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A Cthulhulian tree that could scrub greenhouse gases out of the air

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The common mangrove, a tree that grows along most of the world's coastlines, could help us battle climate change. These trees usually live in tidal zones, and their tenticular networks of roots are revealed at low tide.

But what makes these trees interesting for Earth scientists is their unique ability to suck carbon out of the atmosphere. Though all trees absorb carbon as a part of their respiratory cycles, the mangrove pulls out four times more than other trees. That means mangrove jungles are essentially the world's air purifiers. And we might be able to use them in future geoengineering projects to slow down climate change.

Unfortunately, the mangrove has seen its forests reduced by more than 30 percent over the past fifty years, say scientists in a paper published today in Nature Geoscience. It's possible that the loss of these trees has exacerbated the accumulation of greenhouse gases. This map (below) shows where mangroves grow - they are a major feature of the coastline on almost every continent. Just the way you'd expect if they were vital to the maintenance of our fresh air.


Research ecologist Daniel Donato, an author of the study, said:

Mangroves have long been known as extremely productive ecosystems that cycle carbon quickly, but until now there had been no estimate of how much carbon resides in these systems. That's essential information because when land-use change occurs, much of that standing carbon stock can be released to the atmosphere. When we did the math, we were surprised to see just how much carbon is likely being released from mangrove clearing.


In other words, if we want to reduce carbon emissions, one way to do it very effectively would be to start planting more mangroves - oh, and stop cutting down existing ones.

What makes mangroves such efficient air filters, and why did they evolve to do it? In a release about their study, the US Forest Service explains:

The mangrove forest's ability to store such large amounts of carbon can be attributed, in part, to the deep organic-rich soils in which it thrives. Mangrove-sediment carbon stores were on average five times larger than those typically observed in temperate, boreal and tropical terrestrial forests, on a per-unit-area basis. The mangrove forest's complex root systems, which anchor the plants into underwater sediment, slow down incoming tidal waters allowing organic and inorganic material to settle into the sediment surface. Low oxygen conditions slow decay rates, resulting in much of the carbon accumulating in the soil. In fact, mangroves have more carbon in their soil alone than most tropical forests have in all their biomass and soil combined.


In other words, the mangrove stores all that carbon in the soil, and quickly. It seems clear that people should start growing these trees on every southern coastline to slow climate change. And what's really interesting is imagining how modified trees like this might provide the cornerstone of terraforming projects on another planet, where we need to scrub noxious gases out of the atmosphere really quickly while also enriching the soil.

Read more about the scientific research via Nature News

Map by Pinpin

Photo via EcoPrint/Shutterstock