What is a carbon sink and how do they protect our planet?

In geological time, humans have only been around for a flash. But we're already hurting the ancient processes that sustain our planet. 

There should be a filter that lets you view the world according to carbon content, similar to infrared. That picture you shared earlier of your poke bowl would be dripping with white-hot carbony goodness. And is that your new niece? I think she just unloaded some fresh carbon in her diaper (Instagram — if you’re reading this, please return my calls).

Hopefully then, people might get hip to the fact that carbon is everything. You’ve already met one of its celebrity compounds: carbon dioxide — one part carbon to two parts oxygen (CO2). And we have a lot to thank it for. It's essential for our body function, and works as a blanket to keep Earth at a liveable temperature. But with high and rising CO2 emissions, we're trapping too much heat and throwing the planet out of whack.

The kicker comes when we also stop the environment from correcting itself. In this article, we swivel a light onto carbon sinks, and the defensive role they play.

King of the elements

Carbon is called the ‘king of the elements’ because it’s basically everywhere. In you, me, the ground you walk on, the last meal you ate. And it doesn’t stay still. You may remember the carbon cycle from science class. It explains the timeless passage of carbon across our planet — falling from the atmosphere onto the land and oceans, through animals and plants, into the earth’s crust, and back into the atmosphere. A vast, planetary symphony that sustains all existence, and stirs in us mortal themes of life, death, and rebirth. Which is all well and good, except for we humans are royally funking it up.

Enter carbon sinks, which have become quite the buzzword. Their exact definition changes depending on who you ask. Ocean Climate calls them “a natural or artificial reservoir that absorbs and stores the atmosphere's carbon with physical and biological mechanisms.” National Geographic is more metrical: “Carbon sinks are places that absorb more carbon than they release.” Ok, cool. But what are they? Let's stick with NASA's categories: plants, soils, and the ocean. 

Carbon sink examples

Now, I don’t love the metaphor, (for me, sinks are cracked, grease-stained kitchen fixtures, not steaming rainforests or infinite oceans) but it fits. Carbon sinks ‘drain’ carbon dioxide from the atmosphere. Soaking it up like big sponges. This leaves less of it to float around, heating the planet and causing unnatural climate change. 

Did you know? According to NASA, “so far, land, plants, and the ocean have taken up about 55% of the extra carbon people have put into the atmosphere while about 45% has stayed in the atmosphere.”

How does this work? Each sink has its superpowers. Forests, with their trillions (yes, trillions) of trees, act as lungs of the earth — breathing in carbon dioxide and storing it via photosynthesis. When a tree, or any organism, dies, it ‘returns’ to the carbon cycle by decomposition, moving carbon downwards through the soil. The ocean traps carbon in a similar way — through death and the food chain — but also via direct absorption, and photosynthesis of plankton. This carbon is swept deep into the ocean’s interior, before settling into the seabed. Together, these sinks help keep the planet and everything on it in balance.

Human impact on the carbon cycle

Humans don’t create carbon. The amount of carbon on the planet stays the same, changing only form. But the problem is that burning so much fossil fuel is unnatural to the carbon cycle. Fossil fuels are carbon deposits — dead organic matter that carbon sinks have hidden for millions of years, only to be released back into the atmosphere by us.

Things get slippery when this extra atmospheric CO2 begins hurting carbon sinks; essentially stopping the planet from healing itself. While some thought that sinks would ‘level up’ to deal with excess carbon, like muscles grow to handle extra stress, a recent Stanford study contradicts this. Here, the researchers suggest that even if extra carbon dioxide drove plant growth, this would require more nutrients. And that would summon more carbon that would otherwise remain locked in the soil. 

The planet has lost 1/3 of its forest since the Ice Age.

The issue is aggravated by the fact we’re cutting down swathes of forests for land and agriculture. While deforestation is an ancient problem (the planet has lost ⅓ of its forests since the Ice Age), it's worth noting that half of this was in the last century alone. And the oceans have been ‘forced’ to absorb more and more carbon dioxide from the atmosphere, making seawater more acidic. This has a strange fallout. Scientists have noticed that ocean acidification stops key members of the ecosystem — like crabs, corals and snails — from developing shells and skeletons properly.

Sink or swim

It’s easy to take for granted that which we can't see. It’s why you (generally) don’t find people raving about oxygen, or actors thanking hydrogen in their acceptance speech. But carbon is everywhere, and we should be aware, however faintly, of its journey around the world. This carbon-consciousness often underlies a sustainable lifestyle.

Similarly, let's give carbon sinks some love. They’re awesome, natural processes that harmonize the planet. Thankfully, some initiatives are trying to turn the tale: using human activity to help the carbon cycle, not hinder it. This could be through carbon sequestration — artificially storing carbon — or by supporting the natural carbon sinks we have.

Klima lets you fund climate protection like planting saplings in Tanzania, or building lush forests in Panama. We're happy to do our part. While the war against climate change will be won or lost by larger society, we help you play a soldier’s role in defending our planet — or rather, helping the planet defend itself. 

Take climate action with Klima

Neelesh Vasistha
by Neelesh Vasistha
Senior Copywriter
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