scholarly journals Biological regulation of atmospheric chemistry en route to planetary oxygenation

2017 ◽  
Vol 114 (13) ◽  
pp. E2571-E2579 ◽  
Author(s):  
Gareth Izon ◽  
Aubrey L. Zerkle ◽  
Kenneth H. Williford ◽  
James Farquhar ◽  
Simon W. Poulton ◽  
...  
Keyword(s):  
Organic Carbon ◽  
Atmospheric Chemistry ◽  
Atmospheric Oxygen ◽  
Earth System ◽  
Atmospheric Methane ◽  
Biological Regulation ◽  
Biological Source ◽  
The Earth ◽  
Methane Fluxes ◽  
Haze Formation

Emerging evidence suggests that atmospheric oxygen may have varied before rising irreversibly ∼2.4 billion years ago, during the Great Oxidation Event (GOE). Significantly, however, pre-GOE atmospheric aberrations toward more reducing conditions—featuring a methane-derived organic-haze—have recently been suggested, yet their occurrence, causes, and significance remain underexplored. To examine the role of haze formation in Earth’s history, we targeted an episode of inferred haze development. Our redox-controlled (Fe-speciation) carbon- and sulfur-isotope record reveals sustained systematic stratigraphic covariance, precluding nonatmospheric explanations. Photochemical models corroborate this inference, showing Δ36S/Δ33S ratios are sensitive to the presence of haze. Exploiting existing age constraints, we estimate that organic haze developed rapidly, stabilizing within ∼0.3 ± 0.1 million years (Myr), and persisted for upward of ∼1.4 ± 0.4 Myr. Given these temporal constraints, and the elevated atmospheric CO2 concentrations in the Archean, the sustained methane fluxes necessary for haze formation can only be reconciled with a biological source. Correlative δ13COrg and total organic carbon measurements support the interpretation that atmospheric haze was a transient response of the biosphere to increased nutrient availability, with methane fluxes controlled by the relative availability of organic carbon and sulfate. Elevated atmospheric methane concentrations during haze episodes would have expedited planetary hydrogen loss, with a single episode of haze development providing up to 2.6–18 × 1018 moles of O2 equivalents to the Earth system. Our findings suggest the Neoarchean likely represented a unique state of the Earth system where haze development played a pivotal role in planetary oxidation, hastening the contingent biological innovations that followed.

Plastics in the Earth system

Science ◽  
2021 ◽  
Vol 373 (6550) ◽  
pp. 51-55
Author(s):  
Aron Stubbins ◽  
Kara Lavender Law ◽  
Samuel E. Muñoz ◽  
Thomas S. Bianchi ◽  
Lixin Zhu
Keyword(s):  
Organic Carbon ◽  
Global Scale ◽  
Earth System ◽  
Earth System Science ◽  
System Science ◽  
Global Problem ◽  
The Earth

Plastic contamination of the environment is a global problem whose magnitude justifies the consideration of plastics as emergent geomaterials with chemistries not previously seen in Earth’s history. At the elemental level, plastics are predominantly carbon. The comparison of plastic stocks and fluxes to those of carbon reveals that the quantities of plastics present in some ecosystems rival the quantity of natural organic carbon and suggests that geochemists should now consider plastics in their analyses. Acknowledging plastics as geomaterials and adopting geochemical insights and methods can expedite our understanding of plastics in the Earth system. Plastics also can be used as global-scale tracers to advance Earth system science.

scholarly journals A Bayesian framework for deriving sector-based methane emissions from top-down fluxes

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Daniel H. Cusworth ◽  
A. Anthony Bloom ◽  
Shuang Ma ◽  
Charles E. Miller ◽  
Kevin Bowman ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Transport Model ◽  
Estimation Method ◽  
Relative Weight ◽  
Optimal Estimation ◽  
Atmospheric Methane ◽  
Permian Basin ◽  
Top Down ◽  
Methane Fluxes ◽  
Reduce Emissions

AbstractAtmospheric methane observations are used to test methane emission inventories as the sum of emissions should correspond to observed methane concentrations. Typically, concentrations are inversely projected to a net flux through an atmospheric chemistry-transport model. Current methods to partition net fluxes to underlying sector-based emissions often scale fluxes based on the relative weight of sectors in a prior inventory. However, this approach imposes correlation between emission sectors which may not exist. Here we present a Bayesian optimal estimation method that projects inverse methane fluxes directly to emission sectors while accounting uncertainty structure and spatial resolution of prior fluxes and emissions. We apply this method to satellite-derived fluxes over the U.S. and at higher resolution over the Permian Basin to demonstrate that we can characterize a sector-based emission budget. This approach provides more robust comparisons between different top-down estimates, critical for assessing the efficacy of policies intended to reduce emissions.

scholarly journals Exploring the potential of machine learning for simulations of urban ozone variability

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Narendra Ojha ◽  
Imran Girach ◽  
Kiran Sharma ◽  
Amit Sharma ◽  
Narendra Singh ◽  
...  
Keyword(s):  
Machine Learning ◽  
Atmospheric Chemistry ◽  
Model Performance ◽  
Meteorological Conditions ◽  
Earth System ◽  
The Earth ◽  
Model Complex ◽  
Quality Assessments ◽  
The Himalaya ◽  
Urban Ozone

AbstractMachine learning (ML) has emerged as a powerful technique in the Earth system science, nevertheless, its potential to model complex atmospheric chemistry remains largely unexplored. Here, we applied ML to simulate the variability in urban ozone (O3) over Doon valley of the Himalaya. The ML model, trained with past variations in O3 and meteorological conditions, successfully reproduced the independent O3 data (r2 ~ 0.7). Model performance is found to be similar when the variation in major precursors (CO and NOx) were included in the model, instead of the meteorology. Further the inclusion of both precursors and meteorology improved the performance significantly (r2 = 0.86) and the model could also capture the outliers, which are crucial for air quality assessments. We suggest that in absence of high-resolution measurements, ML modeling has profound implications for unraveling the feedback between pollution and meteorology in the fragile Himalayan ecosystem.

scholarly journals Comparison of the HadGEM2 climate-chemistry model against in-situ and SCIAMACHY atmospheric methane data

2014 ◽  
Vol 14 (9) ◽  
pp. 12967-13020 ◽  
Author(s):  
G. D. Hayman ◽  
F. M. O'Connor ◽  
M. Dalvi ◽  
D. B. Clark ◽  
N. Gedney ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Land Surface ◽  
Earth System Model ◽  
System Model ◽  
High Latitudes ◽  
Earth System ◽  
Atmospheric Methane ◽  
Surface Sites ◽  
Atmospheric Observations ◽  
The Uk

Abstract. Wetlands are a major emission source of methane (CH4) globally. In this study, we have evaluated wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates were investigated: (a) from an offline run driven with CRU-NCEP meteorological data and (b) from the same offline run in which the modelled wetland fractions were replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS) remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999–2007) is in line with other recently-published estimates. There are regional differences as the unconstrained JULES inventory gave significantly higher emissions in the Amazon and lower emissions in other regions compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2), we have evaluated these JULES wetland emissions against atmospheric observations of methane. We obtained improved agreement with the surface concentration measurements, especially at northern high latitudes, compared to previous HadGEM2 runs using the wetland emission dataset of Fung (1991). Although the modelled monthly atmospheric methane columns reproduced the large–scale patterns in the SCIAMACHY observations, they were biased low by 50 part per billion by volume (ppb). Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE–ACE assimilated TOMCAT output resulted in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain JULES-derived wetland fraction improved the description of the wetland emissions in JULES and gave a good description of the seasonality observed at surface sites influenced by wetlands, especially at high latitudes. We found that the annual cycles observed in the SCIAMACHY measurements and at many of the surface sites influenced by non-wetland sources could not be reproduced in these HadGEM2 runs. This suggests that the emissions over certain regions (e.g., India and China) are possibly too high and/or the monthly emission patterns for specific sectors are incorrect. The comparisons presented in this paper have shown that the performance of the JULES wetland scheme is comparable to that of other process-based land surface models. We have identified areas for improvement in this and the atmospheric chemistry components of the HadGEM Earth System model. The Earth Observation datasets used here will be of continued value in future evaluations of JULES and the HadGEM family of models.

scholarly journals Comparison of the HadGEM2 climate-chemistry model against in situ and SCIAMACHY atmospheric methane data

2014 ◽  
Vol 14 (23) ◽  
pp. 13257-13280 ◽  
Author(s):  
G. D. Hayman ◽  
F. M. O'Connor ◽  
M. Dalvi ◽  
D. B. Clark ◽  
N. Gedney ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Land Surface ◽  
Earth System Model ◽  
System Model ◽  
Climatic Research Unit ◽  
Earth System ◽  
Atmospheric Methane ◽  
Surface Sites ◽  
Atmospheric Observations ◽  
The Uk

Abstract. Wetlands are a major emission source of methane (CH4) globally. In this study, we evaluate wetland emission estimates derived using the UK community land surface model (JULES, the Joint UK Land Earth Simulator) against atmospheric observations of methane, including, for the first time, total methane columns derived from the SCIAMACHY instrument on board the ENVISAT satellite. Two JULES wetland emission estimates are investigated: (a) from an offline run driven with Climatic Research Unit–National Centers for Environmental Prediction (CRU-NCEP) meteorological data and (b) from the same offline run in which the modelled wetland fractions are replaced with those derived from the Global Inundation Extent from Multi-Satellites (GIEMS) remote sensing product. The mean annual emission assumed for each inventory (181 Tg CH4 per annum over the period 1999–2007) is in line with other recently published estimates. There are regional differences as the unconstrained JULES inventory gives significantly higher emissions in the Amazon (by ~36 Tg CH4 yr−1) and lower emissions in other regions (by up to 10 Tg CH4 yr−1) compared to the JULES estimates constrained with the GIEMS product. Using the UK Hadley Centre's Earth System model with atmospheric chemistry (HadGEM2), we evaluate these JULES wetland emissions against atmospheric observations of methane. We obtain improved agreement with the surface concentration measurements, especially at high northern latitudes, compared to previous HadGEM2 runs using the wetland emission data set of Fung et al. (1991). Although the modelled monthly atmospheric methane columns reproduce the large-scale patterns in the SCIAMACHY observations, they are biased low by 50 part per billion by volume (ppb). Replacing the HadGEM2 modelled concentrations above 300 hPa with HALOE–ACE assimilated TOMCAT output results in a significantly better agreement with the SCIAMACHY observations. The use of the GIEMS product to constrain the JULES-derived wetland fraction improves the representation of the wetland emissions in JULES and gives a good description of the seasonality observed at surface sites influenced by wetlands, especially at high latitudes. We find that the annual cycles observed in the SCIAMACHY measurements and at many of the surface sites influenced by non-wetland sources cannot be reproduced in these HadGEM2 runs. This suggests that the emissions over certain regions (e.g. India and China) are possibly too high and/or the monthly emission patterns for specific sectors are incorrect. The comparisons presented in this paper show that the performance of the JULES wetland scheme is comparable to that of other process-based land surface models. We identify areas for improvement in this and the atmospheric chemistry components of the HadGEM Earth System model. The Earth Observation data sets used here will be of continued value in future evaluations of JULES and the HadGEM family of models.

3. Regulation

2016 ◽  
pp. 38-56
Author(s):  
Tim Lenton
Keyword(s):  
Carbon Dioxide ◽  
Atmospheric Carbon Dioxide ◽  
Atmospheric Oxygen ◽  
Biogeochemical Cycles ◽  
Global Temperature ◽  
Earth System ◽  
Animal Life ◽  
The Past ◽  
The Earth ◽  
Earth’S Climate

The Earth system has maintained habitable conditions for life over geological periods of time. These conditions include an equable global temperature, enough atmospheric carbon dioxide to fuel photosynthesis, and sufficient nutrients to grow. Furthermore, for at least the past 370 million years there has been enough atmospheric oxygen to support complex, mobile animal life, but not so much that wildfires decimated vegetation. ‘Regulation’ introduces the ways in which the biogeochemical cycles of the Earth system are self-regulated, how they are coupled to the Earth’s climate, and how scientists study this regulation.

Climate and composition impacts of a net-zero anthropogenic methane future using an emissions-driven chemistry-climate model

2021 ◽  
Author(s):  
Zosia Staniaszek ◽  
Paul T. Griffiths ◽  
Gerd A. Folberth ◽  
Fiona M. O'Connor ◽  
Alexander T. Archibald
Keyword(s):  
Tropospheric Ozone ◽  
Radiative Forcing ◽  
Methane Emissions ◽  
Radiation Budget ◽  
Baseline Scenario ◽  
Earth System ◽  
Atmospheric Methane ◽  
The Earth ◽  
Net Zero ◽  
Emissions Scenario

<div> <p>Methane (CH<sub>4</sub>), the second most important greenhouse gas in terms of radiative forcing, is on the rise; but there are extensive opportunities for mitigation with existing technologies. Anthropogenic emissions account for around 60% of the global methane source, and the recent atmospheric methane growth rate puts us on a trajectory comparable to the most extreme future methane scenarios in the sixth Coupled Model Intercomparison Project (CMIP6). </p> </div><div> <p>We use a new methane emissions-driven configuration of the UK Earth System Model (UKESM1) to explore the role of anthropogenic methane in the earth system. The full methane cycle is represented, including surface deposition, chemistry and interactive wetland emissions. As a baseline scenario we used Shared Socioeconomic Pathway 3-7.0 (SSP3-7.0) – the highest methane emissions scenario in CMIP6. In an idealised experiment, all anthropogenic methane emissions were instantaneously stopped from 2015 onwards in a coupled atmosphere-ocean simulation running from 2015-2050, to make a net-zero anthropogenic methane emissions scenario.  </p> </div><div> <p>Within a decade, significant changes can be seen in atmospheric composition and climate, compared to SSP3-7.0. The atmospheric methane burden declines to below pre-industrial levels within 12 years, and by the late 2030s reaches a constant level around 44% below that of the present day (2015). The tropospheric ozone burden and surface mean ozone concentrations decreased by 12% and 15% respectively by 2050 – key in terms of limiting global warming as well as improving air quality and human health. </p> </div><div> <p>By 2050 the net-zero anthropogenic methane scenario results in a global mean surface temperature (GMST) 1˚C lower than the baseline, a significant value in the context of climate goals such as the Paris Agreement. Through decomposition of the radiation budget, the change in climate can be directly attributed to the reduction in methane and indirectly to the resulting changes in ozone, clouds and ozone precursors such as CO. In addition, the changes in climate result in impacts on the interactive wetland emissions via changes in temperature and wetland extent, highlighting the coupled nature of methane in the earth system. </p> </div><div> <p>Cessation of anthropogenic methane emissions has profound impacts on near-term warming and on tropospheric ozone, but ultimately cannot single-handedly achieve the necessary reductions for meeting Paris goals. </p> </div>

scholarly journals Representativeness of single lidar stations for zonally averaged ozone profiles, their trends and attribution to proxies

2018 ◽  
Vol 18 (9) ◽  
pp. 6427-6440 ◽  
Author(s):  
Christos Zerefos ◽  
John Kapsomenakis ◽  
Kostas Eleftheratos ◽  
Kleareti Tourpali ◽  
Irina Petropavlovskikh ◽  
...  
Keyword(s):  
Atmospheric Chemistry ◽  
Southern Oscillation ◽  
Correlation Coefficients ◽  
The Arctic ◽  
Earth System ◽  
Quasi Biennial Oscillation ◽  
The Earth ◽  
Ozone Trends ◽  
Anthropogenic Contributions ◽  
The Arctic Oscillation

Abstract. This paper is focusing on the representativeness of single lidar stations for zonally averaged ozone profile variations over the middle and upper stratosphere. From the lower to the upper stratosphere, ozone profiles from single or grouped lidar stations correlate well with zonal means calculated from the Solar Backscatter Ultraviolet Radiometer (SBUV) satellite overpasses. The best representativeness with significant correlation coefficients is found within ±15∘ of latitude circles north or south of any lidar station. This paper also includes a multivariate linear regression (MLR) analysis on the relative importance of proxy time series for explaining variations in the vertical ozone profiles. Studied proxies represent variability due to influences outside of the earth system (solar cycle) and within the earth system, i.e. dynamic processes (the Quasi Biennial Oscillation, QBO; the Arctic Oscillation, AO; the Antarctic Oscillation, AAO; the El Niño Southern Oscillation, ENSO), those due to volcanic aerosol (aerosol optical depth, AOD), tropopause height changes (including global warming) and those influences due to anthropogenic contributions to atmospheric chemistry (equivalent effective stratospheric chlorine, EESC). Ozone trends are estimated, with and without removal of proxies, from the total available 1980 to 2015 SBUV record. Except for the chemistry related proxy (EESC) and its orthogonal function, the removal of the other proxies does not alter the significance of the estimated long-term trends. At heights above 15 hPa an “inflection point” between 1997 and 1999 marks the end of significant negative ozone trends, followed by a recent period between 1998 and 2015 with positive ozone trends. At heights between 15 and 40 hPa the pre-1998 negative ozone trends tend to become less significant as we move towards 2015, below which the lower stratosphere ozone decline continues in agreement with findings of recent literature.

Impact of snow darkening via dust, black carbon, and organic carbon on boreal spring climate in the Earth system

2015 ◽  
Vol 120 (11) ◽  
pp. 5485-5503 ◽  
Author(s):  
Teppei J. Yasunari ◽  
Randal D. Koster ◽  
William K. M. Lau ◽  
Kyu‐Myong Kim
Keyword(s):  
Organic Carbon ◽  
Black Carbon ◽  
Earth System ◽  
Boreal Spring ◽  
The Earth

Phanerozoic Oxygen

2017 ◽  
Author(s):  
Donald Eugene Canfield
Keyword(s):  
Oxygen Consumption ◽  
Organic Carbon ◽  
Sea Level ◽  
Time Scale ◽  
Atmospheric Oxygen ◽  
Sea Level Change ◽  
Oxygen Production ◽  
Level Change ◽  
History Of ◽  
Geologic Processes

This chapter discusses the modeling of the history of atmospheric oxygen. The most recently deposited sediments will also be the most prone to weathering through processes like sea-level change or uplift of the land. Thus, through rapid recycling, high rates of oxygen production through the burial of organic-rich sediments will quickly lead to high rates of oxygen consumption through the exposure of these organic-rich sediments to weathering. From a modeling perspective, rapid recycling helps to dampen oxygen changes. This is important because the fluxes of oxygen through the atmosphere during organic carbon and pyrite burial, and by weathering, are huge compared to the relatively small amounts of oxygen in the atmosphere. Thus, all of the oxygen in the present atmosphere is cycled through geologic processes of oxygen liberation (organic carbon and pyrite burial) and consumption (weathering) on a time scale of about 2 to 3 million years.

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