Hey, Emily's Hugh, thanks for listening to Ted talks daily today, we're going to hear about something you probably don't consider very often seaweed in his archive talk from TED Summit 2019, the environmentalist Tim Flannery makes the case for how this humble weed could play a huge role in bringing down our greenhouse gases. Halfway through, he shares a pretty astonishing stat for just how effective seaweed farming can be in addressing climate change. It sounds geeky, but will make for excellent cocktail party conversation.

This is seaweed, it's pretty humble stuff, but it does have some remarkable qualities, for one, it grows really fast. So the carbon that is part of that seaweed just a few weeks ago was floating in the atmosphere as atmospheric CO2, driving all the adverse consequences of climate change. For the moment, it's locked safely away in the seaweed, but when that seaweed rots and by the smell of it, it's not far away when it rots, that CO2 will be released back to the atmosphere.

Wouldn't it be fantastic if we could find a way of keeping that CO2 locked up long term and thereby significantly contributing to the climate, to solving the climate problem? What I'm talking about here is drawdown, it's now become the other half of the climate challenge, and that's because we have delayed so long in terms of addressing climate change that we now have to do two very big and very difficult things at once. We have to cut our emissions and clean our energy supply at the same time that we draw significant volumes of carbon dioxide out of the atmosphere.

If we don't do that, about 25 per cent of the CO2 we put in the air will remain there by human standards forever. So we have to act. This is really a new phase in addressing the climate crisis and it demands new thinking. So ideas like carbon offsets really don't make sense in the modern era. You know, when you offset something, you say, I'll permit myself to put some greenhouse gas into the atmosphere, but then I'll offset by drawing it down when you've got to both cut your emissions and draw down CO2, that thinking doesn't make sense anymore.

And when we're talking about drawdown, we're talking about putting large volumes of greenhouse gases, particularly CO2, out of circulation. And to do that, we need a carbon price. We need a significant price that will pay for that service that will all benefit from.

We've made almost no progress so far with the second half of the climate challenge. It's not on most people's radar. And, you know, I must say, at times I hear people saying I've lost hope that we can do anything about the climate crisis. And look, I've had my sleepless nights, too. I can tell you that I'm here today as an ambassador for this humble wheat seaweed. It is really I think it has the potential to be a big part of our challenge of addressing the challenge of climate change and a big part of our future.

Now, what the scientists are telling us we need to do over the next 18 odd years to the end of this century is to cut our greenhouse gas emissions by three per cent every year and draw three gigatons of CO2 out of the atmosphere every year. Those numbers are so large that they baffle us, but that's what the scientists tell us we need to do. So how might we go about drawing down greenhouse gases at a large scale? There's really only two ways of doing it.

And I've done a very deep dive into drawdown and I'll pre-empt my analysis. This stuff comes out smelling, comes up smelling like roses. At the end of the day, it does. It's one of the best options. But there are many, many possibilities. There are chemical pathways and biological pathways. So two ways really of getting the job done. The biological pathways are fantastic because the energy source that's needed to drive them, the sun is effectively free.

We use the sun to drive photosynthesis in plants, break apart that CO2 and capture the carbon. There are also chemical pathways. They sound ominous, but actually they're not bad at all. The difficulty they face is that we have to actually pay for the energy that's required to do the job or pay to facilitate that energy. Direct their capture is a great example of a chemical pathway and people are using that right now to take CO2 out of the atmosphere and manufacture biofuels or manufacture plastics.

Great progress is being made, but it will be many decades before those chemical pathways are drawing down a gigaton of CO2 a year. The biological pathways offer us a lot more hope. I think in the short term, you've probably heard about reforestation, planting trees as a solution to the climate problem. You know, can it's a fair question. Can we plant our way out of this problem by using trees? I'm sceptical about that for a number of reasons.

One is just the scale of the problem. I mean, all trees that are seeds, little tiny things that it's many decades before they've reached their full carbon capture potential. And secondly, if you look at the land surface, you see that it's so heavily utilized. We get our food from it. We get our forestry products from it, biodiversity protection, water and everything else. To expect that we'll find enough space to deal with this problem I think is going to be quite, quite problematic.

But if we look offshore, we see a solution where there's already an existing industry and where there's a clearer way forward. The oceans cover about 70 per cent of our planet. They play a really big role in regulating our climate. And if we can enhance the growth of seaweed in them, we can use them, I think, to develop a climate altering crop. There are so many different kinds of seaweed's there's unbelievable genetic diversity in seaweed and they're very ancient.

That was some of the first multicellular organisms ever to evolve. People are using special kinds of seaweed now for particular purposes, like developing very high quality pharmaceutical products. But you can also use seaweed to take a seaweed bath. It's supposed to be good for your skin. I can't testify to that, but you can do it. The scalability is the big thing about seaweed farming. You know, if we could cover nine percent of the world's ocean in seaweed farms, we could draw down the equivalent of all of the greenhouse gases we put up in any one year, more than 50 gigatons.

Now, I thought that was fantastic. When I first read it, I thought I'd better calculate how big nine per cent of the world's oceans is. It turns out it's about four and a half. Australia's the place I live in. And how close are we to that at the moment? How many going seaweed farms do we actually have out there? Zero. But we do have some prototypes and therein lies some hope. It's really different from anything you'll see on land.

And the reason being that, you know, seaweed is not like trees. It doesn't have non-productive parts like roots and trunks and branches and bark. The whole of the plant is pretty much photosynthetic. So it grows fast. Seaweed can grow a metre a day and. How do we sequester the carbon again is very different from on land. All you need to do is cut that seaweed off, drifts into the ocean abyss. Once it's down a kilometer, the carbon in that seaweed is effectively out of the atmospheric system for centuries or millennia.

But if you plant a forest, you've got to worry about forest fires, bugs, et cetera, et cetera, releasing that that carbon. You know, the the mid-ocean is basically a vast biological desert. There's no nutrients there that we used up long ago. But just 500 meters down, there is cool, very nutrient rich water. And with just a little bit of clean, renewable energy, you can pump that water up and you see the nutrients in it to irrigate your seaweed crop.

So I think this is really has so many benefits. It's changing a biological desert, the mid-ocean into a productive, maybe even planet saving solution. So what could go wrong? Well. Anything we're talking about at this scale is involves a planetary scale intervention, and we have to be very careful. I think that piles of stinking seaweed are probably going to be the least of our problems. There's other unforeseen things that will happen. I mean, one of the things that really worries me when I talk about this is the fate of biodiversity in the deep ocean.

Know, if we're putting gigatons of seaweed into the deep ocean, we're affecting life down there. The good news is that we know that a lot of seaweed already reaches the deep ocean after storms or through submarine canyons. So we're not talking about a novel process here. We're talking about enhancing a natural process and we learn as we go.

I mean, it may be that these ocean going seaweed farms will need to be mobile to distribute the seaweed across vast areas of the ocean rather than creating a big stinking pile in one place. It may be that we'll need to char the seaweed. So create a sort of an inert and mineral biochar before we dispatch it into the deep. We won't know until we start the process and we will learn effectively by doing. I just want to take you to contemporary seaweed farming.

Know it's a big business, it's a six billion dollar a year business. These seaweed farms of South Korea, you can see them from space. They are huge. And they're increasingly not just seaweed farms. What people are doing in places like this is something called ocean permaculture and an ocean permaculture. You grow fish, shellfish and seaweed altogether. And the reason it works so well is that the seaweed makes the seawater less acid. It provides an ideal environment for growing marine protein.

If we cover nine percent of the world's oceans in ocean permaculture, we would be producing enough protein in the form of fish and shellfish to give every person in a population of 10 billion, 200 kilograms of high quality protein per year. So we've got a multipotent solution here. We can address climate change. We can feed the world. We can do acidify the oceans. The economics of all of this is going to be challenging, you know, we'll be investing many, many billions of dollars into these solutions and they will take decades to get to the gigaton scale.

The reason that I'm convinced that this is going to happen is that unless we get the gas out of the air, it is going to keep driving adverse consequences. It will flood our cities. It will deprives of food. It will cause all sorts of civil unrest. So anyone who's got a solution to dealing with this problem has a valuable asset. And already, as I've explained. Ocean permaculture is well on the road to being economically sustainable, you know, in the next 30 years we have to go from being a carbon emitting economy to a carbon absorbing economy.

And that doesn't seem like very long. But half of the greenhouse gases that were put into the atmosphere we've put there in the last 30 years. My argument is, if we can put the gas in in 30 years, we can pull it out in 30 years. And if you doubt how much can be done over 30 years, just cast your mind back a century to 1919, compare it with 1950. Now, in 1919 here in Edinburgh, you know, you might have seen a canvas and wood biplane 30 years later, you'd be seeing jet aircraft transport in the streets were horses in 1919.

By 1950, their motor vehicles, 1919, we had gunpowder. 1950, we had nuclear power. We can do a lot in a short period of time, but it all depends upon us believing that we can find a solution. What I would love to do is bring together all of the people with knowledge in this space, the engineers who know how to build structures offshore, the seaweed farmers, the financiers, the government regulators, the people who understand how things are done and chart a way forward, say, how do we go from the existing six billion dollar a year inshore seaweed industry to this new form of industry which has got so much potential but will require large amounts of investment?

I I'm not a betting man, you know, but if I were, I'd tell you my money would be on that stuff. It'd be on seaweed. It's my hero. Thank you.

PR ex.