To Save the Planet From Global Warming, Turn the Sahara Green

By Eliza Strickland | September 15, 2009 5:11 pm

eucalyptusA team of researchers has come up with a simple plan to halt global warming: All we need to do is turn both the Sahara and the Australian outback into vast, shady forests.

While that might sound so ambitious as to be absurd, the climate scientists say the project would be no more expensive or technologically challenging than some of the other geoengineering schemes that are currently under discussion. And researcher Leonard Ornstein says it would certainly get results. Ornstein says that if most of the Sahara and Australian outback were planted with fast-growing trees like eucalyptus, the forests could draw down about 8 billion tons of carbon a year–nearly as much as people emit from burning fossil fuels and forests today. As the forests matured, they could continue taking up this much carbon for decades [ScienceNOW Daily News].

The study, published in the journal Climatic Change, proposes huge desalinization plants on the North African and Australian coastlines to convert sea water to fresh water, and a system of aqueducts and pumps to move the water inland. The young forests would be nourished with drip irrigation to prevent water loss through evaporation, and the sandy wastelands would chang into endless groves of heat-tolerant, tropical trees like eucalyptus. All that water engineering would come at a steep price–about $2 trillion per year–but the researchers say that cost isn’t much more than the projected cost of capturing all the carbon dioxide emissions from the world’s power plants and burying them deep underground. They also note that carbon capture and storage technology is still untested on the commercial scale, while everyone already knows that forests work as carbon sponges.

But like other proposed geoengineering schemes, the researchers note that planting these forests might have side effects. The increased moisture could trigger plagues of locusts in Africa, just as the odd wet year does now. It could also dampen existing soils, stopping iron-rich dust from blowing off the Sahara and into the Atlantic Ocean, where it nourishes sea life, the study points out [ScienceNOW Daily News].

Related Content:
80beats: If We Can’t Stop Emitting CO2, What’s Our Plan B?
80beats: Architects Propose Fantastic Greenhouses Across the Sahara
80beats: Stone-Age Graveyard in the Sahara Recalls an Era of Lakes and Wetlands

Image: flickr / Phospheros

  • bob

    Plant FOOD trees for EVERYONES sake the world NEEDS FOOD TOO!!!!!!!!!!!!!

  • The Sine

    Eucalyptus trees are food–for koalas.

  • Aldrin A.

    It worked in the Southern California deserts in the 1800s – especially around San Diego County where these things grow like crazy. All we need are koalas to feed on them. Wait…

    Eucalyptus – FYI – are native to the Australian Outback and perfect for this kind of geo-experiment.

  • Christina Viering

    Good idea!

  • John Wilkins

    A caveat: eucalypts are fire producers; they are highly flammable, and will set off large scale wildfires (we call ’em bushfires here – scary things. Imagine the entire visible horizon in one direction aflame), so carbon sequestration may not be all that permanent. On the other hand, they will change the local climate rather quickly, so you might get some adjunct growth, although even here since eucalypt litter is highly acidic, that might not help much.

    Also, the inland of Australia is home to several hundred thousand people who make a living from it, as sparse as it is. And no, I am not referring to cattle stations.

  • Aldrin A.

    I agree with Eucalypts being bushfire threats. This is due more for their growth speed than anything. They can shed their barks at an alarming rate and can litter the forest floor quite quickly.

    I live in and around San Diego and we’ve had two catastrophic bushfires in the last decade due more or less from these Eucalypts. But its a price to pay (the threat) to carbon-balance the atmosphere in a big way.

    Has anyone researched how much Eucalypts absorb CO2 compared to, say a regular oak or pine tree or tropical trees like mangoes? Just curious. Is the bushfire threat weighs more than the supposed benefits? If so then it may not be a practical specimen to use in this sort of thing.

  • Dharma Sanjaya

    If i may recall, eucalyptus leaves are toxic to others but koalas, thus, the soil would be rendered lifeless but for eucalyptus, and to say the least, a homogen forest is not truly a forest at all. It would need a vast amount species’ diversity to create a forest. So, we need another tree i guess…

    We should take extra caution not to create another problem, cos we already have many of them (global warming, overpopulation, massive industrialization, and so on).


  • J

    @Aldrin A: Eucalypts would be a good idea in Australia due to their growth speed as you mention, also because they are indigenous to the continent, and are uniquely suited for the Australian conditions. Although they will burn down every year, as John Wilkins mentioned.

    “…huge desalinization plants on the North African and Australian coastlines…”
    Which, in Australia, will be powered nearly entirely by coal fired power stations, as the Australian government has said “no” to nuclear power stations I believe?
    There is currently a debate over desalinization going on in Victoria, as they are building a plant that will be powered by the brown-coal fired power stations in the Latrobe Valley, some of the most polluting power stations in Australia.

    Someone else will need to calculate whether the plant mass would sequester more CO2 than the power stations emit….

  • Ryan

    This article brushed over a very important point. While it is a fact that carbon-sequestering coal plants on a commercial scale are an unproven technology, so is such a mammoth desalinization and continental irrigation system.

    I’m not saying it’s an awful idea or anything, but it’s probably a lot harder than it sounds.

  • Thomas

    What Dharma Sanjaya says. Eucalyptus forests would be very homogenic, and not truly a forest at all. Although I like the idea, perhaps they can find some other plant. Maybe some smaller bushes to start the project off with. Jatropha? We could get some biofuels then as well.

  • Will

    In order to offset the effects of messing with the planet, we should mess with the planet.

    But no worries! We can introduce birds to eat the locusts and truck sand out to be manually dumped into the Atlantic Ocean. It’s all under control!

  • Bob

    We can’t preserve the existing forests and we’re talking about geo-engineering to create new ones???

  • Overquoted

    Also, that would be altering unique environments on a mass scale. Most forests aren’t simply one plant without accompanying organisms that prey on it. You’d also have to stop the spread of the trees beyond designated zones, so they don’t become invasive species.

    All geoengineering projects have issues like these. I suppose we just have to find the one we’re comfortable with.

  • Niq

    If we stop breeding like a virus, then our we would not have to destroy a beautiful desert with trees.
    More moisture in the air will create even more erratic weather. If a tree is killed or we need more (because C02 levels are rising), then put them with the other trees, don’t go creating new problems somewhere else. We have such a fragile ecosystem, and you cant just try and introduce new species without having a decent understanding on what its going to happen the flora and forna that have evolved to be there.
    what a stupid idea. kill all humans!!!

  • morbo

    @ Dharma Sanjaya:
    “If i may recall, eucalyptus leaves are toxic to others but koalas, thus, the soil would be rendered lifeless but for eucalyptus, and to say the least, a homogen forest is not truly a forest at all. It would need a vast amount species’ diversity to create a forest. So, we need another tree i guess…”

    I can see you have never been in Australia or planted a Eucalypt. The toxicity you refer to is if the plant is ingested, Eucalypts actually provide protection for a huge variety of undergrowth which survives in close cohesion with each other. In fact there are problems in Australia if you remove either the undergrowth or the Eucalypt trees then you eventually destroy the fauna/flora completely.

    Most Australians know that Bushfires are not a problem here. Its only when they encroach poorly designed houses. Its stupid to put conventional houses in bush fire prone areas that creates the problem. If we create large tracts of eucalypt forest then its feasible to design the layout of the forest so it minimizes long fire lines.

    Large areas of inland Australia are below sea level so it would be a good idea to flood those areas, however they also hold large salt deposits so I see the need to put in salt tolerant plants (something which is a geographical restriction). I don’t see the need for desalination, more to lower the underground water table.

    “…huge desalinization plants on the North African and Australian coastlines…”
    Which, in Australia, will be powered nearly entirely by coal fired power stations, as the Australian government has said “no” to nuclear power stations I believe?

    Better to say to both as Nuclear is too expensive and all the cheap reactors are too hazardous, Its bloody obvious that if you build a desalination plant in NT then you have access to the best tidal power in Australia, baseline power too with the tides up there, Use the no moving parts pressurized cylinder or toroidal tidal generators would be a good solution.

  • Nomad

    I find it ironic that an objection to this plan might be that it is “messing” with the planet. Every take a flight over any developed country? It is much too late to worry about keeping things “pristine.”
    Naturally, because of the flammability factor, Eucalypts may not be the best choice. I know that Bamboo has a very high respiration rate and can be used as a material which would aid in carbon sequestering. Of course, it is unlikely that bamboo would be possible in the Sahara but there are many areas that bamboo forests might be used. Jatropha Tree is a great idea too.
    I was also wondering if we could skip the desalination process and simply create large areas of salt production, using the sun to evaporate sea water. It would require some calculation on wind directions and an analysis of the potential consequences. Isn’t this a bit better than doing nothing or having an umbrella in space??

  • whatever

    @Plant FOOD trees for EVERYONES sake the world NEEDS FOOD TOO!!!!!!!!!!!!!

    The world needs less mouths to feed.
    Feeding overpopulation is the root of most of these problems.

  • Gecko

    So OK – Plant up all those areas with trees & build the massive desalination plants…
    How long do you think it will be before someone thinks…
    What if we cut down these trees & planted something else here instead… hmm…
    And then built some roads, town & cities, power plants, factories…

  • Matt Newman

    How about we stop cutting our natural forests down???

  • Shaking head

    @ niq….. Hitler tried that dude… He lost

  • samantha

    bush fires are not a problem with a eucalypt. They regenerate themselves after a fire from their lignotubers. Fires actually keep a eucalypt forest healthy because they stimulate new growth.

    that’s why the trees have evolved to be so incredibly flammable. It works to their benefit. And yes, a eucalypt forest is a forest, no matter how homogenic, because life finds ways into all those niches. No matter what. This tree is just a special case because it is so singularly good at living in Australia, that it often forms forests of itself.

    This is a great idea. But those desalinization plants need some other power source. That’s the only problem I see.

  • YouRang

    Desalinization. I’ve often wondered why the Israelis don’t build a tunnel from 700 feet BELOW the Mediterranean Sea to 500 feet ABOVE the Dead Sea and use the natural hydrostatic pressure to reverse osmosis generate water. (~20 atmospheres =700 feet is what is needed to generate reverse osmosis.

  • poopie

    It seems we are swirling around in the toilet already. The Earth is in the process of flushing us. It makes sense to drop a big log in the toilet to clog it and keep us all from going down.

    There was some other genius who talked about pumping sea water directly on the sand to grow harvestable edible algae. The Hersheys Squirts effect might as well have been the name.

    Lastly are the half measures- Green things like painting your roof white to reflect light, or rooftop gardening. These are the Sharts.

  • Skogie

    Wouldn’t it be easier to divert the Missouri River into the Desert Southwest of the United States?

  • Bill Gipson

    Guess you dorks have forgotten the reason it’s not green there now.. It never RAINS and sand is not the best SOIL!!!

  • Philip Thomas

    The Paulownia Tree is a far better bet than Eucalyptus. It is very fast growing, develops a very deep root structure after 2 to three years of watering so becomes virtually self suffient. The leaves provide for cattle food, or nutrition for the tree if left on the ground. The timber is a high quality, rot proof hardwood suitable for furniture, plywood, log-cabin construction etc. Finally, it can be harvested after 5 to 7 years and will then regenerate from the existing root structure.

    Researchers seem to be missing something don’t you think?

  • greg coxson

    The U.S. Peace Corps has been trying to keep the
    Sahara from growing southward. One of their
    key methods — replace eucalyptus with forms
    of tree that use less water. West African
    countries like growing eucalyptus because it is
    a hardwood tree and they can use the wood for
    export. But the eucalyptus use a lot of water,
    not a good property to have in water-poor areas.

    GEC, Olney, Maryland

  • tadchem

    Replace high-albedo (light-reflecting) desert sands with low-albedo (light-absorbing) forests? That would not have the supposedly desired effect of “cooling.”

  • Mel

    OR WE COULD JUST STOP CUTTING TREES DOWN???? Am I on crazy pills??!!!!

  • Timothy

    The best part is there will be no unintended consequences. Modern science, you see, can perfectly predict the effects of converting two of the planet’s largest deserts into rainforests, and those effects will be a net positive for everyone.

    It’s just like state-run healthcare in that way.

    And don’t worry about the cost; all we have to do is confiscate a bit more from your neighbors, which they will hardly even notice on top of everything else, and besides which it’s for their own good. Heck, if we let people keep their own money, they’d just waste it on things like fatty food or private school tuition.

    We needn’t hear any arguments from dissenters, who are by definition global-warming deniers, and quite possibly racists.

  • Tony

    Mel, Timothy,

    Couldn’t have put it better myself 😉

  • Dusty

    Why not just encourage people to plant more trees around the world, and require towns and cities to do more planting?

  • http://NA Matthew

    American’s and their idiotic ideas…

    Ah-hu, as an Australian i can tell you there’s absoultely no chance this would happen or work. One thing worth considering is eucalyptus trees are highly flamable, they’re so prone to bush fires and volatile that you wouldn’t want thousands of these things stacked up against one another. In a dry and windy environment like a desert, combined with highly flamable trees, if a fire ever started you’d never get it under control. That in turn would then release all of your precious carbon emmisions.


  • Rupaul

    Wasn’t the Sahara considerably smaller, at some point in the historic past?

    The American Southwest desert was smaller before the land was overgrazed by beef cattle.

  • Jockaira


    Wouldn’t it make more sense to control our population problems? Or maybe to use that money to buy up large tracts of rain forest in Brasil, Indonesia, Africa, etc…hire professional soldiers with guns to patrol the areas, prevent deforestation, and bribe respective government officials to make sure it happens right?

    It could be the establishment of an entire new profession, Forest Guardian, and welcome income for many third-worlders. Income from regulated logging would be enough to fund this project completely.

    Vast water projects featuring desalinization and long-distance transport are very likely to have unforeseen, expensive, and catastrophic effects…better to make do with what we have.

  • Kate

    This is the composition of air:

    Nitrogen — N2 — 78.084%
    Oxygen — O2 — 20.9476%
    Argon — Ar — 0.934%
    Carbon Dioxide — CO2 — 0.0314%
    Neon — Ne — 0.001818%
    Methane — CH4 — 0.0002%
    Helium — He — 0.000524%
    Krypton — Kr — 0.000114%
    Hydrogen — H2 — 0.00005%
    Xenon — Xe — 0.0000087%
    Ozone — O3 — 0.000007%
    Nitrogen Dioxide — NO2 — 0.000002%
    Iodine — I2 — 0.000001%
    Carbon Monoxide — CO — trace
    Ammonia — NH3 — trace

    Does anyone really believe that altering 0.0314% of the air is going to make a blind bit of difference to the Earth’s climate?

    The Earth is cooling, not warming. The Arctic is growing and spreading. Don’t believe all that hysterical nonsense about the Arctic melting away. They always say that at the end of the Arctic summer, which is May-September.

    As for “fighting climate change” – good luck with that. My money is on nature, the sun and the natural cycle of weather events. Carbon dioxide and human beings have as much influence on the climate as a raindrop in the sea makes it less salty.

  • ahmed the terrorist

    Already I can tell you that in the Sahara it won’t be possible because of political problems : the tuarag tribes are “the people of the desert”, they are violent and armed, and they certainly won’t accept to have “their” desert transformed in an eucalyptus forest (with or without koalas) and they would set fire to it…besides there is also sporadical Al Qaida activity there.

  • Steve The Desal Engineer

    ‘Desalinization’……what a mouthful, why not use ‘desalination’ like the rest of the World (and the desalination industry)?

  • I

    see comment 12 (There may be more, I stopped reading them). Why should we disrupt an ecosystem when we have places like the Amazon rainforests that are being butchered on a daily basis. Find ways to stop that and replant all these forests that have been destroyed and you don’t need to geo engineer anything new, nor would our wait time be so long.
    If people start trying to make deserts green, we will destroy what are really the only habitats that we haven’t screwed up yet.
    Wow. Go humans in your infinite wisdom…

  • Shaking head


  • Rick

    One reason the middle east and the sahara are deserts is humans in the first place. Why not make the deserts bloom?

    We should be planting more trees, and working on ways to farm less ‘single’ crops. Microbiology, biology… the first step is to learn how to isolate something, and successfully grow it, but this should only be the first step… huge forests of one type of plant is doomed to fail.

  • Stevo

    @Sina I think you are on to something.. if we plan Eucalyptus trees, and then seed the forest with Koalas, we could eat the Koalas! Thus solving the food problem! Everyone agree? Good.

  • Stevo

    oops.. I meant @SINE

  • Frank

    Kate- instead of reciting your chem 101 book to show your smarts, why don’t you take a boat to the North Pole, and jump in the water.

    How can we have an productive discussion if, oh to hell with it….

  • Andy Cunningham

    At last. We can control the weather. Who would have thunk it?

  • Cyril

    18th Sept. 2009
    Plant a tree for each tree cut down. In London, where I live, I have seen
    thousands of trees demolished every day but not replaced any where. Make it compulsory to replace every tree cut all over the world.

    Builders should be encouraged to build houses in the trees.
    Tree houses, walk ways in the trees, more fun for children and grownups.
    No need to go into the deserts to plant more trees. Do it where they can grow easily.
    Grow more fruit trees to supplement food problems.
    No need to use sea water. Use under ground water and Re-cycle water. Each household should have a water cleaning system.
    These type of steps are easy for each person in our world and certainly would cost less.
    People of today have forgotten their duties in pusuit of their Rights.
    Tell them that you have to fulfil you Duties in order to have your Rights.
    Easy no brainer idea.

  • Andy

    So what happens to the carbon when the trees die? The tree rots and the carbon is released back into the air. It hasn’t been permanently captured. And if you burn the forest it would get released faster. It seems the reason CO2 levels are increasing is because we are injecting locked-away carbon from underground into a closed system. To bring down these levels we would need to permanently remove the CO2 again. This scheme doesn’t seem a ‘fix’. Any climate specialists out there that can confirm this?

  • Mike S

    Great ideas, now all we have to do is stop spending so much on wars so we can afford it.

  • Henry Gurwood

    As far as the Sahara is concerned, it might be a big help if the inhabitants could be persuaded to breed a lot fewer cattle and especially goats. I gather they are very destructive to wild plants, eating every little shoot they come across, and greatly assisting the rate of desertification.

    I don’t have any suggestion as to how they could be persuaded! But these North African and Arab countries do seem to be very big on cattle for prestige as well as just for food.

  • cameron

    The solution to a problem that might change the face of the planet is to…. change the face of the planet. Ingenious!

  • http://Dailymail john

    So what happens if we plant these millions of extra trees, they take the extra carbon out of the air to a so called proper level what do we do then??, cut them down??? because if too much carbon creates warming then surely if we don’t get rid of the trees they will continue to reduce the carbon in the atmosphere thus having a possible rapid cooling effect and other ice age. This is a theory I have read that caused one of the ice ages ie too much vegetation= less carbon = rapid cooling = ice age

  • R,G,Horne

    would not it be far better and cheaper to stop the burning of the brazilian rain forest ? and replant all the trees which have already been cut down,

  • Ray, Liverpool

    Won’t catch on, I’m afraid. No money in it for big business and not enough reasons to take taxes out of peoples’ pockets. That’s what’s important.

  • Ray, Liverpool

    KATE!!! At last a kindred spirit!!! Well said.

  • Toothbrush

    We don’t even need to bloody discuss whether this bleeding idea would or would not work. Hands off the outback. It is a beautiful, wild place. Planting a forest would deface the outback, just as cutting trees down defaces forests. Stop the madness. Geo-engineering can win the award for the most self-absorbed of all half-baked ideas thought up by debilitated brains.

    Less people, less consumption, more eyes opened. That’s all we need, but it ain’t gonna happen.

  • JBB

    So…If these trees are such a great thing for geoengineering, and they’re native to Australia, why is so much of Australia a forbidding desert? And if we’re worried about changing the climate having bad effects nearby, why don’t we do a proof of concept where it’s “safe” (by which I mean ‘more natural’), in Australia where the trees are native? Why are we talking about the Sahara? ’cause it’s a more famous desert?

  • Tr

    Education, individual responsibility, cultural shifts…all necessary for helping the planet heal. And at least with that simple formula, much is being done.
    Until local governments have the courage to stop destructive tendencies of clear cutting to build houses, malls, and ever more roads…..we’ll continue to see the effects. Individuals have the power of their purses and communication. If everyone spoke up to local, regional, national and international entities with their outrage, concern and commitment, again things will change more quickly.
    Every choice we make as consumers has an enormous impact.
    We influence EVERYONE and EVERYTHING we touch in our daily life. If we clean our own act up, it will effect things most in a positive way, especially our own mind/heart.
    We need to confront the tendencies at cause and effect to get the rate of change/protection/appreciation we need.

  • Acteon

    >Guess you dorks have forgotten the reason it’s not green there now.. It never RAINS and sand is not the best SOIL!!!

    It does not rain often because there is no much water to evaporate above the desert but it does rain above the desert:

    Often when it does rain on a desert, the soil produces so much heat that it evaporates the rain before it hits the ground. Having a forest would cool the soil.

    Plants that survive in the Gobi, Sahara, Austrialian and South American Desert should be chosen. It would be best to use solar and wind energy to power the desalinization plants. As the forest grow, rain would start to fall over these areas.

    The mulch from falling leaves and dead trees will cover the ground and help preserve the humidity in the soil.

  • Uncle B

    Where is the great evil whore corporation Monsanto when we need her! Green, less flammable plants for the hillsides of California would be nice! A plant that could invade and lessen deserts over time ? A “Kelp” that yields nitrogen fertilizers, to clean the gulf of Mexico? Plants that bio-degrade and trap the great plastics gyres of the oceans? What? No great leverage in those products? no promise of astounding ROI, international control? Not CIA evolved Awe! Fvck! I thought I had such good ideas!

  • Bryce

    I’ve heard Sahara was once green… even wetlands, and that theyve found fossils of like prehistoric crocodiles in sahara, though I may be wrong. So why don’t we just try to replant it, even if we just do it square metre by square metre untill it can sustain itself. It may take a long time but it’s a hell of a lot better than what we’re doing now ain’t it (which is alot of talking, much like this discussion)

    Also I think somebody said that the desert reflects heat while forests absorb it, to them i say… take your shoes off and walk through it, then say how much it reflects the heat.

    By the way don’t tell me I’m stupid because I already know I don’t know a hell of a lot about all this, just a few suggestions.

  • Darci Thompson

    So, couldn’t we divert the excess ocean water caused by glacial melting into a system whereby we could capture the power of the water movement and use that to actually fuel a desalination plant? (The movement of this water would probably also create higher wind that could be captured with clean energy windmills.) Then, use this desalinated water to maintain newly planted trees native to the areas in which they are planted? This way, we don’t further bastardize yet another ecosystem (esp a light reflecting desert) and put additional CO2 filtering trees closer to the areas where we are dispensing the pollution?

    Seems like a no-brainer to me, but I am not a scientist. I am sure I’m missing something here…


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