‘Climate Protecting’ Palm Oil Backfires …Deforestation May Be Leading To Drought!


Amazon forest by Manaus. Photo: Phil P Harris, CC BY-SA 2.5

Climate Damaging Palm Oil: Rain Deficit in Amazon Due To Deforestation

By Dr. Sebastian Lüning And Prof. Fritz Vahrenholt
[German text translated/edited by P Gosselin]

In a press release on March 13, 2017, the Potsdam Institute for Climate Impact Research (PIK) presented model results on the impacts of drought on the Amazon rainforest. What follows is the the full text, much of which is correct but mixed with some questionable points:

Vicious circle of drought and forest loss in the Amazon

Logging that happens today and potential future rainfall reductions in the Amazon could push the region into a vicious dieback circle. If dry seasons intensify with human-caused climate change, the risk for self-amplified forest loss would increase even more, an international team of scientists finds. If however there is a great variety of tree species in a forest patch, according to the study this can significantly strengthen the chance of survival. To detect such non-linear behavior, the researchers apply a novel complex network analysis of water fluxes

‘The Amazon rainforest is one of the tipping elements in the Earth system,’ says lead-author Delphine Clara Zemp who conducted the study at the Potsdam Institute for Climate Impact Research, Germany. ‘We already know that on the one hand, reduced rainfall increases the risk of forest dieback, and on the other hand, forest loss can intensify regional droughts. So more droughts can lead to less forest leading to more droughts and so on. Yet the consequences of this feedback between the plants on the ground and the atmosphere above them so far was not clear. Our study provides new insight into this issue, highlighting the risk of self-amplifying forest loss which comes on top of the forest loss directly caused by the rainfall reduction.’ This study results from the  German-Brazilian Research Training Group on Dynamical Phenomena in Complex Networks at (IRTG1740) hosted by Humboldt Universität zu Berlin.

Self-amplifying effect comes on top of the forest loss directly caused by reduced rainfall

Under a dry-season halving of rainfall, at least 10 percent of the forest might be lost due to effects of self-amplification alone, adding to the substantial direct forest losses from reduced water availability. Computer simulations built by the scientists suggest that this has already happened in the Amazon about 20,000 years ago, in accordance with evidence from the Earth’s past. Still, they stress that the uncertainties are considerable. Taking into account the puzzlements of the vegetation-atmosphere-feedback, self-amplified forest dieback could amount up to 38 percent of the Amazon basin. In combination with the direct effects of the droughts, in fact most of the Amazon forest might eventually be at risk.

The study cannot provide information about the time scales of the processes, it is rather a sensitivity analysis.

Strikingly, the huge tropical woods produce much of the water they need themselves by evaporating moisture which then rains back onto them. ‘The Amazon water cycle is of course pure physics and biology, but it is also one of nature’s great wonders,’ says co-author Henrique M.J. Barbosa from the Universidade de São Paulo, Brazil. ‘As powerful as the cycle is, it is also surprisingly susceptible to environmental changes – and humankind is imposing massive perturbations on Amazonia by both cutting down the trees and heating up the air with greenhouse gases, which reduces large-scale moisture transport and precipitation, and end up affecting even the untouched patches of the forests.’

Even if average rainfall is stable, extended dry periods increase the risk of tipping

‘Today, the wet season is getting wetter and the dry season drier in Southern and Eastern Amazonia due to changing sea-surface temperatures that influence moisture transport across the tropics,’ says Anja Rammig from Technische Universität München (TUM) and PIK. ‘It is unclear whether this will continue, but recent projections constrained with observations indicate that widespread drying during the dry season is possible in the region.’

Even if average rainfall might not drastically change, extended drought events might tip parts of the Amazon forest into self-amplifying forest loss, eventually turning them into a savanna. ‘Projected rainfall changes for the end of the 21st century will not lead to complete Amazon dieback,’ says co-author Carl Schleussner from Berlin-based scientific think tank Climate Analytics and PIK. ‘But our findings suggest that large parts of it are certainly at risk.’

Interestingly, the more diverse the Amazon vegetation is, the less vulnerable it seems to be.  Diversity has the potential to decrease the effects of self-amplified forest loss. ‘Since every species has a different way of reacting to stress, having a great variety of them can be a means for ecosystem resilience,’ says Marina Hirota from the Federal University of Santa Catarina, Brazil. ‘Preserving biodiversity may hence not just be about loving trees and weeds and birds and bugs; it may also be a tool to stabilize key elements of the Earth system.’

Article: Delphine Clara Zemp, Carl-Friedrich Schleussner, Henrique M. J. Barbosa, Marina Hirota, Vincent Montade, Gilvan Sampaio, Arie Staal, Lan Wang-Erlandsson, Anja Rammig (2017): Self-amplified Amazon forest loss due to vegetation-atmosphere feedbacks. Nature Communications [DOI:10.1038/NCOMMS14681]”

It is plausible that droughts burden rainforests. On the subject of rain trends, we wish to take a closer look. In the press release we read:

Today, the wet season is getting wetter and the dry season drier in Southern and Eastern Amazon…”

Less rain during the dry period is a problem in the southern and eastern Amazon regions. But what is happening in the west and north? Is rainfall perhaps increasing there during the dry period or remaining steady? The remaining trend statements looks at the future, based on questionable modelling that in the past has seldom been reliable.

An important aspect was brought up only briefly at the start of the article, namely the destruction of rain forests through the supposedly green palm oil barons.

The anthropogenic deforestation under the guise of climate protection, according to one study by Spracklen & Gardcia-Carreras (2015) in the Geophysical Research Letters with respect to a reduction in precipitation:

The impact of Amazonian deforestation on Amazon basin rainfall
We completed a meta-analysis of regional and global climate model simulations (n = 96) of the impact of Amazonian deforestation on Amazon basin rainfall. Across all simulations, mean (±1σ) change in annual mean Amazon basin rainfall was −12 ± 11%. Variability in simulated rainfall was not explained by differences in model resolution or surface parameters. Across all simulations we find a negative linear relationship between rainfall and deforestation extent, although individual studies often simulate a nonlinear response. Using the linear relationship, we estimate that deforestation in 2010 has reduced annual mean rainfall across the Amazon basin by 1.8 ± 0.3%, less than the interannual variability in observed rainfall. This may explain why a reduction in Amazon rainfall has not consistently been observed. We estimate that business-as-usual deforestation (based on deforestation rates prior to 2004) would lead to an 8.1 ± 1.4% reduction in annual mean Amazon basin rainfall by 2050, greater than natural variability.”

7 responses to “‘Climate Protecting’ Palm Oil Backfires …Deforestation May Be Leading To Drought!”

  1. CO2isLife

    Climate “Science” on Trial; Clear-Cutting Forests to Save the Trees
    https://co2islife.wordpress.com/2017/02/25/climate-science-on-trial-clear-cutting-forests-to-save-the-trees/

  2. tom0mason

    It’s tough ‘saving the planet’ when all you really want is a profit.

    1. AndyG55

      Just ask the wind turbine advocates..

      … that would be the flower-pothead twins, seb and sob

  3. Ingvar Engelbrecht

    I would be careful about blaming palm oil for deforestation. Most of the palm oil is grown on abonded rubber tree plantages. The “war” on Coconut oil and palm oil is has other roots

  4. Hasbeen

    A few too many if, buts & maybes in this to be taken seriously.

    Sounds like they are trying to get another leg to hold up the global warming gravy train rail line.

  5. CO2isLife

    “It’s Official, Global Warming and Higher CO2 Ended the California Drought!!!”
    https://co2islife.wordpress.com/2017/04/08/its-official-global-warming-and-higher-co2-ended-the-california-drought/

  6. dennisambler

    “The Amazon rainforest is one of the tipping elements in the Earth system,’ says lead-author Delphine Clara Zemp who conducted the study at the Potsdam Institute for Climate Impact Research, Germany”

    Professor Philip Stott, Emeritus Professor of BioGeography at the School of Oriental and African Studies, University of London, wrote this in 2003:

    “At the end of the last ice age, only some 12-18000 years ago, the tropics were covered by seasonal savannah grasslands, cooler and much drier than now. There were no rain forests in the Malay Peninsula and much of Amazonia, and, despite the increasing human development of forested space, there are still more rain forests persisting than existed then. As in Europe and North America, the forests came and went as climate changed; there is no Clementsian “long period of control” under one climate. Beneath many rain forests, there are sheets of ash, a testimony in the soil to past fires and non-forested landscapes.”

    Items like these never get much traction:
    “Brazil: Ancient Amazon Actually Highly Urbanized” August 31st 2008

    “The report in Friday’s edition of the journal Science, describes clusters of towns and smaller villages that were connected by complex road networks and were arranged around large central plazas. Researches also discovered signs of farming, wetland management and fish farms in the ancient settlements that are now almost completely covered by rainforest.”

    http://en.mercopress.com/2008/08/31/brazil-ancient-amazon-actually-highly-urbanized

    “Stone age etchings found in Amazon basin as river levels fall”: 10 November 2010 Guardian

    “Archaeologists who have studied the photographs believe the art – which features images of faces and snakes – is another indication that thousands of years ago the Amazon was already home to large civilisations.

    “Eduardo Neves, president of the Brazilian Society of Archaeology and a leading Amazon scholar, said the etchings appeared to have been made between 3,000 and 7,000 years ago when water levels in the region were lower. The etchings were “further, undeniable evidence” that the region had been occupied by a significant number of ancient settlements and people.””

    http://www.guardian.co.uk/world/2010/nov/10/amazon-brazil-stone-age-etchings?CMP=EMCGT_111110&

    This is still online via wayback:
    SOUTH AMERICA DURING THE LAST 150,000 YEARS – Jonathan Adams, Environmental Sciences Division, Oak Ridge National Laboratory

    “In general, it would seem that 150-130,000 y.a. the continent showed the general glacial-age pattern of colder and more arid conditions. After about 130,000 y.a., climate warmed and moistened and the forests reached a similar area to the present. After 115,000 y.a., cold and aridity began to influence the vegetation, to an arid, cool maximum around 70,000 y.a., followed by erratic but generally fairly cool and drier-than-present conditions throughout the continent. A second cold, arid maximum began around 22,000 years ago and lasted until about 14,000 14C y.a., after which rainfall and temperatures increased and the forests returned over several thousand years.”

    https://web.archive.org/web/19980704172829/http://www.esd.ornl.gov/projects/qen/nercSOUTHAMERICA.html

    Nature does what nature does……