water expands and erodes the vast Greenland and Antarctic ice sheets, which are collectively discourging around 1trillion tons of ice a year, which in turn fuels sea level rises. [Source: Oliver Milman, The Guardian, January 11, 2022]
When oceans absorb carbon dioxide they become more acidic. This degrades coral reefs, home to a quarter of the world’s marine life and the provider of food for more than 500 million people, as well as seagrass meadows and kelp forests and can be particularly harmful to certain species of fish. Long-term ocean warming is strongest in the Atlantic and Southern oceans although the north Pacific has had a “dramatic” increase in heat since 1990 and the Mediterranean Sea posted a clear high temperature record in 2021
Bleached coralAccording to The Guardian: ““As the world warms from the burning of fossil fuels, deforestation and other activities, the oceans have taken the brunt of the extra heat. More than 90 percent of the heat generated over the past 50 years has been absorbed by the oceans, temporarily helping spare humanity, and other land-based species, from temperatures that would already be catastrophic.
Kyle Van Houtan, chief scientist for Monterey Bay Aquarium and the head of a team that published a study on climate change and oceans in PLOS Climate in early 2022 said: "Today, the majority of the ocean's surface has warmed to temperatures that only a century ago occurred as rare, once-in-50-year extreme warming events” and extreme heat has become a new normal across most of the ocean's surface. As the ocean heats up and as its ecosystems collapse, so too does their ability to buffer low-lying coastal regions from severe weather or to serve as a carbon sink for human-generated greenhouse gas emissions. [Source: The Hill, February 2, 2022]
Hottest Ocean Temperatures Ever Recorded in 2021
The hottest ocean temperatures in history were recorded in 2021 — the sixth consecutive year that this record has been broken. Despite an La Niña event, which cools cools waters in the Pacific, 2021 set a heat record for the top 2,000 meters of all oceans around the world,. Modern record-keeping for global ocean temperatures began in 1955. The second hottest year for oceans was 2020, while the third hottest was 2019.[Source: Oliver Milman, The Guardian, January 11, 2022]
“The ocean heat content is relentlessly increasing, globally, and this is a primary indicator of human-induced climate change,” said Kevin Trenberth, a climate scientist at the National Center for Atmospheric Research in Colorado and co-author of the research, published in Advances in Atmospheric Sciences. “The heating trend is so pronounced it’s clear to ascertain the fingerprint of human influence in just four years of records, according to John Abraham, another of the study’s co-authors. “Ocean heat content is one of the best indicators of climate change,” added Abraham, an expert in thermal sciences at University of St Thomas.
According to The Guardian: “The amount of heat soaked up by the oceans is enormous. In 2021, the upper 2,000 meters of the ocean, where most of the warming occurs, absorbed 14 more zettajoules (a unit of electrical energy equal to one sextillion joules) than it did in 2020. This amount of extra energy is 145 times greater than the world’s entire electricity generation which, by comparison, is about half of a zettajoule.
Oceans and Carbon Dioxide
Acting as a large sponge, oceans absorb about a third of the carbon dioxide that humans produce. If it wasn’t for the oceans the Earth could be two degrees warmer rather than one degree it is now. A study published in Science in July 2004 that involves analyzing 70,000 samples taken from around the globe in the 1990s reported that 48 percent of carbons dioxide produced by humans from 1800 and 1994 — 467 billion tons of the gas — had been absorbed by seawater. Not only that the oceans have produced much of the oxygen we breath.
By some estimates carbon dioxide is entering the ocean at a rate of 1 million tons an hour, ten times the natural rate. There is a large concentration of carbon dioxide in the Atlantic Ocean between North America and Europe and North Africa. The concentrations of carbon dioxide here are around 1.2 kilograms per meter, double or quadruple the amounts in most other seas. The North Atlantic Ocean holds the most because that is where cooled surface water sinks, filling more of the water column with carbon.
Elizabeth Kolbert wrote in National Geographic, “The air and the water constantly exchange gases, so a portion of anything emitted into the atmosphere eventually ends up in the sea. Winds quickly mix it into the top few hundred feet, and over centuries currents spread it through the ocean depths. In the 1990s an international team of scientists undertook a massive research project that involved collecting and analyzing more than 77,000 seawater samples from different depths and locations around the world. The work took 15 years. It showed that the oceans have absorbed 30 percent of the CO2 released by humans over the past two centuries. They continue to absorb roughly a million tons every hour. [Source: Elizabeth Kolbert, National Geographic, April 2011]
Global Warming and Sea Life
Marine life absorbs about 2 billion tons of carbon dioxide from the atmosphere a year. Much of the world’s carbon stocks are held in plankton, mangroves, salt marshes and other marine life. Algae in the sea absorbs some of the excessive carbon dioxide but most of it never reach the seabed to become a permanent store. Mangrove forest, salt marshes and sea grass bed cover less than 1 percent of the world’s seabed but they lock away well over half of all carbon absorbed by marine life.
Some underwater creatures such as mussels and freshwater snails emit nitrous oxide, better known as laughing gas — a powerful greenhouse gas that is 310 times more potent than carbon dioxide in trapping heat in the atmosphere.
Carbon dioxide in the air and the seas and warmer sea temperatures result in less oxygen near the surface of the sea and produce oxygen poor zones that extend vertically. The massive dead zones like the on off the west coast of the United States are believed to be caused by global warming and warming sea temperatures and changes between the wind and sea that deprive the water of oxygen. The lack of oxygen will be especially tough on large sea creatures that need lots of oxygen to move around and hunt.
High temperatures have already resulted in the bleaching of coral and disappearance of Arctic ice cover. The high temperatures also stunt growth, reduce food supplies and can force fish to breed in or move to cooler water for which they are not adapted.
Global warming is blamed for causing warmer sea temperatures in the North Sea which in turn have causes many species of fish including cod, sole and whiting to migrate further north in search of cooler water. In the Americas global warming has caused an oyster-infecting bacterium that causes food poisoning in humans to spread from the Gulf of Mexico to waters off Alaska.
Ph (Acid) levels in the ocean
Research by Australia’s Commonwealth Scientific and Industrial Research Organization indicates that climate change is affecting fish growth, with species living in warmer, shallow water growing faster and those living in cooling deep ocean waters growing slower. Ron Thresher, an oceanographer involved with the study told Reuters, “Fish growth rates are closely tied with water temperature s, so warming surface waters mean the shallow-water fish are growing more slowly than they were a century ago. The finding was made by examining 555 fish specimens aged between 2 and 128 born between 1861 and 1992 and comparing that with changes in sea temperatures obtained from 60-year-old records and data obtained from 440-year-old deep water coral.
Extra carbon dioxide molecule in sea water alters the pH level of sea water, making it slightly more acidic. In some places scientists have observed rises in acidity of 30 percent and predict 100 to 150 percent increases by 2100.
The mixture of carbon dioxide and seawater creates carbonic acid, the weak acid in carbonated drinks. The increased acidity reduces the abundance of carbonate ions and other chemicals necessary to form calcium carbonate used make sea shells and coral skeletons. To get an idea what acid can due to shells remember back to high school chemistry classes when acid was added to calcium carbonate, causing it to fizz.
Elizabeth Kolbert wrote in National Geographic, The pH scale, which measures acidity in terms of the concentration of hydrogen ions, runs from zero to 14. At the low end of the scale are strong acids, such as hydrochloric acid, that release hydrogen readily (more readily than carbonic acid does). At the high end are strong bases such as lye. Pure, distilled water has a pH of 7, which is neutral. Seawater should be slightly basic, with a pH around 8.2 near the sea surface. So far CO2 emissions have reduced the pH there by about 0.1. Like the Richter scale, the pH scale is logarithmic, so even small numerical changes represent large effects. A pH drop of 0.1 means the water has become 30 percent more acidic. If present trends continue, surface pH will drop to around 7.8 by 2100. At that point the water will be 150 percent more acidic than it was in 1800. [Source: Elizabeth Kolbert, National Geographic, April 2011]
The acidification that has occurred so far is probably irreversible. Although in theory it's possible to add chemicals to the sea to counter the effects of the extra CO2, as a practical matter, the volumes involved would be staggering; it would take at least two tons of lime, for example, to offset a single ton of carbon dioxide, and the world now emits more than 30 billion tons of CO2 each year. Meanwhile, natural processes that could counter acidification’such as the weathering of rocks on land — operate far too slowly to make a difference on a human time-scale. Even if CO2 emissions were somehow to cease today, it would take tens of thousands of years for ocean chemistry to return to its pre-industrial condition.
Affects of Ocean Acidification on Sea Life
Acid-affected pteropod Elizabeth Kolbert wrote in National Geographic, “Acidification has myriad effects. By favoring some marine microbes over others, it is likely to alter the availability of key nutrients like iron and nitrogen. For similar reasons it may let more sunlight penetrate the sea surface. By changing the basic chemistry of seawater, acidification is also expected to reduce the water's ability to absorb and muffle low-frequency sound by up to 40 percent, making some parts of the ocean noisier. Finally, acidification interferes with reproduction in some species and with the ability of others — the so-called calcifiers — to form shells and stony skeletons of calcium carbonate. These last effects are the best documented ones, but whether they will prove the most significant in the long run is unclear. “[Source: Elizabeth Kolbert, National Geographic, April 2011]
High acidity makes it difficult for some species of mollusks, gastropods and corals to produce their shells and poisons the acid-sensitive eggs of some species of fish such as amberjack and halibut. If populations of these organisms collapse then populations of fish and other creatures that feed on them could also suffer.
Elizabeth Kolbert wrote in National Geographic, “Meanwhile, scientists are just beginning to explore the way that ocean acidification will affect more-complex organisms such as fish and marine mammals. Changes at the bottom of the marine food web — to shell-forming pteropods, say, or coccolithophores — will inevitably affect the animals higher up. But altering oceanic pH is also likely to have a direct impact on their physiology. Researchers in Australia have found, for example, that young clownfish — the real-life versions of Nemo — can't find their way to suitable habitat when CO2 is elevated. Apparently the acidified water impairs their sense of smell. [Source: Elizabeth Kolbert, National Geographic, April 2011]
History of Ocean Acidification — It’s the Rate That Matters
Elizabeth Kolbert wrote in National Geographic: “During the long history of life on Earth, atmospheric carbon dioxide levels have often been higher than they are today. But only very rarely — if ever — have they risen as quickly as right now. For life in the oceans, it's probably the rate of change that matters. [Source: Elizabeth Kolbert, National Geographic, April 2011]
“To find a period analogous to the present, you have to go back at least 55 million years, to what's known as the Paleocene-Eocene Thermal Maximum or PETM. During the PETM huge quantities of carbon were released into the atmosphere, from where, no one is quite sure. Temperatures around the world soared by around ten degrees Fahrenheit, and marine chemistry changed dramatically. The ocean depths became so corrosive that in many places shells stopped piling up on the seafloor and simply dissolved. In sediment cores the period shows up as a layer of red clay sandwiched between two white layers of calcium carbonate. Many deepwater species of foraminifera went extinct.
shells that experienced
heavy acidification “Surprisingly, though, most organisms that live near the sea surface seem to have come through the PETM just fine. Perhaps marine life is more resilient than the results from places like Castello Aragonese and One Tree Island seem to indicate. Or perhaps the PETM, while extreme, was not as extreme as what's happening today.
“The sediment record doesn't reveal how fast the PETM carbon release occurred. But modeling studies suggest it took place over thousands of years — slow enough for the chemical effects to spread through the entire ocean to its depths. Today's rate of emissions seems to be roughly ten times as fast, and there's not enough time for the water layers to mix. In the coming century acidification will be concentrated near the surface, where most marine calcifiers and all tropical corals reside. "What we're doing now is quite geologically special," says climate scientist Andy Ridgwell of the University of Bristol, who has modeled the PETM ocean.
In Waters Where Ocean Acidification Is Already Taking Place
Elizabeth Kolbert wrote in National Geographic, “Owing to a quirk of geology, the sea around Castello Aragonese — a tiny island in the Tyrrhenian Sea 17 miles west of Naples — provides a window onto the oceans of 2050 and beyond. Bubbles of CO2 rise from volcanic vents on the seafloor and dissolve to form carbonic acid. Carbonic acid is relatively weak; people drink it all the time in carbonated beverages. But if enough of it forms, it makes seawater corrosive. "When you get to the extremely high CO2, almost nothing can tolerate that," Jason Hall-Spencer, a marine biologist from Britain's University of Plymouth, explains. Castello Aragonese offers a natural analogue for an unnatural process: The acidification that has taken place off its shore is occurring more gradually across the world's oceans, as they absorb more and more of the carbon dioxide that's coming from tailpipes and smokestacks. [Source: Elizabeth Kolbert, National Geographic, April 2011]
Hall-Spencer has been studying the sea around the island for the past eight years, carefully measuring the properties of the water and tracking the fish and corals and mollusks that live and, in some cases, dissolve there. On a chilly winter's day I went swimming with him to see the effects of acidification up close. We anchored our boat about 50 yards from the southern shore of Castello Aragonese. Even before we got into the water, some impacts were evident. Clumps of barnacles formed a whitish band at the base of the island's wave-battered cliffs. "Barnacles are really tough," Hall-Spencer observed. In the areas where the water was most acidified, though, they were missing.
Searching for food, some limpets had wandered into water that was too caustic for them. Their shells were so thin they were almost transparent. Bubbles of carbon dioxide streamed up from the seafloor like beads of quicksilver. We swam on. Beds of sea grass waved beneath us. The grass was a vivid green; the tiny organisms that usually coat the blades, dulling their color, were all missing. Sea urchins, commonplace away from the vents, were also absent; they can't tolerate even moderately acidified water. Swarms of nearly transparent jellyfish floated by. "Watch out," Hall-Spencer warned. "They sting."
Jellyfish, sea grass, and algae — not much else lives near the densest concentration of vents at Castello Aragonese. Even a few hundred yards away, many native species can't survive. The water there is about as acidified as the oceans as a whole are forecast to be by 2100. "Normally in a polluted harbor you've got just a few species that are weedlike and able to cope with widely fluctuating conditions," Hall-Spencer said once we were back on the boat. "Well, it's like that when you ramp up CO2."
Affects of Ocean Acidification on Coral Reefs
diatom walls broken down by acids Elizabeth Kolbert wrote in National Geographic, “Ocean acidification adds yet another threat, one that may be less immediate but ultimately more devastating to hard, reef-building corals. It undermines their basic, ancient structure — the stony skeleton that's secreted by millions upon millions of coral polyps over thousands of years....To make calcium carbonate, corals need two ingredients: calcium ions and carbonate ions. Acids react with carbonate ions, in effect tying them up. So as atmospheric CO2 levels rise, carbonate ions become scarcer in the water, and corals have to expend more energy to collect them. Under lab conditions coral skeleton growth has been shown to decline pretty much linearly as the carbonate concentration drops off. [Source: Elizabeth Kolbert, National Geographic, April 2011]
Slow growth may not matter much in the lab. Out in the ocean, though, reefs are constantly being picked at by other organisms, both large and small. (When I went snorkeling off One Tree Island, I could hear parrotfish chomping away at the reef.) "A reef is like a city," said Ove Hoegh-Guldberg, who used to direct the One Tree Island Research Station and now heads the Global Change Institute at Australia's University of Queensland. "You've got construction firms and you've got demolition firms. By restricting the building materials that go to the construction firms, you tip the balance toward destruction, which is going on all the time, even on a healthy reef. In the end you wind up with a city that destroys itself."
Affects of Ocean Acidification on Calcium-Producing Organisms
Oa-sami, ocean acid
measuring devise There are concerns that global warming could deplete the oceans of calcifying plankton, including small snails call pteropods. These small creatures (usually about 0.3 centimeters in size) are a critical part of the chain in polar and near polar seas. They are a favorite food of herring, pollock, cod, salmon and whales. Large masses of them are a sign of a healthy environment. Research has shown that their shells dissolve when placed in water acidified by carbon dioxide.
Shells with large amounts of the mineral aragonote — a very soluble form of calcium carbonate — are particularly vulnerable. Pteropods are such creatures, In one experiment a transparent shell was placed in water with the amount of dissolved carbon dioxide expected to be in the Antarctic Ocean by the year 2100. After just two days the shell becomes pitted and opaque. After 15 days it becomes badly deformed and had all but disappeared by day 45.
Elizabeth Kolbert wrote in National Geographic, “Corals, of course, are just one kind of calcifier. There are thousands of others. Crustaceans like barnacles are calcifiers, and so are echinoderms like sea stars and sea urchins and mollusks like clams and oysters. Coralline algae — minute organisms that produce what looks like a coating of pink or lilac paint — are also calcifiers. Their calcium carbonate secretions help cement coral reefs together, but they're also found elsewhere — on sea grass at Castello Aragonese, for instance. It was their absence from the grass near the volcanic vents that made it look so green. [Source: Elizabeth Kolbert, National Geographic, April 2011]
The seas are filled with one-celled calcifying plants called coccolithophores, whose seasonal blooms turn thousands of square miles of ocean a milky hue. Many species of planktonic foraminifera — also one-celled — are calcifiers; their dead shells drift down to the ocean floor in what's been described as a never ending rain. Calcifiers are so plentiful they've changed the Earth's geology. England's White Cliffs of Dover, for example, are the remains of countless ancient calcifiers that piled up during the Cretaceous period.
Acidification makes all calcifiers work harder, though some seem better able to cope. In experiments on 18 species belonging to different taxonomic groups, researchers at the Woods Hole Oceanographic Institution found that while a majority calcified less when CO2 was high, some calcified more. One species — blue mussels — showed no change, no matter how acidified the water.
"Organisms make choices," explained Ulf Riebesell, a biological oceanographer at the Leibniz Institute of Marine Sciences in Kiel, Germany. "They sense the change in their environment, and some of them have the ability to compensate. They just have to invest more energy into calcification. They choose, 'OK, I'll invest less in reproduction' or 'I'll invest less in growth.'" What drives such choices, and whether they're viable over the long term, is not known; most studies so far have been performed on creatures living for a brief time in tanks, without other species that might compete with them. "If I invest less in growth or in reproduction," Riebesell went on, "does it mean that somebody else who does not have to make this choice, because they are not calcifying, will win out and take my spot?"
Ways to Reduce Climate Change Involving the Sea
There are several ways to reduce climate change involving the sea and human activity there. Christine Todd Whitman and Leon Panetta wrote in Politico: Among these are: “Boost Offshore Renewables: Offshore renewables, like wind and wave energy, can help power the nation while cutting emissions. These sources of clean energy can serve as part of a just and equitable transition by providing economic benefits and abundant electricity to the communities that have suffered the most under climate change [Source: Christine Todd Whitman and Leon Panetta, Politico, January 29, 2022, 3:30 AM.
“Reduce Emissions from Shipping: We also need to look to the ocean to significantly reduce contributors of greenhouse gas emissions, such as maritime shipping, which generates more emissions than airlines. The administration, working with ports and the shipping industry, can implement strategies that will move us to zero-carbon shipping by 2050 to drastically reduce the climate contributions of cargo ships and freighters at sea. Infrastructure improvements at ports, fleet upgrades and alternative fuels can all be part of the effort.
“Rebuild Coastal Ecosystems: By protecting the ocean, we also enable the ocean to protect us through natural climate mitigation. Carbon-rich coastal environments like salt marshes, seagrass meadows and mangrove forests all naturally absorb carbon up to four times more effectively than trees on land. And when we conserve these habitats for their climate benefits, we are also protecting natural coastal infrastructure that will safeguard communities against storms and rising sea levels. This is particularly crucial for supporting marginalized communities, including low-income neighborhoods that were built in flood zones and are on the front lines of the climate crisis.
Another idea that is being considered is collecting large amounts of sea water, electronically separating the salt into positive-charged sodium and negatively-charged chloride. The chloride is removed and the water is placed into the ocean, altering its chemistry . To regain its balance the dissolved carbon dioxide changes into carbonates, creating more rooms for carbon dioxide to be sucked from the air. There are a lot of problems with the chemical: cost, a lack of technology to change sea water and risks to marine life.
World mangrove distribution
Using Plankton and Mangroves to Combat Global Warming
One idea is to spread vast amounts of iron compounds in the ocean to promote the growth of phytoplankton, which in turn would feed millions of fish that would die in a boom and bust cycle and sink to bottom and lock up the carbon their tissues. Tests of this theory shows the fish quickly decay releasing any carbon dioxide they might otherwise locked up. Russ George, CEO of Planktos, is investigating how much carbon dioxide plankton soaks up and has suggested growing huge floating fields of plankton to soak up the gas. Planktos has released tons of iron over a 10,000'square area of ocean to see how well plankton grows there. Environmental groups such as Greenpeace and the WWF have opposed the experiment over concerns for the welfare of marine life.
Mangrove roots, like those of other plants, need oxygen. Since estuarine mud contains virtually no oxygen and is highly acidic, they have to extract oxygen from the air. Mangrove roots extract oxygen with above-ground, flange-like pores called lenticels, which are covered with loose waxy cells that allow air in but not water. Some species of mangrove have the lenticels on their prop roots. Others have them on their trunks or have pneumatophores (fingerlike projection that grow up from the organic ooze). A single large tree such as “Sonneratia alba” can produce thousands of rootlike snorels that radiate out in all direction.
Mangroves sit like platforms on the mud. Their roots are imbedded in the mud just deep enough so plants don't wash away. The areal roots also spread out in such a way that act like buttresses. Scientists have determined carbon inputs and outputs of mangrove ecosystems by measuring photosynthesis, sap flow and other process in the leaves of mangrove plants. They have found that mangroves are excellent carbon sinks, or absorbers of carbon dioxide. Research by Jin Eong On, a retired professor of marine and coastal studied in Penang, Malaysia, believes that mangroves may have the highest net productivity of carbon of any natural ecosystem. (About a 100 kilograms per hectare per day) and that as much as a third of this may be exported in the form of organic compounds to mudflats. On’s research has show that much of the carbon ends up in sediments, locked away for thousands of years and that transforming mangroves into shrimp farms can release this carbon dioxide back into the atmosphere 50 times faster than if the mangrove was left undisturbed.
A United Nations task force on mangroves and the environment recommending: 1) setting up a blue carbon fund to help developing countries to protect mangroves as well as rain forests; 2) place a value on mangroves that takes into consideration their value as carbon sinks; and 3) allow coastal and ocean carbon sinks to be traded in same fashion as those for terrestrial forests. Christian Nellemann, an author a United Nations report on the issue, told the Times of London, “There is an urgency to act now to maintain and enhance these carbon sinks. We are losing these crucial ecosystem much faster than rainforests and at the very time we need them. If current trends continue they [mangrove and coastal ecosystems] may be largely lost within a couple of decades.”
Image Source: National Oceanic and Atmospheric Administration (NOAA) noaa.gov/ocean and Wikimedia Commons, except giant jellyfish from Hector Garcia blog
Text Sources: Mostly National Geographic articles. Also the New York Times, Washington Post, Los Angeles Times, Smithsonian magazine, Natural History magazine, Discover magazine, Times of London, The New Yorker, Time, Newsweek, Reuters, AP, AFP, Lonely Planet Guides, Compton’s Encyclopedia and various books and other publications.
Last updated April 2022