Megaprojects: Terraforming The Sahara | Answers With Joe

this video is supported by skillshare in a little over a month the mars perseverance rover is going to be landing on mars and it's going to be following in the footsteps of curiosity in a lot of ways including the bizarre complicated landing technique first it burns through the atmosphere using a heat shield to protect against the friction caused by the martian atmosphere then it deploys a drogue chute to slow and steady its descent before it jettisons the heat shield and then drops from the spacecraft's shell and propulsively lowers to the ground using retro rockets at just the right distance above the ground the rover is in lowered by a crane to a soft touchdown the cord disengages and the rockets then fly away to crash off in the distance so heat shield parachutes rockets crane and if any of those go wrong the whole thing goes up in smoke there's a reason why they call this seven minutes of terror but there's a good reason for all this rube goldberg complexity landing on mars is hard it's it's kind of the worst of landing on earth and the worst of landing on the moon together the earth has a thick atmosphere so when you're coming in at orbital velocity it creates friction which creates a lot of heat that you have to deal with but because it's a thick atmosphere you can just gently parachute down to the ground or just glide to the ground in the case of space planes the moon has virtually no atmosphere so you don't have to worry about heat shields which is nice but you also don't have an atmosphere to slow you down so you have to rely completely on on rockets to go all the way to the ground but then there's mars mars has a very very thin atmosphere it's only one percent of ours so it's just enough to where you have to worry about the heat and have heat shields and all that but it's not enough to just parachute down to the surface so you still have to rely on rockets to get all the way to the ground hence rube goldberg and this thin atmosphere doesn't just create a challenge with landing on mars it also creates a challenge with living there which is why anytime you hear people talking about you know future mars civilization you hear the word terraforming a lot how exactly we go about doing that there's a lot of ideas everything from nuking the poles to creating giant oxygen generators to just piping in atmosphere from other places around the solar system to making genetically altered plants that could actually live in that atmosphere and thicken it up now all of these are big and crazy obviously but if we want to think about terraforming a planet maybe we could start by doing something much smaller something right here on earth say the sahara desert because it turns out terraforming the sahara is possible and it might actually help save our planet maybe [Music] when you mention the sahara desert you probably get an image of your head of an endless expanse of sand dunes with very little vegetation and practically inhospitable to human life and for a big chunk of the sahara that's pretty much true but it hasn't always been that way now obviously landscapes change over geologic time scales continents shift land rises and falls hell there used to be a c where i'm recording this right now that's not what i'm talking about there's an area called tesilli nagera in algeria where in 1910 a large cache of prehistoric art was found some were petroglyphs carved into the sandstone rock others were painted on depicting dancing people hunting parties god-like figures and animals and it was the animals that got the attention of the researchers because these people living in the middle of the most inhospitable desolate desert in the whole world drew on their cave walls images of giraffes and crocodiles and hippos not exactly desert fauna this told researchers a couple of things one that these paintings were old like old like 12 000 years old and the other thing it told them was that the sahara was very different back then in fact the cave painting spanned back thousands of years and you could actually see the land changing in the cave paintings the oldest ones showed a sahara situation with those animals that i was talking about about 5 000 years ago it switched to more domesticated animals indicating more grasslands and then in the last couple thousand years you see camels and desert animals we now know that the ecology of northern africa changed so dramatically because of something called the african humid period which took place at the end of the late pleistocene in early holocene eras and it was pretty much what it sounds like it was a period where africa was exceptionally rainy especially in northern africa the sahara at the time was a lush savannah that was crisscrossed by rivers and lakes that don't exist today in fact one of the lakes existed where modern day lake chad is but it was vastly bigger it was bigger than all the great lakes put together and they called it mega chad which sounds like the final boss that you fight after you defeat all the other chads this rain and the plant life that came with it created feedback loops that altered the climate throughout the entire world so what would it take to make that happen again could terraforming sahara lead to a cooling of the planet a paper published in the journal science in 2018 asked this very question using a climate model with dynamic vegetation they set out to show that quote large-scale installations of solar and wind farms covering the sahara desert could lead to an increases in local temperature and precipitation through increased surface friction and reduced albedo albedo being the amount of light that's reflected off of the surface okay so that that's that's a lot to process so let's break this down a little bit the researchers primarily focused on the sahara in a neighboring region called the sahel for a few reasons first of all it's the world's largest desert at 9.2 million square kilometers offering a huge supply of solar and wind energy it's sparsely inhabited and the sahel is sensitive to land changes because it's a transition region between the desert and the wooded savannah both regions are near europe and the middle east and solar and wind investment in the sahel may promote economic development in the area considered one of the world's poorest regions so yeah they simulated wind and solar farms across 9 million square kilometers of the sahara and found out that it could create 82 terawatts of energy just for reference the entire global demand for energy right now is around 20 terawatts so the energy impact is an obvious plus to this plan but how would this lead to a greening of the sahara well it has to do with the albedo that i mentioned earlier you usually hear albedo being referenced in terms of the ice caps because that snow and ice and the ice caps reflects a lot of energy back out into space so as the ice caps melt it's exposing more land and creating more ocean which are darker they absorb more of the energy it creates more heat and it creates a sort of positive feedback loop this is why the shrinking of the ice caps are so worrisome to scientists but according to this study anyway it kind of works backwards in the sahara all that sand in the sahara is very reflective which gives it a high albedo and yet it's one of the hottest and driest places in the world so the idea is that if you cover the sahara with solar panels it'll lower the albedo and then combine that with wind farms that can actually alter the air pressure in the direction of air flow and according to their simulation this would lead to more rain about a quarter of a millimeter per day just enough to create some vegetation growth according to the study quote these changes together trigger a positive albedo precipitation vegetation feedback they ran the simulation in various ways some with just solar some with just wind some with both and they found that precipitation increased to 0.59 millimeters a day when both farms were combined which is about 150 percent increase according to dr eugenia calne one of the study's co-authors quote the rainfall increase is a consequence of complex land atmosphere interactions that occur because solar panels and wind turbines create rougher and darker land services plus there was an increase of 0.57 millimeters per day in the sahel which is a region just below the sahara that it's been kind of expanding into for a while now in fact there's a major project going on in africa for about 14 years now called the great green wall and the idea is to plant millions of trees along the southern border of the sahara to keep it from expanding it was started in 2007 and it's projected to cost about 8 billion dollars it's being funded by the european union the united nations and the world bank but it has come under some scrutiny from certain climate scientists like dennis garrity from the world agroforestry center who said quote this was a stupid way of restoring land in the sahel thanks because the problem wasn't just that the trees needed to be planted they also needed to be cared for so in a lot of these areas where they were planting these trees there weren't a lot of people living there so they would plant these saplings there wasn't anybody around to to go and look after them and make sure that they grew so a lot of them died in fact it's been estimated that 80 percent of the trees that were planted in some of these areas died but the interesting thing is some regions fare better than others like niger and barina faso niger it's not niger like nigeria nigeria was a british colony [Music] nigeria was a french colony niger oh okay well anyway researchers became curious why it was working better in those areas and they looked into it and it turned out that farmers in the area had been using these really old like old land management techniques that had been handed down for centuries and these actually worked better for example there's a type of tree that goes dormant during the wet season when most trees grow so most farmers were just cutting them down because they seemed pretty useless but these farmers in barina faso and niger were planting these trees throughout their crops and it worked because they defoliated at the beginning of the wet season so these leaves would fall to the ground it would rain and then those leaves would fertilize the crops and since they didn't have any leaves during the growing season they didn't shade the crops the crops could still get full sun and these trees would maintain moisture keep the ground moist and then prevent a soil erosion anyway the point is the great green wall project has definitely come under some scrutiny but it did expose these old school land management techniques that actually work and those are now being emulated across the sahel region which is pretty awesome but yeah it's a cool project i'll put a link down in the description if you want to go check it out and support it but anyway according to the study covering the sahara with solar panels and wind farms might create enough rainfall that the whole great green wall concept becomes unnecessary greening that sahara would create millions of new square kilometers of crop land which would help ease the food instability of the region it would boost the economy and well-being of the people living in the sahara that's a hell in the middle east all that extra vegetation could pull billions of tons of co2 out of the air and sequester it into the ground and oh yeah it would generate the entire world's energy supply many many times over this would solve so many problems so why you may be asking aren't we doing this it's probably because we're talking about covering the entire sahara desert with solar panels that's 9.2 million square kilometers just for reference for the americans out there if you were to cover 9.2 million square kilometers of the united states that would cover the entire united states including alaska plus about 40 000 square kilometers this is what you might call a mega project another way of putting it just covering 1.2 percent of the sahara would take care of the whole world's energy needs and that is 4 600 times larger than the largest current solar installation in the world but let's just say we want to do it and we want to cover 9.2 million square kilometers of the sahara with solar panels what would that entail well some quick math says that you can reasonably fit 516 151 solar panels in one square kilometer multiply that number by 9.2 million and you get 4 trillion 748 billion 589 million 200 000 solar panels and we can round that number down to 4 trillion to make space for facilities and maintenance and crops and stuff like that so four trillion we're down to four trillion what what what would be needed for that so according to solyndra which is a solar panel company they state that it takes 5 000 solar panels to create one megawatt of power and those 5000 panels require these amounts of materials divide 4 trillion by 5 000 and you get 800 million so multiply these figures by 800 million and you're looking at producing 56 billion tons of glass 44.8 billion tons of steel 37.6 billion tons of concrete 15.2 billion tons of aluminum 5.6 billion tons of silicon 5.6 billion tons of copper and 4.8 billion tons of plastic all of which are many times more than our global yearly supply now obviously we don't need 4 trillion solar panels to produce all the world's energy needs that would actually be more in the 50 billion solar panel range but that still wouldn't produce the greening of the sahara that we're going for but what about the wind farm how many windmills would we need let's just go big so the intercon e126 is one of the world's biggest onshore wind turbines it stands at a total height of 198.5 meters and its rotor diameter is 126 meters its three blades can sweep a twelve thousand six hundred and sixty eight square meter area or three point one three acres if we place one intercon wind turbine for every three acres we would need 757 million seven hundred and eighty nine thousand eight hundred thirty turbines i couldn't find how much material goes into those turbines but i did see that they're about 18 million dollars each to to build and install so to put in that many of these turbines would cost 10 quadrillion 609 trillion 58 billion dollars so start saving your change kids isn't it frustrating how all of these simple solutions to climate change are always like way more difficult than just transforming our technology and lifestyles now there is one other reason why greening the sahara might be a bad idea and it has to do with the amazon rainforest so yeah while we talk about how transforming the sahara could pull a lot of carbon out of the air the amazon rainforest is doing that right now it's often called the lungs of the world because it produces so much oxygen and it sequesters over 2 billion tons of co2 into the ground every year and these lungs have a not small case of human pneumonia the amazon rainforest is being cut down at an alarming rate over 11 000 square kilometers were deforested in 2020 which was the highest rate since 2008 but maybe it turns out one of the worst things we could do to the amazon would be greening the sahara because believe it or not the amazon kind of relies on the sahara for nutrients because one of the things that makes the sahara the sahara are the dust storms with no plant life or vegetation to hold down the soil winds just blow the dust all over the world and some of that saharan dust gets blown across the atlantic now this happens every year some years it's worse than others actually in july of 2020 we had a massive saharan dust storm that hit the united states they called it a godzilla dust storm because i guess we were looking for apocalypses around every corner in 2020 but it's not necessarily a bad thing these same dust storms bring nutrients with them that deposit over the amazon rainforest specifically a lot of this dust is coming from the bodily depression near lake chad i remember how i said that lake chad used to be much much bigger well the plants and the animals that used to live in that lake are now just mineral deposits in the ground and those minerals contain phosphorus phosphorus is an essential element for plant growth but it's actually kind of sparse in the amazon rainforest plants and trees usually get phosphorus from the defoliating leaves that fall to the ground but it rains so much in the amazon rainforest that a lot of that gets washed away into rivers and you know sent out into the ocean it's been compared to a slowly draining bathtub but luckily thanks to all those dust storms in the sahara over 22 000 tons of phosphorus gets dumped over the amazon rainforest every year which pretty much makes up the deficit so the amazon is being saved by mega chad and we know that it's the dry conditions of the sahara that make this possible thanks to nasa's calypso satellite satellite data from 2007 to 2013 show that there is a direct correlation between the amount of dust going across the atlantic to the amount of rainfall that occurred in the sahara in the sahel the year before when rainfall increased the amount of dust traveling the next year decreased so yeah transforming the sahara would probably have drastic effects on the amazon ecosystem but still regardless the sahara is still expanding and this has dire consequences for millions of people living the sahel a study published in the journal of climate in 2018 said quote the sahara desert has expanded significantly over the 20th century by 11 to 18 depending on the season and by 10 when defined using annual rainfall with the desert borders encroaching into agricultural areas in chad mauritania and sudan this is what the great green wall is being meant to fight against the study blamed climate change but specifically the way climate change is affecting other weather patterns including the atlantic multi-decadal oscillation and the hadley circulation these weather patterns work in 60 to 80 year cycles of warm and cold phases but if you really want to see the sahara go green and you're patient enough just wait because that african humid period it will return it's actually caused by a procession in the earth's orbit and has come and gone many times throughout earth's history but you might want to get cozy because it's probably going to take a couple hundred thousand years so yeah terraforming the sahara actually is probably not a great idea i guess you could say the scientists in these studies were so busy wondering whether or not they could they didn't stop to think if they should but exploring this topic isn't just fun it also helps to reiterate just how connected we all are on this weird big wet rock so let's hope those old school land management techniques do the trick to keep the sahara from expanding any further it may turn out those people from thousands of years ago really knew what they were doing and they were pretty decent painters but hey if nothing else the sahara is an amazing landscape with a clear sky might be a great place to get some nighttime photographs so if that's something you might be into i can recommend the class nightscapes landscape astrophotography on skillshare taught by photographer ian norman this class will help you find the right locations for shooting dark skies the right techniques to capture the images you're after and the equipment to help you make the images that will blow your mind and more important below everybody else's mind this is of course just one of hundreds of courses you can take on skillshare covering all kinds of subjects like photography but also photo editing film and video production graphic design music as well as productivity classes and business classes you name it you know it's 2021 it's a brand new year it's a perfect time to start learning some new things and 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lurie lima retislawarami crystal mcdonald c cooper chris boucher jim kennedy john manning gerson coimbria de fe grado nedo nailed it uh sherry lamont paul hanley adams steve bartz thomas bell elena scott robert irish and paul busaki thank you guys so much again if you would like to join them and be a part of the community just click the little join button down below it's five dollars a month that's the only uh that's the only tier that we have right now but yeah go check it out also real quick shout out to ryan goldsberry and joe habuti for the help with some of the math around this video i really appreciate it please like and share this video if you liked it and if this is your first time here google thinks you might like this video so you can go check that out or any of the others on the face on them and if you like them and you want to see more i invite you to subscribe come pack up videos every monday alright that's it for now you guys go out there have an eye opening rest of the week stay safe and i'll see you next monday love you guys take care

Channel: Joe Scott

Views: 538,317

Rating: 4.9101586 out of 5

Keywords: answers with joe, joe scott

Id: 2hmAeLYMrQg

Length: 19min 19sec (1159 seconds)

Published: Mon Jan 11 2021