Narration

Hi everyone, it's me again - Carbie, the condescending and over-simplifying cartoon carbon molecule.

In my previous video I explained how I spent 300 million years trapped below the Earth's surface as “oil” before being freed in 1858, and my spare energy has been used by the bipeds for their various fun and games.

In this video I take a closer look at what me and my gazillions and gazillions of carbon friends are getting up to, and the trips we take around the planet.

Here's the big picture [carbon cycle diagram]. Confusing? Don't worry, I'll try to break it down for ya.

The easiest way is for me to start explaining is starting between

THE ATMOSPHERE AND THE BIOSPHERE

I spend some time cycling in and out of plants.

So, with a bit of energy from the sun, me and five buddies, plus six “dihydroxide” molecules get turned into this [picture of cellulose molecule]. Sweet!

It's called photosynthesis [picture of equation]

Then the plant dies and decomposes or is eaten and digested, and, sooner or later, I am back out in the atmosphere for a bit.

The top half of the planet has a lot more land mass than the south half. So when the forests grow, during summer, atmospheric carbon levels drop, and climb again during the southern summer. It's like the planet, well, breathing. [keeling curve].

By the way, anything that takes carbon dioxide molecules like me out of the atmosphere is a “sink”, anything that releases it is a “source.”

Now, you might think that more carbon dioxide molecules in the atmosphere simply means more plant growth, everything comes out even, problem solved.

But it hasn't turned out like that. I talked to a plant about this. He pointed out that there were other things stopping him getting bigger – the amount of sunlight, the amount of nutrients, the amount of water. It all boiled down, he said, to Liebig's law

So, back to my favourite subject: me!. Most of the time I have been just cycling in and out of plants. Of course, if there are fewer plants for me and my friends to hide in, then we'll stay in the atmosphere.

The crucial thing is this: The various ways that I go into the atmosphere and I'm pulled out – it's more complicated than I've been telling you – are in balance. What's new is that gazillions of carbon dioxide molecules are being released from long-term storage, whenever humans dig up fossil fuels and burn them.

ATMOSPHERE AND OCEANS

As you go north, it gets colder. That means that this [C02 and H20 equation] happens more. So some carbon gets caught, and sinks down in the deep oceans. But that takes ages, and is only happening at a few postage stamp sized bits of the big basket ball the bipeds call earth.

At the warmer bits of the ocean, carbies can get caught up as shells, and some will sink to the ocean floor. Again, a time- consuming process,. As the oceans become more acidic, there are fewer shelled critters to do that stuff, because the acidity means they can't build their shells so easily.

And even gnarlier, as water warms at the tropics, dissolved carbon dioxide is released from the ocean's surface back into the atmosphere.

Sure, the ocean stores carbon, but the bipeds shouldn't Revelle in this though.. For every 10% increase in atmospheric concentration, the oceans only take up... 1%

VOLCANOES

Some carbie is released from volcanoes too (along with water vapour and sulphates), but the amount is roughly balanced by the process of weathering of rocks. Volcanoes are a bit of a red herring, since human emissions are roughly 100 times bigger than volcano carbon emissions...

Conclusion

Remember though, the key thing is that every year unimaginable numbers of carbon dioxide molecules are released from where they've been trapped for 300 million years.

The Earth System's been doing a reasonable job of sponging up us molecules, but the sponges are getting full, and less effective. And things are getting hotter. Me, I don't mind, but then I am a fictional representation of an inanimate object anyhow. If I were human, I'd be shitting bricks.