Can We Terraform the Sahara to Stop Climate Change? 

I wouldn't normally push Patreon, but with production quantity and quality going up, every bit helps. If you gain value from the content and want to give back in some way, consider supporting on Patreon: www.patreon.com/realengineering (edit: discussion point, should I remove comments of climate change deniers, or let my intelligent audience drown them out?)

How about not transforming rainforests into sahara v.2? Sounds even easier.

If they want to plant that many trees, a Monoculture would be a horrible idea, A minimum of 4 tree species would be needed

Seems amazing that turning a desert into a forest would have negative consequences overall, clearly shows how complex this systems are

It needs to be done in stages: bind clay to the sand, then create hardy grass and shrub land. Only then plant trees. But to be honest , using marine phytoplankton would be a lot faster.

Eucalyptus trees? They are some of the biggest water sucking trees known in the forestry industry. Plus the Eucalyptus tree (aka gum-tree) is highly flammable, hence the incredibly vast and uncontrollable forest fires that often occur in Australia. These trees, while converting Carbon into Oxygen also release a highly flammable oily gas, which hangs in the air around the tree tops and when ignited, burns like petrol! This is also why a Eucalyptus forest fire tends to spread rather quickly, especially at the top of the trees, rather than at the bottom. I am not convinced Eucalyptus is the best option for such a solution. If your Sahara Eucalyptus Forest, catches fire, you'll be contributing to global Warming like no-one has ever contributed before! Another problem with Eucalyptus trees, as mentioned, is their enormous thirst for water. I have seen this with my own eyes here in South Africa where we have a pretty large Forestry industry. Mountainous areas which once had plenty of fresh water springs, have become dry after Eucalyptus Forest have been established on them. Other areas that I have become known to be dry as a kid, suddenly produce sprawling water springs as soon as the Eucalyptus Forests there are being chopped down again. Sadly, only to cause erosion, since the natural flora has been destroyed and cannot be re-established because the Eucalyptus trees have turned the ground acidic. Eucalyptus can be a real problem when taken out of it's natural environment and planted elsewhere. Sure the tree comes from Australia and thus you can use it in the Australian Outback if you want, just be careful when taking it elsewhere. Eucalyptus can have terrible side effects for the ground it stands on and it is probably the most flammable tree we know! For all you know, the Outback could once have been full of Eucalyptus trees a few thousand years ago, only to turn it into a desert after a huge fire. And now nothing else will grow in it's place due to high acid levels in the ground. Since you are the one talking about facts, perhaps you wanna check ALL your facts first, before making such a video, suggesting the possibility of planting Eucalyptus trees in deserts everywhere. I really cannot see how it can be the best tree (or plant) for the job. I am pretty sure there are other plants better suited and even better adapted for this job. Perhaps the Namib Desert can inspire you? It is quite an incredible place and I believe, it is also the oldest desert in the world?

is it just me or did he say that the eukalyptus tree is the habitat for these cute little shits

I could be doing homework and finals but I feel like I learn more from these videos then from school. Keep up the good work.

The Sahara was once green, I watched a interesting documentary that stated the Sahara became a desert due to climate change thousands of years ago. However, it didn't turn into a desert due to a hotter climate but was due to a cooling climate in the area. This caused the monsoons to stop it's yearly rains and created the Sahara desert.

Sounds easier than terraforming Mars as our planet B.

It would be a bad idea to do this with only a single species of tree.

The Australian outback, mainly as a consequence of La Nina weather patterns, periodically floods leading to a temporary but measurable reduction in global sea levels and downward pressure on global CO2 due to vegetation growth. To have a measurable global impact it is likely an additional 4000 Gigaltrs per year would-be required in the Australian outback.

This seems like a complex enough problem that I find it highly dubious all factors have been considered. There would almost certainly be unintended consequences that have not yet been predicted.

Ironically, the Sahara was green with lakes and rivers the last time the Earth's temperature rose.

Find it so funny he calls koalas "These cute little shits."

You had me at "cute little shits"... #BRILLIANT

You can also look at wood char sequestration. You grow trees, char the outside and bury them. It keeps them from breaking down for a long time and takes carbon out of the cycle. You could probably do this with all of the Christmas trees sold each year.

A mono-culture of eucalyptus? That would be horrid for the ecological diversity.

I support this project, i hate sand it's coarse and rough and it gets everywhere....

Great video, but I have some questions: Do we specifically need trees to capture carbon? There are other plants that can capture more carbon with less water, like bamboo and camelina. There are also plants that require large amounts of water, but said water doesn't need to be freshwater, like algae and seaweed, which can thrive in wastewater or saltwater. There's other technologies that may be more profitable, practical or simpler than solar panels or wind turbines. There's the trompe, which can make compressed air using just water and with no moving parts. (Besides the air pressure valves) Then there's a type of engine invented by a Spanish man in the late 1860's-early 1870's which could boil water into steam using a combination of zinc (for some reason), manganese dioxide (as a catalyst) and potassium chlorate (the main fuel, the same material used for percussion caps). The byproducts, from what I understand, are oxygen and potassium chloride (a type of salt which can be converted back into potassium chlorate, and is the major feedstock for potassium chlorate in the first place). I'm not saying that carbon capture is the golden nugget, nor am I denying your research. I'm simply suggesting that the above mentioned technologies may be worth researching.

I born in the African Sahara and I've been living there all my life(30yo now) I'm 100% with the idea of afforestation the Sahara. I've graduated from different Agriculture schools, institutions, and centers I have 3 diplomats right now, All of them were about how to boost agriculture activities and afforestation for a better diversity ecosystem and reducing climate change... But the most and the biggest problem here is the Fundings! who will fund and sponsor that big project cuz NO ONE will invest there with his own money! It's a large scale investment; we're talking about Billions of dollars here. I and my colleagues have been working on that idea but we stopped cuz we had no finding acquisitions and the locals here though we are a bunch of lunatics dreamers. But I'm still believing in the idea every single day and as soon as I get the financial support I'll start right away. Thanks for the video @Real Engineering

Meanwhile, the international community is fairly easygoing with the Amazonian basin being cut down. Weird.

This is an absolutely great idea if only the math works out, but unfortunately it doesn't. Here is why. Most of the calculation is accurate, up until the electricity cost. As was mentioned, irrigation of the Sahara desert using desalination requires 19600 terawatt hours a year, that is roughly the amout of electricity generated in the entire world. Are you seriously trying to convince us it only takes 1.96 Billion USD to generate the whole world's electricity! As a matter of fact, this is the part where you get it wrong, assuming electrity generation cost of 0.1USD per kilowatthour (and I'm guessing this is the figure you are using), it takes a humongous 1.96 Trillion (i.e. 1960 Billion) USD to just generate the amout of electricity required, 1000 times more than your calculation, let alone the money needed to build the required infrastructure. I'm not saying the proposed idea is without merit, but you have seriously downplayed the expense, like 1000 times downplayed. As a engineer myself, I find this miscalculation intolerable, assuming it's a miscalculation, not a number trick, which politicians like to use, not engineers. P.S. 2 million views, why I am the only one to notice this miscalculation, I guess people should look closer at the math. Please upvote my comment so that people can realise this is too good to be true.

Did your CO2 figures for solar panels take into account the amount of fossil fuels required to make them?

I'd recommend everyone to watch "Kiss the ground" on Netflix. It's a documentary that came out 2 days ago which is about Climate change and how land use can impact it. It's very encouraging! One of the best documentaries I've ever watched!

"These cute little shits" This went from professional to funny and back to professional in a second. That was awesome.

3:23 did you just say cute little shits?

What about diversifying and using other faster growing plants like hemp, which could provide a multitude if useful products?

I don‘t understand: if the Amazon rainforest needs the Sahara‘s dust, then what did it look like thousands of years ago when the Sahara was green?

Maybe I wasn't listening well enough but I didn't hear any reference to soil quality and lack of nutrients

can we stop terraforming the good land into desert first ?

And this experiment was set back because of the supremely fire-vulnerable eucalyptus was used, without understanding the other factors needed to build soil carbon, crucial in helping soils sequester water, and reduce wasteful flooding...

Just talk to Tom Nook after completing some tasks in the game, it could take a while.

World: We need to solve OUR Carbon emissions problem *Sees Cost* You got this, right Africa?

What did the Amazon tress and Atlantic plankton to for nutrients during the saharan wet periods?

You need several different types of trees. If you use just one, if a virus for the tree comes around, it could wipe out massive spans of the new forests, among many other issues of going with just one type of tree.

3:23 gotta say, that caught me off guard

This idea of afforestation never crossed my mind, it actually blew it. I am amazed thanks for the videos and keep up the great work.

A: putting solar panels in the Sahara desert is bad because shifting sand dunes would only bury them over time. B: stopping the shifting dunes (drying land) with gravel, dead tree stumps, and clay soils; would be more beneficial at moisture retention than planting trees. C: planting trees that require a lot of water is too expensive. So growing desert shrubs, cactus, and grasses is more economical sound. D: jungle trees in the Amazon get most of their nutrients from moss growing on the branches. So planting more types of bark moss and eliminating parasitic plants would help that jungle. E: spreading animal manure over the pen ocean from factory farms is more beneficial than desert dust. F: if we allow "hot deserts$ to remain uncovered that will keep global temperatures rising. Eventually, the Sahara would erode so much it would turn into marshland/bogland.

I'm from Australia, Eucalyptus is a fire weed. We have massive bush fires from them each year. They drop bark and dry leaves all year round the fires are huge because in the leaves is a highly flammable oil which burns like petrol. We get this from less than 10% coverage of the landmass! California has this problem too as returning soldiers took the trees back in the 1940s. Pick another tree...

Don't eucalyptus trees tend to self combust all the time?

i think we need to replant the amazon first

Australian bush fires say . NO YOU DONT C--T !….. HOLD MY F---ING BEER !.

Eucalyptus doesn’t allow any undergrowth to survive and is much more flammable than other trees.witness the terrible fires in both Australia and in Portugal, where devastating fires have been blamed on rampant growth of this tree.

Me: What happened to the Sahara desert? Time traveler: You mean Sahara forest? Me: *Surprised Shaq face*

why dont just stop deforesting Rainforests?

It would be cheaper to make a 1000 to 2000 kilometers salt lake . The precipitation from a lake that size would generate enough rainwater to cover large parts of the the desert. You'll also remove some amount of salt that's been mined from the ground and deposited back in the oceans. You could make more economy this way as well. Though fishing and/or evaporation ponds. Depending how deep the lake is, could slow the sea from rising. Just some food for thought.

An interesting idea, but you're forgetting a small detail. Once the land is forested, it's going to look very attractive as farm land. People have short attention spans.

Video starts at 02:00 02:23 Let’s grow eucalyptus trees in the Sahara, 06:00 we can use desalination to water the trees, 07:00 solar power to run the desalination plants, 08:00 and carbon taxes can pay for everything! 08:39 But will it actually stop climate change? 10:30 Maybe, but greening the Sahara will screw the world’s ecosystem, 11:20 so we should just use more renewable energy instead, 11:35 ...and it just so happens that we have an online course!

the answer to drastically reducing emissions has been staring at our faces for decades; it is the nuclear energy. hydro and geo are not available everywhere and solar&wind are inherently intermittent and need backup. large scale storage is too expensive and would have a big environmental impact and also increase emissions anyway. so, our only choice to fill the huge gaps in production is nuclear energy, which has one of the lowest emissions. so, let us accept and embrace nuclear energy

If you research the topic, it's theorized that rising CO2 is helping green the southern wedge of the Sahara called the Sahal. This area has been receiving increased rainfall, causing it to green own its own. Of a few theories, one is that as the North Atlantic grows warmer, it causes a change in wind patterns that increases rainfall in the Sahal. The increase in CO2 also helps plants survive in drier climates. Another contributing theory is that as the Sahara desert area heats, it also causes changes in wind patterns that bring more precipitation into the Sahal. As the Sahal greens, it also changes wind patterns that bring in yet more precipitation. Even if we don't do much to reduce CO2 and methane emissions (which are worse), the rate of technology will produce alternatives to energy and meat (the main driver of methane emissions) within the next 60 years. My guess is that at some point in the few-hundred-years future, people will release copious methane or CO2 if the earth grows too cool. I'd rather a very warm than a snowball earth.

The Sahara soil is degraded after thousands of years of overuse. The Sahara was the granary of the Roman Empire when the climate was similar to today. There's a theory that deserts appear because of soil degradation, not because of the lack of water, after long overuse/overgrazing. There is water in the Sahara, only it evaporates because there's no biomass. There are very successful desert reclamation projects where China, Jordan or Sub-Saharan countries are planting drough-resistant grass and some bigger plants and fence off the area to stop grazing by cattle. Then the biomass starts building up and suddenly you have green areas where there used to be a desert. See desert reclamation videos on YT.

Side note: planting one species of tree across half a continent sounds like a recipe for cultivating any disease suited to killing said trees. That could be rectified by using a diverse range of flora which would eventually create something not unlike the amazon where you can go a whole km without seeing the same species of tree. It doesn’t solve the problem of forests absorbing too much energy from the sun, but it would provide more than just a massive increase in o2 worldwide. It would provide all kinds of knew information about life, and could be the gateway to the discovery of an incalculable number of pharmaceuticals we could make great use of. Still, there’s probably a hundred better things to focus on rn - what with climate change being the most important

I think we can take smaller and faster steps by filling up lakes and inland water bodies that had dried up over the past two decades, a very good example is the Aral Sea. Refilling then with water, reintroducing ecosystems will help bring back the busing day’s of the past to their shores and microclimates will be restored.

Fill the Richat structure up with forest. There is usually some water in it, and it has a large aquifer under it. The moisture it produces will land on the plateau above it, run down and settle into the dry lakebed to the north, eventually starting off a chain reaction and restart the Tamarasset branch.

I was worried when I clicked on this that Real Engineering would be in favour of the idea, and was very relieved when he went into the massive downsides and consequences. This is yet another demonstration that climate change is a complex problem that will not be fixed by simple solutions.

Better to store it in Marine grass. Marine grasses capture and retain a much higher CO2 per volume than wood!

Great Idea.... while deforesting the Amazon Rainforest.. we are going to terraform the Sahara...

I haven't read all the comments but when I see this type of idea I'm reminded of other documentaries stating that the particulate matter that is uplifted from the Sahara helps to nourish the Amazon and South American forests. These ideas always seem to admit the difficulty in the project but not the potential negative impact it could have elsewhere. If the atmospheric transfer of this material is halted as a result of terraforming the Sahara it could just remove one of our best carbon capture systems already in place before its established. As others have highlighted you will need diversity to make a ecosystem able to tolerate future environment problems. Don't go putting all your eggs in one basket. It's possible to do but will need a world solution to bring it to fruition in a meaningful timescale.

I'm not a denier. I've noticed a change in climate in my lifetime of 70 years. I remember when I was a kid, winters were colder. We had more snow and ice. I think there are things we can do but we need to be careful. Worst thing would be to rush acting on fear and panic. Cutting carbon emissions is certainly a good idea. Some things I've read seem to indicate wind and solar are not quite as green as we would think. One thing that might help reduce emissions might be found in seaweed for plastics. Another in hemp and bamboo. Fast growing plants with many uses could replace much wood. Retention of forests and good management of them. Seems it would be wise to keep some of the desert areas. Great videos you make.

We could just *BLESS THE RAINS DOWN IN AFRICA*

Pour liquid nitrogen on the ice caps. Done, where is my Nobel prize?

Reforestation should be done with species that belong to the area.

So my dad and I had an idea of running an underground canal from the ocean to create as I like to call an "oasis headquarters" that'll act as the source of water to reinvigorate the Sahara, somewhere along the line have a desalination facility to turn the water pumping into that oasis zone to be fresh water. The largest cost comes in the construction but after it's built it'll be assumably easy to maintain

Industrial Hemp is an excellent candidate for this project. It can be grown quickly and has the fastest co'2 to biomass conversion ratio found in nature. Even more then agroforestry.

I'm glad you brought up the fact that the nutrient rich dust from the Sahara would no longer be blown to the Amazon and the Atlantic. This alone is enough to negate the project in my opinion. Not even bringing into account all the other negatives like the albedo and the energy costs to water and plant the desert, we would be planting one forest and possibly killing another.

As another guy noted - this: Sadly, only to cause erosion [ Eucalyptus trees do ], since the natural flora has been destroyed and cannot be re-established because the Eucalyptus trees have turned the ground acidic. Eucalyptus can be a real problem when taken out of it's natural environment and planted elsewhere. Sure the tree comes from Australia and thus you can use it in the Australian Outback if you want, just be careful when taking it elsewhere. Eucalyptus can have terrible side effects for the ground it stands on... nothing else will grow in it's place due to high acid levels it leaves in the ground. [from acidic leaves dropping continually apparently]

Sahara is dry because of evaporation and soil degradataion, not because of the lack of water. Planting drought-resistant grass and similar plants will be enough to reduce the albedo and the evaporation. This kick-starts the building-up of the biomass. It's already being done, see the Great Sahara Green Wall project, or the very successful Chinese Green Wall in the north. Or the Jordanian experiments with desert reclamation near Petra.

Not many people talk about using new nuclear energy technologies to replace fossil fuel. Why?

China is already doing this with the Gobi Desert. From what I heard they're getting pretty good results out of it.

it's peak hubris thinking we can succesfully manipulate a complicated non-linear system like the climate, glad you adressed it

Start small and keep expanding.

Job interview: Interviewer: It says here you’re a lumberjack. Are you any good? Applicant: Well, you know the Sahara forest? Interviewer: Do you mean the Sahara Desert? Applicant: Is that what they’re calling it now?

I get home from school and immediately a new Real Engineering video! Yessss Edit: Thanks for the favourite!!

If we must reduce earth’s albedo, we need to cover an ocean with reflective foil. Preferably where hurricanes and taifuns are born.

Very interesting. Afforestation would also create more land for sustainable farming,produce building materials,water capture,help to reduce weather extremes and storms amongst other things and generate affordable housing.

Sounds good and all, but if they can't get money from it, it won't be done.

Use more nuclear power. Particularly thorium.

3:21 man I sure hope a fire or something doesn't start in our new forest. We need to used more heat resistant variety I think.

Building large patches such as a few KM² of such forests and then studying their effects might be more helpful and this is the need of the hour.

I wonder how your figures would change if instead we used something like a mangrove tree that can deal with salt water instead of using desalination.

A fantastic video, than you for putting together such an exhaustive explanation! A few thought I had while listening: 1. Evaporation will increase though forestation, further reducing the amount of water needed 2. Eucalyptus is probably a bad choice, as it is thought to be amounts the cause of many spontaneous forest fires in Portugal, where it was imported. The amount of sap they release is very easily ignited when dry . 3. The best option would of course be to bring a full forest habitat. Examples of that are available in places like Brazil, where people have brought back the jungle in zones that were rendered completely bare and arid by cattles.

Sahara: **becoming a rain forest** Amazon: Adios

‘this is fact you are wrong if you deny it’😂😂😂 true but funny

Eucalyptus?! They burn like fireworks and not much grows under them!

I believe Permaculture is much more sustainable. Also provides local food and fuel.

Let’s plant some trees everywhere.

I'm an Englishman living in Aus. And whilst I think this idea is great I'm not sure many Australia's would buy in to it. But back in Britain I think there are things that can be done. One stop building on green space and convert old factories, warehouses and the dying high street in to housing. Encourage people to get milk from the milk man again, that'll but more electric cars on the road and get people using glass over plastic. The government should bring in a system where all your glass, plastic bottles and cans can be recycled at a center where when you bring them in you get 10p an item. That would encourage people to litter less and recycle more. It work very well here in Oz. All cities cites should have cladding on the buildings that allows greenery to grow, this will reduce CO2 in the city and reduce noise. All busses should be like the ones in Southampton where they collect dirty air as they drive and put out clean air after. There are other things to, like encourage people to grow their own food, small veg patch, potato bin, a fruit tree maybe a couple of chickens or ducks. Not all needs to be grown, people can choose. Government should copy Germany and put solar panels on every social housing building and reintroduce the insensitive for solar on housing. Wind farms off the coast, like the plan in Bournemouth. This will also bring sea life back to an area because of the rocks used at the base of the turbine. See Felixstowe for evidence. Loads can be done.

But what about soil nutrients? You can't grow trees in sand.

There is a search engine called ecosia which uses 80% of its income to plants trees and promote important reforestation projects. You guys should look it up and think about using it instead of google

Rather than relying solely on desalination water treatment plants to get the water, it would probably be beneficial to also connect pipelines from the ocean that would drain into massive man-made lakes in the Sahara. The evaporated water would enter into the water cycle and add rain into the environment, and since it's the desert, it's not like the salt water lake would damage the environment.

Forests actually transmute heat, light and carbon into life. Introducing native flora and geo engineering different habitats by optimising hydrology, topography, and geology to accentuate landscape and ecosystem diversity thereby maximising biodiversity and carrying capacity. I’d make as many wetlands as possible, and make many rock formations for reptiles, and salt lakes for flamingos from desalination byproducts, and caves for bats, and ofc arable lands for agriculture and the built environment. And since we’re talking africa here heck yeah we gotta create a massive savannah plains ecosystem with plenty of watering holes

We could also terraform Spain to produce olive oil :-) The olive trees are like a forest that is producing olive oil :-)

Why dont we control deforestation instead?

Could you build a nuclear power plant to power the desalination plant? What about building an artificial river to run through the desert as well?

I'm curious how a terraformed Sahara would affect the formation of hurricanes in the Atlantic.

I went in thinking : "Law of unintended consequences!" But you covered it very well!

There are new studies showing that when there is a large amount of Sahara dust in the atmosphere there is a reduction in Atlantic temperatures. This in turn deduces the likelihood of a major hurricane. Without that dust and a higher ocean temperature we would likely see more powerful storms then ever before. It is an interesting idea though, although I think it would be better if we "put things back" so leave the places that we have to teardown to live, like the Amazon forest, Florida swamps, and move places we can live in harmony. Although thats not easily done.

Taking a walk it recently came to me that the first species entering Land was no animal and no plant, but an archaic type of Fungus. So when it comes to soil building on earth as well as maybe bringing life to other solar trabants funghi would be pioneers as they historically were

you forget the fact that dust from the sahara is a main nutrients source for the amazon rain forest, reforestating the sahara would highly impact the amazon so its not as efficient as we thought