FORESTS AND RAIN: Cutting down the trees in Kenya may have led to less rain locally.
Image: Neil Palmer (CIAT)
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In the last 15 years 200,000 hectares of the Mau Forest in western Kenya have been converted to agricultural land. Previously called a “water tower” because it supplied water to the Rift Valley and Lake Victoria, the forest region has dried up; in 2009 the rainy season—from August to November—saw no rain, and since then precipitation has been modest. Whereas hydropower used to provide the bulk of Kenya’s power ongoing droughts have led investors to pull out of hydro projects; power rationing and epic blackouts are common. In a desperate move to halt environmental disaster by reducing population pressure, the Kenyan government evicted tens of thousands of people from the land.
Severe drought, temperature extremes, formerly productive land gone barren: this is climate change. Yet, says botanist Jan Pokorny of Charles University in Prague, these snippets from Kenya are not about greenhouse gases, but rather the way that land-use changes—specifically deforestation—affect climate; newly tree-free ground “represents huge amounts of solar energy changed into sensible heat, i.e. hot air.” Pokorny, who uses satellite technology to measure changes in land-surface and temperatures, has done research in western Kenya for 25 years, and watched the area grow hotter and drier. The change from forest cover to bare ground leads to more heat and drought, he says. More than half the country used to be forested; it's now less than 2 percent.
Each year Earth loses 12 million to 15 million hectares of forest, according to the World Wildlife Fund, the equivalent of 36 football fields disappearing per minute. Although forests are ebbing throughout the world, in Africa forest-climate dynamics are easily grasped: according to the United Nations Environmental Programme, the continent is losing forests at twice the global rate. Says Pokorny, the conversion of forest to agricultural land, a change that took centuries in Europe, “happened during one generation in western Kenya.” Pokorny's work, coupled with a controversial new theory called the “biotic pump,” suggests that transforming landscapes from forest to field has at least as big an impact on regional climate as greenhouse gas–induced global warming.
After all, de-treeing the landscape alters the way ecosystems function and self-regulate. For Pokorny, the key is evapotranspiration, whereby plants continuously absorb and emit water in the form of vapor. Evaporation consumes heat and thus has a cooling effect. He calls this "the perfect and only air-conditioning system on the planet." On a moderately sunny day, a tree will transpire some 100 liters of water, converting 70 kilowatt-hours of solar energy into the latent heat held in water vapor. When soil is bare and dry—paved over or harvested—the process comes to a halt. The sun hits and warms the ground directly.
This past November found Pokorny flying a small Cessna from Lake Naivasha up the hills to the Mau Forest, where land surface temperatures in woodlands measured 19 degrees C; agricultural land that until recently had been forest hovered close to 50 degrees C. A photo taken from the air shows the dark green of forests diminish along the slope to the lowlands; the valley has clusters of deep forest green among the broad, pale, geometric shapes of cultivated land. His team measures surface temperature as opposed to the usual air temperature metric, two meters above. The surface “is what you are in contact with, and creates the dynamic movement of air,” he says—and ground temperature “indicates the way solar radiation is transformed at the Earth's surface.” His surveys from above combine three measures: “a normal camera, Thermovision [thermal infrared sensors] and our eyes. In putting the pictures together, we see the high temperatures are where there is no vegetation,” which includes swaths of land where forest has been cut.
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15 Comments
Add CommentSounds like a pretty weak theory. Especially the part about the necessity of it being due to the removal of a "natural forest" or "mature trees".
Reply | Report Abuse | Link to thisWhen will ecologists as well as loggers understand that the rainforests are the species' forests? We must understand that these forests are already occupied by all the other species of animals and plants. There is no win-win solution. We must set aside as much as we can a soon as we can to save this Species' Planet.
Reply | Report Abuse | Link to thisHow is this so hard to understand?
Reply | Report Abuse | Link to this"After all, de-treeing the landscape alters the way ecosystems function and self-regulate. For Pokorny, the key is evapotranspiration, whereby plants continuously absorb and emit water in the form of vapor. Evaporation consumes heat and thus has a cooling effect. He calls this "the perfect and only air-conditioning system on the planet." On a moderately sunny day, a tree will transpire some 100 liters of water, converting 70 kilowatt-hours of solar energy into the latent heat held in water vapor. When soil is bare and dry—paved over or harvested—the process comes to a halt. The sun hits and warms the ground directly."
That 70 liters of water doesn't get put in the air, those 70 kWhrs get added in as heat, and when you multiply that by millions of trees, the effect adds up.
Funny, I thought you'd jump all over this line: "Pokorny's work, coupled with a controversial new theory called the “biotic pump,” suggests that transforming landscapes from forest to field has at least as big an impact on regional climate as greenhouse gas–induced global warming."
I'm going to head off all the other deniers that'll jump in on this article by highlighting that the theory predicts that the impact from deforestation has a large REGIONAL impact, not global. In addition, the impacts from deforestation are felt right away instead of having extra heat trapped by GHGs cycle through the Earth's entire climate system with all its thermal inertia.
A lot of forest is lost due to expansion of land required for the growing of bio fuel stock and more palm oil etc. Anti fossil fuel efforts may end in a much greater problem. Trees thrive at higher CO2 levels and the increased wood production, highly useful, if harvested correctly. We need to manage... and not rush into, more half baked energy policies. GK
Reply | Report Abuse | Link to thisTo the layman, "trees thriv(ing) at higher CO2 levels" may seem to make sense, but, as it turns out, it is simply not the case.
Reply | Report Abuse | Link to thishttp://www.skepticalscience.com/co2-plant-food.htm
You may want to adjust your "half baked" assumptiopns.
It has been common knowledge for decades, not even mildly new or controversial, that deforestation causes desertification. This is a silly debate.
Reply | Report Abuse | Link to thisAlso, woe on SA policy in clamping down on quality debate, good skeptics like Carlye depart and you get stuck with halfwits who are not even worth debating with.
I understand a wariness to rerun the 90’s ridiculous, folksy Creationist debate (or kindergarten food-fight) but the situation is different. That polemic had no scientific solution, being not a scientific discussion but a philosophical one, whereas the Climatic debate is a scientific discussion and can be refuted by citing credible sources and using facts and logic.
Sorry, your SKS site reference is unreliable. I would suggest:
Reply | Report Abuse | Link to thishttp://phys.org/news/2012-06-co2-vegetation-locally-globally.html
"Everyone that’s been to grade school knows that what we breathe out, plants breath in, and vice-versa, thus more of what we breath out, i.e. carbon dioxide (though from another source) should mean more for plants to breathe in, which should indicate better plant growth, more plant growth, or the switch from low level breathers to those that thrive on more CO2 in the air. Higgins and Scheiter suggest at least locally, that it’s the last possibility that might create the most change over the coming decades as the Earth’s vegetation slowly responds to finding more CO2 in the air. The two restricted their area of study to the African continent and found first that because grasses that live in the savannah tend to need less CO2 to thrive than do trees, there are large swaths of the continent that favor savannah, which is demonstrated by the abundance of grasslands with the occasional stand of trees. Adding more CO2 to the mix is likely to change that balance they show, to favor tree growth over grasses, leading to more woodland. They also found that increased CO2 levels also tend to favor grasslands over deserts, which for Africa should mean decreasing desert sizes."
Of course this was one study, of Africa, but grade schoolers could find more, I'm sure.
For actual peer reviewed data on the effects of CO2 on trees, see:
http://www.co2science.org/subject/f/forests.php
Go ahead, pick your tree out of the database. GK
"Everyone that’s been to grade school knows that what we breathe out, plants breath in, and vice-versa, thus more of what we breath out, i.e. carbon dioxide (though from another source) should mean more for plants to breathe in, which should indicate better plant growth, more plant growth, or the switch from low level breathers to those that thrive on more CO2 in the air"
Reply | Report Abuse | Link to thisQuite possibly the stupidest statement I have read in a long time. . . . The allusion is absolutely idiotic, on so many fronts. That you included it in your post speaks volumes of your own intelligence.
I know you didn't read the link I provided; your non-sensical response confirms it.
By your logic, it would be irrational that someone who is able to breathe in air that contains a higher oxygen content would not grow to be eight feet tall and weigh 300 pounds (and be healthy to boot).
Fact is, plants need nutrients and water to be more robust, not just CO2. Use your brain, GK. Regarding these requirements, there has been a shift in the reliable supply of them due to pressure put on local and regional environments by agriculture, and climate change in general.
Sorry, but you have to provide a REASON why skepticalscience.com isn't reliable. That's going to be hard because EVERYTHING they post is backed up by peer-reviewed science. You CANNOT dismiss it just because they present solid science that contradicts with your beliefs.
Reply | Report Abuse | Link to thismossboss hit it on the head on how you probably didn't even read the phys.org paper you posted. I know why you skipped past the first paragraph in the story: it totally demolishes the point you're trying to make!
"In all the talk about global warming as a result of human created CO2 emissions..."
And then you ALSO conveniently left out this part too:
"Throwing a wrench into the whole works though is water, of course, in the form of rainfall. If there is no rain, a desert will always be desert."
http://phys.org/news/2012-06-co2-vegetation-locally-globally.html#jCp
So, the article agrees that CO2 emissions are changing the climate, something quite at odds with your denier position. And the fact that Africa is losing forest at TWICE the global average due to human activity too means that all that extra forest isn't going to materialize, demolishing your silly excuse of a point even further.
AND THEN, you have the gall to link to the fossil fuel-funded co2 "science" dot "org". Its funding has exploded in recent years, growing TENFOLD between 2003 and 2006 from $25,000 to OVER $300,000...only to increase FIVE-FOLD again to over $1.5M in 2009:
http://www.sourcewatch.org/index.php?title=Center_for_the_Study_of_Carbon_Dioxide_and_Global_Change
Seriously, you are either being duped by the fossil fuel companies or are paid to spread their propaganda!
A look back: January 27th, 2047 "40 years ago you published ‘An Anthropic Paradox: Nature stubs her T.O.E.’, a gloom and doom, highly prophetic, Paradox about Nature’s Adaptive, Probabilistic Evolutionary Process going terribly awry, leading to the high probability of the Human Species Extinction Event. The following theory explained the inexplicable: Mankind’s blatant disregard for his environment, his gluttonous misuse of natural resources, his failure to properly identify universal survival threats, and the global-wide apathy that impedes man’s progress toward a Class One Civilization
Reply | Report Abuse | Link to thisThe ‘Anthropic Paradox’: Man’s probabilistic evolutionary process has evolved him into an aggressive, highly intelligent, humanoid animal, capable of fabricating an illusion of his own intuitive-derived, experience-based, instinct-driven subjective reality; and incapable of accepting the counter-intuitive objective reality of an external world.
This synthesized illusion of reality (a hologram in effect) had been well documented in the scientific community. Research in neuroscience had irrefutably proven that the mind actually augmented the crude two-dimensional, blurred afferent images, sounds, smells, and context clues, stimulated our sensory receptors into the sharp, clear, crisp ‘fabricated’ images our minds intuitively projected as reality.
Analogous to the animal maternal instinct, the human mind, then, protected it’s ‘illusion’ of reality by deploying an armory, the Human Psyche’s insurmountably powerful defense mechanisms; first, and most formidable, denial and then, as necessary, rationalization, repression, regression, and dissociation, effectively closing off Man’s mind to the external input of alternate counter-intuitive realities, concepts, or change.
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“Unfortunately, your generation, paid little to no attention to your ‘wild rants’ until the ‘Great Fathom of 2041’. The Western United States and the semi-arid regions from North Dakota to Texas developed drought conditions, what rain occurred, came in tumultuous torrents causing catastrophic flooding, and incalculable economic losses, deaths, and pestilence. The Midwest was once again,the Great Dust Bowl. California’s Central Valley no longer irrigated, transformed into a dry, craggy, desolate wasteland. Food prices soared to unprecedented levels. The entire world, on the brink of a global meltdown…..I awoke with a startle, sweating profusely!
www.rcwormus.com
Strange... Both Moss and yourself seem to be incapable of reading any material, other than the extremely biased and fabricated source known as SKS. The question challenged by Moss was that CO2 is good for trees.
Reply | Report Abuse | Link to thisI clearly showed trees love and thrive with enhanced CO2 fertilization. I used an alarmist site and the main data base for CO2 bio studies - to do so.
Of course those who would rather consider your opinion without any research data, are welcome to the resulting error. You may return to your floundering attempts to link funding to our only database. That is all - carry on. GK
No comment on the paragraph that you originally posted and I quoted, Karst? Typical. . . . Troll, then move on with even more lies.
Reply | Report Abuse | Link to thisHere is another site that shows what the Idso clan is up to with their bogus organization:
http://www.exxonsecrets.org/html/orgfactsheet.php?id=24
Okay, so you only accept models when you THINK their conclusions agree with your BELIEFS. Seriously, deniers talk all this bunkum about modeling not being reliable, but when a probably-not-realistic model has even just a tiny kernel of seemingly pro-denial outputs, you're all over it! I'm not surprised, it's just the usual cherry-picking that deniers HAVE to do just to keep all that ACTUAL scientific proof of the dangers of GHG emissions from ruining your little make-believe world.
Reply | Report Abuse | Link to thisIf trees make good climate, we should support commercial forestry, logging, fruit tree plantations. Legit loggers plant more trees than Greenpeace. More than what they cut. Use firewood for heating and cooking.
Reply | Report Abuse | Link to thisA good research project would be to determine the climate changes from the great changes in East Coast Forests. The 1800s early 1900s logged them off and they have been growing back since. Similar projects would be the logging off and regrowth of the North Central states and the Pacific NW, except there much of the forest has not regrown.
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