What’s Slowing Down the Ocean’s Fight Against Climate Change? It’s Slimy

Tiny mucus tails on sinking marine particles could significantly slow the ocean’s ability to absorb CO₂

I’m a very active person who doesn’t feel well when I eat junk food. So, naturally, I’ve been on the slim side for most of my life, especially after I started incorporating more veggies into my diet.

My pregnancies were very complicated, with nausea and vomiting multiple times a day for nine months both times. So, of course, I didn’t gain a lot of weight, but after giving birth, I was surprised that those last pounds wouldn’t go away with my normal lifestyle… But was my new lifestyle normal?

You see, I was exercising, staying active with the kids, and breastfeeding them. Why wasn’t I losing weight? That’s when a friend suggested that I take note of everything I eat to ensure I meet my caloric needs.

She was right. I was overestimating how much I was burning breastfeeding and underestimating how much food I was putting in my mouth while mindlessly taking care of two tinny humans. I had overlooked what the numbers meant, and I was surprised to see no results.

Could we be doing the same when it comes to climate change? Could we be overlooking how much we produce, or worse, how much the Earth is capturing? Well, today’s story highlights that that could be the case. Let’s move from pregnancies to the oceans, shall we?

The oceans have often been described as a massive sink for carbon dioxide (CO₂), helping to offset some of the greenhouse gases emitted into the atmosphere. In all narratives, we count them in for the battle against the impacts of climate change, right? What if we overestimate their power or fail to see the whole picture of how this process works?

A critical part of this CO₂ sequestration process involves “marine snow,” a collection of organic particles that includes dead phytoplankton, bacteria, and other bits of debris, which gradually sink to the ocean floor.

Since some of these organisms are photosynthetic, they capture CO₂ that they will later take down to the bottom of the ocean, where it can be locked away for thousands of years. But recent research suggests that there’s more to this story than we thought. Tiny mucus “tails” seem to be slowing down this natural process.

Marine snow, as it falls through the water, isn’t just a passive carbon shuttle. According to a study led by Stanford University and published in Science, marine snow particles sometimes develop parachute-like mucus structures that act as a drag, significantly slowing their descent.

These mucus tails, made up of transparent exopolymers (substances secreted by organisms), can effectively double the time marine snow particles spend in the ocean’s upper layers. And that extra time could make a big difference in how much carbon actually makes it to the ocean floor.

Curious to know what we mean by “marine snow”? The video below explains it perfectly, and it may help you understand this story better.

The research team discovered this phenomenon using a custom-built rotating microscope developed by Manu Prakash’s lab. The microscope allowed the researchers to track marine snow particles in real time under ocean-like conditions.

In an expedition to the Gulf of Maine, they collected marine snow using sediment traps and immediately studied their behavior on the ship using this advanced tool. This microscope simulated the particles’ vertical travel over long distances, providing an unprecedented look at how marine snow interacts with the surrounding environment. No more guessing or assuming; just observing what happens!

The real-time observations revealed something scientists had never seen before — mucus structures forming around the particles and slowing them down.

The researchers found that these mucus tails act as physical drag lines that significantly reduce the sinking speed of the particles. “What we found underscores the importance of fundamental scientific observation and the need to study natural processes in their true environments,” said Dr. Manu Prakash, the senior author of the study. Indeed, as we’ll see below, as much as with my example, assumptions can be very costly!

This finding also sheds new light on the biological pump — the process by which marine snow helps sequester carbon. The thing is that while scientists have long known about this carbon capture mechanism, they hadn’t fully understood the role these tiny mucus tails play in slowing down the process.

This slower sinking has important consequences. While marine snow is suspended longer in the upper ocean layers, microbes have more time to break down the carbon-rich material.

This means that instead of sinking to the ocean floor and storing carbon for millennia, more of that carbon gets recycled back into the ecosystem, potentially returning to the atmosphere as CO₂. In other words, the oceans may not be absorbing as much carbon as previously thought. Ouch!

The study’s findings suggest that current estimates of the ocean’s carbon sequestration potential may be overly optimistic. “We haven’t been looking the right way,” Dr. Prakash explained, highlighting how much remains to be understood about these complex systems. By including the effects of mucus tails in climate models, scientists can make more accurate predictions about the role oceans play in the global carbon cycle.

Indeed, ignoring the physical characteristics of the elements involved in the process could bias our calculations greatly.

For policymakers and scientists focused on combating climate change, these findings could mean revisiting strategies that rely heavily on ocean-based carbon sequestration. If marine snow is not sinking as fast or as far as we thought, it might not be capturing and storing as much carbon. This could shift the balance in how we think about the oceans’ role in absorbing human-made CO₂.

This could mean we can’t overly depend on the ocean’s capacity, after all.

But the research doesn’t just raise concerns — it also opens new doors for exploration. The researchers plan to further study how environmental stressors, such as rising ocean temperatures or increased acidification, might affect the production of these mucus tails. Now that they know how crucial they can be, we better see the whole picture.

Further, understanding the triggers for mucus formation could offer insights into whether we can predict or even manipulate this process in ways that might enhance the ocean’s carbon storage capabilities. In other words, make the most out of it. Knowledge is the most powerful element!

Ultimately, this study reminds us of how interconnected and complex the Earth’s natural systems are. While the oceans continue to be a crucial carbon sink, we still have much to learn about how these processes work and how much we can rely on them.

The discovery of these mucus tails is just the beginning, and it highlights the importance of field research and direct observation in uncovering the hidden details of one of nature’s most essential systems.

The takeaway is clear: marine snow, with its mucus tails in tow, is slowing down and complicating the ocean’s role in mitigating climate change. Scientists are just beginning to understand the full implications of this discovery, and there’s still a lot more to explore.

But for now, let’s hope. We learned the lesson about climate change as much as I had to after having my kiddos!