Newly Published Research Proves Ocean Pasture Plankton Has For All Of Time Saved The World From Global Warming.
Deep-sea corals reveal how healthy ocean plankton reduced CO2 in the air when levels rose, pulling the ‘greenhouse gas’ blanket from the Earth.
Restoring ocean pastures can again save the world from global warming.
New research from an international team of scientists reveals the power of plankton and how a colder Earthly climate was accompanied by depleted atmospheric CO2 during past ice ages. Their paper published in PNAS details how a vast library deep sea coral specimens reveal climate history over the past million years. The goal of the research has been to better understand how and why the earth goes through periodic climate change.
This work shows how man-made factors can both raise the temperature of the Earth and how our efforts to sustain healthy ocean pastures are the best hope for restoring Nature’s innate ability to keep our planet in the perfect Goldilock’s Zone.
Global Warming Cycles
Earth’s average temperature has naturally fluctuated by about 4 to 5 degrees Celsius over the course of the past million years as the planet has cycled in and out of glacial periods. During that time, the earth’s atmospheric CO2 levels have ranged between 180 and 280 parts per million (ppm) over the course of every 100,000 years or so. At least until the arrival of humanities Fossil Fuel Age where we have raised the concentration of CO2 to over 400 ppm.
For more than 40 years researchers noticed a close correspondence between the fluctuations in CO2 levels and in temperature over the last million years. When the earth has been at its coldest, the amount of CO2 in the atmosphere has always been at its lowest number. During the most recent ice age, which ended only 11,000 years ago, global temperatures were 5 degrees Celsius colder than they are today, and atmospheric CO2 concentrations were at 180 ppm.
Deep Sea Corals Provide A Historical Record Of Climate
Using a library of more than 10,000 deep-sea corals collected by Caltech’s Jess Adkins, an international team of scientists has shown that periods of colder climates are associated with much more lush and abundant phytoplankton filling the world’s ocean pastures. Along with the lush ocean pastures there was seen a reduction in primary plant nutrients in the surface of the Southern Ocean. More ocean plant life meant more atmospheric CO2 was repurposed into that additional ocean life and of course the detritus of those ocean pastures was sinking CO2 into the ocean abyss, sequestration.
“It is critical to understand why atmospheric CO2 concentration was lower during the ice ages. This will help us understand how the ocean will respond to ongoing anthropogenic CO2 emissions,” says Xingchen (Tony) Wang, lead author.
Our Blue Planet Is 72% Ocean
There is 60 times more carbon in the ocean than in the atmosphere—partly because the ocean is so big. The mass of the world’s oceans is roughly 270 times greater than that of the atmosphere. As such, the ocean pastures and their plant life is the utterly dominant regulator of carbon in the atmosphere, acting as both a sink and a source for atmospheric CO2. All other systems are trivial in comparison.
Photosynthesis is the main driver of CO2 absorption from the atmosphere to the ocean. Just like photosynthesizing trees and plants on land, plankton at the surface of the sea turn CO2 into more of themselves some of which is consumed by sea life. As sea life consume the grass of the ocean pastures they redistribute the carbon into the deep ocean, where the carbon is locked away from the atmosphere for a millennia, even eons of time. This process is called the “biological pump.”
Oceans Are In A Forced Drought Of Vital Dust
In order to thrive and sustain a healthy ocean pasture phytoplankton need nutrients—notably, nitrogen, phosphorus, and iron. In the modern Southern Ocean and much of the rest of the world’s oceans, there is a limited amount of iron—which means that there are not enough phytoplankton to fully consume the nitrogen and phosphorus in the surface waters. When there is less living ‘standing’ biomass, there is also less that die and sink to the bottom—which results in a decrease in carbon sequestration. The biological pump is not currently operating as efficiently as it has historically.
Today’s high and rising CO2 is making the Earth greener and that means more plant life is covering the land. More grass growing means less dust blowing. The world’s oceans are in a forced drought of mineral dust and iron that is directly due to the influence of human CO2 emissions.
To track the efficiency of the biological pump over the span of the past 40,000 years, Adkins and his colleagues collected more than 10,000 fossils of the coral Desmophyllum dianthus.
Why coral? Two reasons: first, as it grows, coral accretes a skeleton around itself, precipitating calcium carbonate (CaCO3) and other trace elements (including nitrogen) out of the water around it. That process creates a rocky record of the chemistry of the ocean. Second, coral can be precisely dated using a combination of radiocarbon and uranium dating.
“Finding a few centimeter-tall fossil corals 2,000 meters deep in the ocean is no trivial task,” says Adkins, Smits Family Professor of Geochemistry and Global Environmental Science at Caltech.
Adkins and his colleagues collected coral from the relatively narrow (500-mile) gap known as the Drake Passage between South America and Antarctica (among other places). Because the Southern Ocean flows around Antarctica, all of its waters funnel through that gap—making the samples Adkins collected a robust record of the water throughout the Southern Ocean.
Wang analyzed the ratios of two isotopes of nitrogen atoms in these corals – nitrogen-14 (14N, the most common variety of the atom, with seven protons and seven neutrons in its nucleus) and nitrogen-15 (15N, which has an extra neutron). When phytoplankton consume nitrogen, they prefer 14N to 15N. As a result, there is a correlation between the ratio of nitrogen isotopes in sinking organic matter (which the corals then eat as it falls to the seafloor) and how much nitrogen is being consumed in the surface ocean—and, by extension, the efficiency of the biological pump.
A higher amount of 15N in the fossils indicates that the biological pump was operating more efficiently at that time. An analogy would be monitoring what a person eats in their home. If they are eating more of their less-liked foods, then one could assume that the amount of food in their pantry is running low.
Indeed, Wang found that higher amounts of 15N were present in fossils corresponding to the last ice age, indicating that the biological pump was operating more efficiently during that time. As such, the evidence suggests that colder climates allow more biomass to grow in the surface Southern Ocean—likely because colder climates experience stronger winds, which can blow more iron into the Southern Ocean from the continents. That biomass consumes carbon, then dies and sinks, locking it away from the atmosphere.
This post derives in part from materials provided by Caltech.