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| Titel |
The non-steady state oceanic CO2 signal: its importance, magnitude and a novel way to detect it |
| VerfasserIn |
B. I. McNeil, R. J. Matear |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1726-4170
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| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 10, no. 4 ; Nr. 10, no. 4 (2013-04-03), S.2219-2228 |
| Datensatznummer |
250018180
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| Publikation (Nr.) |
 copernicus.org/bg-10-2219-2013.pdf |
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| Zusammenfassung |
| The role of the ocean has been pivotal in modulating rising atmospheric
CO2 levels since the industrial revolution, sequestering nearly half of
all fossil-fuel derived CO2 emissions. Net oceanic uptake of CO2
has roughly doubled between the 1960s (~1 Pg C yr−1) and 2000s
(~2 Pg C yr−1), with expectations that it will continue to
absorb even more CO2 with rising future atmospheric CO2 levels.
However, recent CO2 observational analyses along with numerous model
predictions suggest the rate of oceanic CO2 uptake is already slowing,
largely as a result of a natural decadal-scale outgassing signal. This recent
CO2 outgassing signal represents a significant shift in our
understanding of the oceans role in modulating atmospheric CO2. Current
tracer-based estimates for the ocean storage of anthropogenic CO2 assume
the ocean circulation and biology is in steady state, thereby missing the new
and potentially important "non-steady state" CO2 outgassing signal. By
combining data-based techniques that assume the ocean is in a steady state,
with techniques that constrain the net oceanic CO2 uptake signal, we
show how to extract the non-steady state CO2 signal from observations.
Over the entire industrial era, the non-steady state CO2 outgassing
signal (~13 ± 10 Pg C) is estimated to represent about 9%
of the total net CO2 inventory change (~142 Pg C). However,
between 1989 and 2007, the non-steady state CO2 outgassing signal
(~6.3 Pg C) has likely increased to be ~18% of net
oceanic CO2 storage over that period (~36 Pg C). The present
uncertainty of our data-based techniques for oceanic CO2 uptake limit
our capacity to quantify the non-steady state CO2 signal, however with
more data and better certainty estimates across a range of diverse methods,
this important and growing CO2 signal could be better constrained in the
future. |
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