Abstract
We present a new high-resolution record of atmospheric CO2 from the Siple Dome ice core, Antarctica over the early Holocene (11.7–7.4 ka) that quantifies natural CO2 variability on millennial timescales under interglacial climate conditions. Atmospheric CO2 decreased by ~10 ppm between 11.3 and 7.3 ka. The decrease was punctuated by local minima at 11.1, 10.1, 9.1 and 8.3 ka with amplitude of 2–6 ppm. These variations correlate with proxies for solar forcing and local climate in the South East Atlantic polar front, East Equatorial Pacific and North Atlantic. These relationships suggest that weak solar forcing changes might have impacted CO2 by changing CO2 outgassing from the Southern Ocean and the East Equatorial Pacific and terrestrial carbon storage in the Northern Hemisphere over the early Holocene.
Highlights
Future climate and ecosystem changes due to the continual increase of atmospheric carbon dioxide concentrations caused by human activities are inevitable (IPCC, 2013)
Carbonate-acid reactions can be related with the millennial time scale CO2 variability, we examined the concentration of non-sea-salt Ca ion in the Siple Dome and Dome C ice
The strong relationship between IRD and atmospheric CO2 indicates that colder climate in the North Atlantic may lower atmospheric CO2 by impacting terrestrial carbon stocks during the early Holocene. δ18Oice from the North Greenland Ice Core Project (NGRIP) ice core (Rasmussen et al, 2006) indicating temperature in 245 Greenland reveal millennial local minima at similar time intervals as those of CO2 (∼11.4, 10.9, 10.2, 9.3 and 8.2 ka), atmospheric CO2 and temperature in Greenland are mismatched at the earliest early Holocene and ~8.2 ka
Summary
Future climate and ecosystem changes due to the continual increase of atmospheric carbon dioxide concentrations caused by human activities are inevitable (IPCC, 2013). Understanding the links between the carbon cycle and climate become important 20 for accurate projection of future climate change. Atmospheric CO2 is controlled by carbon exchange with ocean and land reservoirs, and increased CO2 in the future and consequent changes in the earth system will in turn impact CO2 levels via feedbacks (Friedlingstein et al, 2006). Due to the limited duration of direct measurements of atmospheric CO2, which only started in 1957 (Keeling, 1960), our understanding of the carbon cycle dynamics is limited on longer time scales. Understanding the carbon cycle during interglacial periods is useful because climate boundary conditions are similar to those of the near future.
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