Confusion about Erosion and CO2

[Thomas Goreau]

The role of net and gross carbon fluxes is constantly being confused in the press and by many scientists, who should know better.

A great example is ocean fertilization, which works only in the remote deserts of the sea that far from any source of iron in dust and sediments. In these areas adding Iron can cause phytoplankton blooms, but it is entirely false to claim this could be a major carbon sink because almost all that biomass dies, rots, or is eaten in a few days, only an infinitesimal fraction is buried before it can be converted back to CO2!

A recent publicized paper claims that there is a huge “new” “previously unknown” nitrogen source in rocks. But in fact this is not nitrogen in primary igneous rock minerals, it is coming from the decomposition of organic matter in sediments which was originally fixed biologically and is now being recycled, hundreds of years later, when buried organic carbon is uplifted, exposed, and decomposes.

The latest example of this confusion is the claim that mountain weathering is a source of CO2, not a sink. Weathering of primary and secondary silicate and carbonate minerals consume CO2 from the atmosphere, convert it into bicarbonate ion, which then flows into the sea via rivers. However if the rocks being eroded are sedimentary rocks with high carbon content, decomposition of the organic carbon will release CO2. 

However this is carbon recycling, not primary chemical weathering, which the Woods Hole Oceanographic and Harvard teams seem to have confused!

Mountain Erosion Apparently Increases, Not Reduces, Carbon Dioxide In Atmosphere

By Aaron Mamiit

Mountain erosion, long believed to be reducing the carbon dioxide in the atmosphere, is apparently increasing it, though the source is not geological. Does the discovery have any effect on the phenomenon of climate change? (Photo : Fayez Nureldine | AFP | Getty Images) 

Mountain erosion, a process long thought to be reducing carbon dioxide in the atmosphere, is apparently doing the opposite, according to the findings of a new study.

The study, led by researchers from the Woods Hole Oceanographic Institution, claims that mountain erosion actually produces carbon dioxide. Does the discovery have any effect on our understanding of climate change?

Mountain Erosion Reduces Carbon Dioxide

According to the long-standing hypothesis, mountain erosion and rock weathering can pull the carbon dioxide from the air, as newly exposed rocks trigger reactions with the atmosphere in the formation of calcite and other minerals.

However, WHOI researchers claimed that mountain erosion actually releases more carbon dioxide into the atmosphere than what it absorbs. The study, published in the Science journal, added that the source of the carbon dioxide is not geological.

The carbon dioxide being produced during mountain erosion comes from microbes in the soil that consume the ancient sources of organic carbon that are trapped in the rock before they erode. As the microbes metabolize the minerals, they create carbon dioxide.

The researchers made the discovery while studying Taiwan's Central Range mountains, which are some of the most prone mountains to erosion worldwide. Upon examining the soil samples at the Central Range, they found almost no organic carbon. This is because the microbes were quickly consuming them.

The bacteria that are behind the carbon dioxide production have not yet been identified, but the researchers said that determining the bacteria is the next step of the study.

Will This Change Our Understanding Of Climate Change?

The findings on mountain erosion raise questions on whether this changes things for climate change.

While the reversal of the hypothesis on carbon dioxide reduction caused by mountain erosion was an unexpected one, the researchers claimed that it will not mean much for climate change. The amount of carbon dioxide released by mountain erosion in the atmosphere is small, compared with the carbon dioxide emission caused by humans. In addition, the process of mountain erosion happens over millions of years.

The findings of the study, however, will help better understand how the carbon cycles in mountains work. The researchers are also looking to determine how mountain erosion contributed to stabilizing the amount of carbon dioxide in the Earth's atmosphere over the past millions of years.

"It allowed Earth to have the climate and conditions it's had - one that has promoted the development of complex life forms," said lead author and Harvard University postdoctoral fellow Jordon Hemingway.

Thomas J. F. Goreau, PhD
President, Global Coral Reef Alliance
President, Biorock Technology Inc.
Coordinator, Soil Carbon Alliance
Coordinator, United Nations Commission on Sustainable Development Small Island Developing States Partnership in New Sustainable Technologies
37 Pleasant Street, Cambridge, MA 02139
gor...@globalcoral.org
www.globalcoral.org
Skype: tomgoreau
Tel: (1) 617-864-4226

Books:

Geotherapy: Innovative Methods of Soil Fertility Restoration, Carbon Sequestration, and Reversing CO2 Increase
http://www.crcpress.com/product/isbn/9781466595392

Innovative Methods of Marine Ecosystem Restoration
http://www.crcpress.com/product/isbn/9781466557734