by Adam Jones – click to order a photo or poster
I’ve covered this before, such as when NASA posted satellite data showing that the biosphere is booming thanks to CO2 fertilization. This new study from Goethe University in Frankfurt, Germany suggests that the Umbrella Thorn Acacia trees will make a comeback.
Tree trumps grass to rule the savannas
A new study published today in “Nature” by authors from the Biodiversity and Climate Research Centre and the Goethe University Frankfurt suggests that large parts of Africa’s savannas may well be forests by 2100. The study suggests that fertilization by atmospheric carbon dioxide is forcing increases in tree cover throughout Africa. A switch from savanna to forest occurs once a critical threshold of CO2 concentration is exceeded, yet each site has its own critical threshold. The implication is that each savanna will switch at different points in time, thereby reducing the risk that a synchronous shock to the earth system will emanate from savannas.
Tropical grasslands, savannas and forests, areas the authors call the savanna complex, are expected to respond sensitively to climate and atmospheric changes. This is because the main players, grasses and trees, differ fundamentally in their response to temperature, carbon dioxide supply and fire and are in an unrelenting struggle for the dominance of the savanna complex. The outcome of this struggle determines whether vast portions of the globe’s tropical and sub-tropical regions are covered with grasslands, savannas or forests. In the past such shifts in dominance have played out in slow motion, but the current wave of atmospheric changes has accelerated the potential rate of change.
Experimental studies have generally shown that plants do not show a large response to CO2 fertilization. “However, most of these studies were conducted in northern ecosystems or on commercially important species” explains Steven Higgins, lead author of the study from the Biodiodversity and Climate Reseach Centre and Goethe-University. “In fact, only one experimental study has investigated how savanna plants will respond to changing CO2 concentrations and this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations, and that their growth really starts taking off at the CO2 concentrations we are currently experiencing.“
The vegetation shifts that the Higgins and Scheiter study projects are an example of what some theorists call catastrophic regime shifts. Such catastrophic regime shifts can be triggered by small changes in the factors that regulate the system. These small changes set up a cascade of events that reinforce each other causing the system to change more and more rapidly. The study demonstrated that the savanna complex showed symptoms of catastrophic regime shifts. “The potential for regime shifts in a vegetation formation that covers such vast areas is what is making earth system scientists turn their attention to savannas” comments Higgins.
Knowing when such regime shifts will occur is critical for anticipating change. This study discovered that locations where the temperature rise associated with climate change occurs rapidly, for example in the center of southern Africa, are projected to switch later to forest as the high rate of temperature increase allows the savanna grasses to remain competitive for longer in the face of rising atmospheric CO2 concentration. This means that even though a single location may experience its catastrophic regime shift, the vegetation change when averaged over a region will be smoother. Such gradual transitions in regional vegetation patterns will reduce the potential for shocks to the earth system. “While this may seem reassuring, we have to bear in mind that these changes are still rapid when viewed on geological time scales”, says Higgins.
The practical implications of the study are far reaching. For example, the study identified a belt that spans northern central Africa where fire suppression would encourage savannas to transition to forests. “So if you wanted to sequester carbon as part of a carbon mitigation action, this is where you should do it” explained Higgins “with the caveat that where this will work is shifting as atmospheric conditions change.” A worrying implication is that the grasslands and open savannas of Africa, areas with unique floras and faunas, are set to be replaced by closed savannas or forests. Hence it appears that atmospheric change represents a major threat to systems that are already threatened by over-grazing, plantation forestry and crop production.
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Paper:
Steven I. Higgins and Simon Scheiter (2012). Atmospheric CO2 forces abrupt vegetation shifts locally, but not global. Nature, DOI: 10.1038/nature11238
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What about cutting down all those pesky trees in Africa and stuff timber into abandoned coal mines? Is not it an excellent opportunity to sequester carbon? The project could easily be financed by, let me see, taxpayer’s money? Or does public debt sound better?
A Discovery channel show suggested that the Sahara “greens” when the summer N hemisphere receives the greatest solar input — every 20k yrs (even during glacial periods). Supposedly due to the summer monsoon expanding & encompassing much or most of it. Right now we’re at the min summer input there, so its bone dry, unlike 10k yrs ago.
Interesting if CO2 could help restore even a part of it to a savannah during a summer solar-min period.
steveta_uk says:
July 2, 2012 at 8:01 am
Interesting redefinition of the word “catastrophic”…..
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That was the first thing I noticed. Can’t these supposed scientists write anything with out the scare words like catastrophic anymore?
What this study shows is a return to the good ole’ days.
See: CO2/temp graph
ferdberple says:
July 2, 2012 at 8:31 am
“this study showed that savanna trees were essentially CO2 starved under pre-industrial CO2 concentrations”
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So, it would appear that Al Gore, the Team, Climate Science and the IPCC, in wanting us to cut back to per-industrial CO2 levels, are in fact advocating that we starve trees.
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You got it!
Since CO2 decreases with a decrease in temperature the earth was heading into a level of CO2 that would be too low for C3 plants (most varieties) to reproduce especially when you include the short summers during the next full glaciation. The C4 plants would have a competitive advantage.
In another couple of interglacial cycles you could be seeing the complete wipe out of trees and other C3 varieties. Mankind’s burning of Coal and oil has literally given trees a new lease on life!
To bad the idiot econuts haven’t figured that out yet.
WISE Math says:
July 2, 2012 at 10:43 am
“Experimental studies have generally shown that plants do not show a large response to CO2 fertilization” Which studies might these be? The folks over at CO2science.org hav catalogued an impressive array of studies demonstrating large responses over a wide variety of plants…
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It depends on whether or not the plant is C3, C4 or CAM. C3 plants are more responsive to increases in CO2 because they are closest to starvation levels. Savanah Grasses can be C3 or C4 (drought/heat tolerant) and the C4 type would therefore more tolerant of lower CO2, Trees are generally C3 as is the vast majority of vegetation. I can not find whether Umbrella Thorn Acacia (Acacia tortilis) is C3 or C4.
In poking around I found a book, Serengti III: Human Impacts on Ecosystem Dynamics
The book goes on to indicate the shift to an increase in C4 biomass 50% => 90% was accompanied by
So as usual the Post Normal “Scientists” are trying to take a complicated interplay of a variety of factors and single out CO2 as causing “catastrophic regime shifts.” (rolls eyes)
Age of giant-ism… Sign me up. GK
“A worrying implication is that the grasslands and open savannas of Africa, areas with unique floras and faunas, are set to be replaced by closed savannas or forests. Hence it appears that atmospheric change represents a major threat to systems that are already threatened by over-grazing, plantation forestry and crop production.”
Good Lord. What would it be like to sit and have a beer with a negative sourpuss like this? Horror of horrors, next we will have to suffer the foresting of the Sahara. Weren’t we bemoaning the drying up of Lake Chad and the desertification of the savanah grasslands and the devastation of of ever more wildfires? Interesting the trees on the savannah known as “orchard bush” because of the spacing of the trees. I mapped geology in this country south of Lake Chad in the 1960s. Green trees would have been a blessing. BTW, how many of these researchers know that the dry savannah trees are fireproof.
“Even more impressively some of the trees that grow in the tropical savanna are fire proof.”
http://bing.search.sympatico.ca/?q=Tropical%20Savannah%20Environment%20&mkt=en-ca&setLang=en-CA
Now I wonder why that would be? Those clever trees knew we humans would be doing stuff to the climate that would cause wildfires.
“…what some theorists call catastrophic regime shifts.”
Lose the catastrophic histrionics and call it cascading regime shift. Hardly a catastrophe for the trees. So the savanna shifts north to the Sahel?
Rhys Jaggar says:
July 2, 2012 at 11:33 am
“A classic example of the ‘law of unexpected outcomes’.”
Well, maybe it’s not unexpected to people who really understand savannahs, but I’m sure it would be unexpected to computer modellers who in the main have little understanding of ecosystem biology.
On the main, they have little understanding of anything that doesn’t involve computer models. Period.
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Gail Combs says:
July 2, 2012 at 3:44 pm
I can not find whether Umbrella Thorn Acacia (Acacia tortilis) is C3 or C4.
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Without researching, almost certainly C3. Acacia is in the pea family like Blacklocust or Honeylocust, so it might be a nitrogen-fixer. But not C4.
Acacia tortilis subspecies is a leguminous tree, so their roots host symbiotic ammonia oxidizing bacteria which make Nitrogen available to it.
The curious thing about Acacia tortilis is that the soil under it has one of the highest diversity of non-bacterial microbial lifeforms found under trees.
These varieties of diazotrophs also have ammonia oxidizing genes; and, it turns out that the ammonia oxidizing archaea are even more significant than the classic ammonia oxidizing bacteria in terms of total useable Nitrogen.
Lead article above doesn’t account for things like this Acacia “gift” to different grasses below it.
Some grasses will not show any increase at all from commercial nitrogen supplemental fertilization and yet that same grass variety will then noticeably grow more in soil enriched with ammonia oxidizing archaea. It is generally seen that where commercial Nitrogen fertilization is applied to soil this leads to diminished ammonia oxidizing archaea diversity and less of their beneficial contribution.
Pamela Gray says:July 2, 2012 at 8:36 am
“The “tree-ing” of savannas probably isn’t due to CO2 increase as much as it is due to ENSO oceanic-atmospheric oscillations providing necessary growing conditions for trees.”
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Impact on the biosphere of increased carbon dioxide levels is much less than its effect on climate change. It appears that the accumulation of carbon dioxide can be a very temporary and transient condition in an area. But this is not a permanent phenomenon. However, I agree with Pamela Gray.
Today, one should not overlook that the wild fires in Colorado is acknowledged to relate to the increased carbon dioxide in the atmosphere.
acckkii says:
“Impact on the biosphere of increased carbon dioxide levels is much less than its effect on climate change.”
Do you have ANY testable, verifiable evidence showing that increased CO2 causes “climate change”? If so, produce it. Show a conclusive, direct connection. If you can.
And in Colorado now, as in the planet’s atmosphere, increased CO2 is an effect, not a cause.
This article is vrey simple to figure out:
Using “Catastrophic” regime shifts = More studies = more $$$$$
Not using such language means funding drys up!
I agree with many other sentiments expressed here, where do we humans get off thinking we can pick a point in time and say “this is normal, everything else is abnormal”???
The hubris is only superceded by the disingenuous use of big words that mean nothing.
I’m just saying…….
acckkii says:
July 3, 2012 at 9:51 am
“Today, one should not overlook that the wild fires in Colorado is acknowledged to relate to the increased carbon dioxide in the atmosphere.”
HUH???, Increase carbon dioxide now start wild fires? Spontanious Combustible CO2…. hmmm , do you have 5 Sigmas on that claim?
“is acknowledged to” by whom??
Smokey says:
July 3, 2012 at 10:14 am
“……. CO2 is an effect, not a cause……”
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I said:
“…..its effect on climate change…..”. there is no hint to “CAUSE”.
So there is no challenge on “EFFECT”.
You are quite right. I should have added the word “UNFORTUNATELY” to that part of my comment “….one should not overlook that UNFORTUNATELY the wild fires in Colorado is acknowledged to relate….” to show you it was not my view.
I know that you have seen the below article:
http://wattsupwiththat.com/2012/06/28/what-global-warming-really-looks-like-michael-oppenheimer-fail/
acckki,
I suspect that English is not your first language. So maybe it’s a language thing. But I would still like to see verification of CO2’s effect on climate. If any.
Peter in MD says:
July 3, 2012 at 10:50 am
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acckkii says:
July 3, 2012 at 10:51 am
Smokey says:
July 3, 2012 at 11:11 am
“…..CO2′s effect on climate. If any.”
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If any? Smokey your reply is to much “ABSOLUTE”. I’m sorry no need to say anything about this to Smokey. But you asked for it:
The contribution of carbon dioxide to the warming is expected because of the “greenhouse” effect and the main question is how large it is. The greenhouse effect is nothing else than the absorption of mostly infrared radiation emitted by the Earth by the “greenhouse” gases in the atmosphere, (of course mainly water vapor), but in this case we are discussing about carbon dioxide, one of the five most important gases causing this effect after water vapor.
er…. and what about the supposed massive drought expected per IPCC for much of Africa? (just one more IPCC-gate) Just how is all that nasty drought going to support more trees? /sarc
Others here have already mentioned the issue of grazing animals. Apparently, and not surprisingly, nature is far more complex than even one or two particular species affect on a system. Some time ago I ran across an intriguing article about very significant decrease in trees lining rivers in Yellowstone National Park (USA). The change was attributed to man’s elimination of apex predators – primarily wolves. Which resulted in an explosion of the numbers of large grazing animals (elk? deer? both? I don’t recall the exact species) that typically eat new tree sprouts damaging them to the point that they die off. Voila, less trees.
Add to it any changes in jet stream and therefore rainfall patterns….
So much of what passes for research and science these days seems to try to take the most simplistic view and then apply the results as if it functioned in a vacuum – with no attention paid to or mention of other known confounding factors.
Discouraging and a bit scary doesn’t even begin to cover the state of affairs.
Oh, and as to the term “catastrophic regime change” or similar – I may be off here, but I think that phrase has been used in biology and ecology long before the whole AGW thing began. That it’s just a way to describe any relatively sudden shift in a biological/ecological system. It would be really interesting to know for sure approximately when the term did first go into use. Awfully easy to take issue with it these days simply because of CAGW and all the catastrophizing, sensationalizing, FUD spreading, and so on that is so prevalent these days.
The flip side is that a lot of species depend on savannahs for survival. Giraffes and large herds of wildebeest, etc., couldn’t survive in dense forests. On the other hand, the skyrocketing African population will raze any new forests to the ground before they get a foothold.
acckkii,
Let me repeat: I would still like to see verification of CO2′s effect on climate. If any.
Got facts? So far, you have posted no verifiable facts.
http://www.abc.net.au/news/2012-07-04/plants-adapt-to-climate-change-study/4109238
unusual for the ABC to print something that isn’t 100% eco-rubbish. plants adapting??
Darwin must be rolling his eyes at such a scandalous thought…
regards
Smokey:
Depends on what you mean by “verification of CO2′s effect on climate.”
If you mean the “exact effects to seven decimal places” that’s a crazy standard of proof. If you mean “verification that CO2 can and does affect climate”… well that’s been done.
We demonstrate that CO2 absorbs infrared radiation, thereby impeding outward flow of heat energy from the Earth, well that’s a demonstration that CO2 affects climate. How it affects climate is different from the simple, obvious fact that it does affect climate.
One of the standard results is the amount of additional heating of the surface that is observed as a result of CO2 trapping of heat energy, the exact amount may be questioned but it’s on the order of 30°C. If you mean by evidence that it has to be directly observed, that’s just silly. You’re redefined the process of science into something useless. If you accept that physics does work (so in fact there’s a reason your car actually works, it’s because of the same types of physical evidence-based reasoning), we know that CO2 affects climate, and it has a substantial effect..
We can demonstrate that CO2 affects the hardiness of plants (see figure) that’s a demonstration too. Changes in the atmospheric properties, temperature, precipitation, gas constituents, etc that affect plant hardiness are a measure of climate change, so that figure is a visual confirmation that increases in CO2 has a substantial impact on climate.
That CO2 affects climate is really not in doubt, except by people who have exceptionally wacky notions of how physical law works. The details about how much warming to expect, effects on precipitation, etc., almost nobody in the media gets right what the models and science in general predict, and the models and science are generally wrong, except for parameters that they explicitly or implicitly tune for such as global mean temperature (e.g., modeled precipitation is way off).
Some people choose to define the problem of “verification of the impact of CO2 on climate” to be one that is impossible to ever demonstrate. That serves no practical value and is just pure sophism, from my point of view.
Carrick says,
“If you mean by evidence that it has to be directly observed, that’s just silly.”
Yes, that is exactly what I mean: show me evidence. Without evidence, you are simply speculating based on your own personal belief. That doesn’t cut it here.
Maybe I wasn’t clear enough. I am not disputing physics. I am not disputing that the rise in CO2 is greening the planet; it is. I am disputing the central tenet of runaway global warming believers: that the rise in CO2 causes quantifiable effects on the planet’s ‘climate’, by which they mean global temperature.
If you can show verifiable effects on the planet due specifically to human CO2 emissions, produce your evidence. Post it here. And keep in mind that computer models and pal reviewed papers based on models or conjectures are not evidence. Evidence is verifiable, testable data.
The only evidence so far shows that CO2 is entirely beneficial. At current and projected concentrations, CO2 is harmless. It is essential to life on earth. It does not cause runaway global warming, or any identifiable harm to the planet. More is better.
Does that make it clear enough for you?