The potential role of spectral properties in detecting thresholds in the Earth system: application to the thermohaline circulation

2003 ◽  
Vol 53 (2) ◽  
pp. 53-63 ◽  
Author(s):  
Thomas Kleinen ◽  
Hermann Held ◽  
Gerhard Petschel-Held
Keyword(s):  
System Application ◽  
Spectral Properties ◽  
Potential Role ◽  
Thermohaline Circulation ◽  
Earth System ◽  
The Earth

scholarly journals Reviews and syntheses: Flying the satellite into your model: on the role of observation operators in constraining models of the Earth system and the carbon cycle

2017 ◽  
Vol 14 (9) ◽  
pp. 2343-2357 ◽  
Author(s):  
Thomas Kaminski ◽  
Pierre-Philippe Mathieu
Keyword(s):  
Data Assimilation ◽  
Carbon Cycle ◽  
Automatic Differentiation ◽  
Satellite Observations ◽  
Spectral Radiance ◽  
Special Focus ◽  
Earth System ◽  
The Earth ◽  
Retrieval Scheme

Abstract. The vehicles that fly the satellite into a model of the Earth system are observation operators. They provide the link between the quantities simulated by the model and the quantities observed from space, either directly (spectral radiance) or indirectly estimated through a retrieval scheme (biogeophysical variables). By doing so, observation operators enable modellers to properly compare, evaluate, and constrain their models with the model analogue of the satellite observations. This paper provides the formalism and a few examples of how observation operators can be used in combination with data assimilation techniques to better ingest satellite products in a manner consistent with the dynamics of the Earth system expressed by models. It describes commonalities and potential synergies between assimilation and classical retrievals. This paper explains how the combination of observation operators and their derivatives (linearizations) form powerful research tools. It introduces a technique called automatic differentiation that greatly simplifies both the development and the maintenance of code for the evaluation of derivatives. Throughout this paper, a special focus lies on applications to the carbon cycle.

The role of the Microbial Conveyor Belt on Earth´s system resilience

2021 ◽  
Author(s):  
Mireia Mestre ◽  
Juan Höfer
Keyword(s):  
Human Impacts ◽  
Conveyor Belt ◽  
Earth System ◽  
Planetary Scale ◽  
Microbial Biogeography ◽  
The Earth ◽  
System Resilience ◽  
Global Biogeochemical Cycles

<p>Despite being major players on the global biogeochemical cycles, microorganisms are generally not included in holistic views of Earth’s system. The Microbial Conveyor Belt is a conceptual framework that represents a recurrent and cyclical flux of microorganisms across the globe, connecting distant ecosystems and Earth compartments. This long-range dispersion of microorganisms directly influences the microbial biogeography, the global cycling of inorganic and organic matter, and thus the Earth system’s functioning and long-term resilience. Planetary-scale human impacts disrupting the natural flux of microorganisms pose a major threat to the Microbial Conveyor Belt, thus compromising microbial ecosystem services. Perturbations that modify the natural dispersion of microorganisms are, for example, the modification of the intensity/direction of air fluxes and ocean currents due to climate change, the vanishing of certain dispersion vectors (e.g., species extinction or drying rivers) or the introduction of new ones (e.g., microplastics, wildfires). Transdisciplinary approaches are needed to disentangle the Microbial Conveyor Belt, its major threats and their consequences for Earth´s system resilience.</p>

scholarly journals Quantifying drivers of chemical disequilibrium in the Earth's atmosphere

2012 ◽  
Vol 3 (2) ◽  
pp. 1287-1320
Author(s):  
E. Simoncini ◽  
N. Virgo ◽  
A. Kleidon
Keyword(s):  
Potential Role ◽  
Earth System ◽  
New Approach ◽  
Earth’S Atmosphere ◽  
Ch4 Production ◽  
The Earth ◽  
Thermochemical Equilibrium ◽  
Earth's Atmosphere ◽  
High Degree ◽  
Comparable Magnitude

Abstract. It has long been observed that Earth's atmosphere is uniquely far from its thermochemical equilibrium state in terms of its chemical composition. Studying this state of disequilibrium is important both for understanding the role that life plays in the Earth system, and for its potential role in the detection of life on exoplanets. Here we present a methodology for assessing the strength of the biogeochemical cycling processes that drive disequilibrium in planetary systems. We apply it to the simultaneous presence of CH4 and O2 in Earth's atmosphere, which has long been suggested as a sign of life that could be detected from far away. Using a simplified model, we identify that the most important property to quantify is not the distance from equilibrium, but the power required to drive it. A weak driving force can maintain a high degree of disequilibrium if the residence times of the compounds involved are long; but if the disequilibrium is high and the kinetics fast, we can conclude that the disequilibrium must be driven by a substantial source of energy. Applying this to Earth's atmosphere, we show that the biotically-generated portion of the power required to maintain the methane-oxygen disequilibrium is around 0.67 TW, although the uncertainty in this figure is about 50% due to uncertainty in the global CH4 production. Compared to the chemical energy generated by the biota by photosynthesis, 0.67 TW represents only a very small fraction and, perhaps surprisingly, is of a comparable magnitude to abiotically-driven geochemical processes at the Earth's surface. We discuss the implications of this new approach, both in terms of enhancing our understanding of the Earth system, and in terms of its impact on the possible detection of distant photosynthetic biospheres.

scholarly journals The Role of Fire in Achieving the Sustainable Development Goals of the United Nations

Proceedings ◽  
2020 ◽  
Vol 30 (1) ◽  
pp. 65
Author(s):  
Artemi Cerdà
Keyword(s):  
Water Pollution ◽  
Sustainable Development ◽  
United Nations ◽  
Sustainable Development Goals ◽  
Water Yield ◽  
Earth System ◽  
The Sustainable Development ◽  
The Earth ◽  
Development Goals

The Sustainable Development Goals (SDGs) of the United Nations do not mention Fire as a key factor in achieving an environmentally-friendly human society. This paper reviews the key aspects of the impact of fire that make it necessary to update the SDGs. Upon reviewing the scientific literature, it was found that fire has been part of the Earth System for the last 400 million years, and that it is part of biogeochemical cycles. From a geological perspective, fire shaped the current Earth System. Humans have used fire in the last million years as hunter-gatherers, and the last Pleistocene period evolved with the presence of fire. Since the Neolithic revolution, humankind spread the use of fire, without which agriculture would not have progressed as it did. Fire is still used today as a tool to clear forests, scrublands and meadows in order to establish agriculture fields. To achieve the SDGs, we cannot ignore the role of fire. Fire should be present, as it is part of the geological cycle of the planet; it is part of rural culture and plays a key role in hydrological, erosional and biological cycles. We discuss the following issues related to fire in connection with the SDGs: (i) biota; (ii) soil properties; (iii) carbon cycle; (iv) sediment and water yield; (v) air and water pollution; and (vi) risk assessment. We conclude that: (i) fire is key to flora and fauna diversity; (ii) soil properties are temporally changed after exposure to fire; (iii) the carbon cycle is disturbed by fire, but the long-term impact can be a reduction in the CO2 content in the atmosphere; (iv) sediment and water yield are enhanced by forest fires, but only during the period of disturbance; (v) air and water pollution are ephemeral; and (vi) the risk associated with fire necessitates careful planning. Prescribed fires may be part of the solution, but there is a need to educate citizens on the role that fire plays. More research is necessary due to the diversity of the biomass and the complex history of fire on the planet. Fire is part of the Earth System and the SDGs should include it as a key element in their agenda.

Superlinear scaling of riverine biogeochemical function with watershed size

2021 ◽  
Author(s):  
Wilfred Wollheim ◽  
Tamara Harms ◽  
Andrew Robison ◽  
Lauren Koenig ◽  
Ashley Helton ◽  
...  
Keyword(s):  
Allometric Scaling ◽  
Spatial Scales ◽  
River Networks ◽  
Power Exponent ◽  
Earth System ◽  
Network Function ◽  
Scaling Relationships ◽  
The Earth ◽  
Watershed Size

Abstract River networks are a crucial component of the earth system because they regulate carbon and nutrient exchange between continents, the atmosphere, and oceans. Quantifying the role of river networks at broad spatial scales must accommodate spatial heterogeneity, discharge variability, and upstream-downstream connectivity. Allometric scaling relationships of cumulative biogeochemical function with watershed size integrate these factors, providing an approach for understanding the role of fluvial networks in the earth system. Here we demonstrate that allometric scaling relationships of cumulative river network function are linear (power exponent ~ 1) when biogeochemical reactivity is high and river discharges are low, but become increasingly superlinear (power exponent > 1) as reactivity declines or discharge increases. Superlinear scaling indicates that biogeochemical function of entire river networks within a watershed is an emergent property that increases disproportionately with increasing watershed size. Expanding observation networks will increase precision in riverine fluxes of carbon and nutrients estimated by allometric scaling functions.

Glaciation: A Very Short Introduction

2018 ◽  
Author(s):  
David J. A. Evans
Keyword(s):  
Sea Level ◽  
Fresh Water ◽  
Ice Sheets ◽  
Earth System ◽  
Short Introduction ◽  
Depositional Processes ◽  
The Earth ◽  
Global Sea Level

Vast, majestic, and often stunningly beautiful, glaciers lock up some 10 per cent of the world’s fresh water. These great bodies of ice play an important part in the Earth system, carving landscapes and influencing climate on regional and hemispheric scales, as well as having a significant impact on global sea level. Glaciation: A Very Short Introduction offers an overview of glaciers and ice sheets as systems, considering the role of geomorphology and sedimentology in studying them, and their impacts on our planet in terms of erosional and depositional processes. Looking at our glaciers today, and their ongoing processes, it considers the extent to which we can use this knowledge in reconstructing and interpreting ancient glacial landscapes.

scholarly journals The role of karst in engineering and environmental geosciences

2011 ◽  
Vol 3 (1) ◽  
pp. 149-158
Author(s):  
H. C. Ho
Keyword(s):  
Water Pollution ◽  
Land Subsidence ◽  
Natural Hazard ◽  
Drainage System ◽  
Nutrient Cycles ◽  
Earth System ◽  
The Earth ◽  
Soluble Rock ◽  
Groundwater Drainage

Abstract. Karst is a unique landform developed by soluble rock. It usually relates to groundwater drainage system, and provides important water resources. Current researches indicate that karst is closely related to the earth system and environmental protection, and it can also create potential natural hazard such as sinkhole flooding and land subsidence in urban area. Its relationship with hydrogeology has also been an important factor for studying water pollution, and nutrient cycles on engineering geosciences and agricultural geology.

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