Posted: January 30, 2013 by tallbloke in solar system dynamics

I think it’s worth putting this up for discussion. It probably makes access to what Makarieva et al’s work is all about easier for some.

Stormy Science

Full text with editorial summary:
Jeremy Hance (February 01, 2012).
New meteorological theory argues that the world’s forests are rainmakers. 

1.>> Will you tell us how the biotic pump works?
2.>> Why do you associate the biotic pump with natural forests rather than with individual tree species? Cannot a tree plantation act as biotic pump?
3.>> Have there been any significant changes to your biotic pump theory over the last couple of years?
4.>> Have you seen wider acceptance in the scientific community for your theory?
5.>> Can you give an example of why the current understanding of condensation and precipitation is wrong?
6.>> Recent evidence has linked the decline and fall of the Maya civilization to deforestation leading to less precipitation. How could the biotic pump theory connect to this?
7.>> How do you see deforestation in the Amazon as impacting regional precipitation?
8.>> How do…

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  1. Stephen Wilde says:

    I’m sure there is a biotic pump but there is a much larger and all pervasive pump in the form of adiabatic expansion and contraction caused by surface heating from insolation and declining pressure with height caused by the gravitional field.

    One doesn’t need vegetation to give rise to a tendency for low pressure to develop in continental interiors as a result of insolation.

    It is true that such low pressure only occurs as long as insolation is occurring so during the night high pressure would tend to develop but that simplicity is confounded on a rotating sphere such that the high and low pressure cells become permanent or semi permanent and are spread all round the globe.

    Furthermore any given planet even without a water cycle and with no vegetation will have climate zones where air rises or falls or flows between high and low pressure cells.

    There is no doubt that water and vegetation will modify the basic configuration but neither are necessary for it.

    Even Wikipaedia recognises that in principle:

    “The water cycle is also affected by deforestation. Trees extract groundwater through their roots and release it into the atmosphere. When part of a forest is removed, the trees no longer transpire this water, resulting in a much drier climate. Deforestation reduces the content of water in the soil and groundwater as well as atmospheric moisture. The dry soil leads to lower water intake for the trees to extract. Deforestation reduces soil cohesion, so that erosion, flooding and landslides ensue.

    Shrinking forest cover lessens the landscape’s capacity to intercept, retain and transpire precipitation. Instead of trapping precipitation, which then percolates to groundwater systems, deforested areas become sources of surface water runoff, which moves much faster than subsurface flows. That quicker transport of surface water can translate into flash flooding and more localized floods than would occur with the forest cover. Deforestation also contributes to decreased evapotranspiration, which lessens atmospheric moisture which in some cases affects precipitation levels downwind from the deforested area, as water is not recycled to downwind forests, but is lost in runoff and returns directly to the oceans. According to one study, in deforested north and northwest China, the average annual precipitation decreased by one third between the 1950s and the 1980s.

    Trees, and plants in general, affect the water cycle significantly:
    their canopies intercept a proportion of precipitation, which is then evaporated back to the atmosphere (canopy interception);
    their litter, stems and trunks slow down surface runoff;
    their roots create macropores – large conduits – in the soil that increase infiltration of water;
    they contribute to terrestrial evaporation and reduce soil moisture via transpiration;
    their litter and other organic residue change soil properties that affect the capacity of soil to store water.
    their leaves control the humidity of the atmosphere by transpiring. 99% of the water absorbed by the roots moves up to the leaves and is transpired.

    As a result, the presence or absence of trees can change the quantity of water on the surface, in the soil or groundwater, or in the atmosphere. This in turn changes erosion rates and the availability of water for either ecosystem functions or human services.

    The forest may have little impact on flooding in the case of large rainfall events, which overwhelm the storage capacity of forest soil if the soils are at or close to saturation.

    Tropical rainforests produce about 30% of our planet’s fresh water.”

    Could someone say what is really new in the above paper ?

  2. oldbrew says:

    They seem to have run into the ‘high bar’ problem as well.

    ‘After the negative review was posted, we replied to all the arguments. Since then the paper was suspended, it has now been in open review for over fifteen months and it’s been twenty months since our submission. As any scientist will tell you, such extraordinary impediments and delays would discourage any researcher; they are disrupting the normal scientific process. But we remain hopeful that our efforts are not in vain.’

  3. oldbrew says:

    Could the apparent ‘high bar’ be in any way related to this?

    ‘However, the greenhouse effect on Earth is mostly determined by water vapor and clouds, i.e., by atmospheric moisture, which is the main greenhouse substance. The absorption interval of CO2 molecules covers less than 20 percent of the spectrum of thermal radiation of the Earth’s surface, while atmospheric moisture absorbs thermal radiation rather uniformly over the entire spectrum. Therefore, the impact of increasing CO2 concentrations on the greenhouse effect can be completely compensated by a relatively minor change in the hydrological cycle over land.’

    This has been put forward before, but whether it appears in any published papers is another question.

  4. Stephen Wilde says:

    I’ve previously proposed just that:

    ” extra energy in the air from extra GHGs increases the evaporation rate which increases the speed of the hydrological cycle which prevents the extra energy in the air from warming the oceans whether via the ocean skin theory or otherwise.

    AGW is thus falsified because the air cannot warm the oceans and the air circulation systems always adjust to bring surface air temperatures back towards sea surface temperatures”

    from here:

    Friday, July 17th 2009, 3:23 PM EDT

    but I wouldn’t say that water vapour is responsible for the greenhouse effect in the first instance because in fact it is a matter of mass, gravity and energy input.

  5. Stephen Wilde says:

    They also say this:

    “Conversely, destruction of forests leads to disruption of the hydrological cycle, which expectedly causes significant fluctuations of the magnitude of the global greenhouse effect, up to complete loss of climate stability and transition of Earth’s climate to a state incompatible with life.”

    So what we have here is simply a variant of AGW theory whereby they abandon the failed CO2 meme and shift instead to water vapour and then say that if we reduce forests too much then we will see much the same outcome as CO2 alarmists propose but this time from disrupting the entire water cycle.

    Is it all just a repositioning execrcise ?

    And still no recognition of declining pressure with height causing the lapse rate or the inevitability of climate zones whatever happens to forests.

    There is a distinct lack of general meteorological knowledge in their narrative too.

  6. tallbloke says:

    Here’s the comment I put on the site earlier today:

    In the application of the biotic pump theory to large scale longer term changes such as the Walker Circulation mentioned in 8 and the loss of precipitation in the Amazon in 7, has any consideration been given to possible influence from the longer term oceanic oscillations such as the PDO and AMO?

    I agree that conservation of natural forests is extremely important, however I think we should consider the possibility that some of the changes in moisture regimes might be reversed by the reversal in sign of these oceanic indices. Better to correctly factor in these oscillations in advance of them falsifying a theory which doesn’t include them?

  7. Stephen Wilde says:

    Not just ocean cycles either but also any other natural variables including solar.

    They seem to think there would be no climate zones were it not for forests.

    I’m concerned that their scientific objectivity is swayed by a more politico / religious perspective about the biosphere as a whole:

    They are effectively underpinning their biocentric ideas with an assumption that the entire water cycle and climate with it are governed by the biosphere in a Gaia type fashion.

    Here is an illuminating comment:

    “Psychologically, citizens of the developed countries, with their many centuries’ tradition of the economic leaders’ identity, will find it extremely difficult to admit their current status of economic slaves. However, without such an analysis the crisis will be deepening spontaneously, with a glaring possibility of a new military conflict where the well-armed slaves will again attempt to get rid of their shackles with those of the slaveholders who still do not have nuclear weapons. “

  8. tallbloke says:

    I think you need to remember that to Russian people, our political outlook looks equally quaint. 🙂

    As for the Gaia thing, They are ecologists, and they are right. The only reason our planet has a 20% oxygen atmosphere is because of microbial and other lifeforms. You won’t find a lifeless planet with a high percentage of highly reactive gas in its atmosphere. It would all have reacted. On top of which, the organic life supplies a lot of the condensation nuclei for cloud and droplet formation. And as they point out, the tree canopy of forests provides a greater evaporation area than open water, as well as shading and retaining the soil moisture.

    I think it’s great to get an ecologists perspective into the climate debate.

    Having said that, they may have overegged it a bit. Britain has a lot less forest than it had 700 years ago. Still a pretty rain soaked island. But in the continental interiors, I think they are right.

  9. oldbrew says:

    Stephen Wilde says: ‘So what we have here is simply a variant of AGW theory whereby they abandon the failed CO2 meme and shift instead to water vapour’

    And clouds – ‘water vapour and clouds’. They seem to lump them together as ‘atmospheric moisture’ but clouds can also restrict incoming sunlight obviously. Which leads back to the question of whether clouds are net negative, neutral or positive…

  10. Stephen Wilde says:

    Rog, points duly taken and I support them in principle but they accept the greenhouse gas theory simply replacing CO2 with water and clouds to produce a similarly catastrophic man made prognosis.

    We have gone a long way towards setting out the flaws in the gas based theory.

    As regards Gaia I actually accept the idea in its broadest impersonal sense but would submit that we are a part of the process rather than an intrinsically destructive component and that in due course our numbers will be restrained voluntarily with long term sustainability following but not if objectivity gets overlain by politics or belief systems.

    By the way, two of my four grandparents were Russian 🙂

  11. tallbloke says:

    Stephen, I don’t think that they are right that the global average near surface temperature would change much. After all, at least 70% of the surface never had trees on it anyway. But they are saying we can damage our local climates where we live – on the land masses. Why do you think Easter Island was abandoned after they cut down all the trees? There is a possibility the Mayans and Aztecs ran into tree chopping trouble too.

  12. Stephen Wilde says:


    No problem with the idea that we can mess up locally and regionally but they really are discussing ‘global’.

    Not so much temperatures this time but as regards water supplies.

    “complete loss of climate stability and transition of Earth’s climate to a state incompatible with life.”

    Instead of rationing energy this lot want to subordinate civilisation to an assumed threat to global precipitation.

    No forests, no rain.

    Daft, I know, but there it is.

    Precipitation came before vegetation did it not ?

    It would still continue after forests were removed. Different distribution maybe but you have pointed out how stable global humidity has been so how could it ever become incompatible with life just by replacing forests with cultivation ?

    My BS monitor is registering 15 on a scale of 1 to 10.

    Even without considering their belief structure we can see that it doesn’t hold up scientifically.

  13. Stephen Wilde says:

    “The biotic pump is a mechanism in which natural forests create and control ocean-to-land winds, bringing moisture to all terrestrial life”

    “As long as one continues to ignore the role of condensation in driving winds, one will continue to ignore the real role of forests in the water cycle and climate. Given the deforestation threat, there is no time to lose.”

    Sound familiar ?

    All life is dependent on it and there is no time to lose.

    Merely a variant of AGW theory which similarly ignores the roles of mass, gravity and insolation and of the sun and oceans

  14. Stephen Wilde says:

    tallbloke said:

    “But in the continental interiors, I think they are right”

    Let’s think that through.

    Continental interiors are dry because they are a long way from the oceans so humidity gets dropped as rain or snow before oceanic air gets there or is kept as a low level vapour due to solar heating at the surface.

    So. plant lots of trees between coast and interior but do it progressively so that the trees draw in moisture a step at a time.

    Bear in mind the permanent climate zones set up by the rotating planet and uneven heating of land and oceans.

    At some point the effect of the climate zones is going to put a stop to forest encroachment unless we irrigate accordingly.

    How much irrigation would we need to get forests to encroach significantly into the Australian interior (their example) ?

    Look at Western Australia. Lots of nearby ocean bringing in humidity but desert pretty much from the coast. The reason being descending air from the subtropical high pressure cell.

    To get forests established there they have to change the entire global circulation.

    Just by planting trees !

    Not realistic. As far as we know the European climate was much the same as now when trees were more numerous.

    Likewise the Western Sahara etc etc.

    That is an example supporting my comment about the lack of knowledge of basic meteorology.

    I agree that we need trees and should preserve them but failure to sustain forests per se so will not have the consequences they predict.

  15. tallbloke says:

    I agree they have overegged it, as I said earlier. The regional effects can be significant though. Recall that deforestation is the reason for the loss of snow on Kilimanjaro. Seasonal meltwater from a natural storage can be extremely important for populations living in marginal territory.

    Makarieva’s calculation is that the limit temperature for life is around 230K. That’s near the temperature birds and bats started dying in Australia soon after the first ships arrived. They are not offering that figure as a plausible global temperature for Earth with no forests. They are not stupid, and they know 70% of Earth is covered in ocean.

    There are 1001 other reasons we should be preserving forests. Biodiversity is important for discovering naturally medicinal plants etc.

  16. Thank you for your interest in our work. Please not that the PDF of the corresponding paper can still be downloaded from Springer site (will be available for about one week I think):
    Otherwise the manuscript is available here.

    The existence of the descending branch of the Hadley cell does not explain the Australian desert (nor Sahara). As can be seen from the figure, the most important point is not that there is little precipitation inside the continent, but that this precipitation is always significantly less than it is over the source (ocean) at the same latitude (bear in mind the east-to-west wind direction). The pattern is the same in Australia both during the dry and wet seasons.

    In contrast, in the Eurasian seven thousand kilometers’ forest belt in summer precipitation over the continent is higher than over the ocean and nearly constant over the entire boreal zone. In winter the continent behaves much like the deserted Australia, with all precipitation (whatever its amount) concentrated over the ocean on the west (from where the winds blow).

    Should Eurasia followed Australia in summer as well (with a dry region in the east) people would be probably saying — well, it is clearly because the prevailing winds cannot bring moisture so far east, so nothing doing, it is a climatic zone limitation.

    In the meantime forests do change the regional wind patterns against the global patterns. In the tropical zone the predominant wind direction is from east to west (the trade winds), still the Congo forest acquires most of its moisture from the Atlantic ocean — against the dominant oceanic wind direction.

    Australia and Sahara both used to be much wetter quite recently on a geological timescale and had a rather luxurious vegetation. It provides support for the idea that the physical limitations of climatic zones (that would have existed on a lifeless Earth), while undoubtedly important, can be partially or fully overcome by significant regional changes of the evaporation/precipitation process associated with forest recovery or decline.

    Regarding Gaia and our approach here’s a relevant link.

  17. tallbloke says:

    Anastassia: Welcome, and thank you for making the time to join this discussion. Please could you give us your views on the effect of the long term ~60 year oceanic oscillations and how their inclusion in your theory might affect your conclusions. I asked this on your blog with the following:

    In the application of the biotic pump theory to large scale longer term changes such as the Walker Circulation mentioned in 8 and the loss of precipitation in the Amazon in 7, has any consideration been given to possible influence from the longer term oceanic oscillations such as the PDO and AMO?

    I agree that conservation of natural forests is extremely important, however I think we should consider the possibility that some of the changes in moisture regimes might be reversed by the reversal in sign of these oceanic indices. Better to correctly factor in these oscillations in advance of them falsifying a theory which doesn’t include them?

  18. Stephen Wilde says:

    Thank you Anastassia.

    I am open to persuasion and our difference seems to be one of degree as regards the forest / precipitation relationship.

    I’m still puzzled as to why you focus on condensation given that it is evaporation that causes low pressure (over and above what would have happened anyway) in the first instance.

    Why do you feel that need to focus on the condensation part of the water cycle when observation of clouds shows us that the upward flow goes straight through and on upward without any restraint that would be caused by inward air flows from anywhere other than from below ?

    What part if any do you think the adiabatic processes play given the reduction of pressure with height ?

    As regards Eurasian forests I think their latitudinal consistency is due to moisture coming up from the south rather than from the west. In the southern hemisphere the prevailing flow is disrupted far less than in the northern hemisphere. Also Australasia is much flatter than Eurasia so less orographic uplift to cause condensation and rainfall.

    As regards the Sahara I think it is very susceptible to latitudinal climate zone shifts that cause it to alternate between wet and dry epochs.

    The longitudinal positioning of the main high pressure cells is partly governed by the ocean / land mass distribution with oceans tending to favour slightly lower pressure so the main subtropical high pressure cells are closer to land masses than they otherwise would be.

    So I think there are equally valid meteorological explanations for the observations that you have made as regards rainfall patterns between oceans and land.

    The wetness of the Congo, the Amazon and South East Asia is mainly down to the location of the ITCZ rather than the presence of forests. The ITCZ probably existed pre vegetation.

    Likewise the middle latitude forests are a product of wetness beneath the mid latitude jets.

    Australia is simply in the wrong place for frontal rainfall and too low and flat fror much orographic rainfall.

  19. michael hart says:

    As Stephen Wilde asks, “Could someone say what is really new in the above paper ?”

    The authors appear half-way towards describing “The Tansley Effect”.

    Readers of SF author Frank Herbert will recognise the term as the (primary?) influence he draws from in his description of the planet Arrakis in his great work “Dune”.

    On a more personal note, there is a book, in an unfrequented part of the Suzzallo library at the University of Washington that is titled “The Tansley Effect”. Herbert studied Earth Sciences at the University of Washington prior to writing Dune and almost certainly cannot have failed to read the book. When I spotted it on the shelves it was the oldest looking book in the aisle and had not been used for many years (library books were still date-stamped when borrowed from the library). I really felt like I was holding a piece of history. To book collectors and SF lovers that is a book that is valuable beyond price.

    It is still probably there, I hope, or now hidden away in the basement storage section where books were being moved to around the turn of the millennium.