 |
| Titel |
Recent trends and drivers of regional sources and sinks of carbon dioxide |
| VerfasserIn |
S. Sitch, P. Friedlingstein, N. Gruber, S. D. Jones, G. Murray-Tortarolo, A. Ahlstrom, S. C. Doney, H. Graven, C. Heinze, C. Huntingford, S. Levis, P. E. Levy, M. Lomas, B. Poulter, N. Viovy, S. Zaehle, N. Zeng, A. Arneth, G. Bonan, L. Bopp, J. G. Canadell, F. Chevallier, P. Ciais, R. Ellis, M. Gloor, P. Peylin, S. L. Piao, C. Le Quere, B. Smith, Z. Zhu, R. Myneni |
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| ISSN |
1726-4170
|
| Digitales Dokument |
URL |
| Erschienen |
In: Biogeosciences ; 12, no. 3 ; Nr. 12, no. 3 (2015-02-02), S.653-679 |
| Datensatznummer |
250117796
|
| Publikation (Nr.) |
 copernicus.org/bg-12-653-2015.pdf |
|
|
|
|
|
| Zusammenfassung |
| The land and ocean absorb on average just over half of the anthropogenic
emissions of carbon dioxide (CO2) every year. These CO2 "sinks"
are modulated by climate change and variability. Here we use a suite of nine
dynamic global vegetation models (DGVMs) and four ocean biogeochemical
general circulation models (OBGCMs) to estimate trends driven by global and regional
climate and atmospheric CO2 in land and oceanic
CO2 exchanges with the atmosphere over the period 1990–2009, to attribute
these trends to underlying processes in the models, and to quantify the
uncertainty and level of inter-model agreement. The models were forced with
reconstructed climate fields and observed global atmospheric CO2; land
use and land cover changes are not included for the DGVMs. Over the period
1990–2009, the DGVMs simulate a mean global land carbon sink of −2.4 ± 0.7 Pg C yr−1
with a small significant trend of −0.06 ± 0.03 Pg C yr−2 (increasing sink). Over the more limited period 1990–2004, the
ocean models simulate a mean ocean sink of −2.2 ± 0.2 Pg C yr−1
with a trend in the net C uptake that is indistinguishable from zero (−0.01 ± 0.02 Pg C yr−2). The two ocean models that extended the
simulations until 2009 suggest a slightly stronger, but still small, trend of
−0.02 ± 0.01 Pg C yr−2. Trends from land and ocean models compare
favourably to the land greenness trends from remote sensing, atmospheric
inversion results, and the residual land sink required to close the global
carbon budget. Trends in the land sink are driven by increasing net primary
production (NPP), whose statistically significant trend of 0.22 ± 0.08 Pg C yr−2 exceeds a significant trend in heterotrophic respiration of
0.16 ± 0.05 Pg C yr−2 – primarily as a consequence of
widespread CO2 fertilisation of plant production. Most of the
land-based trend in simulated net carbon uptake originates from natural
ecosystems in the tropics (−0.04 ± 0.01 Pg C yr−2), with almost no
trend over the northern land region, where recent warming and reduced
rainfall offsets the positive impact of elevated atmospheric CO2 and
changes in growing season length on carbon storage. The small uptake trend
in the ocean models emerges because climate variability and change, and in
particular increasing sea surface temperatures, tend to counter\-act the trend
in ocean uptake driven by the increase in atmospheric CO2. Large
uncertainty remains in the magnitude and sign of modelled carbon trends in
several regions, as well as regarding the influence of land use and land cover changes on
regional trends. |
| |
|
| Teil von |
|
|
|
|
|
|
|
|