Thicker-leaved tropical plants may flourish as CO2 rises, which could be good for climate


Research News


How plants will fare as carbon dioxide levels continue to rise is a tricky problem and, researchers say, especially vexing in the tropics. Some aspects of plants’ survival may get easier, some parts will get harder, and there will be species winners and losers. The resulting shifts in vegetation will help determine the future direction of climate change.

To explore the question, a study led by the University of Washington looked at how tropical forests, which absorb large amounts of carbon dioxide, might adjust as CO2 continues to climb. Their results show that multiple changes occurring in plants’ leaves and competition between species could preserve these ecosystems’ ability to absorb carbon dioxide from the atmosphere. The resulting paper was published Jan. 16 in Global Biogeochemical Cycles.

“Our findings suggest that plants with some types of responses, like making their leaves thicker, will ultimately grow better in tropical forests than their competitors,” said senior author Abigail Swann, a UW associate professor of atmospheric sciences and of biology. “If these better-growing plants become more common in the forest, the total rates of water and carbon exchange could stay closer to what they are now.”

A previous study by Swann’s group showed that tropical plants leaves’ becoming thicker as CO2 climbs would worsen climate change, because thicker leaves might also be smaller. Plants would then capture less sunlight for photosynthesis, absorb less carbon dioxide from the air and emit less water vapor, all exacerbating the heating due to climate change.

The new work expands the scope of this question to include competition between plant species, and the ratio of carbon and nitrogen in their leaves. Higher carbon dioxide in the atmosphere makes it a bit easier for plants to photosynthesize. But if nitrogen can’t keep up, the plant becomes less efficient at producing energy.

“Although it is observed to happen, the verdict is still out on why exactly plants grow thicker leaves under high CO2,” Swann said. The new modeling study suggests an explanation: “Thicker leaves can concentrate the nitrogen so that photosynthesis rates per area of leaf are high.”

The authors ran simulations for Barro Colorado Island, a forested tropical island in Panama where the model had been well tested against conditions on the ground. The simulations included one or two species of broad-leaf evergreen tropical trees, such as wild cashew and Ecuador laurel. The trees were programmed to have various responses to the higher carbon dioxide and could compete with one another for space.

Trees that were programmed to have more carbon relative to nitrogen in their leaves became less efficient at photosynthesis, which helps them to grow, and emitted less water vapor, which helps trees stay cool. But tree species whose leaves also thickened were better at absorbing carbon and producing water vapor, helping them to grow tall and stay cool, and could also outcompete their neighbors.

“Our work suggests that by shifting which plants are growing in the forest there may be less dire consequences of higher CO2 than other studies have suggested,” Swann said. “There is a lot we still don’t know about how plants are responding to climate change — this work really sets up some best guesses about which plants will grow best in future tropical forests that we can test with more observations.”


This research was funded by the National Science Foundation and the U.S. Department of Energy. Lead author was UW graduate student Marlies Kovenock; co-authors are Charles Koven and Ryan Knox at Lawrence Berkeley National Laboratory; and Rosie Fisher at the National Center for Atmospheric Research.

From EurekAlert!

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April 2, 2021 6:10 am

The CO2 is feeding the world population, limit CO2 the hunger and pestilence will return to many.

Reply to  Vuk
April 2, 2021 6:20 am

Absolutely. The extra greening provided by CO2 is something like getting an extra continent to grow things on. Or something like that. wuwt

Reply to  commieBob
April 2, 2021 7:04 am

in another few hundred years, CO2 levels will fall so fast it becomes another mass-produced commodity

as a trillion or so humans expand farming into giant tunnels deep in the bedrock, total farmed area will increase by an order of magnitude even as yields increase too

and then you’ll finally get paid for breathing

Reply to  TallDave
April 2, 2021 10:31 am

A trillion or so humans?

Last edited 1 year ago by Notanacademic
Reply to  Notanacademic
April 2, 2021 2:18 pm

A trillion humans in a few hundred years. It could happen. 🙂 It’s going to be pretty cozy though.

The Earth’s area is 510 million square km. That’s about 500e12 (ie. 500 x 10^12) square meters. A trillion is 1e12. So, 500 square meters per person. Of course that includes the oceans and everywhere else people don’t currently live.

Folks would probably have to live in giant tunnels deep in the bedrock.

Reply to  commieBob
April 2, 2021 3:26 pm

It went right over my head the first time but not twice, nice try though. I hadn’t even had a drink oh the shame 😧

Reply to  commieBob
April 2, 2021 11:32 am
Bill Everett
Reply to  commieBob
April 2, 2021 4:42 pm

Based upon the satellite mapping I have seen which shows the highest C02 levels corresponding to the locations of the most intense vegetation, I wonder if the increase of vegetation isn’t the major source of CO2 increase. Why else would CO2 levels be higher where it is absorbed more than in areas of less vegetation where it is absorbed less?

Reply to  Bill Everett
April 2, 2021 7:45 pm

Well obviously the plants migrate to where they get the most CO2. 😉

Bill Everett
Reply to  commieBob
April 6, 2021 5:28 am

Well then why is the “most CO2” there in the first place’

Bill Everett
Reply to  commieBob
April 6, 2021 5:51 am

Seeds go where the wind blows them but most fall to Earth near their source. They don’t “migrate” toward increased levels of CO2.

Reply to  Vuk
April 2, 2021 8:26 am

Thicker is better…500 ppm CO2 by 2100! Remember, more CO2 means more vigorous plant growth which means more CO2 sequestration…win win win!

John Bell
April 2, 2021 6:18 am
Reply to  John Bell
April 2, 2021 6:53 am

 There is overwhelming consensus amongst climate scientists that anthropogenic activity is responsible for the most recent episode of climate change (Cook et al., 2016)

Some article.

Reply to  fretslider
April 2, 2021 7:17 am

Let’s vote on the second law, so consensus can abolish entropy, that which really messes up a lot of grand schemes.

Reply to  fretslider
April 2, 2021 8:09 am

Which, if it were true, is proof positive that climate “scientists” are a bunch of complete idiots.

Reply to  philincalifornia
April 2, 2021 8:39 am

I did say some article

I need an Uncle Sam Babel Fish.

Bill Everett
Reply to  fretslider
April 2, 2021 4:21 pm

The input of CO2 into the atmosphere by human activity is far to small to have any noticeable effect upon the air temperature or climate of the Earth. Calculate the average annual human input of CO2 into the atmosphere and see how small it is.

Bill Everett
Reply to  fretslider
April 6, 2021 5:57 am

From 1960 until 2020 the average annual human input of CO2 into the atmosphere was 8/100ths of one ppm. That almost non-existent amount was not responsible for any detectable change of temperature or climate.

Reply to  John Bell
April 2, 2021 11:55 pm

When comments are not allowed there is no conversation

April 2, 2021 6:49 am

…some types of responses, like making their leaves thicker, will ultimately grow better in tropical forests than their competitors”

Like survival of the fittest?

“Although it is observed to happen, the verdict is still out on why exactly plants grow thicker leaves under high CO2”

Because they can.

April 2, 2021 6:54 am

…and yet, in every greenhouse they jack up the CO2….every plant does better

Reply to  Latitude
April 2, 2021 7:19 am

Works for weed.

Steve Case
Reply to  Scissor
April 2, 2021 9:10 am

Ha ha ha ha ha ha ha!
First chuckle of my day

Reply to  Steve Case
April 2, 2021 10:23 am

I was serious. Not sure if the same applies to mushrooms, aka fungi. 🙂

April 2, 2021 6:59 am

wow UAH anomaly went negative in March

it was also colder last month than the warmest month of 1988, when Hansen told Congress 2021 would be about 2.5 degrees warmer

Reply to  TallDave
April 2, 2021 7:20 am

Good catch.
Yup, that was a big move. Probably one of the largest in the entire record.

CD in Wisconsin
Reply to  TallDave
April 2, 2021 9:34 am

“wow UAH anomaly went negative in March”

Indeed, ever so slightly negative. Life could get a little too interesting for the alarmists if the current cooling trend on the satellite record continues.

I am not a scientist, but it appears that we have about 0.7 deg. C of cooling since the El Nino peak back in early late 2015-early 2016. Just 0.3 deg. C of additional cooling will give us one entire degree Celsius of cooling, and in just 5 years time.

What is it that the alarmists say about the Earth warming too fast?

Richard M
Reply to  CD in Wisconsin
April 2, 2021 12:51 pm

We already have at least .2 C of additional cooling booked according to global SSTs. In addition, in the last two weeks the Nino 1-2 area has seen substantial cold water upwelling. This usually means a strengthening La Nina which could continue until early 2022.

If this plays out then this La Nina will probably bottom out similar to the last two stronger La Nina events signaling no warming in the 21st century.

Neal in Texas
April 2, 2021 7:10 am

What language do you use to program trees? And, where do you find the interface to connect to the tree and download your program? /sarc

Last edited 1 year ago by Neal in Texas
Reply to  Neal in Texas
April 2, 2021 7:21 am

Keith Olbermann humming to them resonates, as they have approximately equivalent levels of intelligence.

Abolition Man
Reply to  Scissor
April 2, 2021 8:36 am

My tree friends are mortified that you think them to be as stupid as Olbermann! They wanted me to tell you that they believe he is a sociopath, bordering on psychopathic violent behavior, who needs to be returned to whatever loony bin he escaped from!
The aspen are quaking at the thought of trying to have a conversation with that nut!

Reply to  Abolition Man
April 2, 2021 10:25 am

I apologize.

Reply to  Neal in Texas
April 2, 2021 8:07 am

Trees in the past have been programmed in the Half-Wit language – favoured by scientists like Prince Charles.

Incredibly, it’s the first known verbal/programme interface on record – that I know of..

Charles of course is more than modest about the whole thing, simply saying: “I just come and talk to the plants, really – very important to talk to them. They respond.”

My Fraxinus excelsior tells me to get lost. Talk about gratitude.

Reply to  Neal in Texas
April 3, 2021 12:03 am

Something like this:

  1. Consider the problem
  2. Phrase the question
  3. Design the AlGoreythm
  4. Get the answer you want
  5. State “It’s worse than we thought”
  6. Declare the end of the world
  7. Demand more grant money or the kitty gets it.
  8. Loop back to 3 to get an even worserer answer
  9. Retire on a big fat pension
April 2, 2021 7:14 am

Critical race theory science gives us: “case” = false positive; “less dire” = no effect whatsoever.

Reply to  Scissor
April 2, 2021 8:11 am

Exactly, where’s the dire?

We’ve been searching for it for 40 years. Time to give up, I’d say.

Reply to  philincalifornia
April 2, 2021 10:26 am

Models all around.

Abolition Man
Reply to  Scissor
April 2, 2021 8:55 am

Some folks are starting to call it the Fauxi virus! After all, he got paid more than any other federal employee to have a rational and cogent plan for dealing with a possible pandemic!
Instead of following decades of scientific research and studies, he decided to follow the diktats of the CCP and called for lockdowns and pooh poohed therapeutics! That means his advice led to tens of thousands of deaths, and that’s not even counting his support for the GOF experiments that probably created the virus in the first place!

Bruce Cobb
April 2, 2021 7:14 am

“…which could be good for climate…”It could be good for space aliens too.
Climate is what it is. Nothing is “good” or “bad” for it. Nothing we need to worry about anyway.

Pamela Matlack-Klein
April 2, 2021 7:20 am

CO2 levels are still too close to disaster and yet these “scientists” are now worrying about how plants will cope with the “huge” increase? Greenhouse plants where the CO2 is bumped up to 1200 ppm don’t seem to be having any difficulty so why would our modest increase to 415 bother them? Everything is a potential emergency for these people.

Joseph Zorzin
Reply to  Pamela Matlack-Klein
April 2, 2021 8:13 am

“Everything is a potential emergency for these people.” Which I wouldn’t care if they think that way if they weren’t taking over our governments.

Peta of Newark
April 2, 2021 7:26 am

They’re growing thicker leaves because they’re running out of water
IOW: There’s a desert creeping up, just behind you.

Nice to see mention of The Most Humongous & Epic Liebig Limiter there ever was (on land anyway)

If you want plants to grow better with extra CO2, strangely as happens inside ‘greenhouses’.,you jack up their nitrogen fertiliser.
NB ‘Fertiliser’ Not food

If you want Global Greening, you jack up the Global Nitrogen

Previously that was done without a second thought, until some panic stricken clown heard the words ‘Acid Rain’ and took off on a fit of screaming heeby jeebies.

Thereafter vast amounts of money were spent (and energy wasted) preventing the escape of Nitrogen (water soluble variety: NOx) from … just everywhere really.
Cars, trucks, power stations AND most important notably, escapes from farms.

Notable is the Modus Operandus of Nitrogen in that it primarily feeds the soil bacteria and fungi. They chew up old cellulose and lignin, releasing (shock horror) CO2.
From out of the ground to boot!

Oddly enough, the parts where plants absorb CO2 (food, not fertiliser) is on the underside of their leaves.

Was it coincidence, or causation that atmospheric CO2 started really ramping up when huuuuuge amounts of Nitrogen started being applied to farmland, just after WW2
Coz you can’t stop NOx escaping from farmland.
But are we really in trouble, Climate Scientists want it to stop and Cronies imagine they can actually do it
And you thought AOC was spendthrift…

Oh well, lets all go get some goats…. they make nice curry. Apparently.

Paul C
April 2, 2021 8:24 am

So, thicker leaves MIGHT also be smaller. There might also be more of them. Next they’ll be investigating why forest trees are so tall. All that energy wasted to bring the crown/canopy closer to the light. If only the trees would form a consensus not to grow tall, they could photosynthesise near the ground, saving so much effort.
Just how much light penetrates to the rainforest floor? Apparently more than into the University of Washington!

Abolition Man
April 2, 2021 8:41 am

The quotes in the last paragraph say it all; things may not be as bad as we hoped but we’re really not sure! Send more money!
Science has definitely left the building!

Last edited 1 year ago by abolition man
April 2, 2021 8:44 am

Ya think? Mother Nature knows best, and will take care of herself.

April 2, 2021 9:06 am

Greta claims to see increasing/alarming CO2, but fails to see thriving plant life,

April 2, 2021 9:24 am

According to the article: A previous study by Swann’s group showed that tropical plants leaves’ becoming thicker as CO2 climbs would worsen climate change, because thicker leaves might also be smaller. Plants would then capture less sunlight for photosynthesis, absorb less carbon dioxide from the air and emit less water vapor, all exacerbating the heating due to climate change.

If the plants capture less sunlight, then more is reflected back into space. Increasing the Earth’s albedo. Emitting less water vapor, which is a major greenhouse gas. Therefore exacerbating the cooling due to climate change. OMG. We’re doomed no matter what.

Krishna Gans
April 2, 2021 9:25 am

Dr. Roy Spencer, March 2021

comment image

Last edited 1 year ago by Krishna Gans
Reply to  Krishna Gans
April 2, 2021 10:27 am

Back to the future.

April 2, 2021 9:49 am

And don’t forget ocean greening …

Right-Handed Shark
April 2, 2021 9:59 am

So let me get this straight. More CO2 absorbtion by plants means more growth, which inhibits growth thereby reducing the amount of CO2 they absorb. Makes about as much sense of the rest of “climate science”, I suppose.

April 2, 2021 11:10 am

Elevated CO2 (eCO2) plants process more carbon into carbohydrates. We humans think of “sugar” as substance, however in plants it also serves an osmotic function. This is relevant when O2 uptake by certain cells is reduced.

eCO2 osmotic leaf conditions are influenced by the osmotic “sugars”, “salts” (a broader category than our table salt reference) & temperature. Different plants cope in relatively less impacted ways to these influences.

Tropical plant leaves are challenged by abundant moisture. Their special need is to have leaves which interact water (hydro-phobic) & they exhibit variability among different kinds of plants in regard to how thick their hydro-phobic barrier can become; those with relatively thinner barriers are less hydro-phobic.

Our human understanding of getting wet in the rain lead us to believe plant leaf interactions with rain is about shedding water. This is not actually what is involved in the results original post reported: some tropical plants in eCO2 exhibit different out comes.

It is ethylene plant hormone (phyto-hormone) in tropical leaves which has a relationship to tropicals benefiting from of thicker, more hydro-phobic leaves. In the most simple explanation the benefit is due to how it affords more out-gassing of ethylene.

So, back to the confluence of eCO2 increased leaf “sugar” osmotic influence, variable genetic response to “salts” & temperature. When the leaf interior compartment level of oxygen (O2) is relatively low then the plant produces more ethylene & under eCO2 this can
happen more frequently when the plant leaves relatively thin.

What we are looking at is that tropical plants benefit if they can move ethylene out from their leaves. The ethylene needs to diffuse out through the kind of internal leaf conditions different kinds of tropicals present. When relative O2 levels inside fall that triggers more local ethylene production.

In plain language when there is an ethylene build up inside tropical leaves it inhibits elongation. Ethylene & auxin ‘cross-talk”, so when gibberellin phyto-hormone synthesized in young leaves tries to boost leaf expansion it is less effective. This is since gibberellin’s action of boosting auxin transport to the site is counter-manded when local ethylene levels are high (because the ethylene isn’t gassing out & away as quickly as it might – that ethylene ratio to auxin impacts what leaf might do).

April 2, 2021 12:11 pm

Since forests are always in some state of succession/change, blaming any change on CO2 seems irrational

Smart Rock
April 2, 2021 12:26 pm

“Models” again. Really, if this study was deemed important, why couldn’t they grow some of these tropical trees in a controlled environment (i.e. a real greenhouse) where they could change CO2, water, temperature and light to precisely specified levels. They could change one of the environmental constraints at a time and see which factors led to what changes in plant morphology. It might take some actual work, and it might take several years, but they would have REAL DATA, instead of model outputs where the models reflect their original assumptions at the start.

Nah, that’s too much like hard work. Besides, hands-on science is soooo twentieth century! Let’s just stick with the models and pretend we know what we’re doing.

Laws of Nature
April 2, 2021 12:53 pm

Hi Anthony and Charles,

sorry, I dont know where else to ask this, but what is going on with the UAH temperature this month?
Actually, I am curious more generally, how can it oscillate so much between months at all? Didn´t they get the memo that climate changes on decadel time scales!? 🙂

Reply to  Laws of Nature
April 4, 2021 10:56 am

Variations in cloud cover over a 2-3 days and advection (weather fronts) over 1 to 3 weeks, and sea surface temperature over 1-3 months bounce the surface temperature up and down randomly. Consequently the monthly averages show the randomness of surface temp. “Monthly” is about the worst possible choice one could make to perform a root cause analysis.

Last edited 1 year ago by DMacKenzie
Climate believer
April 2, 2021 1:11 pm

“The simulations included one or two species of broad-leaf evergreen tropical trees, such as wild cashew and Ecuador laurel.”

I believe there are around 500 species of tree on that island.

“this work really sets up some best guesses…”

That’s some serious guessing guys.

April 2, 2021 2:39 pm

In the days of the dinosaurs, Earth had a richer amount of oxygen and CO2.
This helped make animals and plants bigger.

April 3, 2021 3:56 am

More co2 means more plants, more oxygen and more food. Net gain, zero downside.

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