scholarly journals Carbon Dioxide Removal via Macroalgae Open-ocean Mariculture and Sinking: An Earth System Modeling Study

2022 ◽  
Author(s):  
Jiajun Wu ◽  
David P. Keller ◽  
Andreas Oschlies
Keyword(s):  
Carbon Dioxide ◽  
Dissolved Inorganic Carbon ◽  
Net Primary Production ◽  
System Modeling ◽  
Open Ocean ◽  
Carbon Dioxide Removal ◽  
Earth System ◽  
Nutrient Competition ◽  
Carbon Reservoir ◽  
Modeling Study

Abstract. In this study we investigate open-ocean macroalgae mariculture and sinking (MOS) as ocean-based carbon dioxide removal (CDR) method. Embedding a macroalgae model into an Earth system model, we simulate macroalgae mariculture in the open-ocean surface layer followed by fast sinking of the carbon-rich macroalgal biomass to the deep seafloor (depth > 3,000 m). We also test the combination of MOS with artificial upwelling (AU), which fertilizes the macroalgae by pumping nutrient-rich deeper water to the surface. The simulations are done under RCP4.5 a moderate emission pathway. When deployed globally between years 2020 and 2100, the simulated CDR potential of MOS is 270 PgC, which is further boosted by AU to 447 PgC. More than half of MOS-sequestered carbon retains in the ocean after cessation at year 2100 until year 3000. The major side effect of MOS on pelagic ecosystems is the reduction of phytoplankton net primary production (PNPP) due to the nutrient competition and canopy shading by macroalgae. MOS shrinks the mid layer oxygen minimum zones (OMZs) by reducing the organic matter export to, and remineralization in, subsurface and intermediate waters, while it creates new OMZs on the seafloor by oxygen consumption from remineralization of sunken biomass. MOS also impacts the global carbon cycle, reduces the atmospheric and terrestrial carbon reservoir when enhancing the ocean carbon reservoir. MOS also enriches the dissolved inorganic carbon in the deep ocean. Effects are mostly reversible after cessation of MOS, though recovery is not complete by year 3000. In a sensitivity experiment without remineralization of sunk MOS biomass, the entire MOS-captured carbon is permanently stored in the ocean, but the lack of remineralized nutrients causes a long-term nutrient decline in the surface layers and thus reduces PNPP. Our results suggest that MOS has a considerable potential as an ocean-based CDR method. However, MOS has inherent side effects on marine ecosystems and biogeochemistry, which will require a careful evaluation beyond this first idealized modeling study.

scholarly journals Collateral transgression of planetary boundaries due to climate engineering by terrestrial carbon dioxide removal

2016 ◽  
Vol 7 (4) ◽  
pp. 783-796 ◽  
Author(s):  
Vera Heck ◽  
Jonathan F. Donges ◽  
Wolfgang Lucht
Keyword(s):  
Carbon Dioxide ◽  
Global Warming ◽  
Carbon Dioxide Removal ◽  
Small Range ◽  
Earth System ◽  
Planetary Boundaries ◽  
Climate Engineering ◽  
Terrestrial Carbon ◽  
The Earth ◽  
Atmospheric Carbon

Abstract. The planetary boundaries framework provides guidelines for defining thresholds in environmental variables. Their transgression is likely to result in a shift in Earth system functioning away from the relatively stable Holocene state. As the climate system is approaching critical thresholds of atmospheric carbon, several climate engineering methods are discussed, aiming at a reduction of atmospheric carbon concentrations to control the Earth's energy balance. Terrestrial carbon dioxide removal (tCDR) via afforestation or bioenergy production with carbon capture and storage are part of most climate change mitigation scenarios that limit global warming to less than 2 °C. We analyse the co-evolutionary interaction of societal interventions via tCDR and the natural dynamics of the Earth's carbon cycle. Applying a conceptual modelling framework, we analyse how the degree of anticipation of the climate problem and the intensity of tCDR efforts with the aim of staying within a "safe" level of global warming might influence the state of the Earth system with respect to other carbon-related planetary boundaries. Within the scope of our approach, we show that societal management of atmospheric carbon via tCDR can lead to a collateral transgression of the planetary boundary of land system change. Our analysis indicates that the opportunities to remain in a desirable region within carbon-related planetary boundaries only exist for a small range of anticipation levels and depend critically on the underlying emission pathway. While tCDR has the potential to ensure the Earth system's persistence within a carbon-safe operating space under low-emission pathways, it is unlikely to succeed in a business-as-usual scenario.

Ocean Chlorophyll as a Precursor of ENSO: An Earth System Modeling Study

2018 ◽  
Vol 45 (4) ◽  
pp. 1939-1947 ◽  
Author(s):  
Jong-Yeon Park ◽  
John P. Dunne ◽  
Charles A. Stock
Keyword(s):  
System Modeling ◽  
Earth System ◽  
Earth System Modeling ◽  
Modeling Study

scholarly journals Collateral transgression of planetary boundaries due to climate engineering by terrestrial carbon dioxide removal

2016 ◽  
Author(s):  
Vera Heck ◽  
Jonathan F. Donges ◽  
Wolfgang Lucht
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Global Warming ◽  
Carbon Dioxide Removal ◽  
Earth System ◽  
Planetary Boundaries ◽  
Climate Engineering ◽  
Terrestrial Carbon ◽  
The Earth ◽  
Atmospheric Carbon

Abstract. The planetary boundaries framework as proposed by Rockström et al. (2009) provides guidelines for defining thresholds in environmental variables. Their transgression is likely to result in a shift in Earth system functioning away from the relatively stable Holocene state. As the climate change boundary is already transgressed, several climate engineering methods are discussed, aiming at a reduction of atmospheric carbon concentrations to control the Earth's energy balance. Terrestrial carbon dioxide removal (tCDR) via afforestation or bioenergy production with carbon capture and storage are part of most climate change mitigation scenarios that limit global warming to less than 2 °C. We analyse the co-evolutionary interaction of societal interventions via tCDR and the natural dynamics of the Earth's carbon cycle. Applying a conceptual modelling framework, we analyse how societal monitoring and management of atmospheric CO2 concentrations with the aim of staying within a "safe" level of global warming might influence the state of the Earth system with respect to other carbon-related planetary boundaries. Within the scope of our approach, we show that societal management of atmospheric carbon via tCDR can lead to a transgression of the planetary boundaries of land system change and ocean acidification. Our analysis indicates that the opportunities to remain in a desirable region within carbon-related planetary boundaries depend critically on the sensitivity and strength of the tCDR management system, as well as underlying emission pathways. While tCDR has the potential to ensure the Earth system's persistence within a carbon safe operating space under low emission pathways, this potential decreases rapidly for medium to high emission pathways.

scholarly journals The Carbon Dioxide Removal Model Intercomparison Project (CDR-MIP): Rationale and experimental design

2017 ◽  
Author(s):  
David P. Keller ◽  
Andrew Lenton ◽  
Vivian Scott ◽  
Naomi E. Vaughan ◽  
Nico Bauer ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Carbon Dioxide Removal ◽  
Radiation Budget ◽  
Earth System ◽  
Emission Scenarios ◽  
Model Intercomparison ◽  
The Earth ◽  
Intercomparison Project ◽  
Removal Model

Abstract. The recent IPCC reports state that continued anthropogenic greenhouse gas emissions are changing the climate threatening "severe, pervasive and irreversible" impacts. Slow progress in emissions reduction to mitigate climate change is resulting in increased attention on what is called Geoengineering, Climate Engineering, or Climate Intervention – deliberate interventions to counter climate change that seek to either modify the Earth's radiation budget or remove greenhouse gases such as CO2 from the atmosphere. When focused on CO2, the latter of these categories is called Carbon Dioxide Removal (CDR). The majority of future emission scenarios that stay well below 2 °C, and nearly all emission scenarios that do not exceed 1.5 °C warming by the year 2100, require some form of CDR. At present, there is little consensus on the impacts and efficacy of the different types of proposed CDR. To address this need the Carbon Dioxide Removal Model Intercomparison Project (or CDR-MIP) was initiated. This project brings together models of the Earth system in a common framework to explore the potential, impacts, and challenges of CDR. Here, we describe the first set of CDR-MIP experiments that are designed to address questions concerning CDR-induced climate "reversibility", the response of the Earth system to direct atmospheric CO2 removal (direct air capture and storage), and the CDR potential and impacts of afforestation/reforestation, as well as ocean alkalinization.

scholarly journals The Carbon Dioxide Removal Model Intercomparison Project (CDRMIP): rationale and experimental protocol for CMIP6

2018 ◽  
Vol 11 (3) ◽  
pp. 1133-1160 ◽  
Author(s):  
David P. Keller ◽  
Andrew Lenton ◽  
Vivian Scott ◽  
Naomi E. Vaughan ◽  
Nico Bauer ◽  
...  
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Carbon Dioxide Removal ◽  
Atmospheric Co2 ◽  
Earth System ◽  
Emission Scenarios ◽  
Model Intercomparison ◽  
The Earth ◽  
Intercomparison Project ◽  
Removal Model

Abstract. The recent IPCC reports state that continued anthropogenic greenhouse gas emissions are changing the climate, threatening severe, pervasive and irreversible impacts. Slow progress in emissions reduction to mitigate climate change is resulting in increased attention to what is called geoengineering, climate engineering, or climate intervention – deliberate interventions to counter climate change that seek to either modify the Earth's radiation budget or remove greenhouse gases such as CO2 from the atmosphere. When focused on CO2, the latter of these categories is called carbon dioxide removal (CDR). Future emission scenarios that stay well below 2 °C, and all emission scenarios that do not exceed 1.5 °C warming by the year 2100, require some form of CDR. At present, there is little consensus on the climate impacts and atmospheric CO2 reduction efficacy of the different types of proposed CDR. To address this need, the Carbon Dioxide Removal Model Intercomparison Project (or CDRMIP) was initiated. This project brings together models of the Earth system in a common framework to explore the potential, impacts, and challenges of CDR. Here, we describe the first set of CDRMIP experiments, which are formally part of the 6th Coupled Model Intercomparison Project (CMIP6). These experiments are designed to address questions concerning CDR-induced climate reversibility, the response of the Earth system to direct atmospheric CO2 removal (direct air capture and storage), and the CDR potential and impacts of afforestation and reforestation, as well as ocean alkalinization.>

Ratcheting Ambition to Limit Warming to 1.55C Trade-Offs between Emission Reductions and Carbon Dioxide Removal

2017 ◽  
Author(s):  
Christian Holz ◽  
Lori S Siegel ◽  
Eleanor Johnston ◽  
Andrew P Jones ◽  
John Sterman
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Removal ◽  
Emission Reductions ◽  
Trade Offs

Ecosystem modeling of methane and carbon dioxide fluxes for boreal forest sites

2001 ◽  
Vol 31 (2) ◽  
pp. 208-223 ◽  
Author(s):  
Christopher Potter ◽  
Jill Bubier ◽  
Patrick Crill ◽  
Peter Lafleur
Keyword(s):  
Carbon Dioxide ◽  
Boreal Forest ◽  
Land Surface ◽  
Net Primary Production ◽  
Ground Cover ◽  
Methane Flux ◽  
Growing Season ◽  
Ecosystem Model ◽  
Heat Fluxes ◽  
Water Levels

Predicted daily fluxes from an ecosystem model for water, carbon dioxide, and methane were compared with 1994 and 1996 Boreal Ecosystem–Atmosphere Study (BOREAS) field measurements at sites dominated by old black spruce (Picea mariana (Mill.) BSP) (OBS) and boreal fen vegetation near Thompson, Man. Model settings for simulating daily changes in water table depth (WTD) for both sites were designed to match observed water levels, including predictions for two microtopographic positions (hollow and hummock) within the fen study area. Water run-on to the soil profile from neighboring microtopographic units was calibrated on the basis of daily snowmelt and rainfall inputs to reproduce BOREAS site measurements for timing and magnitude of maximum daily WTD for the growing season. Model predictions for daily evapotranspiration rates closely track measured fluxes for stand water loss in patterns consistent with strong controls over latent heat fluxes by soil temperature during nongrowing season months and by variability in relative humidity and air temperature during the growing season. Predicted annual net primary production (NPP) for the OBS site was 158 g C·m–2 during 1994 and 135 g C·m–2 during 1996, with contributions of 75% from overstory canopy production and 25% from ground cover production. Annual NPP for the wetter fen site was 250 g C·m–2 during 1994 and 270 g C·m–2 during 1996. Predicted seasonal patterns for soil CO2 fluxes and net ecosystem production of carbon both match daily average estimates at the two sites. Model results for methane flux, which also closely match average measured flux levels of –0.5 mg CH4·m–2·day–1 for OBS and 2.8 mg CH4·m–2·day–1 for fen sites, suggest that spruce areas are net annual sinks of about –0.12 g CH4·m–2, whereas fen areas generate net annual emissions on the order of 0.3–0.85 g CH4·m–2, depending mainly on seasonal WTD and microtopographic position. Fen hollow areas are predicted to emit almost three times more methane during a given year than fen hummock areas. The validated model is structured for extrapolation to regional simulations of interannual trace gas fluxes over the entire North America boreal forest, with integration of satellite data to characterize properties of the land surface.

Evaluating feedstocks for carbon dioxide removal by enhanced rock weathering and CO2 mineralization

2021 ◽  
pp. 104955
Author(s):  
Carlos Paulo ◽  
Ian M. Power ◽  
Amanda R. Stubbs ◽  
Baolin Wang ◽  
Nina Zeyen ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Carbon Dioxide Removal ◽  
Rock Weathering ◽  
Co2 Mineralization
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