Enhanced levels of carbon dioxide are likely cause of global dryland greening, study says
Enhanced levels of atmospheric carbon dioxide are a likely key driver of global dryland greening, according to a paper published today in the journal Scientific Reports.
The positive trend in vegetation greenness has been observed through satellite images, but the reasons for it had been unclear.
After analyzing 45 studies from eight countries, Lixin Wang, assistant professor of earth sciences in the School of Science at Indiana University-Purdue University Indianapolis, and a Ph.D. student in Wang’s group, Xuefei Lu, concluded the greening likely stems from the impact of rising levels of atmospheric carbon dioxide on plant water savings and consequent increases in available soil water.
“We know from satellite observations that vegetation is greener than it was in the past,” Wang said. “We now understand why that’s occurring, but we don’t necessarily know if that’s a good thing or not.”
In some regions, greening could be caused by species change, with greener invasive plants replacing indigenous ones or bushes encroaching on grasslands that are used to graze cattle, Wang said.
Defined broadly as zones where mean annual precipitation is less than two-thirds of potential evaporation, drylands are the largest terrestrial biome on the planet, home to more than 2 billion people.
Recent regional scale analyses using satellite-based vegetation indices such as the Normalized Difference Vegetation Index have found extensive areas of dryland greening in areas of the Mediterranean, the Sahel, the Middle East and northern China, as well as greening trends in Mongolia and South America, according to the paper.
Lu and Wang considered other potential drivers that could have caused the greening, including increased rainfall and changes in land-management practices. But only carbon dioxide provided a global explanation for changes to dryland vegetation.
To date, the global average concentration of carbon dioxide in the atmosphere has increased by nearly 27 percent between 1960 and 2015, with the expectation of a continued rise in years to come, according to the researchers.
The researchers believe the greening is a response to higher atmospheric carbon dioxide inducing decreases in plant stomatal conductance — the measure of the rate of passage of carbon dioxide entering, or water vapor exiting, through the stomata of a leaf — and increases in soil water, thus enhancing vegetation growth.
The researchers examined the sensitivity of soil water change to varying levels of carbon dioxide, finding a significant positive change in soil water along the carbon dioxide enrichment gradient.
“The stability of the rate of change justifies using higher carbon dioxide enrichment levels to interpret soil water responses to currently observed carbon dioxide enrichment,” Wang said.
The analysis also showed that elevated carbon dioxide significantly enhanced soil water levels in drylands more so than it did in non-drylands, with soil water content increasing by 9 percent in non-drylands compared to 17 percent in drylands, Wang said. Determining the mechanisms of stronger soil water responses in drylands will require further investigation.
Studies including Wang’s earlier work in Africa have shown that even small changes in soil moisture in drylands could be significant enough to cause large changes in vegetation productivity.
“Importantly, the observed response lends weight to the hypothesis that any additional soil water in the root zone is then available to facilitate vegetation growth and greening under enhanced carbon dioxide,” Wang said. “Future studies using global-scale process-based models to quantitatively assess the carbon dioxide impact on soil moisture is needed to further validate the hypothesis.”
Going forward, Wang said, the positive effect of carbon dioxide-induced water savings may eventually be offset by the negative effect of carbon dioxide-induced temperature increases when the temperature increase crosses a certain threshold.
Another author of the paper is Matthew McCabe, an associate professor from King Abdullah University of Science and Technology in Saudi Arabia.
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Recent Australian research by University NSW and Melbourne University has found the 5 decades from 1950 to 2000 to be amongst the wettest periods in Eastern Australia in the last 500 years. In addition the five worst drought years in the past 500 years all happened prior to 1900.
Climate scientists elsewhere also see an increasing fire risk as CO2 levels increase resulting in greater growth in vegetation providing higher fuel loads.
“We know from satellite observations that vegetation is greener than it was in the past,” Wang said. “We now understand why that’s occurring, but we don’t necessarily know if that’s a good thing or not.”
Good or bad, here I thought most “vegetation” (on at least this planet) was green.
If CO2 was increasing AND the size of deserts were also increasing, the CAGW crowd would be wildly cheering on that man-made destruction of the environment. Bunch of sick bastards.
Let us name their condition Environmental Hypochondria. They want the earth lying in a hospital bed stuck with a million tubes and nothing less will satisfy them. They need sickness in the environment in order to feel good about themselves. Bunch of sick bastards.
Eugene WR Gallun
Eugene: those tubes are not empty, they are sucking the money out of the host.
Crispin in Waterloo but really in Shaijiazhuang
Truth illuminates. Thankyou
Eugene WR Gallun
A clear case of terrestrial Munchausen by Proxy.
So after telling us for years that CO2 is causing desertification and that’s a bad thing, now they’re suggesting that de-desertification is a bad thing.
Gee, I guess you can have it both ways!
How does increasing CO2 affect tree rings?
TedL: You would have to ask the genius ‘Mann scientist’ who has aced the study of tree rings. Only he is qualified to answer your question!
Y’man “Mannheim Steamroller?”
A good point. Specious CO2 fertilization correlation has always been one of the many serious problems with using tree rings as thermometers.
Yes the deserts are greening! But it is not a “green” greening. Think “rotten” ice. GK
Perhaps the oil industry has become “green” and Greenpeace needs to change its name to the Brownies or the Bedouins.
It’s a well known fact that CO2’s rise from 280ppm to 400ppm (1850~2015) has increased crop yields and forest growth by around 25%…
Some alarmists have tried to claim CO2’s mythical “large” warming effect has caused severe weather to increase, thus decreasing CO2’s net fertilization effect, but even the IPCC now admits there hasn’t been ANY global increasing trends of severe weather incidence nor intensity…
How much longer will CAGW be taken seriously???
CAGW is a complete bust..
But SCIENCE is HARD, and that’s BORING when the warmistas can have so much FUN scaring all the little sheepsters half to death! Remember those guys who used to stand on street corners in goofy robes with signs that said The End Is Coming? Well, we should pay this batch the same amount of attention.
“Study: increased carbon dioxide is greening deserts globally”
Can someone tell me where “deserts” comes from in this?
Greening of vegetation – fine – extra CO2 would do that.
But deserts are rather short of vegetation …..
“A waterless, desolate area of land with little or no vegetation, typically one covered with sand:
the desert of the Sinai peninsula is a harsh place
[MASS NOUN]: drought and deforestation are turning fragile grasslands into desert”
No mention in the original paper either….
file:///C:/Users/Tony/Downloads/GV2M_S5_Myneni_Tuesday_14_00.pdf
Most of the world’s deserts aren’t sandy wastes,
Generally areas that receive less than 250 mm [10 inches] of rain per year are considered deserts.
The amount of evaporation per year effects how “deserty” a desert is.
Much of what is considered desert in Australia is well vegetated…….but by plants that tolerate arid conditions and intermittent rainfall. When it does rain heavily, every ten years or so, it often floods.
There are really dry deserts, much of Antartica for instance and the Atacama desert in Chile [ average rainfall around 15mm or 2/3 of an inch]
Reposted this on my German KlimaWandler.blogspot,com site with some personal musings.
“We now understand why that’s occurring, but we don’t necessarily know if that’s a good thing or not.”
Sour grapes? Or something clever like this: if we spread the notion that it might not be good then we can continue to write our grant applications with the term “CO2” in it and get at the money.
“We know from satellite observations that vegetation is greener than it was in the past,” Wang said. “We now understand why that’s occurring, but we don’t necessarily know if that’s a good thing or not.”
Oh dear oh dear these guys are heretics obfuscating over the conventional Green wisdom-
https://www.greeningaustralia.org.au/about-us
Either that or this mob are about to join the dole queue along with the 350 CSIRO climastrology buffs-
https://www.greeningaustralia.org.au/about-us/board-of-directors
https://www.greeningaustralia.org.au/about-us/executive-team
Generally grasslands will be maintained by grazing, but, if the grazers have been removed, such as the BLM’s goal in our Western states, bushes and trees will indeed move in.
Ya think? Here in southern New England, if you don’t mow your hayfield for two years it’ll be already converting to invasive vines and weeds; don’t mow for five, and now it’s 3rd-growth scrub timber saplings and you’ll need a flame thrower and a bulldozer to clear it. GRASSLANDS are our fastest-disappearing habitat due to the selling off of former farmland for suburban sprawl.
To the extent that grass is lost to bush because of CO2 we might expect new grass to grow in drier places, but to the extent that it is lost to invasive species like mesquite, it has a better chance of not being replaced, and of endangering grassland species like zebras and their Asian relatives (Indian asses). And some of this greening is no doubt due to mesquite as well. –AGF
Here’s the link:http://www.nature.com/articles/srep20716
Don’t forget, ocean phytoplankton also benefits from increased CO2.
“In some regions, greening could be caused by species change, with greener invasive plants replacing indigenous ones or bushes encroaching on grasslands that are used to graze cattle, Wang said.”
They are struggling very hard to find some possible explanation why increased vegetation caused by CO2 will be a very bad thing and therefore yet another reason to reduce the ‘infernal’ CO2. They will not find it.
“…but we don’t necessarily know if that’s a good thing or not.”
— Imagine the opposite case, with greenery dying in arid areas and saying “We don’t know if that’s a good thing or not.”
Steve, somebody that clueless probably couldn’t figure out how to reproduce, and that’s definitely a good thing.
This from 3 years ago….
http://www.csiro.au/en/News/News-releases/2013/Deserts-greening-from-rising-CO2
CSIRO’s had bit of bad press recently but this shows that sections of it are still doing science as opposed to measuring opinion
When will Mankind start to take bows for averting the truly Global Catastrophe of CO2 Plant Death.
The Plant Kingdom had succeeded in eating out most of the atmosphere’s CO2 and found themselves stunted in growth as a result,literally starving for more CO2. .
But as the atmospheric CO2 level dropped close to the Plant Kingdom death level of 200ppm, when Photosynthesis ceases, the world’s biota faced a calamity. If all the Plants died, it was only a matter of time before all Animals, humans included, died as well.
Thanks to modern Mankind’s efforts, the threat of the Catastrophic Global Death Spiral, “CGDS”, has been averted. When clean energy from Wind, Water, Fusion and Fission are adopted, Mankind will have to create a program to feed the Plant Kingdom, by forcing CO2 into the atmosphere. I suggest a program of forest clear-cutting, and creating forest fires, in-situ oil/gas well and coal seam fires, as a start.
Thanks Mankind for rescuing the World! Where do I go to get my Nobel Prize?