文章基本信息

标题：Influence of high-latitude warming and land-use changes in the early 20th century northern Eurasian CO2 sink
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作者：Ana Bastos ; Anna Peregon ; Érico A Gani 等
期刊名称：Environmental Research Letters
印刷版ISSN：1748-9326
电子版ISSN：1748-9326
出版年度：2018
卷号：13
期号：6
页码：065014
DOI：10.1088/1748-9326/aac4d3
语种：English
出版社：IOP Publishing Ltd
摘要：While the global carbon budget (GCB) is relatively well constrained over the last decades of the 20th century [1], observations and reconstructions of atmospheric CO₂ growth rate present large discrepancies during the earlier periods [2]. The large uncertainty in GCB has been attributed to the land biosphere, although it is not clear whether the gaps between observations and reconstructions are mainly because land-surface models (LSMs) underestimate inter-annual to decadal variability in natural ecosystems, or due to inaccuracies in land-use change reconstructions. As Eurasia encompasses about 15% of the terrestrial surface, 20% of the global soil organic carbon pool and constitutes a large CO₂ sink, we evaluate the potential contribution of natural and human-driven processes to induce large anomalies in the biospheric CO₂ fluxes in the early 20th century. We use an LSM specifically developed for high-latitudes, that correctly simulates Eurasian C-stocks and fluxes from observational records [3], in order to evaluate the sensitivity of the Eurasian sink to the strong high-latitude warming occurring between 1930 and 1950. We show that the LSM with improved high-latitude phenology, hydrology and soil processes, contrary to the group of LSMs in [2], is able to represent enhanced vegetation growth linked to boreal spring warming, consistent with tree-ring time-series [4]. By compiling a dataset of annual agricultural area in the Former Soviet Union that better reflects changes in cropland area linked with socio-economic fluctuations during the early 20th century, we show that land-abadonment during periods of crisis and war may result in reduced CO₂ emissions from land-use change (44%–78% lower) detectable at decadal time-scales. Our study points to key processes that may need to be improved in LSMs and LUC datasets in order to better represent decadal variability in the land CO₂ sink, and to better constrain the GCB during the pre-observational record.