Miniature Sea Creatures: Nature’s Unsung Heroes in the Battle Against Climate Change

In 2016, Dartmouth academic Mukul Sharma contemplated the notion that significantly reducing carbon emissions to fulfill international objectives appeared unfeasible.

It was the subsequent year following the signing of the Paris Agreement – a global accord addressing climate change that aims to limit the rise in global average temperatures to below 2 degrees Celsius.

While examining the Marcellus Shale, a major source of fracked gas in the United States, he began to devise solutions.

He discovered a profound connection between the carbon in that shale and clay, which had coexisted for hundreds of millions of years after being settled underwater.

Sharma mused that the process which formed an extensive reservoir for fossil fuels could offer insights into how humanity might initiate carbon removal from the atmosphere. Thus, he began experimenting with a concept: what if humans scattered clay dust on the ocean surface?

“Eliminating CO2 from the atmosphere is incredibly crucial,” Sharma remarked. “A significant solution lies in the ocean. One method we can employ is by boosting the biological pump.”

Minuscule plants and clay

The ocean has already been tirelessly working to assist Earth in combating climate change. It has absorbed roughly 90% of the heat generated by human activity through greenhouse gas emissions and sequesters around a quarter of all carbon dioxide emissions.

The biological pump represents the ocean’s natural mechanism for capturing carbon. Tiny organisms known as phytoplankton function similarly to trees. They photosynthesize and absorb carbon dioxide – and they can store this carbon at significant depths.

However, Sharma explains, this pump operates with low efficiency. In contrast to trees, phytoplankton have a lifespan of about 20 days. Once they perish, bacteria in the ocean consume them.

“Consequently, virtually all the carbon that the phytoplankton have absorbed is released back,” he stated.

Sharma recognized that clay readily absorbs carbon. His team commenced experiments by introducing clay into water, discovering that it captured organic carbon produced by phytoplankton.

In laboratory experiments and studies utilizing water and plankton from the Gulf of Maine, they also observed that when bacteria are present, they adhere to the clay and the carbon.

“They seek to attach themselves,” Sharma said. “The first action they take is generating copious amounts of extremely viscous material.”

This substance ensnares phytoplankton as well. The adhesive clumps descend through the water, laden with clay and other materials they gather on their descent. Subsequently, they become nourishment for zooplankton – tiny creatures residing deep in the ocean, but ascending during nighttime to feed.

Courtesy

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Dartmouth College

“Any organic matter falling down, they will consume,” he stated. “Then they descend again, excreting what they have eaten.”

Their excrement is denser due to the clay, prompting them to move rapidly toward the ocean floor, potentially sequestering carbon deep beneath the surface.

Sharma asserts that further investigation is required to ascertain how much carbon could be captured using clay, as well as to understand any other repercussions of introducing clay to certain ocean regions. One potential consequence is that some ocean areas might experience a depletion of oxygen, leading to anoxic conditions.

Yet, he remarks, the method is in alignment with nature’s approach.

“This is how nature sequesters carbon,” he remarked. “All these substantial deposits of oil and gas that you observe around have – through very akin processes – been formed over millions of years.”

There are also contemporary instances. The Sahara Desert blows dust into the Atlantic Ocean, which other researchers assert boosts carbon sequestration.

Human activity continues to contribute carbon to the atmosphere – almost 40 billion tons annually. To prevent further warming of the atmosphere, Sharma emphasizes the need to locate alternative deposition sites for it.

His team is gearing up for a field experiment off the Southern California coast next.

“One must always proceed carefully here,” he said. “It’s akin to traveling to the moon. You want to ensure you reach the destination without the rocket exploding halfway and that you can return safely.”