Rising Temperatures Increase Importance of Oceanic Evaporation as a Source for Continental Precipitation

2019 ◽  
Vol 32 (22) ◽  
pp. 7713-7726 ◽  
Author(s):  
Kirsten L. Findell ◽  
Patrick W. Keys ◽  
Ruud J. van der Ent ◽  
Benjamin R. Lintner ◽  
Alexis Berg ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Crop Yields ◽  
Climatic Conditions ◽  
System Model ◽  
Evaporative Demand ◽  
Moisture Recycling ◽  
The Past ◽  
The Earth ◽  
Agricultural Regions ◽  
Global Mean

Abstract Understanding vulnerabilities of continental precipitation to changing climatic conditions is of critical importance to society at large. Terrestrial precipitation is fed by moisture originating as evaporation from oceans and from recycling of water evaporated from continental sources. In this study, continental precipitation and evaporation recycling processes in the Earth system model GFDL-ESM2G are shown to be consistent with estimates from two different reanalysis products. The GFDL-ESM2G simulations of historical and future climate also show that values of continental moisture recycling ratios were systematically higher in the past and will be lower in the future. Global mean recycling ratios decrease 2%–3% with each degree of temperature increase, indicating the increased importance of oceanic evaporation for continental precipitation. Theoretical arguments for recycling changes stem from increasing atmospheric temperatures and evaporative demand that drive increases in evaporation over oceans that are more rapid than those over land as a result of terrestrial soil moisture limitations. Simulated recycling changes are demonstrated to be consistent with these theoretical arguments. A simple prototype describing this theory effectively captures the zonal mean behavior of GFDL-ESM2G. Implications of such behavior are particularly serious in rain-fed agricultural regions where crop yields will become increasingly soil moisture limited.

Rising Temperatures Increase Importance of Oceanic Evaporation as a Source for Continental Precipitation

2020 ◽  
Author(s):  
Kirsten Findell ◽  
Patrick Keys ◽  
Ruud van der Ent ◽  
Benjamin Lintner ◽  
Alexis Berg ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Amazon Basin ◽  
Crop Yields ◽  
Climatic Conditions ◽  
Indus River ◽  
Evaporative Demand ◽  
Moisture Recycling ◽  
Agricultural Regions ◽  
The Ganges ◽  
Global Mean

<p>Understanding vulnerabilities of continental precipitation to changing climatic conditions is of critical importance to society at large. Terrestrial precipitation is fed by moisture originating as evaporation from oceans and from recycling of water evaporated from continental sources. In this study, continental precipitation and evaporation recycling processes in the Earth system model GFDL-ESM2G are shown to be consistent with estimates from two different reanalysis products. The GFDL-ESM2G simulations of historical and future climate also show that values of continental moisture recycling ratios were systematically higher in the past and will be lower in the future.</p><p>Global mean recycling ratios decrease 2%–3% with each degree of temperature increase, indicating the increased importance of oceanic evaporation for continental precipitation. Theoretical arguments for recycling changes stem from increasing atmospheric temperatures and evaporative demand that drive increases in evaporation over oceans that are more rapid than those over land as a result of terrestrial soil moisture limitations. Simulated recycling changes are demonstrated to be consistent with these theoretical arguments. A simple prototype describing this theory effectively captures the zonal mean behavior of GFDL-ESM2G.</p><p>Key sources of terrestrial evaporation, notably the interior of the Amazon basin and parts of the Ganges-Brahmaputra and Indus River basins, may experience reductions in moisture recycling. This has implications for key sink regions of terrestrial recycled precipitation, especially in rain-fed agricultural regions where crop yields will become increasingly soil moisture limited, such as the La Plata River basin, the corn producing regions of North America, southern Africa and the Sahel.</p><p>The results presented here have been published last year in Journal of Climate dx.doi.org/10.1175/JCLI-D-19-0145.1</p><p> </p>

scholarly journals A Control Theory Approach to Optimal Irrigation Scheduling in the Oklahoma Panhandle

1980 ◽  
Vol 12 (1) ◽  
pp. 165-171 ◽  
Author(s):  
Thomas R. Harris ◽  
Harry P. Mapp
Keyword(s):  
Great Plains ◽  
Crop Production ◽  
Crop Yields ◽  
Low Cost ◽  
Primary Source ◽  
Irrigation Scheduling ◽  
Climatic Conditions ◽  
Theory Approach ◽  
Agricultural Producers ◽  
The Past

Climatic conditions in semiarid regions like the Oklahoma Panhandle result in wide fluctuations in rainfall, dryland crop yields, and returns to agricultural producers in the area. Irrigated crop production increases peracre yields and significantly reduces fluctuations in yields and net returns.Irrigated production of food and fiber in the Oklahoma Panhandle has developed rapidly during the past three decades, increasing from 11,500 to 385,900 acres since 1950 (Schwab). The primary source of irrigation water in the area is the Ogallala Formation, an aquifer underlying much of the Great Plains region. Until the past couple of years, the presence of relatively low cost natural gas led producers to expand irrigated production and apply high levels of water to crops irrigated in the area.

scholarly journals Proxy evidence for state-dependence of climate sensitivity in the Eocene greenhouse

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
E. Anagnostou ◽  
E. H. John ◽  
T. L. Babila ◽  
P. F. Sexton ◽  
A. Ridgwell ◽  
...  
Keyword(s):  
Climate Sensitivity ◽  
Global Climate ◽  
State Dependence ◽  
The State ◽  
State Dependency ◽  
The Past ◽  
Global Mean Temperature ◽  
The Earth ◽  
Modelling Studies ◽  
Global Mean

Abstract Despite recent advances, the link between the evolution of atmospheric CO2 and climate during the Eocene greenhouse remains uncertain. In particular, modelling studies suggest that in order to achieve the global warmth that characterised the early Eocene, warmer climates must be more sensitive to CO2 forcing than colder climates. Here, we test this assertion in the geological record by combining a new high-resolution boron isotope-based CO2 record with novel estimates of Global Mean Temperature. We find that Equilibrium Climate Sensitivity (ECS) was indeed higher during the warmest intervals of the Eocene, agreeing well with recent model simulations, and declined through the Eocene as global climate cooled. These observations indicate that the canonical IPCC range of ECS (1.5 to 4.5 °C per doubling) is unlikely to be appropriate for high-CO2 warm climates of the past, and the state dependency of ECS may play an increasingly important role in determining the state of future climate as the Earth continues to warm.

scholarly journals On the probability of habitable planets

2013 ◽  
Vol 12 (3) ◽  
pp. 177-185 ◽  
Author(s):  
François Forget
Keyword(s):  
Liquid Water ◽  
Climate Models ◽  
Climatic Conditions ◽  
Point Of View ◽  
Habitable Zone ◽  
One Dimensional ◽  
The Past ◽  
Surface Liquid ◽  
New Generation ◽  
Global Mean

AbstractIn the past 15 years, astronomers have revealed that a significant fraction of the stars should harbour planets and that it is likely that terrestrial planets are abundant in our galaxy. Among these planets, how many are habitable, i.e. suitable for life and its evolution? These questions have been discussed for years and we are slowly making progress. Liquid water remains the key criterion for habitability. It can exist in the interior of a variety of planetary bodies, but it is usually assumed that liquid water at the surface interacting with rocks and light is necessary for emergence of a life able to modify its environment and evolve. The first key issue is thus to understand the climatic conditions allowing surface liquid water assuming a suitable atmosphere. These have been studied with global mean one-dimensional (1D) models which have defined the ‘classical habitable zone’, the range of orbital distances within which worlds can maintain liquid water on their surfaces (Kasting et al. 1993). A new generation of 3D climate models based on universal equations and tested on bodies in the solar system are now available to explore with accuracy climate regimes that could locally allow liquid water. The second key issue is now to better understand the processes which control the composition and the evolution of the atmospheres of exoplanets, and in particular the geophysical feedbacks that seem to be necessary to maintain a continuously habitable climate. From that point of view, it is not impossible that the Earth's case may be special and uncommon.

scholarly journals Clouds and the Faint Young Sun Paradox

2010 ◽  
Vol 6 (3) ◽  
pp. 1163-1207 ◽  
Author(s):  
C. Goldblatt ◽  
K. J. Zahnle
Keyword(s):  
Greenhouse Effect ◽  
Surface Albedo ◽  
Geological Evidence ◽  
High Cloud ◽  
The Past ◽  
Low Clouds ◽  
The Earth ◽  
High Clouds ◽  
Global Mean ◽  
Modest Reduction

Abstract. We investigate the role which clouds could play in resolving the Faint Young Sun Paradox (FYSP). Lower solar luminosity in the past means that less energy was absorbed on Earth (a forcing of -50 W m−2 during the late Archean), but geological evidence points to the Earth being at least as warm as it is today, with only very occasional glaciations. We perform radiative calculations on a single global mean atmospheric column. We select a nominal set of three layered, randomly overlapping clouds, which are both consistent with observed cloud climatologies and reproduce the observed global mean energy budget of Earth. By varying the fraction, thickness, height and particle size of these clouds we conduct a wide exploration of how changed clouds could affect climate, thus constraining how clouds could contribute to resolving the FYSP. Low clouds reflect sunlight but have little greenhouse effect. Removing them entirely gives a forcing of +25 W m−2 whilst more modest reduction in their efficacy gives a forcing of +10 to +15 W m−2. For high clouds, the greenhouse effect dominates. It is possible to generate +50 W m−2 forcing from enhancing these, but this requires making them 3.5 times thicker and 14 K colder than the standard high cloud in our nominal set and expanding their coverage to 100% of the sky. Such changes are not credible. More plausible changes would generate no more that +15 W m−2 forcing. Thus neither fewer low clouds nor more high clouds can provide enough forcing to resolve the FYSP. Decreased surface albedo can contribute no more than +5 W m−2 forcing. Some models which have been applied to the FYSP do not include clouds at all. These overestimate the forcing due to increased CO2 by 20 to 25% when pCO2 is 0.01 to 0.1 bar.

scholarly journals Development of Observation-based Global Multi-layer Soil Moisture Products for 1970 to 2016

2021 ◽  
Author(s):  
Yaoping Wang ◽  
Jiafu Mao ◽  
Mingzhou Jin ◽  
Forrest M. Hoffman ◽  
Xiaoying Shi ◽  
...  
Keyword(s):  
Soil Moisture ◽  
Earth System Model ◽  
System Model ◽  
Surface Model ◽  
Earth System ◽  
Model Simulations ◽  
The Earth ◽  
Wide Range ◽  
In Situ Observations

Abstract. Soil moisture (SM) datasets are critical to understanding the global water, energy, and biogeochemical cycles and benefit extensive societal applications. However, individual sources of SM data (e.g., in situ and satellite observations, reanalysis, offline land surface model simulations, Earth system model simulations) have source-specific limitations and biases related to the spatiotemporal continuity, resolutions, and modeling/retrieval assumptions. Here, we developed seven global, gap-free, long-term (1970–2016), multi-layer (0–10, 10–30, 30–50, and 50–100 cm) SM products at monthly 0.5° resolution (available at https://doi.org/10.6084/m9.figshare.13661312.v1) by synthesizing a wide range of SM datasets using three statistical methods (unweighted averaging, optimal linear combination, and emergent constraint). The merged products outperformed their source datasets when evaluated with in situ observations and the latest gridded datasets that did not enter merging because of insufficient spatial, temporal, or soil layer coverage. Assessed against in situ observations, the global mean bias of the synthesized SM data ranged from −0.044 to 0.033 m3/m3, root mean squared error from 0.076 to 0.104 m3/m3, and Pearson correlation from 0.35 to 0.67. The merged SM datasets also showed the ability to capture historical large-scale drought events and physically plausible global sensitivities to observed meteorological factors. Three of the new SM products, produced by applying any of the three merging methods onto the source datasets excluding the Earth system models, were finally recommended for future applications because of their better performances than the Earth system model–dependent merged estimates. Despite uncertainties in the raw SM datasets and fusion methods, these hybrid products create added value over existing SM datasets because of the performance improvement and harmonized spatial, temporal, and vertical coverages, and they provide a new foundation for scientific investigation and resource management.

scholarly journals Network dynamics of drought-induced tipping cascades in the Amazon rainforest

2020 ◽  
Author(s):  
Nico Wunderling ◽  
Arie Staal ◽  
Boris Sakschewski ◽  
Marina Hirota ◽  
Obbe Tuinenburg ◽  
...  
Keyword(s):  
Anthropogenic Activities ◽  
Climatic Conditions ◽  
Amazon Rainforest ◽  
Atmospheric Moisture ◽  
Secondary Effects ◽  
Moisture Recycling ◽  
Critical Thresholds ◽  
The Earth ◽  
Rainfall Regimes

Abstract Tipping elements are nonlinear subsystems of the Earth system that can potentially abruptly and irreversibly shift if environmental change occurs. Among these tipping elements is the Amazon rainforest, which is threatened by anthropogenic activities and increasingly frequent droughts. Here, we assess how extreme deviations from climatological rainfall regimes may cause local forest-savanna transitions that cascade through the coupled forest-climate system. We develop a dynamical network model to uncover the role of atmospheric moisture recycling in such tipping cascades. We account for the heterogeneity in critical thresholds of the forest caused by adaptation to local climatic conditions. Our results reveal that, despite this adaptation, increased dry-season intensity may trigger tipping events particularly in the southeastern Amazon. Moisture recycling is responsible for one-fourth of the tipping events. If the rate of climate change exceeds the adaptive capacity of some parts of the forest, secondary effects through moisture recycling may exceed this capacity in other regions, increasing the overall risk of tipping across the Amazon rainforest.

scholarly journals Ecological features of No-till technology in the conditions of the Southern Steppe of Ukraine

2020 ◽  
Vol 108 (4) ◽  
pp. 47-53
Author(s):  
T. Manushkina ◽  
◽  
А. Drobitko ◽  
T. Kachanova ◽  
O. Heraschenko
Keyword(s):  
Soil Moisture ◽  
Crop Yields ◽  
Steppe Zone ◽  
Climatic Conditions ◽  
Soil Density ◽  
Erosion Processes ◽  
Ecological Features ◽  
No Till ◽  
Soil Microbiological Activity ◽  
Soil Moisture Reserves

Ecological features of No-till technology in the conditions of the Southern Steppe of Ukraine The effect of No-till technology on soil density, soil moisture reserves, soil microbiological activity, and crop yields was studied. The increase in crop yield up to 14.3-22.9% by No-till technology allowed us to draw a conclusion about optimizing soil fertility indicators in the climatic conditions of the southern Steppe zone of Ukraine in comparison with traditional intensive technologies. It was shown that the introduction of No-till technology will allow improve environmental processes in the soil, reduce the anthropogenic load on agroecosystems and the manifestation of erosion processes, increase crop yields and reduce energy costs for their cultivation. Keywords: soil, No-till technology, soil density, soil moisture, fertility, yield.

scholarly journals Застосування нейронних мереж для автоматизованого керування вологозабезпеченістю сільськогосподарських культур

2018 ◽  
pp. 201-204
Author(s):  
Л. І. Лєві
Keyword(s):  
Soil Moisture ◽  
Crop Yields ◽  
Control Object ◽  
Climatic Conditions ◽  
Management Systems ◽  
Agricultural Crops ◽  
Weather Factors ◽  
Rational Use ◽  
Moisture Management ◽  
Control Accuracy

Розглянуто нейромережевий підхід до автоматизованого керування вологозабезпеченістю сільськогосподарських культур. Сучасний стан теорії і практики створення штучних нейронних мереж і нейрокомп’ютерів надав можливість розробки принципово нових алгоритмів і методів керування складними нелінійними динамічними об'єктами. Це дозволяє підвищити точність керування вологістю ґрунту, забезпечити отримання планових врожаїв сільськогосподарських культур, економити водні та енергетичні ресурси за рахунок їх раціонального використання. The highest yield of agricultural crops is achieved with the optimal amount of moisture, nutrition, heat, air and light. At the same time, the water regime of the soil is necessary for crops and is created by the appropriate irrigation regime, which establishes the norms, timing and amount of irrigation depending on the biological characteristics of the crops, natural and economic conditions. In determining the irrigation water flow, water consumption or total evaporation is taken into account, depending on climatic conditions, the amount of thermal energy supplied to the surface, soil moisture, the type and yield of the crop. Therefore, issues of adaptation and self-study of automated soil moisture management systems under the influence of random weather factors, changes in the characteristics of the control object, improvement of control accuracy due to the operational accounting of the effect of disturbances on the object, ensuring the production of planned crop yields while rational use of energy and water resources are relevant. In addition, modern moisture management systems for agricultural crops should not only ensure sufficient control accuracy, but also predict the plants need for water for a certain period, minimize energy and water costs without yield loss, be reliable and convenient in operation, provide the operator with complete and timely information about the value of all parameters and the state of the control system. To solve these problems, an approach to automating the process of controlling irrigation systems using neural networks has been considered. The proposed approach allows to improve the accuracy of soil moisture management, to ensure the production of planned crop yields, to save water and energy resources due to their rational use.

scholarly journals Clay Minerals at the Paleocene–Eocene Thermal Maximum: Interpretations, Limits, and Perspectives

Minerals ◽  
2020 ◽  
Vol 10 (12) ◽  
pp. 1073
Author(s):  
Fabio Tateo
Keyword(s):  
Clay Minerals ◽  
Sedimentary Facies ◽  
Climatic Conditions ◽  
Transport Mechanisms ◽  
Source Areas ◽  
Sedimentary Records ◽  
The Past ◽  
The Earth ◽  
Thermal Maximum ◽  
Integrated Interpretation

The Paleocene–Eocene Thermal Maximum (PETM) was an “extreme” episode of environmental stress that affected the Earth in the past, and it has numerous affinities concerning the rapid increase in the greenhouse effect. It has left several biological, compositional, and sedimentary facies footprints in sedimentary records. Clay minerals are frequently used to decipher environmental effects because they represent their source areas, essentially in terms of climatic conditions and of transport mechanisms (a more or less fast travel, from the bedrocks to the final site of recovery). Clay mineral variations at the PETM have been studied by several authors in terms of climatic and provenance indicators, but also as tracers of more complicated interplay among different factors requiring integrated interpretation (facies sorting, marine circulation, wind transport, early diagenesis, etc.). Clay minerals were also believed to play a role in the recovery of pre-episode climatic conditions after the PETM exordium, by becoming a sink of atmospheric CO2 that is considered a necessary step to switch off the greenhouse hyperthermal effect. This review aims to consider the use of clay minerals made by different authors to study the effects of the PETM and their possible role as effective (simple) proxy tools for environmental reconstructions.

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