Wednesday, June 12, 2013

Research: More carbon is flowing into the water than anyone knew

A lot of the planet’s carbon, which scientists assume is in the soil, is actually flowing into the water.

And in some ways—from a climate change perspective—that could be a good thing, according to a team of researchers that includes University of Hawai`i oceanographer Fred Mackenzie.

Okay, your eyes are going to glaze over when you read this, but a quick takeaway is this: New research is constantly improving, clarifying and tightening estimates of what’s likely to happen in our climate future.

(Image: An aerial of sediment flowing from the land into the aquatic environment. Credit: Pierre Regnier, Copyright ESA 2003)

When carbon is washed into the rivers, lakes and oceans, a lot of it can be stored there in the form of sediment. And that sediment is far less likely to release the carbon back into the atmosphere. That is because in a warming climate, soil will release carbon before underwater sediment will.

That’s one point made by Mackenzie and a large team of researchers in their paper, Anthropogenic perturbation of the carbon fluxes from land to ocean, in the journal Nature Geoscience. An abstract is available here

This is complex stuff, but essentially it means the models of climate change will get a little more accurate, presuming that folks developing global warming estimates adjust their assumptions, the authors say: “So far, global carbon budget estimates have implicitly assumed that the transformation and lateral transport of carbon along this aquatic continuum has remained unchanged since pre-industrial times.”

In fact, the carbon transport to aquatic bodies has not been stable. It has increased over time, the authors say. And what that means is that there’s a lot of carbon hidden in sediments that haven’t been included in global carbon calculations.

Says a press release on the study: “increased leaching of carbon from soil, mainly due to deforestation, sewage inputs and increased weathering, has resulted in less carbon being stored on land and more stored in rivers, streams, lakes, reservoirs, estuaries and coastal zones – environments that are together known as the ‘land-ocean aquatic continuum’.”

“The budget of anthropogenic CO2 reported by the Intergovernmental Panel on Climate Change (IPCC) currently does not take into account the carbon leaking from terrestrial ecosystems to rivers, estuaries and coastal regions. As a result of this leakage, the actual storage by terrestrial ecosystems is about 40% lower than the current estimates by the IPCC,” said co-author Pierre Regnier from Université Libre de Bruxelles.

An interesting note from the study: not all that much of the carbon, only about 10 percent, ends up in the oceans. 

© Jan TenBruggencate 2013


ssty said...

Please explain this "complex stuff" a little more. My limited understanding is that carbon is an issue in climate change only when organic compounds are burned to form CO2. I presume that the carbon flowing into aquatic environments is in the form of organic material in the soil, which is not being burnt anyway. So how does this affect the climate change prediction?

Jan T said...

Others can better answer this than I, but CO2 comes from many sources, not only the burning of organic matter. The point here is that some portion that was assumed to be more available to the atmosphere may need to be considered more locked-away.