Where did it go, George?

Carbon dioxide is about as elusive an adversary as they come — it’s invisible, belched out by the tonne every day in a variety of industries and everyday activities as well as being one of the greenhouse gases responsible for slowly warming the planet. It’s also an important measurement for greenhouse gas emissions, with one tonne of CO2 representing one unit of “global warming potential” (GWP).

So, as governments around the world design ways to trap it or pay for it, the question remains: where is it all going (aside from the atmosphere, that is)?

The answers range from trees to man-made sequestration projects, but not all are confined to dry land. Here, then, are a few particularly moist places that CO2 has been hiding in our planet.

Wetlands

These soggy, much-maligned swamps may be breeding grounds for mosquitoes and real estate scams, but they’re also repositories for as much as 20 per cent of the world’s carbon. Ironically, increasing global temperatures may add another layer to the same problem by drying out these wetlands, releasing their stored CO2.

The revelation that wetlands hold large volumes of carbon isn’t necessarily fresh news, with a study from the University of Missouri having found that submerged trees retain carbon better than their dryer counterparts.

The Amazon

If wetlands are gigantic puddles, then The Amazon River, the largest river in the world, is certainly no drip. “Drawing down” large quantities of atmospheric CO2, the point at which the river meets the Atlantic Ocean acts as a massive “carbon sink,” with micro-organisms called diazotrophs processing CO2 and nitrogen into a solid form that sinks to ocean floor.

According to a study published in Proceedings of the National Academy of Sciences (PNAS), though polar seas are more likely to dissolve the gas, “warm oceans may be where a permanent carbon sink is more likely.”

The Ocean

With billions of litres of water flowing from the Amazon into the sea, the world’s oceans take their turn with the absorption of CO2 . Though models predicting the exact nature of the oceans’ relationship to greenhouse gases is still being mapped out, what’s clear is that the waters making up most of the Earth’s surface have an enormous capacity for absorbing our emissions.

Simply dumping CO2 into the ocean is no solution to the greenhouse gas dilemma, however. Given the potential for a new balance of CO2 to either acidify the ocean or simply rebalance the concentrations in the atmosphere and ocean , any technology designed to lock CO2 in the ocean needs to demonstrate that it can be contained permanently.

After all, with an adversary this difficult to spot, it’s nice to keep it in where we can find it.