Compound effects of Antarctic sea ice on atmospheric pCO2 change during glacial–interglacial cycle

Kurahashi-Nakamura, Takasumi; Abe‐Ouchi, Ayako; Yamanaka, Yasuhiro; Misumi, Kazuo

doi:10.1029/2007gl030898

Cited by 21 publications

(51 citation statements)

References 14 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The export fluxes of particulate organic matter of 10.5 and 10.4 GtC yr −1 in PIa and PIb ( Fig. 1e and f) are in line with observationally-based estimates of 5-20 GtC yr −1 (Jahnke and Jahnke, 2004;Falkowski et al, 1998;Laws et al, 2000;Louanchi and Najjar, 2000).…”

Section: Solubilitysupporting

confidence: 68%

“…The excess nitrate off the coast of Chile and in the Atlantic sector of the Southern Ocean is attributable to the deep-water supply via coastal upwelling or convective mixing. Our model does not consider temperature-dependent biological production (Oschlies and Garcon, 1999) or temperature-dependent remineralization (Laws et al, 2000). LGb Table 2.…”

Section: Validation Of Present Ocean Carbon Cycle Simulationmentioning

confidence: 99%

See 1 more Smart Citation

Quantifying the ocean's role in glacial CO2 reductions

et al. 2012

Self Cite

View full text Add to dashboard Cite

Abstract.A series of Last Glacial Maximum (LGM) marine carbon cycle sensitivity experiments is conducted to test the effect of different physical processes, as simulated by two atmosphere-ocean general circulation model (AOGCM) experiments, on atmospheric pCO 2 . One AOGCM solution exhibits an increase in North Atlantic Deep Water (NADW) formation under glacial conditions, whereas the other mimics an increase in Antarctic Bottom Water (AABW) associated with a weaker NADW. None of these sensitivity experiments reproduces the observed magnitude of glacial/interglacial pCO 2 changes. However, to explain the reconstructed vertical gradient of dissolved inorganic carbon (DIC) of 40 mmol m −3 a marked enhancement in AABW formation is required. Furthermore, for the enhanced AABW sensitivity experiment the simulated stable carbon isotope ratio (δ 13 C) decreases by 0.4 ‰ at intermediate depths in the South Atlantic in accordance with sedimentary evidence. The shift of deep and bottom water formation sites from the North Atlantic to the Southern Ocean increases the total preformed nutrient inventory, so that the lowered efficiency of Southern Ocean nutrient utilization in turn increases atmospheric pCO 2 . This change eventually offsets the effect of an increased abyssal carbon pool due to stronger AABW formation. The effects of interhemispheric glacial sea-ice changes on atmospheric pCO 2 oppose each other. Whereas, extended sea-ice coverage in the Southern Hemisphere reduces the airsea gas exchange of CO 2 in agreement with previous theoretical considerations, glacial advances of sea-ice in the Northern Hemisphere lead to a weakening of the oceanic carbon uptake through the physical pump. Due to enhanced gas solubility associated with lower sea surface temperature, both glacial experiments generate a reduction of atmospheric pCO 2 by about 20-23 ppmv. The sensitivity experiments presented here demonstrate the presence of compensating effects of different physical processes in the ocean on glacial CO 2 and the difficulty of finding a simple explanation of the glacial CO 2 problem by invoking ocean dynamical changes.

show abstract

Section: Solubilitysupporting

confidence: 68%

Section: Validation Of Present Ocean Carbon Cycle Simulationmentioning

confidence: 99%

Quantifying the ocean's role in glacial CO2 reductions

et al. 2012

Self Cite

View full text Add to dashboard Cite

show abstract

“…We found that light limitation of highly productive regions in both hemispheres caused by increased sea ice cover led to a global loss of 160 Pg C, equivalent to 8 ppm pCO 2 . Similar responses have been simulated in other models that consider the impact of sea ice on biological production and do not consider temperature and salinity changes associated with sea ice growth (Kurahashi-Nakamura et al, 2007;Sun and Matsumoto, 2010).…”

Section: Carbonmentioning

confidence: 57%

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

et al. 2016

View full text Add to dashboard Cite

Abstract. The ocean's ability to store large quantities of carbon, combined with the millennial longevity over which this reservoir is overturned, has implicated the ocean as a key driver of glacial-interglacial climates. However, the combination of processes that cause an accumulation of carbon within the ocean during glacial periods is still under debate. Here we present simulations of the Last Glacial Maximum (LGM) using the CSIRO Mk3L-COAL (Carbon-OceanAtmosphere-Land) earth system model to test the contribution of physical and biogeochemical processes to ocean carbon storage. For the LGM simulation, we find a significant global cooling of the surface ocean (3.2 • C) and the expansion of both minimum and maximum sea ice cover broadly consistent with proxy reconstructions. The glacial ocean stores an additional 267 Pg C in the deep ocean relative to the pre-industrial (PI) simulation due to stronger Antarctic Bottom Water formation. However, 889 Pg C is lost from the upper ocean via equilibration with a lower atmospheric CO 2 concentration and a global decrease in export production, causing a net loss of carbon relative to the PI ocean. The LGM deep ocean also experiences an oxygenation (> 100 mmol O 2 m −3 ) and deepening of the calcite saturation horizon (exceeds the ocean bottom) at odds with proxy reconstructions. With modifications to key biogeochemical processes, which include an increased export of organic matter due to a simulated release from iron limitation, a deepening of remineralisation and decreased inorganic carbon export driven by cooler temperatures, we find that the carbon content of the glacial ocean can be sufficiently increased (317 Pg C) to explain the reduction in atmospheric and terrestrial carbon at the LGM (194 ± 2 and 330 ± 400 Pg C, respectively). Assuming an LGM-PI difference of 95 ppm pCO 2 , we find that 55 ppm can be attributed to the biological pump, 28 ppm to circulation changes and the remaining 12 ppm to solubility. The biogeochemical modifications also improve model-proxy agreement in export production, carbonate chemistry and dissolved oxygen fields. Thus, we find strong evidence that variations in the oceanic biological pump exert a primary control on the climate.

show abstract

“…Recently, Kurahashi‐Nakamura et al [2007, hereafter KN2007] attempted to investigate this biological effect (sea ice blocking PAR) using an ocean‐only general circulation model. They did not explicitly model a change in sea ice coverage but simulated the effect of it by changing the sea ice mask area over which biological production is prohibited.…”

Section: Introductionmentioning

confidence: 99%

“…Our climate model has dynamical models of sea ice and ocean circulation. These features offer important advantages over both the box model of SK2000 and the ocean‐only general circulation model of KN2007, although as we note below there are some limitations to using an intermediate‐complexity model as well. In addition to the two effects of sea ice on atmospheric p CO2 (air‐sea gas exchange cap and biological production), which have been investigated previously, we also examine the effects of changes in ocean dynamics and hydrography that accompany changes in sea ice coverage in our simulation.…”

Section: Introductionmentioning

confidence: 99%

Effects of sea ice on atmospheric pCO₂: A revised view and implications for glacial and future climates

Sun

Matsumoto

2010

J. Geophys. Res.

View full text Add to dashboard Cite

[1] Sea ice is a key component in the global carbon cycle and climate system. In the traditional view, the sole effect of expanded sea ice coverage is to reduce the atmospheric pCO 2 by inhibiting air-sea gas exchange. However, this view neglects the effect that sea ice capping has on the biological production. By limiting light for photosynthesis, larger sea ice coverage would reduce the strength of the biological pump and therefore increase atmospheric pCO 2 . Recently, Kurahashi-Nakamura et al. (2007) suggested that the opposing impact of biology on atmospheric pCO 2 will more than offset the gas exchange effect, such that atmospheric pCO 2 will actually increase with larger sea ice coverage. In an effort to resolve this controversy, we use an intermediate-complexity, global model of biogeochemistry and climate to determine the sensitivity of atmospheric CO 2 concentration to changes in the sea ice coverage, driven by prescribed changes in sea ice albedo. When sea ice in our model is increased by 34% globally relative to the control run, gas solubility, ice capping effect and stratification increase, while biological production decreases; overall atmospheric pCO 2 is reduced by 9.4 ppmv. Our results broadly support the notion that the biological response of sea ice capping is as important as its physical response. Furthermore, we show that the overall change in atmospheric pCO 2 is indeed inversely related to sea ice coverage, but it is not because sea ice caps off gas exchange but because gas solubility is increased by lower temperatures that accompany sea ice expansion in our model simulations.Citation: Sun, X., and K. Matsumoto (2010), Effects of sea ice on atmospheric pCO 2 : A revised view and implications for glacial and future climates,

show abstract

Compound effects of Antarctic sea ice on atmospheric pCO₂ change during glacial–interglacial cycle

Cited by 21 publications

References 14 publications

Quantifying the ocean's role in glacial CO<sub>2</sub> reductions

Quantifying the ocean's role in glacial CO<sub>2</sub> reductions

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

Effects of sea ice on atmospheric pCO₂: A revised view and implications for glacial and future climates

Contact Info

Product

Resources

About

Compound effects of Antarctic sea ice on atmospheric pCO2 change during glacial–interglacial cycle

Cited by 21 publications

References 14 publications

Quantifying the ocean's role in glacial CO&lt;sub&gt;2&lt;/sub&gt; reductions

Quantifying the ocean's role in glacial CO&lt;sub&gt;2&lt;/sub&gt; reductions

The simulated climate of the Last Glacial Maximum and insights into the global marine carbon cycle

Effects of sea ice on atmospheric pCO2: A revised view and implications for glacial and future climates

Contact Info

Product

Resources

About

Compound effects of Antarctic sea ice on atmospheric pCO₂ change during glacial–interglacial cycle

Quantifying the ocean's role in glacial CO<sub>2</sub> reductions

Quantifying the ocean's role in glacial CO<sub>2</sub> reductions

Effects of sea ice on atmospheric pCO₂: A revised view and implications for glacial and future climates