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Biotic pump of atmospheric moisture as driver of the hydrological cycle on land
Hydrology and Earth System Sciences
Abstract and Figures
In this paper the basic geophysical and ecological principles are jointly analyzed that allow the landmasses of Earth to remain moistened sufficiently for terrestrial life to be possible. 1. Under gravity, land inevitably loses water to the ocean. To keep land moistened, the gravitational water runoff must be continuously compensated by the atmospheric ocean-to-land moisture transport. Using data for five terrestrial transects of the International Geosphere Biosphere Program we show that the mean distance to which air fluxes can transport moisture over non-forested areas, does not exceed several hundred kilometers; precipitation decreases exponentially with distance from the ocean. 2. In contrast, precipitation over extensive natural forests does not depend on the distance from the ocean along several thousand kilometers, as illustrated for the Amazon and Yenisey river basins and Equatorial Africa. This points to the existence of an active biotic pump transporting atmospheric moisture inland from the ocean. 3. Physical principles of the biotic moisture pump are investigated based on the previously unstudied properties of atmospheric water vapor, which can be either in or out of aerostatic equilibrium depending on the lapse rate of air temperature. A novel physical principle is formulated according to which the low-level air moves from areas with weak evaporation to areas with more intensive evaporation. Due to the high leaf area index, natural forests maintain high evaporation fluxes, which support the ascending air motion over the forest and "suck in" moist air from the ocean, which is the essence of the biotic pump of atmospheric moisture. In the result, the gravitational runoff water losses from the optimally moistened forest soil can be fully compensated by the biotically enhanced precipitation at any distance from the ocean. 4. It is discussed how a continent-scale biotic water pump mechanism could be produced by natural selection acting on individual trees. 5. Replacement of the natural forest cover by a low leaf index vegetation leads to an up to tenfold reduction in the mean continental precipitation and runoff, in contrast to the previously available estimates made without accounting for the biotic moisture pump. The analyzed body of evidence testifies that the long-term stability of an intense terrestrial water cycle is unachievable without the recovery of natural, self-sustaining forests on continent-wide areas.
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... The estimate of total evaporation is separated into the evaporation of biomass (evapotranspiration) and that of the water mirrors of reservoirs and water basins, including the Amazon rainforest. The model was compared with other conventional models such as the Biotic Pump and Orchidee [2], [3], to establish convergences in the spatial variations of the coupling force and the observed forces, taking into account the differences in parameterization, climatology, and hydrological regimes. ...
... The DECASAI model [1] complements conventional climate models such as Orchidee and Biotic Bomb [3], [2], by taking into account the topography and sentimentality of regions within the tropical belt. It specifically accounts for the role of inland water bodies in the evaporation process and considers their hydraulic and pluvial behavior, as well as other convective and thermodynamic ranges. ...
... In addition, the theories of the biotic pump [2], and the ORCHIDEE [3], were useful in associating the approach of the DECASAI Model [1], by calculating convection and evaporation considering: the prevailing winds and the geopotential height to obtain the adiabatic gradient of the air (υ) below 11km, based on this, the radius of a condensed drop can be obtained from convective water vapor, driving the energy of the liquid phase in compensation and decreasing entropy. The model can be coupled to conventional models, in particular the Biotic Pump Theory and ORCHIDEE, which needs the generated information on water vapor convection in the tree crowns and evapotranspiration to measure foliar behavior, respectively; taking as an example the evaporation of the Amazon rainforest. ...
The application of the Determination of the Effect of Climate Anomalies on Soil-Atmosphere Interaction (DECASAI) model is described, which allows estimating the water evaporation over bodies of water and soils, based on a thermodynamic and kinetic approach. The model studies seasonal climate anomalies with emphasis on prolonged droughts (ENSO), to predict the vulnerability of selected water bodies, in their hydraulic and pluvial aspects. The model is integrated into the Biotic Pump Theories, evapotranspiration, and other conventional models such as Orchidee using the new absent information provided by the model in their calculations. The analysis estimated the critical radius of the condensed water droplets, for application in the conventional models. The proposed model is sufficiently robust and complementary for use in certain localities located in the Hadley cells, depending on their continentality.
... Initially, tree transpiration was identified as the primary source of water in continental areas (Jasechko et al. 2013). Moreover, a mechanism by which forests pump water into the atmosphere and sustain the moisture necessary for their survival was proposed by Makarieva and Gorshkov (2007) and further elaborated by Sheil and Murdiyarso (2009). This mechanism involves a reduction in atmospheric pressure at lower levels, which draws clouds over forested regions. ...
The uneven global distribution of rainfall significantly impacts water resources and environmental sustainability, emphasising the need for reliable climate prediction models. Accurate predictions are vital for sectors such as food security, urban planning and disaster management. Data from ground stations, radars and satellites are essential, despite challenges like instrumental errors. Satellites, with their comprehensive sensors, are crucial for atmospheric observations, aiding in the prediction of large‐scale climatic events. Climate models such as CHIRPS, GLDAS, TerraClimate, and PERSIANN use different approaches to analyse precipitation data, which is key to understanding its spatial and temporal variability. This study evaluated (rainfall data) from these four climate models over 20 years (within the Brazilian territory), focusing on the spatiotemporal behaviour of rainfall using statistical metrics such as R², RMSE, and MAPE. The findings showed that CHIRPS had the best performance (R² = 0.843; RMSE = 42.83; MAPE = 0.09%), excelling in both overall database and extreme event analyses. TerraClimate, initially the lowest‐performing model (R² = 0.413; RMSE = 91.56; MAPE = 0.23%), improved significantly when combined with elevation through multiple linear regression (MLR), achieving R² of 0.718, RMSE of 31.14, and MAPE of 9.56%. This made TerraClimate a viable model for studying the Flying Rivers. The study highlights that model selection should align with the specific characteristics of the area under consideration, with CHIRPS being particularly suitable for the studied region. This research enhances the understanding of the effectiveness of these models in estimating rainfall compared to in situ measurements, which is crucial for various applications. The authors advocate for further studies to advance research on the Flying Rivers, their significance, and the impacts of climate change on them.
... Similar to the discussion around the role of water vapour in fuelling cyclones there have been parallel developments around the role of water vapour (and forests as a major source of water vapour over land) in driving the winds that carry rainfall into continents. Theory and observations suggest that forests create persistent areas of low pressure that draw in moist warm low-lying air from surrounding regions and feeding rainfall inland [22,25,46,47]. This process is often referred to as the "Biotic Pump". ...
Tropical cyclones, hurricanes and typhoons (“cyclones”) threaten the lives and livelihoods of many millions of people. The magnitude of this threat justifies scrutiny of all potential mitigation strategies. Here we consider a neglected factor: forests. Forests may influence storm formation, intensity, and behaviour through interactions involving temperature, friction, moisture and aerosols. Understanding these relationships could guide cyclone mitigation and preparedness. With global deforestation continuing and reforestation efforts expanding, the relationships between forests and cyclones are not simply academic—it's a critical consideration for climate adaptation, disaster risk reduction, and sustainable development. Here we show that, despite major unknowns and uncertainties, forest conservation and expansion are likely to reduce cyclone frequency and severity.
... While evapotranspiration by forests pumps water back into the atmosphere, which can increase rainfall in a region, it also reduces total water flows in a watershed (Ellison et al., 2012). Forests may also act as a pump of atmospheric moisture by attracting moist air from oceans to inland regions (Makarieva and Gorshkov, 2007;Sheiland Murdiyarso, 2009), but this role of forests in hydrological processes at the regional scale still remains debated (Meesters et al., 2009). The role of forests and trees in regulating atmospheric water and regional rainfall has been overlooked by scientific assessments on ecosystems and climate change, despite its place, for example, in moderating droughts effects due to global climate change. ...
... This 'moisture pull' of forests results in increased precipitation over terrestrial areas, and it also stabilizes and extends rainfall patterns. This theory has been heavily contested, yet seemingly without definitive resolution (Jaramillo et al., 2018;Meesters et al., 2009). Given the increased disturbance of forest ecosystems, understanding the mechanisms behind the biotic pump is critical for predicting changes in global weather patterns and developing strategies to mitigate the adverse effects of deforestation (or afforestation and reforestation) on climate system dynamics. ...
Vegetation often understood merely as the result of long-term climate conditions. However, vegetation itself plays a fundamental role in shaping Earth's climate by regulating the energy, water, and biogeochemical cycles across terrestrial landscapes. It exerts influence by altering surface roughness, consuming significant water resources through transpiration and interception, lowering atmospheric CO2 concentration, and controlling net radiation and its partitioning into sensible and latent heat fluxes. This influence propagates through the atmosphere, from microclimate scales to the entire atmospheric boundary layer, subsequently impacting large-scale circulation and the global transport of heat and moisture. Understanding the feedbacks between vegetation and atmosphere across multiple scales is crucial for predicting the influence of land use and cover changes and for accurately representing these processes in climate models. This short review aims to discuss the mechanisms through which vegetation modulates climate across spatial and temporal scales. Particularly, we evaluate the influence of vegetation on circulation patterns, precipitation and temperature, both in terms of trends and extreme events, such as droughts and heatwaves. The main goal is to highlight the state of science and review recent studies that may help advance our collective understanding of vegetation feedbacks and the role they play in climate.
... Transpiration from trees, coupled with evaporation from the soil ("evapotranspiration"), also has substantial effects on the hydrological cycle, influencing the moisture regime [54]. C4 plants also cannot generate the transport of water from the oceans inland that trees can accomplish using the "biotic pump" [55]. Because of these factors, forests are poorly adapted to low-CO2 environments. ...
Carbon dioxide is a chemically active molecule that plays a vital role in Earth's ecosphere. CO affects the acidity of seawater and has multiple negative effects on marine organisms. It is also a fundamental component of the photosynthesis and respiration reactions. There is evidence that higher CO concentration can make the photosynthetic reaction faster in some plants, but also negatively impact the respiration reaction in aerobic lifeforms. The effects of this chemical and biochemical perturbation on the biosphere and on human health may be more important than generally highlighted in the discussion on CO, usually focused on thermal effects only. These considerations stress the importance of rapidly reducing CO emissions and, whenever possible, remove the excess from the atmosphere. They also show that geoengineering technologies based on Solar Radiation Management (SRM) alone cannot be sufficient to contrast the negative effects of CO anthropogenic emissions.
In increasingly dryer and hotter conditions cities need to adapt in the (near) future. To design drought-sensitive cities much can be learned from the program of water-sensitive cities. In this program a research center was established, policy-implications have been derived and the findings were applied in many local projects. A drought-sensitive program should link research, governance, and practice. Moreover, to fully integrate drought conditions in the development of our cities, the future dryer conditions should be anticipated, embraced and, if possible reversed. This needs to be done by connecting long-term visions with short-term interventions and to integrate spatial projects at the regional and larger scale with hyperlocal spatial transformations, which are visible for urban residents and make a difference for their daily livability.
l presente è un articolo di review sul rapporto tra le foreste e il ciclo dell’acqua, con particolare riguardo al processo indicato come “pompa biotica”. Il Pianeta sta assistendo ad un cambiamento globale senza precedenti. Si registra un forte aumento della temperatura ed una diminuzione della disponibilità di acqua dolce.La deforestazione influisce negativamente sul ciclo dell’acqua, modificando il processo naturale di trasporto a grande distanza dell’aria umida dall’oceano alle aree interne dei continenti. Questo processo, scoperto solo da pochi anni, è stato denominato pompa biotica, ed è attivato proprio dalle foreste, specialmente da quelle naturali. Vengono analizzati i meccanismi di funzionamento di questo processo, la relazione con le foreste naturali e gli effetti negativi della sua alterazione.
This review of recent advances in biosphere research aims to provide information on selected issues related to changes in biodiversity, ecosystem functioning, social and economic interactions with ecosystems, and the impacts of climate change on the biosphere. We highlight advances on nine themes that have been recently published in peer-reviewed journals that are gaining importance in the scientific community and have the potential to guide future actions as well as inspire future research questions. Our focus is on the interactions between climate, biosphere and society, and on strategies to sustain, restore or promote ecosystems and their services. While mitigating climate change is expected to reduce many risks and associated costs, rapid emission reductions are also crucial to secure various co-benefits of ecosystems, such as coastal protection or stabilization of regional hydrological cycles. In this context, conservation measures implemented in cooperation with local actors are key to efficient resource allocation. At the same time, holistic action frameworks at the global level are required to guide and support such efforts.
The Tropical Rainfall Measuring Mission (TRMM) satellite measurements from the precipitation radar and TRMM microwave imager have been combined to yield a comprehensive 3-yr database of precipitation features (PFs) throughout the global Tropics (6368 latitude). The PFs retrieved using this algorithm (which number nearly six million Tropicswide) have been sorted by size and intensity ranging from small shallow features greater than 75 km2 in area to large mesoscale convective systems (MCSs) according to their radar and ice scattering characteristics. This study presents a comprehensive analysis of the diurnal cycle of the observed precipitation features' rainfall amount, precipitation feature frequency, rainfall intensity, convective-stratiform rainfall portioning, and remotely sensed convective intensity, sampled Tropicswide from space. The observations are sorted regionally to examine the stark differences in the diurnal cycle of rainfall and convective intensity over land and ocean areas. Over the oceans, the diurnal cycle of rainfall has small amplitude, with the maximum contribution to rainfall coming from MCSs in the early morning. This increased contribution is due to an increased number of MCSs in the nighttime hours, not increasing MCS areas or conditional rain rates, in agreement with previous works. Rainfall from sub-MCS features over the ocean has little appreciable diurnal cycle of rainfall or convective intensity. Land areas have a much larger rainfall cycle than over the ocean, with a marked minimum in the midmorning hours and a maximum in the afternoon, slowly decreasing through midnight. Non-MCS features have a significant peak in afternoon instantaneous conditional rain rates (the mean rain rate in raining pixels), and convective intensities, which differs from previous studies using rain rates derived from hourly rain gauges. This is attributed to enhancement by afternoon heating. MCSs over land have a convective intensity peak in the late afternoon, however all land regions have MCS rainfall peaks that occur in the late evening through midnight due to their longer life cycle. The diurnal cycle of overland MCS rainfall and convective intensity varies significantly among land regions, attributed to MCS sensitivity to the varying environmental conditions in which they occur.
Data are drawn from the first field season of a major Anglo-Brazilian collaborative study of micrometeorology and plant physiology of Amazonian rain forest. In dry daylight conditions the temperature, humidity and humidity deficit of the top two-thirds of the canopy are similar to those of the atmosphere above, but air at the base of the canopy is strongly decoupled. At night the behaviour is reversed. The response to convective storms is rapid but fairly short-lived.-D.G.Tout
The total land area of the world exceeds 13 billion hectares, but less than half of it can be used for agriculture, including grazing. The world’s potentially arable land is estimated at 3031 million hectares, or 22% of the total land area. The potential cultivable land is distributed as follows: 2154 and 877 million hectares, respectively, in developing and developed countries representing 28% and 15% of the land area (Dudal, 1982). About 1461 million hectares or 40% of the world potentially arable land is cultivated (Dregne, 1982; Dudal, 1982), with 784 and 677 million hectares representing 36% and 77% of the potentially cultivable land in developing and developed countries, respectively. Ironically, the 1461 million hectares of land now being cultivated does not include an estimated 2000 million hectares of once biologically productive land that has been degraded or destroyed.
The literature on the micrometeorology of temperate and tropical forests is reviewed to determine whether structural or species difference between these biomes alters their interaction with the atmosphere. Considerable consistency is found in the value of those whole-canopy features of most importance to this interaction, namely solar-reflection coefficient, through-canopy radiation absorption, aerodynamic roughness, the symptoms of near-surface K-theory failure, the canopy store for rainfall interception and the magnitude and environmental response of their bulk stomatal (surface) resistance. Typical values of these parameters and functions are given with a view to their potential use in climate simulation models. Attention is drawn to the fact that this similar micrometeorological response can generate different time-average surface energy partitions when interacting with different climates and, in particular, alters between the edge and the middle of continents. -from Author
Short-range forecasting of severe convective weather in the United States may have improved due to the improved observing systems being put in place, but scientific theories needed to explain the new, high-resolution observations are still lacking. A good example is the conflicting interpretation made on a visible satellite imagery taken by the GOES-7 geostationary satellite. Weaver and Purdom suggested that storm-environment interaction occurred prior to an initial tornado touchdown in Hesston, Texas, but time traces of storm parameters indicate otherwise. Examination made on the visible satellite imagery leaves open the possibility that a storm located on the northern flank of the Hesston storm may have interacted with it prior to the tornado.
A comprehensive and accurate global water vapor dataset is critical to
the adequate understanding of water vapor's role in the earth's climate
system. To begin to satisfy this need, the authors have produced a
blended dataset made up of global, 5-yr (1988-92), 1° × 1°
spatial resolution, atmospheric water vapor (WV) and liquid water path
products. These new products consist of both the daily total
column-integrated composites and a multilayered WV product at three
layers (1000-700, 700-500, 500-300 mb). The analyses combine WV
retrievals from the Television and Infrared Operational Satellite
(TIROS) Operational Vertical Sounder (TOVS), the Special Sensor
Microwave/Imager, and radiosonde observations. The global,
vertical-layered water vapor dataset was developed by slicing the
blended total column water vapor using layer information from TOVS and
radiosonde. Also produced was a companion, over oceans only, liquid
water path dataset. Satellite observations of liquid water path are
growing in importance since many of the global climate models are now
either incorporating or contain liquid water as an explicit variable.
The complete dataset (all three products) has been named NVAP, an
acronym for National Aeronautics and Space Administration Water Vapor
Project.This paper provides examples of the new dataset as well as
scientific analysis of the observed annual cycle and the interannual
variability of water vapor at global, hemispheric, and regional scales.
A distinct global annual cycle is shown to be dominated by the Northern
Hemisphere observations. Planetary-scale variations are found to relate
well to recent independent estimates of tropospheric temperature
variations. Maps of regional interannual variability in the 5-yr period
show the effect of the 1992 ENSO and other features.
