How the Biotic Pump links the hydrological cycle and the rainforest to climate: Is it for real? How can we prove it?

Bunyard, Peter

doi:10.22518/9789588745886

Cited by 7 publications

(8 citation statements)

References 43 publications

(66 reference statements)

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“…There are also processes that somehow coordinate stomatal opening and closing within and even among leaves (Kaiser and Paoletti 2014) and that can lead to pulsed, cyclic and even chaotic patterns of moisture release (Johnsson 2015). There is some evidence, from Costa Rica and Finland (in summer) that a cyclic pattern of moisture release occurs over actively transpiring forests with a mean period of 70 to 80 min (Bunyard 2014 andpers. comm.…”

Section: Vapourmentioning

confidence: 99%

“…Observations in the tropics show that evergreen forests maintain relatively high humidity year round including dry periods (Bunyard 2014). The evergreen forests of the seasonal Amazon also maintain significant transpiration through the year (Myneni et al 2007;Wu et al 2016).…”

Section: Instabilities and Implicationsmentioning

confidence: 99%

“…While laboratory evaluations appear theoretically feasible, see for example the ideas in appendix 4 of , in practice it is technically demanding to separate the effects of temperature, buoyancy and molecular densities in an enclosed apparatus (e.g., Bunyard 2014;Bunyard et al 2017). Furthermore, small-scale studies may remain difficult to interpret in the context of real largescale atmospheric behaviours.…”

Section: New Insightsmentioning

confidence: 99%

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Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

144

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Theory and evidence indicate that trees and other vegetation influence the atmospheric water-cycle in various ways. These influences are more important, more complex, and more poorly characterised than is widely realised. While there is little doubt that changes in tree cover will impact the water-cycle, the wider consequences remain difficult to predict as the underlying relationships and processes remain poorly characterised. Nonetheless, as forests are vulnerable to human activities, these linked aspects of the water-cycle are also at risk and the potential consequences of large scale forest loss are severe. Here, for non-specialist readers, I review our knowledge of the links between vegetation-cover and climate with a focus on forests and rain (precipitation). I highlight advances, uncertainties and research opportunities. There are significant shortcomings in our understanding of the atmospheric hydrological cycle and of its representation in climate models. A better understanding of the role of vegetation and tree-cover will reduce some of these shortcomings. I outline and illustrate various research themes where these advances may be found. These themes include the biology of evaporation, aerosols and atmospheric motion, as well as the processes that determine monsoons and diurnal precipitation cycles. A novel theory-the 'biotic pump'-suggests that evaporation and condensation can exert a major influence over atmospheric dynamics. This theory explains how high rainfall can be maintained within those continental land-masses that are sufficiently forested. Feedbacks within many of these processes can result in non-linear behaviours and the potential for dramatic changes as a result of forest loss (or gain): for example, switching from a wet to a dry local climate (or visa-versa). Much remains unknown and multiple research disciplines are needed to address this: forest scientists and other biologists have a major role to play. New ideas, methods and data offer opportunities to improve understanding. Expect surprises.

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Section: Vapourmentioning

confidence: 99%

Section: Instabilities and Implicationsmentioning

confidence: 99%

Section: New Insightsmentioning

confidence: 99%

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Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Sheil

2018

For. Ecosyst.

144

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“…If that energy were delivered in a few pulses during daylight hours, those bursts of ET would impact on the rate of cloud condensation and hence on the surface flow of air. Some evidence exists from the ground-based meteorological station within the Biological Station of La Selva in Costa Rica, that the absolute humidity at the surface undergoes some ten pulses during daylight hours [9]. Whereas 5 Ws would give airflows of 2.85 ms -1 , the pulses of absolute humidity from ET could give airflows of 7 ms -1 (Trade Winds) and require a condensation rate of 30 pascals per second per cubic metre (30 Ws).…”

Section: Discussionmentioning

confidence: 99%

Further experimental evidence that condensation is a major cause of airflow

Bunyard¹,

Hodnett²,

Peña³

et al. 2019

DYNA

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This paper further explores the physics of water condensation, using an experimental structure designed for that purpose. The data show a highly significant correlation (R2 >0.94, p value <0.001) between observed airflows and partial pressure changes from condensation, when the results of different experiments are pooled. Changes in air density on cooling provide insufficient energy to account for the airflow. The finding is that the kinetic energy of the chilled air falls short by an order of magnitude, even to move a relatively small proportion of the 20 kg of air contained within the structure. Meanwhile the physics of condensation indicate a surplus of kinetic energy is made available from the air surrounding the locus of condensation. At low rates of condensation a considerable proportion of the available kinetic energy in the enclosed air is absorbed in friction and turbulence. That proportion reduces with higher rates of condensation.

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“…En resumen, con base en la física de la evaporación y la condensación, la selva es responsable de los ríos atmosféricos de vapor de agua que proporcionan la lluvia estacional desde la Argentina hasta el Medio Oeste de Estados Unidos. (Makarieva et al, 2014;Bunyard et al, 2019;Bunyard, 2014).…”

Section: Y Finalmenteunclassified

James Lovelock: la visión de un científico excepcional

Bunyard¹

2022

Rev. Acad. Colomb. Cienc. Ex. Fis. Nat.

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En los años 60, la NASA pidió a James Lovelock, inventor del detector de captura de electrones, que desarrollara instrumentos para detectar vida en Marte. Al considerar cómo se manifestaría la vida, se dio cuenta de que la atmósfera de la Tierra estaba a órdenes de magnitud del equilibrio químico y que ese desequilibrio no podía deberse puramente a procesos abiológicos, sino que era mantenido en un estado dinámicamente estable por efecto de la vida en el planeta. En aquella época, el análisis espectrométrico de la atmósfera de Marte indicaba que estaba cerca del equilibrio químico y Lovelock concluyó que era poco probable que Marte albergara vida. Dado que la Tierra había tenido organismos biológicos durante al menos 3,2 mil millones de años, Lovelock llegó a la conclusión de que la vida era responsable de la homeostasis planetaria en el sentido de mantener las condiciones óptimas de la superficie, de ahí su Hipótesis Gaia.

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How the Biotic Pump links the hydrological cycle and the rainforest to climate: Is it for real? How can we prove it?

Abstract: Edición: febrero de 2014Queda prohibida toda reproducción por cualquier medio sin previa autorización escrita del editor. El contenido del libro no representa la opinión de la Universidad Sergio Arboleda y es responsabilidad del autor.

Cited by 7 publications

References 43 publications

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Forests, atmospheric water and an uncertain future: the new biology of the global water cycle

Further experimental evidence that condensation is a major cause of airflow

James Lovelock: la visión de un científico excepcional

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