scholarly journals Including a full carbon cycle into the <i>i</i>LOVECLIM model (v1.0)

2014 ◽  
Vol 7 (3) ◽  
pp. 3937-3984 ◽  
Author(s):  
N. Bouttes ◽  
D. M. Roche ◽  
V. Mariotti-Epelbaum ◽  
L. Bopp
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Climate Model ◽  
Carbon Dioxide Concentration ◽  
Deep Ocean ◽  
Carbon Cycle Model ◽  
Radiative Balance ◽  
Natural Variations ◽  
Good Agreement

Abstract. The atmospheric carbon dioxide concentration plays a crucial role in the radiative balance and as such has a strong influence on the evolution of climate. Because of the numerous interactions between climate and the carbon cycle, it is necessary to include a model of the carbon cycle within a climate model to understand and simulate past and future changes of the carbon cycle. In particular, natural variations of atmospheric CO2 have happened in the past, while anthropogenic carbon emissions are predicted to continue in the future. To study changes of the carbon cycle and climate on timescales of a few hundred to a few thousand years, we have included a simple carbon cycle model into the iLOVECLIM Earth System Model. In this study, we describe the ocean and terrestrial biosphere carbon cycle models and their performance relative to observational data. We focus on the main carbon cycle variables including the carbon isotope ratios δ13C and the Δ14C. We show that the model results are in good agreement with modern observations both at the surface and in the deep ocean for the main variables, in particular phosphates, DIC and the carbon isotopes. The model can thus be used for long-term past and future climate–carbon studies.

scholarly journals Including an ocean carbon cycle model into <i>i</i>LOVECLIM (v1.0)

2015 ◽  
Vol 8 (5) ◽  
pp. 1563-1576 ◽  
Author(s):  
N. Bouttes ◽  
D. M. Roche ◽  
V. Mariotti ◽  
L. Bopp
Keyword(s):  
Carbon Cycle ◽  
Atmospheric Carbon Dioxide ◽  
Climate Model ◽  
Dissolved Inorganic Carbon ◽  
Carbon Dioxide Concentration ◽  
Deep Ocean ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Radiative Balance ◽  
Ocean Carbon

Abstract. The atmospheric carbon dioxide concentration plays a crucial role in the radiative balance and as such has a strong influence on the evolution of climate. Because of the numerous interactions between climate and the carbon cycle, it is necessary to include a model of the carbon cycle within a climate model to understand and simulate past and future changes of the carbon cycle. In particular, natural variations of atmospheric CO2 have happened in the past, while anthropogenic carbon emissions are likely to continue in the future. To study changes of the carbon cycle and climate on timescales of a few hundred to a few thousand years, we have included a simple carbon cycle model into the iLOVECLIM Earth System Model. In this study, we describe the ocean and terrestrial biosphere carbon cycle models and their performance relative to observational data. We focus on the main carbon cycle variables including the carbon isotope ratios δ13C and the Δ14C. We show that the model results are in good agreement with modern observations both at the surface and in the deep ocean for the main variables, in particular phosphates, dissolved inorganic carbon and the carbon isotopes.

Shallow-depth slab decarbonation prevents recharge of the deep carbon cycle

2020 ◽  
Author(s):  
Leonie Strobl ◽  
Andreas Beinlich ◽  
Markus Ohl ◽  
Oliver Plümper
Keyword(s):  
Carbon Cycle ◽  
Subduction Zone ◽  
Atmospheric Carbon Dioxide ◽  
Carbon Dioxide Concentration ◽  
Oceanic Lithosphere ◽  
Aqueous Fluid ◽  
Shallow Depth ◽  
Plate Motion ◽  
The Earth

&lt;p&gt;Long-term oscillations of the Earth&amp;#8217;s atmospheric carbon dioxide concentration and climate are intrinsically linked to tectonic plate motion controlling CO&lt;sub&gt;2&lt;/sub&gt; uptake in rocks, their transport into the Earth&amp;#8217;s mantle and recycling back into the atmosphere by volcanic activity. In this long-term deep carbon cycle, the efficiency of mantle ingassing is controlled by the stability of carbon carrier phases at subduction zone pressure-temperature conditions, during deformation and their interaction with subduction zone dehydration fluids. However, the current understanding of carbonate stability under these conditions is controversial. This is reflected by studies predicting carbonate transport deep into the asthenospheric mantle [1, 2] in contrast to more recently postulated shallow-depth carbon release from subducting slabs [e.g. 3]. Some of this controversy is related to the lack of available field sites that allow for the quantification of subduction-related decarbonation and its driving force. Here we present novel observations on the release of carbon during subduction of previously carbonated, ultramafic, oceanic lithosphere. Our observations are based on a recently discovered, exceptionally well-exposed, outcrop in northern Norway [4] containing frozen-in decarbonation reaction textures at the km scale. Our observations and textural analyses indicate breakdown of magnesium carbonate and serpentine to secondary olivine at depths shallower than 20 km. Secondary olivine is present as up to fist-sized nodules pseudomorphically replacing magnesite and as veins delineating escape pathways for the carbon-bearing aqueous fluid. We present first field observations and reaction textures and will discuss implications for the efficiency of carbon transport into the Earth&amp;#8217;s mantle by subduction of carbonate-bearing oceanic lithosphere.&lt;/p&gt;&lt;p&gt;[1] Kerrick, D.M. &amp; Connolly, J.A.D. (1998). Geology &lt;strong&gt;26&lt;/strong&gt;, 375-378.&lt;/p&gt;&lt;p&gt;[2] Dasgupta, R. &amp; Hirschmann, M.M. (2010). EPSL &lt;strong&gt;298, &lt;/strong&gt;1-13.&lt;/p&gt;&lt;p&gt;[3] Kelemen, P.B. &amp; Manning, C.E. (2015). PNAS &lt;strong&gt;112&lt;/strong&gt;, E3997-E4006.&lt;/p&gt;&lt;p&gt;[4] Beinlich, A., Pl&amp;#252;mper, O., H&amp;#246;velmann, J., Austrheim, H. &amp; Jamtveit, B. (2012). Terra Nova &lt;strong&gt;24, &lt;/strong&gt;446-455.&lt;/p&gt;

The rate of dissolution of calcium carbonate from the surface of deep-ocean turbidite sediments

1990 ◽  
Vol 331 (1616) ◽  
pp. 41-49 ◽  
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Bottom Water ◽  
Natural Radionuclide ◽  
Carbon Dioxide Concentration ◽  
Deep Ocean ◽  
Sediment Surface ◽  
Carbonate Sediments ◽  
Sedimentary Record ◽  
Atmospheric Carbon

It is known that past periods of high atmospheric carbon dioxide concentration are associated with poor carbonate preservation in the deep-ocean sedimentary record. Bottom water can become more aggressive towards carbonate sediments during such periods. To interpret the sedimentary record more exactly, and to predict future atmospheric carbon dioxide levels, it is necessary to know the rate of solution of carbonate for a given degree of bottom-water undersaturation. In parts of the Atlantic Ocean, turbidite sedimentation mechanisms have emplaced carbonate-rich material in contact with undersaturated bottom water. The time of the emplacement event can be determined from natural radionuclide distributions, and the degree of carbonate dissolution in this time can be measured. This provides a direct measurement of dissolution rate from a natural sediment surface at a known degree of undersaturation. The range of applicability of the method is explored with a mathematical model, and field data from a 5430 m depth Atlantic site are presented.

scholarly journals Multicentury Changes to the Global Climate and Carbon Cycle: Results from a Coupled Climate and Carbon Cycle Model

2005 ◽  
Vol 18 (21) ◽  
pp. 4531-4544 ◽  
Author(s):  
G. Bala ◽  
K. Caldeira ◽  
A. Mirin ◽  
M. Wickett ◽  
C. Delire
Keyword(s):  
Carbon Cycle ◽  
Radiative Forcing ◽  
Fossil Fuel ◽  
Global Climate ◽  
Second Century ◽  
Cycle Model ◽  
Carbon Cycle Model ◽  
Living Biomass ◽  
Long Term Consequences

Abstract A coupled climate and carbon (CO2) cycle model is used to investigate the global climate and carbon cycle changes out to the year 2300 that would occur if CO2 emissions from all the currently estimated fossil fuel resources were released to the atmosphere. By the year 2300, the global climate warms by about 8 K and atmospheric CO2 reaches 1423 ppmv. The warming is higher than anticipated because the sensitivity to radiative forcing increases as the simulation progresses. In this simulation, the rate of emissions peaks at over 30 Pg C yr−1 early in the twenty-second century. Even at the year 2300, nearly 50% of cumulative emissions remain in the atmosphere. Both soils and living biomass are net carbon sinks throughout the simulation. Despite having relatively low climate sensitivity and strong carbon uptake by the land biosphere, these model projections suggest severe long-term consequences for global climate if all the fossil fuel carbon is ultimately released into the atmosphere.

scholarly journals Space-based geoengineering: Challenges and requirements

2009 ◽  
Vol 224 (3) ◽  
pp. 571-580 ◽  
Author(s):  
C R McInnes
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Large Scale ◽  
Climate Model ◽  
Carbon Dioxide Concentration ◽  
Complex Solution ◽  
Lagrange Point ◽  
Simple Climate Model ◽  
Earth’S Climate

The prospect of engineering the Earth's climate (geoengineering) raises a multitude of issues associated with climatology, engineering on macroscopic scales, and indeed the ethics of such ventures. Depending on personal views, such large-scale engineering is either an obvious necessity for the deep future, or yet another example of human conceit. In this article a simple climate model will be used to estimate requirements for engineering the Earth's climate, principally using space-based geoengineering. Active cooling of the climate to mitigate anthropogenic climate change due to a doubling of the carbon dioxide concentration in the Earth's atmosphere is considered. This representative scenario will allow the scale of the engineering challenge to be determined. It will be argued that simple occulting discs at the interior Lagrange point may represent a less complex solution than concepts for highly engineered refracting discs proposed recently. While engineering on macroscopic scales can appear formidable, emerging capabilities may allow such ventures to be seriously considered in the long term. This article is not an exhaustive review of geoengineering, but aims to provide a foretaste of the future opportunities, challenges, and requirements for space-based geoengineering ventures.

scholarly journals Timing and magnitude of Southern Ocean sea ice/carbon cycle feedbacks

2020 ◽  
Vol 117 (9) ◽  
pp. 4498-4504 ◽  
Author(s):  
Karl Stein ◽  
Axel Timmermann ◽  
Eun Young Kwon ◽  
Tobias Friedrich
Keyword(s):  
Carbon Cycle ◽  
Southern Ocean ◽  
Sea Ice ◽  
General Circulation ◽  
Deep Ocean ◽  
General Circulation Models ◽  
Ice Dynamics ◽  
Carbon Cycle Model ◽  
Ocean Stratification ◽  
Ocean Ventilation

The Southern Ocean (SO) played a prominent role in the exchange of carbon between ocean and atmosphere on glacial timescales through its regulation of deep ocean ventilation. Previous studies indicated that SO sea ice could dynamically link several processes of carbon sequestration, but these studies relied on models with simplified ocean and sea ice dynamics or snapshot simulations with general circulation models. Here, we use a transient run of an intermediate complexity climate model, covering the past eight glacial cycles, to investigate the orbital-scale dynamics of deep ocean ventilation changes due to SO sea ice. Cold climates increase sea ice cover, sea ice export, and Antarctic Bottom Water formation, which are accompanied by increased SO upwelling, stronger poleward export of Circumpolar Deep Water, and a reduction of the atmospheric exposure time of surface waters by a factor of 10. Moreover, increased brine formation around Antarctica enhances deep ocean stratification, which could act to decrease vertical mixing by a factor of four compared with the current climate. Sensitivity tests with a steady-state carbon cycle model indicate that the two mechanisms combined can reduce atmospheric carbon by 40 ppm, with ocean stratification acting early within a glacial cycle to amplify the carbon cycle response.

scholarly journals A simple object-oriented and open source model for scientific and policy analyses of the global carbon cycle – Hector v0.1

2014 ◽  
Vol 7 (5) ◽  
pp. 7075-7119
Author(s):  
C. A. Hartin ◽  
P. Patel ◽  
A. Schwarber ◽  
R. P. Link ◽  
B. P. Bond-Lamberty
Keyword(s):  
Carbon Cycle ◽  
Open Source ◽  
Climate Models ◽  
Modular Design ◽  
Climate Model ◽  
Global Climate ◽  
Coupled Model ◽  
Object Oriented ◽  
Climate Mitigation ◽  
Carbon Cycle Model

Abstract. Simple climate models play an integral role in policy and scientific communities. They are used for climate mitigation scenarios within integrated assessment models, complex climate model emulation, and uncertainty analyses. Here we describe Hector v0.1, an open source, object-oriented, simple global climate carbon-cycle model. This model runs essentially instantaneously while still representing the most critical global scale earth system processes. Hector has three main carbon pools: an atmosphere, land, and ocean. The model's terrestrial carbon cycle includes respiration and primary production, accommodating arbitrary geographic divisions into, e.g., ecological biomes or political units. Hector's actively solves the inorganic carbon system in the surface ocean, directly calculating air–sea fluxes of carbon and ocean pH. Hector reproduces the global historical trends of atmospheric [CO2] and surface temperatures. The model simulates all four Representative Concentration Pathways with high correlations (R>0.7) with current observations, MAGICC (a well-known simple climate model), and the Coupled Model Intercomparison Project version 5. Hector is freely available under an open source license, and its modular design will facilitate a broad range of research in various areas.

scholarly journals Historical (1850–2000) gridded anthropogenic and biomass burning emissions of reactive gases and aerosols: methodology and application

2010 ◽  
Vol 10 (2) ◽  
pp. 4963-5019 ◽  
Author(s):  
J.-F. Lamarque ◽  
T. C. Bond ◽  
V. Eyring ◽  
C. Granier ◽  
A. Heil ◽  
...  
Keyword(s):  
Carbon Monoxide ◽  
Climate Models ◽  
Climate Model ◽  
Historical Period ◽  
Term Trend ◽  
Model Simulations ◽  
Reactive Gases ◽  
Long Term Trend ◽  
Good Agreement

Abstract. We present and discuss a new dataset of gridded emissions covering the historical period (1850–2000) in decadal increments at a horizontal resolution of 0.5° in latitude and longitude. The primary purpose of this inventory is to provide consistent gridded emissions of reactive gases and aerosols for use in chemistry model simulations needed by climate models for the Climate Model Intercomparison Program #5 (CMIP5) in support of the Intergovernmental Panel on Climate Change (IPCC) Fifth Assessment Report (AR5). Our best estimate for the year 2000 inventory represents a combination of existing regional and global inventories to capture the best information available at this point; 40 regions and 12 sectors are used to combine the various sources. The historical reconstruction of each emitted compound, for each region and sector, is then forced to agree with our 2000 estimate, ensuring continuity between past and 2000 emissions. Simulations from two chemistry-climate models is used to test the ability of the emission dataset described here to capture long-term changes in atmospheric ozone, carbon monoxide and aerosol distributions. The simulated long-term change in the Northern mid-latitudes surface and mid-troposphere ozone is not quite as rapid as observed. However, stations outside this latitude band show much better agreement in both present-day and long-term trend. The model simulations indicate that the concentration of carbon monoxide is underestimated at the Mace Head station; however, the long-term trend over the limited observational period seems to be reasonably well captured. The simulated sulfate and black carbon deposition over Greenland is in very good agreement with the ice-core observations spanning the simulation period. Finally, aerosol optical depth and additional aerosol diagnostics are shown to be in good agreement with previously published estimates and observations.

scholarly journals Impact of brine-induced stratification on the glacial carbon cycle

2010 ◽  
Vol 6 (2) ◽  
pp. 681-710 ◽  
Author(s):  
N. Bouttes ◽  
D. Paillard ◽  
D. M. Roche
Keyword(s):  
Carbon Cycle ◽  
Climate Model ◽  
Sediment Cores ◽  
Deep Ocean ◽  
Atmospheric Co2 ◽  
Vertical Diffusion ◽  
Ocean Salinity ◽  
Carbon Reservoir ◽  
Pore Water Salinity ◽  
The Impact

Abstract. During the cold period of the Last Glacial Maximum (LGM, about 21 000 years ago) atmospheric CO2 was around 190 ppm (Monnin et al., 2001), much lower than the pre-industrial concentration of 280 ppm. The causes of this substantial drop remain partially unresolved, despite intense research. Understanding the origin of reduced atmospheric CO2 during glacial times is crucial to comprehend the evolution of the different carbon reservoirs within the Earth system (atmosphere, terrestrial biosphere and ocean). In this context, the ocean is believed to play a major role as it can store large amounts of carbon (Sigman and Boyle, 2000), especially in the abyss, which is a carbon reservoir that is thought to have expanded during glacial times. To create this larger reservoir, one possible mechanism is to produce very dense glacial waters, thereby stratifying the deep ocean and reducing the carbon exchange between the deep and surface ocean (Paillard and Parrenin, 2004). The existence of such very dense waters has been inferred in the LGM deep Atlantic from sediment pore water salinity (Adkins et al., 2002). Based on these observations, we study the impact of a brine mechanism on the glacial carbon cycle. This mechanism relies on the formation and rapid sinking of brines, very salty water released during sea ice formation, which brings salty dense water down to the bottom of the ocean. It provides two major features: a direct link from the surface to the deep ocean along with an efficient way of setting a strong stratification. We show with the CLIMBER-2 coupled carbon-climate model (Petoukhov et al., 2000) that such a brine mechanism can account for a significant decrease in atmospheric CO2 and contribute to the glacial-interglacial change. This mechanism can be amplified by low vertical diffusion resulting from the brine-induced stratification. The results obtained substantially improve the modeled glacial distribution of oceanic δ13C as well as the deep ocean salinity in line with reconstructions from sediment cores (Curry and Oppo, 2005; Adkins et al., 2002), suggesting that such a mechanism could have played an important role during glacial times.

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