The planet would be much hoter if it was not for fecal pellets. Through the oceans of the world, tiny organisms known as phytoplankton harvest the energy of the sun, engulfing carbon dioxide and releasing oxygen. They are eaten by small animals called Zooplankton, which poop pellets flowing in the seabed. Which is essentially a giant toilet, therefore rinse from carbon to the surface in the depths, where it remains locked away from the atmosphere, thus keeping the amount of CO2 up there.
But while humans are pumping more and more carbon in the sky, relentlessly increasing the temperatures of the ocean, the disturbing signals flash that this dresser could change deeply. Consider the northeast of the Pacific, off the coast of Alaska, where two large heat waves seized the sea, one from 2013 to 2015 and the other from 2019 to 2020. A new study revealed that the two events transformed the composition of phytoplankton and zooplankton, essentially obstructing the toilet and preventing carbon-lower transport in depths.
“These long -term studies help to put everything in context and are also really ringing alarms,” said Anya Štajner, doctoral student in biological oceanography at the Institution of Oceanography, which was not involved in research. “The ocean changes. And not only will it affect the ocean – it will affect life in the ocean. And finally it will affect us, because we count on the ocean for our air, our food, our climate regulations. ”
Of course, each part of the world’s oceans has its own chemistry, biology and unique ecology, so what is happening there may not happen everywhere. But with these heat bursts, this sea band has reduced its ability to sequester the gas that heats the planet. It is a precarious situation, since the oceans capture a quarter of the CO2 emissions of humanity. “Although we can generalize that what we have seen here would generally occur through other waves of marine heat in the ocean, such as carbon accumulation, I think it is important to also assess the region,” said Colleen Kellogg, a microbial oceanographer at Hakai Institute of Canada and co-author of the document, which has published today in the journal Nature Communications.
The researchers have exploited a decade of data from the biogeochemical floats of Argo, who were walking autonomous in the water column by taking readings of ocean chemistry. When they reach the surface, they scout this data in satellite. In this way, scientists have obtained a flow of readings of 10 years without having to be constantly on a boat in the Subcarctic Pacific Ocean in the Northeast, which is not known for hospital winters.
© 2022 Mbari
The two waves of oceanic heat began as those we live on earth, the atmosphere warming up things. Indeed, the ocean absorbed 90% of the additional heat that humans have created. Consequently, while in the 19th century, only 2% of the surface of the ocean experienced episodes of extreme temperatures, this figure is now much greater than 50%. Such events will only become more common and more intense unless humanity considerably reduces its greenhouse gas emissions and quickly. In this case, the northern Pacific has again broken records recently, perhaps partly due to the regulations in 2020, reducing the amount of aerosols generated by ships, which generally cool the planet by reflecting the energy of the sun in space.
Like our most ferocious atmospheric explosions of heat, a lack of wind during the two events still aggravated things. As a rule, after seawater warms in spring and summer, winter winds blow through the surface, pushing it. This obliges the deeper and cooler waters to run up to fill the void, keeping the water column more uniform, in terms of temperature. This did not happen during the two heat waves, and the sea remained more stagnant, as normally did later in the year.
Because the warmer water is less dense, it remains on the surface, creating a sort of cap. “Then, in the spring and summer, this water is even warmer, because it did not cool winter before,” said Mariana Bif, a marine biogeochemist at the University of Miami and the main author of the newspaper. (Bif led research during his stay at Monterey Bay Aquarium Research Institute.) “Thus, the impact of marine heat waves begins in the atmosphere, then it is transferred to the ocean.”
However, the two heating events were not created. The first coincided with an El Niño – a strip of lukewarm water off the coasts of South America – which increased the temperatures in the northeast of the even higher Pacific. The second saw a marked decrease in salinity due to changes in ocean circulation. Because the water with a lower salinity is less dense, it hangs around the surface, while the more salty things flow. This has further strengthened the hot cap.
The absence of winter baratting also meant that the nutrients generally drawn of deeper waters have been cut, denying phytoplankton in this ceiling of the elements they needed to cultivate. Together, high heat and weak nutrients on the surface have completely changed the environment for organisms that live there and carbon treatment.
The oceans just took an important step
This transformed the ecosystem. Like plants on earth, different types of phytoplankton need different quantities of nutrients and in different proportions. “Usually, for example, in areas where you have this big mixture and large nutrients, you have a bunch of large phytoplankton that produce a lot of carbon – a lot of biomass,” said Bif.
As the conditions have changed during heat waves, it is the smallest of phytoplankton species that benefited from it. They needed fewer nutrients to flower, so they proliferated as the largest species decreased. And because different species of zooplankton dine on phytoplankton of size differently, the smallest who ate the smallest species suddenly had much more subsistence. “These guys will make small fecale pastilles, which would somehow float in water more than pouring,” said Kellogg. “This could therefore contribute to the reduction of carbon moving from the surface to the deep ocean.”
Because the researchers had access to this data from top to bottom of the water column, they could monitor how all this carbon flowed during heat waves. Or rather, as was not the case – because the ocean carbon toilets worked badly. In the first event, carbon particles stack 660 feet deep and, in the second, between 660 and 1,320 feet. In these areas, zooplankton grazers continued to chew the particles, breaking them into smaller pieces which could not flow. In the second marine heat wave, an increase in particularly small zooplankton meant more production of smaller and non -alcoholic fecal granules.
Not only did the toilet do not rush the carbon properly, but more and more waste was added to these waters while the heat waves were rolling. This has given bacteria a lot of organic matter to break down, adding CO2 to the sea. Finally, the currents would bring this water rich in CO2 to the surface, where gas can be released in the atmosphere.
From now on, scientists will have to monitor more heat waves in other parts of the world’s oceans to see if the same dynamic is at stake, and how much it could cook the capacity of the sea to kidnap carbon. At the same time, phytoplankton and zooplankton suffer through crises other than heat, such as ocean acidification potentially interferes with the capacity of certain species to cultivate protective shells.
If there is less phytoplankton, there will be less oxygen out of the oceans and less food for zooplankton which feeds all kinds of other animals of the sea, including whales. “Pay attention to what is going on at the base of the web web web will give us a lot of information,” said Štajner, “both on how things go to these biggest marine animals that are important to us, but also to ideas on our climate.”
Fortunately, with thousands of argo biogeochemical floats collecting data around the planet, researchers get an ever more cautious image in the way the seas change and phytoplankton with them. “The oceans are very subchanting, very sub-studied,” said Bif. “But they play a central role in the climate. We cannot understand what we cannot observe.”
