By hoarding water underground, vegetation will help saturate soil, boosting rain runoff
Plant physiology will be as significant as climate change in future river flooding.
October 22, 2019
The next time a river overflows its banks, don’t just blame the rain clouds. Earth system scientists from the University of California, Irvine have identified another culprit: leafy plants.
In a study published in Nature Climate Change, the researchers describe the emerging role of interrelationships of organisms and their environment in understanding flooding. Adapting to an overabundance of carbon dioxide in the atmosphere, trees, plants and grasses constrict their pores to regulate the amount of CO2 they consume, a mechanism that limits the release of water from leaves through evaporation.
“Plants get more water-efficient and leak less underground soil moisture through their pores in a carbon-rich atmosphere,” said study co-author Mike Pritchard of UCI. “Add this up over billions of leaves in very sunlit, leafy places, especially the tropics, and it means there is a bunch more soil moisture stored up underground, so much so that climate models predict rainfall events will saturate the ground and more rain will run into rivers.”
Pritchard said this so-called forest effect dominates atmospheric responses to CO2 on most land masses up to 30 degrees north and south of the equator, which is where most people live. And he noted that this plant-based phenomenon could have a large influence on flooding in the Mississippi River basin.
“I was really interested in the Mississippi because it’s in our own national backyard,” Pritchard said. “It’s a big, complex basin fed by multiple sources.”
He said the twin effects of plant physiology in the U.S. Southeast and precipitation anomalies caused by atmospheric warming farther north in the Mississippi basin “are conspiring to juice up the future flood statistics in equal proportion.”
The research is funded by NSF’s Division of Atmospheric and Geospace Sciences.
HT/Daniel L
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Higher CO2 levels: increase crop yields, increases biomass to better feed all life on earth, increases all plants’ root network which DECREASES soil erosion, and increases plants’ drought resistance….
“Scientists” who say higher CO2 levels will increase river flooding are either blithering idiots or are immoral and unethical grant-grubbing charlatans.
We had an eight inch rainfall event between September 21st and October 16th 2019 in NW London, UK, including two 2 inch+ events in 12hrs.
I had a variety of leafy plants in my garden and they utilised this rain to grow extremely rapidly over a three week period.
My soil happens to have been well looked after the past five years and there was no run off, no standing water, nothing but effective absorption and drainage through pores developed by worms. The soil was bone dry at the start of the event after six weeks of drought (the second long dry period of summer 2019). At the end of it, it was recharged to depth.
Run off leading to doenstream flooding is a function of various things, including but not limited to:
1. % of rainfall not reaching the ground uninterrupted through adherence to plant structures off the ground.
2. Absorption capacity of soil where rain is falling, linked to soil type, organic matter content of soil, structure of soil (notably worm passages etc), gradient of land etc.
3. % of any run off delayed from reaching lower river courses by leaky or non-leaky dams, % overspill into flatter terrain capable of absorbing excess water over time, prevalence of ditches capable of storing surface water.
4. Rate of absorption of rainfall by vegetation, linked to rates of photosynthesis, respiration and transpiration (anyone else noticed that tomatoes increase their rate of water absorption from 16C up to 32C?)
5. % saturation of soil prior to current rainfall event.
My observation is that soil condition is a far greater factor in inability to drain heavy rainfall that what particular plants happen to be growing. Or what temperature it happens to be.
Samurai,
I see zero evidence that whoever wrote this has even high school level knowledge of botany, let alone hydrology.
There is a demonstrable ignorance of edaphology.
IOW…no evidence any scientist was involved.
Nicholas McGinley,
He appears to be a computer modeller.
Well, color me unsurprised.
That certainly ‘splains a lot.
A perfect example of picking a few known facts, ignoring others and completely disregarding unknowns.
The end result is that a completely wrong conclusion is drawn, either on purpose for political reasons or simply though stupidity. Let’s hear your vote. Mine is for stupidity.
N.B.; the trail where the authors leap to stupendous results, without verification, certification or observation.
N.B.; where plants originally leaked excess water and now ‘retain water”?
Presumably, plants replaced their leaked water with more water intake; otherwise the plants suffer for lack of water.
Yet, somehow, the authors conclude that plants that did not “leak” result in more water in the soils?
A comparison would be that sinks/tubs leaking water in a bathroom result in less water on the floor versus sinks/tubs that do not leak result in more water on the floor?
Reductio ad absurdum: If there’s a plant, reduced evapotranspiration; No plant, no evapotranspiration, all water runs off. Now which is the most favourable outcome, I wonder?
““Adapting to an overabundance of carbon dioxide in the atmosphere, trees, plants and grasses constrict their pores to regulate the amount of CO2 they consume, a mechanism that limits the release of water from leaves through evaporation.”
No, plants do NOT “consctrict their pores to regulate the amount of CO2 they consume”… and it is NOT “adapting to an overabundance of carbon dioxide in the atmosphere”…
Plants open their pores to obtain CO2 from the air. They get water from the ground. Opening the pores to obtain CO2 from the air causes the simultaneous loss of water vapor OUT of the pores. Higher atmospheric CO2 levels means they obtain the CO2 in less time and close their pores sooner. This is NOT an “adaptation” to CO2 “overabundance”, as it works the same way in any Greenhouse with artificially elevated CO2. It is a win-win situation for plant life, as they lose less water in the transaction and become more water efficient, leading to healthier plants, and biota in general.
This study has it all backward, trying desperately to make a good thing into a bad one with purposely negative terminology (“overabundance of CO2”, “constrict their pores”, “regulate the CO2 they consume”). Standard climate “science”, unfortunately.
I can only imagine the horror when Fowler, Kooperman, Randerson & Pritchard discover that fully 70% of the surface area of the entire planet is wide open to evaporation of water into the atmosphere… all that leaky water vapor emanating from vast pools of naked surface waters!
So the plants are countering the water-table declines caused by groundwater pumping, thus reducing subsidence-related flooding?
The only palpable sign of climate change IS the Great Greening and its other manifestation – burgeoning harvests. This greening and plentitude is untold $ trillions for the benefit side of CO2.
The central planners have been worrying about this apparently unexpected bounty since it was reported by NASA about 6 yrs ago. Except for some desperate, lame and laughable attempts at painting a dire picture of this exciting phenomenon shortly after the NASA report, there has been essentially a pregnant silence on the subject. Even sceptics somehow have largely kept their heads down for some reason.
I have been promoting a quantification of this for several years, seeing it to be a sledgehammer argument against alarmist nonsense. Grossly, I learned a number of years ago the world’s trees had been counted – 3 trillion of them. I learned that in 35 yrs forests expanded 14% (up to 2013), so let’s conservatively say 16% to today – so we’ve added 480billion trees to the planet, not to mention shrubs, grasses, fattening of existing plants etc., plus oceans of new pelagic relatives. Any foresters or arborists out there to analyze all there?
Since the nature of fringing growth into arid regions (the main noticeable greening places) is an exponential process, logically the CO2 growth rate in the atmosphere will attenuate to a plateau, even doing nothing deliberate to abate it. CO2 is simply overwhelmingly beneficial.6
Two very different issues being confounded here. First, the extra water efficiency of plants in higher CO2 translates to faster growth in areas which are limited by water. Where there is already adequate water, such as tropical forests, it has little or no effect as however much CO2 is in the air, it gets sucked up pretty fast.
Once again, where there is no water stress, the impact on soil moisture is also negligible as the very definition of water stress is inadequate soil moisture, leading to reduced leaf turgor and closing of leaf stmata (pores) to conserve water.
It is drawing a very long bow from higher CO2, through less water stress, to increased soil saturation and then on to more flooding with a series of rather tenuous links which will probably only apply in a very small number of environments. I am sure the authors have some experimental data to back this up, but as a general mechanism to point to higher flooding, this is just extrapolation of the highest order.
Every time I see a “study” like this I can’t help but wonder about how seemingly little knowledge the authors must have about this planet’s climate history in regards to life on earth. Based on models like this, one must wonder how the dinosaurs (and the mammals that came after their extinction event) could possibly have survived, let alone thrived, in such a cataclysmic world. Except for the fossil records show that life flourished during earth’s warmer periods. And as for past mass extinctions, most (as far as anyone can determine) have been caused by excessive vulcanism, freezing temperatures and asteroid impacts. None of the warm periods have been catastrophic (and indeed some were much warmer than today; how did plants back then ever cope?) to animals and even to humans in recent history. Seems that so many climate “scientists” are quite deficient when it comes to geological history…..
The worst thing that happened to the Miss. River was *levees*! Simply physics – Building/raising levees raises the riverbed which, in turn, raises the water level.
Think about that whenever cities along the Big Muddy.
Elevated CO2 has increased root growth to an even greater percent than leaves. The cited report should have taken that into it’s modeling, if has not done so.
Am multitasking so will post this & follow with an old example for orientation soon.
For example: Going from 350 ppm CO2 to 700 ppm CO2 in soybeans results in a 110% increase in root length. Their root diameter increases 27%, their cortex diameter increases 23% & their stele diameter increases by 28%.
In context of root fluid content that increases by 80%, as measured in ml. As per 1992 “Response of plant roots to elevated atmospheric carbon dioxide”; free full text available on-line has more data in Table 1.
In soybeans elevated CO2 does not however increase the number of lateral roots. This is a feature of how plant hormones differentially respond to CO2 levels – which is why I’ve previously said elevated CO2 can be considered a stressor to current plants.
I admit I’ve only skimmed previous posts, but a point raised by Gregory Wrighthouse, in an interview plugging his book Inconvenient Facts, was that increased soil moisture is contributing to a reduction in forest fires.
I’m no botanist and even I can recognize this is complete nonsense, and as such the BBC and Dungaria will be all over it. If they aren’t already.
Wow! This must be one of the dumbest papers ever published. I can’t wait for this superstition to be placed alongside Bigfoot, where it belongs.
Umm virtually all of the Mississippi basin is higher than latitude 30 N. The St. Louis area pictured is about 38 Latitude North. Baton Rouge is about 30 N. So once again, more easily identified climate baloney..
They say “Plants get more water-efficient and leak less underground soil moisture through their pores in a carbon-rich atmosphere,”
This is true. Water efficiency, a terrible thing I guess. Yet there are more plants to absorb water. Trees are larger and need more water. Root systems are stronger and hold the soil and nutrients better.
BTW, run off in poorly grown areas is much heavier.
I’ve never read such a bunch of crap. ”Science” these days seems to be as much about speculating on someone’s dreams as it is about observation and experiment.
The thing that I hate more than the fact that global warming causes droughtflood summers is that it causes warmcold winters. Even worse is all the raindroughtsnow.
Welcome to the wonderful make-believe world of ”Climate change.” Anything can happen and usually does.
More underground storage of water on land should moderate the rise in sea levels.
What about the aquifers – are they
https://www.google.com/search?q=australia+aquifer+map&oq=Australia+&aqs=chrome.
https://www.google.com/search?q=australia+aquifer+map&oq=Australia+&aqs=chrome.
– are they locked, locked up, sealed off
https://www.google.com/search?client=ms-android-huawei&sxsrf=ACYBGNTa_ktPnjvnFhs3CTrrXIkm-qzVCg%3A1572343309273&ei=DQ64Xa6vEOjJrgS6p7iwBw&q=Us+aquifer+map&oq=Us+aquifer+map&gs_l=mobile-gws-wiz-serp.
Surely this is a good thing? Isn’t more moisture left in the ground better and likely to make droughts less likely? Some people just don’t like to consider there may be an upside to more CO2 I guess. I wish people would call it that BTW- not ‘carbon’, but I also wish I had a Ferrari- I suppose I just want too much…..