Yale E360 - With CO2 Levels Rising, World’s Drylands Are Turning Green "But scientists warn this added vegetation may soak up scarce water supplies."
Jon Schull
By Fred Pearce
https://e360.yale.edu/features/greening-drylands-carbon-dioxide-climate-change
Didi Pershouse
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rob de laet
Didi Pershouse
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Anastassia Makarieva
Didi Pershouse
- Vegetation generally builds soil's porous structure, and over time, it builds the structure deeper and deeper, so that more vegetation creates more capacity for soil to hold water in what is essentially a larger and larger in-soil reservoir.
- Vegetation reduces soil surface temperature, and reduces evaporation from the soil surface (though this may be offset by increased transpiration?).
- And vegetation (especially complex multi-story vegetation) dramatically slows winds, which are drying.
Jon Schull
Most kind to copy me in. Thanks.Perhaps you know Dominick Spracklen's work in this area, which I report (along with flying rivers in Brazil) in my book A Trillion Trees. A Trillion Trees: How We Can Reforest Our World by Fred Pearce | Goodreads--Fred
From: rob de laet <robd...@yahoo.com>
Sent: 17 April 2026 14:11
To: EcoRestoration Alliance <ecorestorat...@googlegroups.com>; Jon Schull <jsc...@gmail.com>
Cc: pearc...@hotmail.co.uk <pearc...@hotmail.co.uk>
Subject: Re: [ERA] Yale E360 - With CO2 Levels Rising, World’s Drylands Are Turning Green "But scientists warn this added vegetation may soak up scarce water supplies."
Hart Hagan
Thanks for this great thread.
This article is being discussed: With CO2 Levels Rising, World’s Drylands Are Turning Green - Yale E360, by Fred Pearce.
Fred Pearce is author of A Trillion Trees, which is well worth reading. He is cited as an authoritative source in How plants cool the planet - YouTube, by Jimi Sol, sponsored by EcoRestoration Alliance.
Pearce's book is informative, well written, well organized and covers all the key issues related to protecting our forests.
He does an excellent job of explaining the biotic pump, including a colorful story of how a Cessna pilot measured the Brazilian rivers in the sky.
I take issue with his analysis of wildfires, a topic for another day, but I feel justified in leaning on his authority that forests regenerate themselves with greater success than "tree planting" efforts. Pearce shares my skepticism of such projects, as demonstrated in this article: Phantom Forests: Why Ambitious Tree Planting Projects Are Failing - Yale E360.
The article … With CO2 Levels Rising, World’s Drylands Are Turning Green - Yale E360 … explores whether plants are growing more due to additional CO2, and whether this additional growth might be drying out the landscape as some of the plants absorb and transpire more than their fair share of water. If so, to what extent is this trend a cause of desertification?
Notwithstanding my appreciation of Pearce’s other work, I find this article somewhat tiresome, mainly because it majors in minors and ignores major causes of warming and cooling and major causes of hydration and desiccation.
For example, see here:
“This supercharging of plant growth seems unlikely to be short-lived if fossil-fuel burning causes atmospheric concentrations of CO2 to continue rising.”
This sentence and the article as a whole attribute all warming to CO2, and none of it to the absence of vegetation or water cycles.
By contrast, this article found that temperatures in the Eastern US are 1 degree celsius lower as a result of reforestation over the last 100 years.
So there is scientific support for the notion that vegetation creates a cooling effect locally and regionally.
And it’s not hard to take a laser thermometer and record a dramatic difference in surface temperatures when comparing bare ground with vegetation of any type. 30-50 degrees Fahrenheit difference is not unusual.
The mainstream climate conversation hardly acknowledges the easily observable difference in temperatures caused by the presence or absence of vegetation. This is an important omission that virtually defines the mainstream climate movement. Higher temperatures come from greenhouse gases, not surface temperatures, or so we are told.
The article has little to say about human activities that tend to eliminate vegetation, such as logging and industrial agriculture, which cause obvious and avoidable losses in vegetation.
This paragraph is an example:
“Myneni’s subsequent statistical analysis suggested that some 70 percent of this global greening could be attributed to CO2 fertilization. Other factors included local changes in nitrogen deposition from air pollution, rainfall, and land cover.”
“Pollution” seems worthy of mention, but is it more impactful than logging? Or how about chemical intensive industrial crop farming, with heavy tillage and agrochemicals.
How much “global greening” would we see if the public were allowed to place meaningful limits on logging? Currently the timber industry decides when and where to log, since they have captured both government and the media.
And how much “global greening” would we see if farmers were encouraged to use cover crops, instead of leaving soil bare? A simple change in public policy would make this happen.
Here is another example of majoring in minors:
“Why did past predictions of rampant desertification prove so wrong? One reason, says Evans, is that researchers came to believe that their standard measure of the dryness of the atmosphere, the aridity index, would reliably predict the potential for vegetation to grow.
There’s no discussion of the potential for humans to green deserts, as demonstrated in these videos, most of them featuring ERA members:
How the UN is Holding Back the Sahara Desert (Andrew Millison)
How to green the world's deserts and reverse climate change | Allan Savory
The California Wildfires Won't Stop Until We Do This (Zach Weiss)
How Rain Gardens Make Streets Greener & Reduce Flooding (Brad Lancaster)
Thinking Like Water - Docuseries Trailer (Bill Zeedyk)
Humans can create deserts or oases. Mainly we create deserts. That could change, if we got control of industry. Not to micromanage, but to place meaningful limits on business activities.
But what do you make of “science” that narrowly focuses on CO2 and ignores the more direct ways in which human activities make the landscape better or worse, hotter or cooler, wet or dry.
Canadian scientist Vaclav Smil did a biomass inventory and concluded that humans have eliminated about half the biomass (the total weight of living things) by about half in the last 5,000 years.
You can’t do that without eliminating a lot of plants, because most biomass above ground consists of plants and trees, and most of the rest (e.g., animals, fungi, bacteria) depend on the plants.
One of our main tasks is to stand against carbon tunnel vision, because it diverts attention from myriad human caused harms to the natural world that are more direct, more preventable and (arguably) more impactful than greenhouse gases.
Hart Hagan
Also, for those that get this, I notice that when copying my emails on this to ecorestoration alliance, they bounce back. So I guess none of them reach this wider audience...--Fred
From: Fred Pearce <pearc...@hotmail.co.uk>
Sent: 18 April 2026 10:04
To: Hart Hagan <nhh...@gmail.com>; Jon Schull <jsc...@gmail.com>
Cc: rob de laet <robd...@yahoo.com>; EcoRestoration Alliance <ecorestorat...@googlegroups.com>
Subject: Re: [ERA] Yale E360 - With CO2 Levels Rising, World’s Drylands Are Turning Green "But scientists warn this added vegetation may soak up scarce water supplies."
Incidentally, I well recognise the Barnes paper about reforestation in the eastern US offsetting global warming over the past century. I cite it in a film in which I appear (and which I researched) for the American Hardwood Export Council. (They contacted me to work on the film, after reading A Trillion Trees.) The film is here: American Hardwood Export CouncilAnd my blogs for them mention the paper too: Fred Pearce | American Hardwood Export Council--Fred
From: Hart Hagan <nhh...@gmail.com>
Sent: 18 April 2026 03:15
To: Jon Schull <jsc...@gmail.com>
Cc: Fred Pearce <pearc...@hotmail.co.uk>; rob de laet <robd...@yahoo.com>; EcoRestoration Alliance <ecorestorat...@googlegroups.com>
Jon Schull
invitation sent
Hart Hagan
When Anastassia was presenting in my class How Trees & Forests Shape Our Climate, she offered this analysis. Anastassia, please correct me if I get any of this wrong.
How do plants get blamed for the loss of water?
Imagine three watersheds:
Watershed #1: There is little or no vegetation. Therefore, when it rains, all of the rain flows back into the streams.
Watershed #2: There is some vegetation, maybe even a substantial amount of vegetation. But there is not enough to activate a biotic pump. When it rains, the plants soak up much of the water and transpire much of it out of their leaves. But the plants are not bringing any more rain. Therefore, the streams get less water. Arguably, the plants are depriving the streams of water they would otherwise receive.
Watershed #3 is a mature or old growth forest. It is big enough and mature enough to activate the biotic pump, which, by definition, brings more rain. Under these circumstances, the vegetation serves to bring more water to the watershed and provide the streams with more water.
I assert that when people say plants take more than their fair share of water, we are talking about an area similar to Watershed #2. This is the type of watershed that has plants, but not a functioning biotic pump.
I do NOT think it follows that plants should be blamed for this problem. It’s not a plant problem. It is a management problem. For whom and by whom is the watershed being managed? For what purpose is the watershed being managed?
Are these plants growing in a farm, or a forest, or an urban landscape? If it’s a farm, is it regenerative, or conventional, or somewhere in between? If it is a forest, is it being managed for wildlife habitat, or for timber? If it is an urban landscape, is it being managed to conform to a rigid industrial aesthetic? Or is it being managed to provide habitat for bees, butterflies and birds?
Farms, forests and urban landscapes can be managed to serve as a sponge, soaking up rainfall. Or not. Farms can be planted on contour or designed according to a keyline method, which captures rainfall.
Farms can be managed according to Gabe Brown’s Five Principles of Soil Health so that they capture rainfall and release it gently into the streams. Or they can be heavily tilled and subjected to chemical fertilizers and the worst practices of industrial agriculture, in which case most of the rainfall will run quickly into the storm drains, carrying tons of topsoil per acre.
Walter Jehne and Didi Pershouse have spoken, written and taught about how the soil can become a sponge to soak up rainfall.
Alejandro Carrillo has demonstrated how holistic management of livestock can turn a desert into a place that is still a desert but experiences an increase in rainfall and hosts a rich and diverse community of plants and wildlife.
Under these circumstances, plants and animals serve to improve the soil and capture more rainfall. In a degraded desert, what little rain comes, usually turns into a flood and is lost before it can do any good.
Also, Alejandro has discovered a way to reduce the mesquite trees in his northern Mexico ranch. Mesquite has a reputation for stealing water and some work to eliminate it using toxic chemicals. But somehow, for reasons I do not fully understand, Alejandro’s livestock management methods have created a landscape where the mesquite gets crowded out by a diverse, mostly native, plant community.
Back to our three types of watersheds. Remember that Watershed #2 has a substantial plant community, but not a biotic pump.
Is it not true that a watershed like Watershed #2 can contribute water to the watershed? I don’t think you need a biotic pump to contribute water to the watershed.
Watershed #2 can be a sponge, soaking up rainfall. Plants capture rainfall because rain clings to their leaves and branches. Also, plants improve the soil, increasing soil organic matter and increasing water infiltration rates, so that when it rains, the rain soaks into the ground and stays there to feed plant life and the soil food web.
Remember the five videos that I shared with you in a previous post. These are all stories about people improving the land and capturing rainfall.
How the UN is Holding Back the Sahara Desert (Andrew Millison)
How to green the world's deserts and reverse climate change | Allan Savory
The California Wildfires Won't Stop Until We Do This (Zach Weiss)
How Rain Gardens Make Streets Greener & Reduce Flooding (Brad Lancaster)
Thinking Like Water - Docuseries Trailer (Bill Zeedyk)
I submit to you that plant communities can be managed to soak up rainfall and contribute water to their watersheds, even if the biotic pump is not working.
The biotic pump is vital. That’s why forest protection is so important. That’s why I write articles like this in my passionate, if humble, attempt to protect our forests.
Mature Forests Resist Wildfire, Because They Hold More Moisture
What Do Our Forests REALLY Need? Hint: It's not what they tell you in the news
But the biotic pump takes decades or centuries to develop. We need to protect our forests so that they can keep the biotic pump if they still have it. And we need to protect the forests that do not yet have a biotic pump but will in the future if allowed to mature.
In the meantime, we can manage our farms, forests and urban landscapes in such a way as to capture rainfall. It’s not hard. It does require some time and attention, but nature does most of the work.
To view this discussion visit https://groups.google.com/d/msgid/ecorestoration-alliance/30d05ce8-ecac-49f8-b741-c52a8c94535an%40googlegroups.com.
Judith D. Schwartz
Mongabay: While many advocate tree planting, some say additional trees can deplete moisture due to transpiration. What is the story?
Anastassia Makarieva: In a study now under review, we found it depends on whether the surrounding air is wet or dry. Imagine a very dry atmosphere and a small tree plantation transpiring at the expense of limited soil moisture. It becomes more humid, but far from the saturation needed for condensation. If there is no condensation, this transpired moisture is likely blown away by horizontal winds. Here, tree planting would only worsen the aridity, with competition for limited water among local stakeholders. This scenario is widely discussed, and in China it is seen as setting a limit on eco-restoration.
On the other hand, if a native forest evolved in the context of local climate conditions, trees “wisely” transpire when the atmosphere is sufficiently moist. This added transpired moisture leads to more vigorous heat transfer, precipitation and moisture transport. The forest receives more water than it has expended for transpiration — and all life benefits from greater water availability.
Sheil, Douglas
Sent: Saturday, April 18, 2026 5:36:24 PM
To: EcoRestoration Alliance <ecorestorat...@googlegroups.com>
Neal Spackman
Hart Hagan
Anastassia Makarieva
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