Not too much water in sub-Saharan Africa this millennium! I mean, it is the rainy season, but still, Science In The Bath is going to be more like a splash of water in the sink. Interestingly, and totally irrelevantly to this video, a new kind of water has been discovered trapped inside diamonds, deep inside the Earth. Anyway, this video isn’t about diamonds; it’s about something much more precious. This video is about soil! You know you love it. To be fair, this video isn’t all about soil, but the best bits are. Mmm soil. Wait! But first, let’s spend a few precious seconds talking about climate change; it’s the big one these days. So as we all know, there are some pretty rare, probably shiny, probably embossed people in the world who think that climate change might not be a big deal, because it’s easy to point to times in the past when CO2 was much higher, and say “life was loving it back then.” It sounds like this makes sense, so it’s fair enough that people get sucked in. If you meet someone who’s thinking that, or if you’re thinking that yourself, then the thing to know is that the problem isn’t that the climate is changing; the problem is that it’s changing fast. Living things have always survived by adapting and evolving. Some people say that sharks haven’t needed to evolve for millions of years, but actually that’s not true; they’ve changed a lot. Probably got more cunning too. The problem is that living things can only change so fast. This is why rapid environmental changes have always led to mass extinctions. This is something we know for sure by looking at the nice fossils. Due to our rapidly changing climate, Animal extinctions are accelerating faster than ever before in the history of human civilisation. There are about 2,500 animals (that we know of) on the brink of extinction right now. 20 years ago, there were only 850. Many of these species “on the brink” are possibly already extinct; it’s just that we don’t necessarily consider species extinct until detailed surveys have been carried out. But nowadays extinctions are occurring faster than surveys. Have you ever heard the call of the Kauai O’o bird? Here’s a recording of the last one alive calling out for a mate that isn’t there. That’s extinct now too. I’m really worried about the oceans; not just because of the 300kg of plastic waste that enters them every single second, but because 1/3 of the CO2 that we produce gets dissolved in them almost immediately. When carbon dioxide dissolves, it forms an acid, fundamentally changing the chemistry of the oceans. This also has the amazing side effect of making the oceans noisier, which means that animals that use sound, to communicate and find their way, might get more confused. It’s because there’s a chemical in the oceans called borate, which absorbs sound, acting sort of like cotton wool, muffling the sound everywhere. But borate is destroyed by acid, which means that sound travels a lot further in an acidic ocean. Our oceans are so, so vast that we always thought their chemistry would be completely unchangeable, and yet somehow our farming and industry is now managing to change them. This is really obvious just by looking at the coral dying off globally. Pretty worrying, right? The changes in our oceans are occurring at a rate that hasn’t been seen for at least 250 million years. And what happened 250 million years ago? An extinction event literally called “The Great Dying,” where the oceans became highly acidic, methane-producing bacteria flourished, and 96% of all living species disappeared, forever. The prevailing scientific thought, which is always pretty conservative anyway, is that more or less all oceanic species will suffer short and long term as the oceans continue to acidify. Researchers do brilliant work, trying to predict how human-caused changes to the climate will affect our environment, but no one knows for sure what will happen. Despite some uncertainty in specifics, the one thing that basically everyone agrees on is that the more and the faster we change our climate, the more we expose ourselves to the very real risk of bringing about our own extinction. Two signs of rapid climate change that spring to mind are the en-masse dying of the beautiful Baobab trees in Africa that previously stood healthily for hundreds of years, and the French champagne maker, Tattinger, buying land to grow grapes in England. The reason I’m making this video isn’t so much about champagne or the ocean though. It’s about one of the biggest and least talked about problems caused by climate change and our growing population, and what we can do about it. You know it; this video is about soil. It doesn’t seem like it should be a big deal, right? Well, without it, almost nothing would live, so that’s a factor. Plus, I love the smell of soil when it rains. That smell is called petrichor, which comes from the word ichor: the blood of Greek gods. This smell forms most easily when light rain hits the soil. Basically the rain droplets trap tiny bubbles of air underneath them, and these bubbles pick up the smell of the soil, form an aerosol, and then drift up into the air, and into our noses. The aerosol droplets often carry loads of harmless bacteria up into the air with them. Some of those bacteria can end up at really high altitudes. In fact, a lot of snowflakes find themselves forming around a certain kind of bacteria, which is harmful to (some) plants, cunningly sneaking into the treetops, ninja style, in a friendly-looking lump of snow. Speaking of snow, with the planet warming up, lots of powerful people are becoming increasingly worried about water: basically liquid snow. And they’re right to worry: there isn’t enough freshwater to go around in many parts of the world, and it’s getting worse. Iran, for example, relies heavily on underground reservoirs of water that are nearing total depletion. Water shortages are a very worrying consequence of climate change and population growth, and more people are dying every single minute due to lack of access to clean water. However, there is an important difference between water shortage and soil shortages, because, even though it’s expensive to do, we at least have the technology to generate fresh water. On the other hand, something we don’t have the science and technology to deal with at all is if we run out of soil. Get this. Half of all of global topsoil has degraded in the last 150 years, and the rate is accelerating. An entire Costa Rica’s worth of topsoil is lost every single year. This is sort of a disaster that no one ever really expected would be possible: the soil has always been there, it’s always been fertile, and it’s always grown our food, but now it’s disappearing. At the current rate, some people have predicted that the world only has 60 years of topsoil left, before it runs out. However, this statistic assumes that the soil will run out evenly everywhere, and obviously that won’t happen, which means some areas of the world are going to be running out much sooner. As I said before, about half of global topsoils are already considered to be worryingly degraded. As I also said before, we have no science or technology to replace the degrading topsoil. Give me a little call if that isn’t the case. You might be wondering about fertilisers, and if we can just use chemical fertilisers to replace some of the nutrients in the soil. I was thinking that, but it turns out the problem is a lot more complicated. FYI, this video has a lot of positive and optimistic things about what we can do to make a positive different at the end. But for now, here are some more worrying and scary deets. It takes around 500 years for a single cm of topsoil to recover naturally. This means we’re talking the entire length of human civilisation multiple times over to recover the topsoil in some parts of the world. Quite a few attempts have been made to raise awareness by making soil seem more cool. For example, in 2015, the UN announced the year: The International Year of Soils. Remember that? No. And several high-profile people in the media have referred to topsoil as “our silent ally”. Ever felt the inclination to call upon topsoil in your hour of need? Nope, me neither. But guys, 95% of everything we eat comes from soils, and we like eating things. As the soil increasingly runs out, we’re all going to start increasingly thinking that soil is pretty cool. So why am I in Benin, surrounded by soil? Well, partly it’s temperature regulation. Like a pig rolling in mud, or a plant cunningly digging its roots deep into the cool Earth, I’m feeling pretty cool in here. I’m also here because BNP Paribas Foundation are sponsoring some really cool scientists that are working on the soil here. I’ve been learning a lot from them, so here’s some key knowledge. Soil is sort of like the placenta of the Earth; it’s the dividing line between the pure mineral rock surface below, and the living stuff (the biosphere) at the top. Few plants can grow on rock directly. Healthy soil is very different to degraded soil. It’s full of living things. In fact, one single teaspoon of healthy soil contains more living organisms than there are humans on the planet. It’s also not too salty, it smells great, it holds itself together well, and it’s a bit squishy, so it can absorb water too. In fact, the organic matter in healthy soil can hold 20 times its own weight in water, and acts sort of like a sponge, which is really convenient, considering the world is running out of water. In the Peak District, where I spent my younger years toddling about, the soil forms voluptuous, smooth, green curves. When the rain falls, the soil absorbs it, and when the wind blows, the soil just ignores it. But a degraded cornfield, somewhere like Iowa (not here: this is still Benin) can sometimes lose as much as half of its topsoil when the wind gets up, because the soil is just not held together properly anymore. And when the rain falls, rather than the water absorbing into the soil, it stays on the top, causing flooding, dragging pesticides and fertilisers into the rivers, causing a load of other problems. Crucially, the water doesn’t reach the roots of the plants that are desperately trying to grow. As the soil degrades, we depend more and more on irrigation to water all the plants, which has to be planned, built and maintained, which is all a bit annoying, and expensive too. Plus it uses up water that could be going elsewhere. If our soils weren’t so degraded, and were absorbing the rain properly, then we definitely wouldn’t be struggling so much to keep up with the global demand for freshwater. Here’s a cool bit of detail on another reason why it’s so important that soil can absorb water well. One of the key things in soil for plants is nitrates. These generally get into the soil because nitrogen in the air reacts with water droplets and dust particles in the atmosphere above us and then falls to the ground in rain. It’s absolutely crucial that this nitrogen-containing rain can percolate (love that word) slowly through the soil, so the bacteria there have a chance to grab onto the nitrogen, and convert it into forms that the plants can use. In degraded soil, it’s really difficult for these bacteria to convert the nitrogen, because the water just stays on the top, and then washes away. It takes time, it takes love, it takes patience to convert. Since degrading soil gets increasingly bad at absorbing key minerals like nitrates, it becomes increasingly vital for farmers to use chemical fertilisers, to artificially get those minerals into the soil. But those chemical fertilisers can sometimes disturb the fragile balance even more, by killing off some of those key bacteria that need to be there. So why is this degradation happening? Why is the soil quality plummeting globally? The main reason is hyper-intensive farming, which means doing everything possible to get the maximum yield from the land every single year, without considering the long-term health of the soil. This also normally involves something called monoculture, which means growing the same plant on the same field every single year. Particularly bad plants for monoculture are your coffee, your wheat, your soybean and your palm oil. So one of the really cool things about Benin is that they’re actually not really doing monoculture: they’re mixing crops together really well. So how many different crops are there in this field? Oh many, many, many different crops. Here is cassava. Cassava – cool. Pepper as well, tomato, maize, watermelon, beans, coffee, potatoes. So by mixing together all of the different crops, we can ensure that the land is not having one nutrient removed constantly every single year. So one of the really important ones to mix in is legumes, right? Yes, legumes, like beans. Have you got beans around these parts? Yes; we have beans. Between this and this you can have 7.8m. Ah, cool. Okay, so rather than somewhere like Indonesia, where palm oil is farmed really intensively, and they really pack the palms in, here in Benin, they separate them out into these diamonds, that are quite widely spread, and then in the middle, they fill it with food crops, which gives them loads of other benefits, because they have different products to sell, but also, it means that you can get a huge amount more out of the field in the long-term. So in the short term you might not be able to get as much palm oil, but actually the soil lasts, which is really important. Here in Benin, the SOCA programme is working hard to optimise the very opposite of monoculture: mixing plants together for the long-term benefit of the soil. As soils are degraded on our over-intense farms, forests are being cleared away increasingly rapidly to make space for new farms. Even here in Benin, where forests are venerated and protected by traditional beliefs, they’re still being cleared away. The awful thing is that modern farming practises sometimes take just a few decades to reduce this soil that’s been fertile for millions of years to degraded dirt. On top of this, changing forests into farmland is responsible for about 10% of greenhouse gas increases globally, simply because forests and healthy soils are so good at absorbing carbon, and degraded soils are not. And not to forget animal farming! Allowing animals to overgraze an area of land, nibbling up all that juicy grass, can be just as bad as intensive crop farming. A lot of clever people reckon that our global food supply capacity would be about 58% higher right now if we hadn’t allowed so much of our topsoil to degrade. All of this stuff kind of makes it sound like it’s farmers who have to solve this problem, not normal people like us, but that’s not really true. There’s one thing that we can all do to make an enormous positive difference, very, very easily: stop eating beef. To find out more about why cutting out beef can be enormously advantageous not just for soil but for land use, greenhouse gas emissions, water and more, check out my campaign called #NoBeef. For now, here are some of the key deets. To get exactly the same amount of protein it requires about 7 times more land space to have that protein as beef, rather than chicken. It requires about 30 times more land space to get that protein as beef rather than plants. Why does beef need so much land? It’s not just land that the cows need to graze on; it’s also land needed to grow the crops that they need to eat. If you’re a farmer producing crops for cows to eat, then to stay in business these days, all of your land needs to be working to maximum capacity all the time, which is not good for the long-term health of the soil. Simply by not buying beef, you significantly reduce the demands on global farmland and soils. You reduce the demands even more every time you decide not to buy meat at all. Soy is a plant absolutely bursting with protein, though a lot of work needs to be done on farming it more sustainably. Still, even the way it’s farmed now, it’s way better for the environment than beef. Also legumes (like peas, beans and chickpeas) are almost always a good choice for protein, since the land really benefits from having them grown on it, because they’re really good at taking nitrogen out of the air, and feeding it into the soil. If people bought less beef, or meat in general, there would be much less pressure on farmers to constantly produce maximal yields. There would be years when farmers would be able to leave the land unused, and there would be years when they could grow different crops. Check out my Science In The Bath on crop rotation. I love rotating crops. And there would be years when they could use natural fertilisers. Natural fertilisers may be less effective than artificial fertilisers in the short-term, but they’re much better for the soil in the long-term, because they help to provide a structure, and they help to restore that natural balance of friendly bacteria. Soil is one of our most precious resources, and what I want to make sure is that everybody knows that there is a lot that we can do as individuals to help in preserving it, just through the choices that we make at the supermarket. Again, check out my campaign called #NoBeef to find out how you can make a huge difference just by cutting down on beef. Something else we can all do to help is to compost our food waste (and to enjoy doing it). About half of household waste, globally, could be composted, and isn’t, which is crazy because compost is essentially just topsoil waiting to happen. So yes, there are definitely things that we can do as individuals to make a positive difference, but still, things need to change on farms if we’re to keep the food supply safe for years to come. I know that most of you don’t own farms. Or do you all? But I’m going to tell you some of the things that need to change on farms anyway, because they’re actually really interesting! For thousands of years, ploughing has been used to kill weeds, to aerate the soil, and to bring more fertile soil to the top for the seeds to grow in. We now know that soil doesn’t really need that much aerating, if it’s healthy. And more importantly, most farmland soil has been turned so many times now, that the soil below is no more fertile than the soil above. In fact, there’s really very little to gain from regularly, heavily ploughing a field. It’s much better to plough as infrequently as possible, and as gently as possible too. Generally it just damages the fragile organic structure of the soil at the surface, making it more vulnerable to being washed or blown away, and even worse, it disturbs the microorganisms there that are trying to regain a foothold so that they can restore the soil over the next few hundreds or thousand years. And yet heavy ploughing continues the world over, despite it arguably being negative for everyone. I’m not sure how ploughing affects worms but I will tell you this: worms are really important for healthy soil, and, totally unrelated, any worms caught too close to the north or south pole, when an ice age hits, freeze to death. In fact, there are still worms working their way to the north, that haven’t made it as far north as they were before the last ice age hit. They’re nearly there though. In general, we somehow need to put pressure on policymakers to support better farming practises. One of the practises I particularly like is called agroforestry. That’s when you plant trees in with the crops, and the trees help to support the healthy soils, at least around the trees. I like trees. Two more cool things… Firstly, I met a researcher at Oxford called Andrew Smith, who told me that the answer to recovering degraded soils might be succulents. These stubby, squishy little plants are generally thought of as not being very useful, but actually they’re one of the few things that can survive on degraded soil. The answer to recovering degraded soil might lie in growing a load of these little legends. Secondly, Benin is one of many Africa nations involved in an ambitious and inspiring project called the Great Green Wall. It’s an 8000km long line of trees built along the entire southern length of the Sahara, and it’s 15% complete so far. This living wall will be three times bigger than the Great Barrier Reef, and, if it’s completed, will play an absolutely crucial role in preventing degraded soils from turning into desert before they can be protected and recovered. Thanks for watching. Thanks to this video’s sponsors. Spread the knowledge and deliciously subscribe for more!