Riverine‐driven interhemispheric transport of carbon

Riverine‐driven interhemispheric transport of carbon Controversy surrounds the role of the ocean in interhemispheric transport of carbon. On one hand, observations in the atmosphere and in the ocean both seem to imply that the preindustrial ocean transported up to 1 Pg C yr−1 from the Northern to the Southern Hemisphere. On the other hand, three dimensional (3‐D) ocean models suggest that global interhemispheric transport of carbon is near zero. However, in this debate, there has been a general neglect of the river carbon loop. The river carbon loop includes (1) uptake of atmospheric carbon due to inorganic and organic erosion on land, (2) transport of carbon by rivers, (3) subsequent transport of riverine carbon by the ocean, and (4) loss of riverine carbon back to the atmosphere by air‐sea gas exchange. Although carbon fluxes from rivers are small compared to natural fluxes, they have the potential to contribute substantially to the net air‐sea fluxes of CO2. For insight into this dilemma, we coupled carbon fluxes from a global model of continental erosion to a 3‐D global carbon‐cycle model of the ocean. With rivers, total southward interhemispheric transport by the ocean increases from 0.1 to 0.35±0.08 Pg C yr−1, in agreement with oceanographic observations. Resulting air‐sea fluxes of riverine carbon and uptake of CO2 by land erosion were installed as boundary conditions in a 3‐D atmospheric model. The assymetry in these fluxes drives a preindustrial atmospheric gradient of CO2 at the surface of −0.6±0.1 μatm for the North Pole minus the South Pole and longitudinal variations that exceed 0.5 μatm. Conversely, the gradient for Mauna Loa minus South Pole is only −0.2±0.1 μatm, much less than the −0.8 μatm gradient extrapolated linearly from historical atmospheric CO2 measurements from the same two sites. The difference may be explained by the role of the terrestrial biosphere. Regardless, the river loop produces large gradients both meridionally and zonally. Accounting for the river carbon loop changes current estimates of the regional distribution of sources and sinks of CO2, particularly concerning partitioning between natural and anthropogenic processes. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png Global Biogeochemical Cycles Wiley

Loading next page...
 
/lp/wiley/riverine-driven-interhemispheric-transport-of-carbon-0fNwxJpyWI
Publisher
Wiley
Copyright
Copyright © 2001 by the American Geophysical Union.
ISSN
0886-6236
eISSN
1944-9224
DOI
10.1029/1999GB001238
Publisher site
See Article on Publisher Site

Abstract

Controversy surrounds the role of the ocean in interhemispheric transport of carbon. On one hand, observations in the atmosphere and in the ocean both seem to imply that the preindustrial ocean transported up to 1 Pg C yr−1 from the Northern to the Southern Hemisphere. On the other hand, three dimensional (3‐D) ocean models suggest that global interhemispheric transport of carbon is near zero. However, in this debate, there has been a general neglect of the river carbon loop. The river carbon loop includes (1) uptake of atmospheric carbon due to inorganic and organic erosion on land, (2) transport of carbon by rivers, (3) subsequent transport of riverine carbon by the ocean, and (4) loss of riverine carbon back to the atmosphere by air‐sea gas exchange. Although carbon fluxes from rivers are small compared to natural fluxes, they have the potential to contribute substantially to the net air‐sea fluxes of CO2. For insight into this dilemma, we coupled carbon fluxes from a global model of continental erosion to a 3‐D global carbon‐cycle model of the ocean. With rivers, total southward interhemispheric transport by the ocean increases from 0.1 to 0.35±0.08 Pg C yr−1, in agreement with oceanographic observations. Resulting air‐sea fluxes of riverine carbon and uptake of CO2 by land erosion were installed as boundary conditions in a 3‐D atmospheric model. The assymetry in these fluxes drives a preindustrial atmospheric gradient of CO2 at the surface of −0.6±0.1 μatm for the North Pole minus the South Pole and longitudinal variations that exceed 0.5 μatm. Conversely, the gradient for Mauna Loa minus South Pole is only −0.2±0.1 μatm, much less than the −0.8 μatm gradient extrapolated linearly from historical atmospheric CO2 measurements from the same two sites. The difference may be explained by the role of the terrestrial biosphere. Regardless, the river loop produces large gradients both meridionally and zonally. Accounting for the river carbon loop changes current estimates of the regional distribution of sources and sinks of CO2, particularly concerning partitioning between natural and anthropogenic processes.

Journal

Global Biogeochemical CyclesWiley

Published: Jun 1, 2001

References

  • Nutrient trapping in the equatorial pacific: The ocean circulation solution
    Aumont, Aumont; Orr, Orr; Monfray, Monfray; Madec, Madec; Maier‐Reimer, Maier‐Reimer
  • Meridional transport of dissolved inorganic carbon in the South Atlantic Ocean
    Holfort, Holfort; Johnson, Johnson; Schneider, Schneider; Siedler, Siedler; Wallace, Wallace
  • Variations in modelled atmospheric transport of carbon dioxide and the consequences for CO 2 inversions
    Law, Law
  • Predicting the oceanic input of organic carbon by continental erosion
    Ludwig, Ludwig; Probst, Probst; Kempe, Kempe
  • Coastal Metabolism and the oceanic organic carbon balance
    Smith, Smith; Hollibaugh, Hollibaugh
  • Testing global ocean carbon cycle models using measurements of atmospheric O 2 and CO 2 concentration
    Stephens, Stephens; Keeling, Keeling; Heimann, Heimann; Six, Six; Murnane, Murnane; Caldeira, Caldeira

You’re reading a free preview. Subscribe to read the entire article.


DeepDyve is your
personal research library

It’s your single place to instantly
discover and read the research
that matters to you.

Enjoy affordable access to
over 18 million articles from more than
15,000 peer-reviewed journals.

All for just $49/month

Explore the DeepDyve Library

Search

Query the DeepDyve database, plus search all of PubMed and Google Scholar seamlessly

Organize

Save any article or search result from DeepDyve, PubMed, and Google Scholar... all in one place.

Access

Get unlimited, online access to over 18 million full-text articles from more than 15,000 scientific journals.

Your journals are on DeepDyve

Read from thousands of the leading scholarly journals from SpringerNature, Elsevier, Wiley-Blackwell, Oxford University Press and more.

All the latest content is available, no embargo periods.

See the journals in your area

DeepDyve

Freelancer

DeepDyve

Pro

Price

FREE

$49/month
$360/year

Save searches from
Google Scholar,
PubMed

Create folders to
organize your research

Export folders, citations

Read DeepDyve articles

Abstract access only

Unlimited access to over
18 million full-text articles

Print

20 pages / month

PDF Discount

20% off