Effects of increasing UV-B radiation and atmospheric CO2 on photosynthesis and growth: implications for terrestrial ecosystems

1997 ◽  
pp. 194-206 ◽  
Author(s):  
Joe H. Sullivan
Keyword(s):  
Terrestrial Ecosystems ◽  
Atmospheric Co2

scholarly journals On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

2019 ◽  
Author(s):  
Brendan Byrne ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Saroja M. Polavarapu ◽  
Anna B. Harper ◽  
...  
Keyword(s):  
Spatial Scales ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Strong Correlations ◽  
Climate Anomalies ◽  
Temperature And Precipitation ◽  
The Tropics ◽  
Emergent Constraint ◽  
The Impact

Abstract. Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against, and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem model to assimilate GOSAT observations. Monthly NEE anomalies are compared to proxies, variables which are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Strong agreement is found in the timing of anomalies in the GOSAT flux inversions with soil temperature and FLUXCOM. Strong correlations are obtained (P  RNINO3.4) in the tropics on continental and larger scales, and in the northern extratropics on sub-continental scales during the summer (R2 ≥ 0.49). These results, in addition to a series of observing system simulation experiments that were conducted, provide evidence that GOSAT flux inversions can isolate anomalies in NEE on continental and larger scales. However, in both the tropics and northern extratropics, the agreement between the inversions and the proxies/FLUXCOM is sensitive to the flux inversion configuration. Our results suggest that regional scales are likely the minimum scales that can be resolved in the tropics using GOSAT observations, but obtaining robust NEE anomaly estimates on these scales may be difficult.

scholarly journals Recent Warming Has Resulted in Smaller Gains in Net Carbon Uptake in Northern High Latitudes

2019 ◽  
Vol 32 (18) ◽  
pp. 5849-5863 ◽  
Author(s):  
Peng Zhu ◽  
Qianlai Zhuang ◽  
Lisa Welp ◽  
Philippe Ciais ◽  
Martin Heimann ◽  
...  
Keyword(s):  
Temperature Sensitivity ◽  
Carbon Balance ◽  
Climate Models ◽  
Carbon Sink ◽  
Gross Primary Production ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Climate Feedback ◽  
Carbon Uptake ◽  
High Latitudes

AbstractCarbon balance of terrestrial ecosystems in the northern high latitudes (NHL) is sensitive to climate change. It remains uncertain whether current regional carbon uptake capacity can be sustained under future warming. Here the atmospheric CO2 drawdown rate (CDR) between 1974 and 2014, defined as the CO2 decrease in ppm over the number of days in spring or summer, is estimated using atmospheric CO2 observations at Barrow (now known as Utqiaġvik), Alaska. We found that the sensitivity of CDR to interannual seasonal air temperature anomalies has trended toward less carbon uptake for a given amount of warming over this period. Changes in interannual temperature sensitivity of CDR suggest that relatively warm springs now result in less of a carbon uptake enhancement. Similarly, relatively warm summers now result in greater carbon release. These results generally agree with the sensitivity of net carbon exchange (NCE) estimated by atmospheric CO2 inversion. When NCE was aggregated over North America (NA) and Eurasia (EA), separately, the temperature sensitivity of NCE in NA has changed more than in EA. To explore potential mechanisms of this signal, we also examine trends in interannual variability of other climate variables (soil temperature and precipitation), satellite-derived gross primary production (GPP), and Trends in Net Land–Atmosphere Carbon Exchanges (TRENDY) model ensemble results. Our analysis suggests that the weakened spring sensitivity of CDR may be related to the slowdown in seasonal soil thawing rate, while the summer sensitivity change may be caused by the temporally coincident decrease in temperature sensitivity of photosynthesis. This study suggests that the current NHL carbon sink may become unsustainable as temperatures warm further. We also found that current carbon cycle models do not represent the decrease in temperature sensitivity of net carbon flux. We argue that current carbon–climate models misrepresent important aspect of the carbon–climate feedback and bias the estimation of warming influence on NHL carbon balance.

scholarly journals Non-deforestation fire vs. fossil fuel combustion: the source of CO<sub>2</sub> emissions affects the global carbon cycle and climate responses

2016 ◽  
Vol 13 (7) ◽  
pp. 2137-2149 ◽  
Author(s):  
Jean-Sébastien Landry ◽  
H. Damon Matthews
Keyword(s):  
Carbon Cycle ◽  
Co2 Emissions ◽  
Fossil Fuel ◽  
Fire Regime ◽  
Terrestrial Ecosystems ◽  
Global Carbon Cycle ◽  
Fuel Combustion ◽  
Atmospheric Co2 ◽  
Fossil Fuel Combustion ◽  
Global Carbon

Abstract. Non-deforestation fire – i.e., fire that is typically followed by the recovery of natural vegetation – is arguably the most influential disturbance in terrestrial ecosystems, thereby playing a major role in carbon exchanges and affecting many climatic processes. The radiative effect from a given atmospheric CO2 perturbation is the same for fire and fossil fuel combustion. However, major differences exist per unit of CO2 emitted between the effects of non-deforestation fire vs. fossil fuel combustion on the global carbon cycle and climate, because (1) fossil fuel combustion implies a net transfer of carbon from geological reservoirs to the atmospheric, oceanic, and terrestrial pools, whereas fire occurring in terrestrial ecosystems does not; (2) the average lifetime of the atmospheric CO2 increase is longer when originating from fossil fuel combustion compared to fire, due to the strong vegetation regrowth following fire disturbances in terrestrial ecosystems; and (3) other impacts, for example on land surface albedo, also differ between fire and fossil fuel combustion. The main purpose of this study is to illustrate the consequences from these fundamental differences between fossil fuel combustion and non-deforestation fires using 1000-year simulations of a coupled climate–carbon model with interactive vegetation. We assessed emissions from both pulse and stable fire regime changes, considering both the gross (carbon released from combustion) and net (fire-caused change in land carbon, also accounting for vegetation decomposition and regrowth, as well as climate–carbon feedbacks) fire CO2 emissions. In all cases, we found substantial differences from equivalent amounts of emissions produced by fossil fuel combustion. These findings suggest that side-by-side comparisons of non-deforestation fire and fossil fuel CO2 emissions – implicitly implying that they have similar effects per unit of CO2 emitted – should therefore be avoided, particularly when these comparisons involve gross fire emissions, because the reservoirs from which these emissions are drawn have very different residence times (millions of years for fossil fuel; years to centuries for vegetation and soil–litter). Our results also support the notion that most net emissions occur relatively soon after fire regime shifts and then progressively approach zero. Overall, our study calls for the explicit representation of fire activity as a valuable step to foster a more accurate understanding of its impacts on global carbon cycling and temperature, as opposed to conceiving fire effects as congruent with the consequences from fossil fuel combustion.

Seasonal and interannual influences of the terrestrial ecosystems on atmospheric CO2: a model study

1996 ◽  
Vol 21 (5-6) ◽  
pp. 537-544 ◽  
Author(s):  
L. François ◽  
B. Nemry ◽  
P. Warnant ◽  
J.-C. Gérard
Keyword(s):  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Model Study

scholarly journals On what scales can GOSAT flux inversions constrain anomalies in terrestrial ecosystems?

2019 ◽  
Vol 19 (20) ◽  
pp. 13017-13035 ◽  
Author(s):  
Brendan Byrne ◽  
Dylan B. A. Jones ◽  
Kimberly Strong ◽  
Saroja M. Polavarapu ◽  
Anna B. Harper ◽  
...  
Keyword(s):  
Interannual Variability ◽  
Spatial Scales ◽  
Net Ecosystem Exchange ◽  
Terrestrial Ecosystems ◽  
Atmospheric Co2 ◽  
Terrestrial Biosphere ◽  
Climate Anomalies ◽  
Temperature And Precipitation ◽  
The Tropics ◽  
The Impact

Abstract. Interannual variations in temperature and precipitation impact the carbon balance of terrestrial ecosystems, leaving an imprint in atmospheric CO2. Quantifying the impact of climate anomalies on the net ecosystem exchange (NEE) of terrestrial ecosystems can provide a constraint to evaluate terrestrial biosphere models against and may provide an emergent constraint on the response of terrestrial ecosystems to climate change. We investigate the spatial scales over which interannual variability in NEE can be constrained using atmospheric CO2 observations from the Greenhouse Gases Observing Satellite (GOSAT). NEE anomalies are calculated by performing a series of inversion analyses using the GEOS-Chem adjoint model to assimilate GOSAT observations. Monthly NEE anomalies are compared to “proxies”, variables that are associated with anomalies in the terrestrial carbon cycle, and to upscaled NEE estimates from FLUXCOM. Statistically significant correlations (P<0.05) are obtained between posterior NEE anomalies and anomalies in soil temperature and FLUXCOM NEE on continental and larger scales in the tropics, as well as in the northern extratropics on subcontinental scales during the summer (R2≥0.49), suggesting that GOSAT measurements provide a constraint on NEE interannual variability (IAV) on these spatial scales. Furthermore, we show that GOSAT flux inversions are generally better correlated with the environmental proxies and FLUXCOM NEE than NEE anomalies produced by a set of terrestrial biosphere models (TBMs), suggesting that GOSAT flux inversions could be used to evaluate TBM NEE fluxes.

scholarly journals Definitions and methods to estimate regional land carbon fluxes for the second phase of the REgional Carbon Cycle Assessment and Processes Project (RECCAP-2)

2020 ◽  
Author(s):  
Philippe Ciais ◽  
Ana Bastos ◽  
Frédéric Chevallier ◽  
Ronny Lauerwald ◽  
Ben Poulter ◽  
...  
Keyword(s):  
Carbon Cycle ◽  
Terrestrial Ecosystems ◽  
Surface Fluxes ◽  
Carbon Accounting ◽  
Atmospheric Co2 ◽  
Second Phase ◽  
Co2 Uptake ◽  
Carbon Budgets ◽  
Regional Land ◽  
Atmospheric Inversions

Abstract. Regional land carbon budgets provide insights on the spatial distribution of the land uptake of atmospheric carbon dioxide, and can be used to evaluate carbon cycle models and to define baselines for land-based additional mitigation efforts. The scientific community has been involved in providing observation-based estimates of regional carbon budgets either by downscaling atmospheric CO2 observations into surface fluxes with atmospheric inversions, by using inventories of carbon stock changes in terrestrial ecosystems, by upscaling local field observations such as flux towers with gridded climate and remote sensing fields or by integrating data-driven or process-oriented terrestrial carbon cycle models. The first coordinated attempt to collect regional carbon budgets for nine regions covering the entire globe in the RECCAP-1 project has delivered estimates for the decade 2000–2009, but these budgets were not comparable between regions, due to different definitions and component fluxes reported or omitted. The recent recognition of lateral fluxes of carbon by human activities and rivers, that connect CO2 uptake in one area with its release in another also requires better definition and protocols to reach harmonized regional budgets that can be summed up to the globe and compared with the atmospheric CO2 growth rate and inversion results. In this study, for the international initiative RECCAP-2 coordinated by the Global Carbon Project, which aims as an update of regional carbon budgets over the last two decades based on observations, for 10 regions covering the globe, with a better harmonization that the precursor project, we provide recommendations for using atmospheric inversions results to match bottom-up carbon accounting and models, and we define the different component fluxes of the net land atmosphere carbon exchange that should be reported by each research group in charge of each region. Special attention is given to lateral fluxes, inland water fluxes and land use fluxes.

A global perspective of ground level, 'ambient' carbon dioxide for assessing the response of plants to atmospheric CO2

2001 ◽  
Vol 7 (7) ◽  
pp. 789-796 ◽  
Author(s):  
L. H. Ziska ◽  
O. Ghannoum ◽  
J. T. Baker ◽  
J. Conroy ◽  
J. A. Bunce ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Ground Level ◽  
Global Perspective ◽  
Atmospheric Co2
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