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?
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.
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|