scholarly journals Feedbacks in Emission-Driven and Concentration-Driven Global Carbon Budgets

2013 ◽  
Vol 26 (10) ◽  
pp. 3326-3341 ◽  
Author(s):  
G. J. Boer ◽  
V. K. Arora
Keyword(s):  
Co2 Emissions ◽  
Carbon Concentration ◽  
Atmospheric Co2 ◽  
Climate Feedback ◽  
Biogeochemical Processes ◽  
Carbon Budgets ◽  
Feedback Analysis ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations ◽  
Atmospheric Concentrations

Abstract Emissions of CO2 into the atmosphere affect the carbon budgets of the land and ocean as biogeochemical processes react to increased CO2 concentrations. Biogeochemical processes also react to changes in temperature and other climate parameters. This behavior is characterized in terms of carbon–concentration and carbon–climate feedback parameters. The results of this study include 1) the extension of the direct carbon feedback formalism of Boer and Arora to include results from radiatively coupled simulations, as well as those from the biogeochemically coupled and fully coupled simulations used in earlier analyses; 2) a brief analysis of the relationship between this formalism and the integrated feedback formalism of Friedlingstein et al.; 3) the feedback analysis of simulations based on each of the representative concentration pathways (RCPs) RCP2.6, RCP4.5, and RCP8.5; 4) a comparison of the effects of specifying atmospheric CO2 concentrations or CO2 emissions; and 5) the quantification of the relative importance of the two feedback mechanisms in terms of their cumulative contribution to the change in atmospheric CO2. Feedback results are broadly in agreement with earlier studies in that carbon–concentration feedback is negative for the atmosphere and carbon–climate feedback is positive. However, the magnitude and evolution of feedback behavior depends on the formalism employed, the scenario considered, and the specification of CO2 from emissions or as atmospheric concentrations. Both feedback parameters can differ by factors of two or more, depending on the scenario and on the specification of CO2 emissions or concentrations. While feedback results are qualitatively useful and illustrative of carbon budget behavior, they apply quantitatively to particular scenarios and cases.

A robust sequential CO2 emissions strategy based on optimal control of atmospheric CO2 concentrations

2007 ◽  
Vol 86 (3-4) ◽  
pp. 357-373 ◽  
Author(s):  
Andrew J. Jarvis ◽  
Peter C. Young ◽  
David T. Leedal ◽  
Arun Chotai
Keyword(s):  
Optimal Control ◽  
Co2 Emissions ◽  
Atmospheric Co2 ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations

scholarly journals LA Megacity: a High-Resolution Land-Atmosphere Modelling System for Urban CO<sub>2</sub> Emissions

2016 ◽  
Author(s):  
Sha Feng ◽  
Thomas Lauvaux ◽  
Sally Newman ◽  
Preeti Rao ◽  
Ravan Ahmadov ◽  
...  
Keyword(s):  
High Resolution ◽  
Co2 Emissions ◽  
Co2 Emission ◽  
Fossil Fuel ◽  
Meteorological Data ◽  
Atmospheric Co2 ◽  
Co2 Concentrations ◽  
Emissions Modelling ◽  
Atmospheric Co2 Concentrations ◽  
Modelling System

Abstract. Megacities are major sources of anthropogenic fossil fuel CO2 emissions. The spatial extents of these large urban systems cover areas of 10,000 km2 or more with complex topography and changing landscapes. We present a high-resolution land-atmosphere modelling system for urban CO2 emissions over the Los Angeles (LA) megacity area. The Weather Research and Forecasting (WRF)-Chem model was coupled to a very high-resolution FFCO2 emission product, Hestia-LA, to simulate atmospheric CO2 concentrations across the LA megacity at spatial resolutions as fine as ~ 1 km. We evaluated multiple WRF configurations, selecting one that minimized errors in wind speed, wind direction, and boundary layer height as validated by its performance against meteorological data collected during the CalNex-LA campaign (May–June 2010). Our results show no significant difference between moderate- (4-km) and high- (1.3-km) resolution simulations when evaluated against surface meteorological data, but the high-resolution configurations better resolved PBL heights and vertical gradients in the horizontal mean winds. We coupled our WRF configuration with the Vulcan 2.2 (10 km resolution) and Hestia-LA (1.3-km resolution) fossil fuel CO2 emission products to evaluate the impact of the spatial resolution of the CO2 emission products and the meteorological transport model on the representation of spatiotemporal variability in simulated atmospheric CO2 concentrations. We find that high spatial resolution in the fossil fuel CO2 emissions is more important than in the atmospheric model to capture CO2 concentration variability across the LA megacity. Finally, we present a novel approach that employs simultaneous correlations of the simulated atmospheric CO2 fields to qualitatively evaluate greenhouse gas measurements over the LA megacity. Spatial correlations in the atmospheric CO2 fields reflect the coverage of individual measurement sites when a statistically significant number of sites observe emissions from a specific source or location. We conclude that elevated atmospheric CO2 concentrations over the LA megacity are composed of multiple fine-scale plumes rather than a single homogenous urban dome. Furthermore, we conclude that FFCO2 emissions monitoring in the LA megacity requires FFCO2 emissions modelling with ~ 1 km resolution since coarser resolution emissions modelling tends to overestimate the observational constraints on the emissions estimates.

scholarly journals A missing link in the carbon cycle: phytoplankton light absorption

2021 ◽  
Author(s):  
Rémy Asselot ◽  
Frank Lunkeit ◽  
Philip Holden ◽  
Inga Hense
Keyword(s):  
Carbon Cycle ◽  
Co2 Emissions ◽  
Light Absorption ◽  
Climate System ◽  
Atmospheric Co2 ◽  
Co2 Concentrations ◽  
Recent Climate ◽  
Atmospheric Co2 Concentrations ◽  
The Impact

Abstract. Marine biota and biogeophysical mechanisms, such as phytoplankton light absorption, have attracted increasing attention in recent climate studies. Under global warming, the impact of phytoplankton on the climate system is expected to change. Previous studies analyzed the impact of phytoplankton light absorption under prescribed future atmospheric CO2 concentrations. However, the role of this biogeophysical mechanism under freely-evolving atmospheric CO2 concentration and future CO2 emissions remain unknown. To shed light on this research gap, we perform simulations with the EcoGEnIE Earth system model and prescribe CO2 emissions following the four Representative Concentration Pathways (RCP) scenarios. Under all the RCP scenario, our results indicate that phytopankton light absorption increases the surface chlorophyll biomass, the sea surface temperature, the atmospheric CO2 concentrations and the atmospheric temperature. Under the RCP2.6, RCP4.5 and RCP6.0 scenarios, the magnitude of changes due to phytoplankton light absorption are similar. However, under the RCP8.5 scenario, the changes in the climate system are less pronounced due to the temperature limitation of phytoplankton growth, highlighting the reduced effect of phytoplankton light absorption under strong warming. Additionally, this work evidences the major role of phytoplankton light absorption on the climate system, suggesting a highly uncertain feedbacks on the carbon cycle with uncertainties that are in the range of those known from the land biota.

scholarly journals Dynamics of global atmospheric CO<sub>2</sub> concentration from 1850 to 2010: a linear approximation

2014 ◽  
Vol 11 (9) ◽  
pp. 13957-13983 ◽  
Author(s):  
W. Wang ◽  
R. Nemani
Keyword(s):  
Co2 Emissions ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Box Model ◽  
Modeling Framework ◽  
Elevated Atmospheric Co2 ◽  
Atmospheric Co2 Concentration ◽  
Co2 Concentrations ◽  
Anthropogenic Co2 ◽  
Atmospheric Co2 Concentrations

Abstract. The increase in anthropogenic CO2 emissions largely followed an exponential path between 1850 and 2010, and the corresponding increases in atmospheric CO2 concentration were almost constantly proportional to the emissions by the so-called "airborne fraction". These observations suggest that the dynamics of atmospheric CO2 concentration through this time period may be properly approximated as a linear system. We demonstrate this hypothesis by deriving a linear box-model to describe carbon exchanges between the atmosphere and the surface reservoirs under the influence of disturbances such as anthropogenic CO2 emissions and global temperature changes. We show that the box model accurately simulates the observed atmospheric CO2 concentrations and growth rates across interannual to multi-decadal time scales. The model also allows us to analytically examine the dynamics of such changes/variations, linking its characteristic disturbance-response functions to bio-geophysically meaningful parameters. In particular, our results suggest that the elevated atmospheric CO2 concentrations have significantly promoted the gross carbon uptake by the terrestrial biosphere. However, such "fertilization" effects are partially offset by enhanced carbon release from surface reservoirs promoted by warmer temperatures. The result of these interactions appears to be a decline in net efficiency in sequestering atmospheric CO2 by ∼30% since 1960s. We believe that the linear modeling framework outlined in this paper provides a convenient tool to diagnose the observed atmospheric CO2 dynamics and monitor their future changes.

scholarly journals Geographic Aspects of Temperature and Concentration Feedbacks in the Carbon Budget

2010 ◽  
Vol 23 (3) ◽  
pp. 775-784 ◽  
Author(s):  
G. J. Boer ◽  
V. Arora
Keyword(s):  
Negative Feedback ◽  
Carbon Concentration ◽  
Carbon Budget ◽  
Co2 Concentration ◽  
Atmospheric Co2 ◽  
Climate Feedback ◽  
Climate Modelling ◽  
Emission Scenarios ◽  
Temperature Feedback ◽  
Concentration Changes

Abstract The geographical distribution of feedback processes in the carbon budget is investigated in a manner that parallels that for climate feedback/sensitivity in the energy budget. Simulations for a range of emission scenarios, made with the Canadian Centre for Climate Modelling and Analysis (CCCma) earth system model (CanESM1), are the basis of the analysis. Anthropogenic CO2 emissions are concentrated in the Northern Hemisphere and provide the forcing for changes to the atmospheric carbon budget. Transports redistribute the emitted CO2 globally where local feedback processes act to enhance (positive feedback) or suppress (negative feedback) local CO2 amounts in response to changes in CO2 concentration and temperature. An increased uptake of CO2 by the land and ocean acts to counteract increased atmospheric CO2 concentrations so that “carbon–concentration” feedbacks are broadly negative over the twenty-first century. Largest values are found over land and particularly in tropical regions where CO2 acts to fertilize plant growth. Extratropical land also takes up CO2 but here the effect is limited by cooler temperatures. Oceans play a lesser negative feedback role with comparatively weak uptake associated with an increase in the atmosphere–ocean CO2 gradient rather than with oceanic biological activity. The effect of CO2-induced temperature increase is, by contrast, to increase atmospheric CO2 on average and so represents an overall positive “carbon–temperature” feedback. Although the average is positive, local regions of both positive and negative carbon–temperature feedback are seen over land as a consequence of the competition between changes in biological productivity and respiration. Positive carbon–temperature feedback is found over most tropical land while mid–high-latitude land exhibits negative feedback. There are also regions of positive and negative oceanic carbon–temperature feedback in the eastern tropical Pacific. The geographical patterns of carbon–concentration and carbon–temperature feedbacks are comparatively robust across the range of emission scenarios used, although their magnitudes are somewhat less robust and scale nonlinearly as a consequence of the large CO2 concentration changes engendered by the scenarios. The feedback patterns deduced nevertheless serve to illustrate the localized carbon feedback processes in the climate system.

Mineral composition of durum wheat grain and pasta under increasing atmospheric CO2 concentrations

2018 ◽  
Vol 242 ◽  
pp. 53-61 ◽  
Author(s):  
Romina Beleggia ◽  
Mariagiovanna Fragasso ◽  
Franco Miglietta ◽  
Luigi Cattivelli ◽  
Valeria Menga ◽  
...  
Keyword(s):  
Durum Wheat ◽  
Mineral Composition ◽  
Atmospheric Co2 ◽  
Wheat Grain ◽  
Co2 Concentrations ◽  
Atmospheric Co2 Concentrations
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