June 28, 2008
Submerged Trees Could Lower Atmospheric Carbon Dioxide

Some trees naturally stay submerged for thousands of years tying up carbon that would otherwise return to the atmosphere.

COLUMBIA, Mo. —The battle to reduce carbon emissions is at the heart of many eco-friendly efforts, and researchers from the University of Missouri have discovered that nature has been lending a hand. Researchers at the Missouri Tree Ring Laboratory in the Department of Forestry discovered that trees submerged in freshwater aquatic systems store carbon for thousands of years, a significantly longer period of time than trees that fall in a forest, thus keeping carbon out of the atmosphere.

“If a tree is submerged in water, its carbon will be stored for an average of 2,000 years,” said Richard Guyette, director of the MU Tree Ring Lab and research associate professor of forestry in the School of Natural Resources in the College of Agriculture, Food and Natural Resources. “If a tree falls in a forest, that number is reduced to an average of 20 years, and in firewood, the carbon is only stored for one year.”

We could store trees underwater in ways that could last tens of thousands of years if we wanted to put some thought in how to do it.

Submerged oak trees in Missouri are as old at 14,000 years.

The team studied trees in northern Missouri, a geographically unique area with a high level of riparian forests (forests that have natural water flowing through them). They discovered submerged oak trees that were as old as 14,000 years, potentially some of the oldest discovered in the world. This carbon storage process is not just ancient; it continues even today as additional trees become submerged, according to Guyette.

Suppose we systematically started sinking trees at the bottom of the Mississippi River with weights. One cool advantage of this idea: If (or rather when) we start to slip into another ice age we could bring those trees back up to the surface, let them dry out, and then burn them to release the CO2 and slow the cooling.

Alternatively, could we come up with a coating for trees that would last thousands of years? Or just use trees to fill in a massive coal mine dig with a bottom coating that would hold water and then cover over it with a material that would keep out air? Maybe a solid salt layer?

Update: Little Liberia illustrates the huge amount of CO2 tied up in trees.

Liberia's greenhouse gas emissions are roughly 250,000 times lower than those of the US, yet its remaining forests store approximately four billion tonnes of carbon dioxide (CO2), equivalent to the amount emitted by 57 million cars over 10 years.


However, the amount of tropical forest our planet loses each year is one-and-a-half times the size of Liberia, releasing almost 20% of total greenhouse gas emissions - more than all the world's cars, trucks and planes combined.

If all the tropical forests torn down to make room for crops to make ecologically friendly (snicker) biomass energy were submerged then the initial tree destruction wouldn't cause a large CO2 level rise as it does now.

But trees only cool the planet if they are planted in the tropics since trees are darker and absorb more sunlight.

The further you move from the equator, though, these gains are eroded; and the team's modelling predicts that planting more trees in mid- and high-latitude locations could lead to a net warming of a few degrees by the year 2100.

"The darkening of the surface by new forest canopies in the high-latitude boreal regions allows absorption of more sunlight that helps to warm the surface," Dr Bala said.

But the long run effect of planting a series of tree crops and then submerging them would eventually outweigh the warming effect of the darker color of trees. Also, if existing forests get cut down, their trees submerged, and then new trees planted those new trees wouldn't be any darker than the trees they replaced.

Share |      Randall Parker, 2008 June 28 06:13 PM  Climate Engineering

Fly said at June 28, 2008 8:17 PM:

I'd rather sequester carbon in a useful form such as solar cells or a space elevator.

Paul said at June 29, 2008 6:27 AM:

This is stupid. Do you any idea of the scale of work required to sequester enough carbon to affect the atmosphere? More than all the fossil fuels burned today, just to keep even. Stupid. And trees don't even grow fast enough to keep up.

Good thing that we don't need to do anything this stupid, because global warming is a lie.

Paul said at June 29, 2008 7:28 AM:

It is possible to use the "logs submerged in water don't rot" trick to do real science.

Here is the link. http://www.worldclimatereport.com/index.php/2008/06/20/finnish-finish-global-warming/

Can't even turn around nowadays without tripping over an anti-global warming story.

bbm said at June 29, 2008 9:06 AM:

Robert Rapier over at R Squared is working at a company that has developed a method to acetylate wood that makes it stronger and resistant to degredation and therefore suitable for structural uses that can theoretically sequester carbon in that form for an arbitrary length of time.

rob said at June 29, 2008 9:22 AM:

Long term structural wood is a useful way to sequester carbon, if you are so compelled. Plants like it ever so much if you let them feed on the carbon from the air. As much as you can stand and more. Going to insane lengths to sequester carbon does not speak highly of the species. Take care, lest you become a wild-eyed fanatic like Jimmy Hansen.

bbm said at June 29, 2008 10:39 AM:

I still think the best way to sequester carbon is the pyrolysis if biomass. You get about 30% of the energy in the biomass, and then you can bury the carbon, or use it as a soil enhancer, or use some of it for industrial processeses.

North America also leads the world IIRC, in RE-forestation.

David Govett said at June 29, 2008 8:44 PM:

Nanofactories will pull carbon from the air to created nanotubes, which will be used in myriad products. Too much energy is expended on worrying about short-term problems. Considerably greater threats loom on the horizon, like full-immersion virtual reality, which will isolate us forever.

Jimmy Lee said at June 30, 2008 7:26 PM:

There are logs in New Zealand that have been buried in peat for 40,000 years or more.

Personally, I like to take logs and burn them. I hate winter.

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