Green Roofs, Urban Biodiversity, and the Climate Crisis: Insights from Dusty Gedge

But that's been the challenge because essentially from November, I think, is biodiversity gain comes in. I'm already saying to some of these developers, I said, like, you know, you're going to have to be really, really careful about what you purchase because if you're going to have to monitor that and it's not installed properly, you know, you're going to have some issues. So you're going to have to up your game.

Hello and welcome to Rethink What Matters, the podcast dedicated to aligning the economy with the ecology and everyone for improved business performance, stronger families, and a greener, cooler planet. And today I'm joined by Dusty Gedge, a recognized leading authority on the design and implementation of green roofs and urban biodiversity. He is a technical and policy advisor in urban green infrastructure and biodiversity enhancement in the UK and abroad. He has been instrumental in writing strategic reports on both green roofs and green infrastructure including the London Green Roof Report. An urban ecologist and former punk, he was, back in the day, a circus performer, juggling, acrobatics, unicycling, escapology, and the third man of four standing on each other's shoulders. That's one from the top to you and me. Also a very keen ornithologist. There are tears ahead, so hold on tight.

So let's go back to the beginning and how you first became interested in green roofs and urban biodiversity.

Well, I mean, I've got a rather, rather interesting history. You know, when I was a teenager, I was a big birdwatcher, naturalist, and I was going to go off and, I don't know, do a degree in forestry or something. And for whatever reason—sex, drugs, and rock and roll—I ran away and did a degree in theatre arts. And became a circus performer and an actor. That's why I moved to London, to Southeast London. But 23 years ago, I'd set up a circus workshop for truants who were smoking too much drugs, and these are young kids. I set up this workshop to, you know, basically try and use circus to get them to go back to school, really. And the guy who paid for that was part of a project in Deptford, Southeast London, And they wanted a bird watcher, and he knew I was a bird watcher. They wanted a professional bird watcher, and I got employed to do all these bird surveys. And I found a bird called the black redstart, which is a protected species. And it's an odd species because the kind of places that it likes to live are bomb sites, post-industrial landscapes, brownfield sites, you know, not pristine wilderness. And because it was protected, we had this idea we could put the habitat on the roof. And right, the rest is history.

And so it went from there. Yeah.

And there's nearly— up until the 2008 plan, nearly all the green roofs that were going in in London were before the Black-Red Star. So King's Cross has got green roofs. I wrote that report 2001 because—

okay, okay, got you. I know that you've contributed to, you know, many projects and publications and conferences, and you've worked with NGOs and private organizations in raising the awareness of, you know, the benefits of green roofs.

Yeah, well, in fact, you know, what I did— I mean, I suppose what I did was really, I was a birdwatcher who found a rare bird, which we might talk about later. But I was really, in a way, a bit of an environmental activist. And my main role 23 years ago was to try and get a a policy in London. And so I basically went to Europe to find out everything. Well, I basically went so that I knew more than anybody else. And I ended up writing the technical document with a colleague of mine, Gary Grant, to support the London Plan. And the policy was enacted in 2008, and we've got a lot of green roofs in London. Brilliant.

Yeah, I've done a podcast with Gary, and he mentioned you. Did he? So yeah, brilliant. And so really glad to be, you know, to be recording this podcast with you, uh, with yourself. Um, you know, and also I see that in terms of why we need to do this, that, uh, there are some 56% of the world's population are in living in cities today.

Well, 75% of the European Union lives in cities. It's even higher, right? Okay.

And apparently it's expected to increase up to 7 out of 10 people in 2050.

There you go. You know, I mean, I mean, what that's saying is majority, you know, UN globally, the majority of people in the world will be living in cities. And cities have a lot of problems. And one of the problems they have is a lack of soil and vegetation, but they have a lot of buildings. So if you put some vegetation on buildings, that should ameliorate many of regarding the climate crisis and the biodiversity crisis. So green roofs help cities adapt to climate change.

I bet you can't believe how, um, how necessary this is today, you know, with obviously global warming and all the problems we've got in society as well.

Well, I think, I think a lot of us, even back 23 years ago, maybe even longer than that, green roofs were on the agenda when I was in the '70s, '80s doing environment, right? But, you know, because of the climate crisis and all the COPs and all that, we're recognizing, you know, now at governmental level that these things are important. I mean, I've just got to tell you, 2004 was the first time the UK government used the word climate change. I remember those things. And, you know, in 2006 we had a heatwave in London and I was getting emails from residents of council flats saying, 'Can you help us get a green roof put up because we're overheating?' That's 2006.

Right, yeah, absolutely. So these things are moving, things are starting to move a lot faster now. So there are many benefits to urban biodiversity and green roofs. Can we just go through those benefits, what they are? Because it's more than just having a pretty roof, isn't it? It's more than just having a green space.

Yeah, I mean, let's look at the headline issues. Obviously, my interest is biodiversity, which we can talk in more detail later. But the main reasons we need green roofs are urban cooling. Roofs do something called the albedo effect. They basically reflect heat back at night, and it makes the city temperature hotter. And cities are generally hotter than the countryside because the countryside has got vegetation. So what is known as the urban heat island effect effect, green roofs, you know, you have to have a lot of them, will help cool cities down. So last year we had, you know, we had the worst heat wave on record. The green roofs might not have looked as pretty as maybe some people want, what they want, but they will help cool the city down. And the other thing associated with that, often after a heat wave, we get these really intense summer storms, right? You know, these aren't 100-year storms. These are intense, short, 5-minute storms. And green roofs are sponges, and they soak it right up, and they ameliorate local flash flooding. Yeah, some flash storms.

Okay, all right. So, so that helps to— water management is a part of that then, stopping, you know, the water actually all building up on top of those roofs and then, you know, overwhelming the drainage. Yeah.

—particularly in summer, intense summer storms, because they're really, really intense. And then you've got all the other things. I mean, a big one for me now is well-being because of COVID people being— yeah, you know, and just watching people in Italy locked away and just going, like, they had a roof to go on and sit in nature. Yeah, yeah, absolutely. So well-being is a very important thing and it's slowly getting up the agenda in cities and livability. And then you've got air pollution, you've got noise pollution. Green roofs are really good at cutting out low-frequency noise, which is aeroplanes, you know, right all the way to Heathrow. Yes, a lot of the noise pollution and, you know, air pollution. And to a certain extent, there's some carbon sequestration. If more— if you've got trees on it, the more. If, if they're marked on the ground roof, which are meadows, you know, less carbon sequestration. The thing about green roofs, and my My friend Paul Collins always says, you're really good at saying this, green roofs do a lot of things reasonably well. Most other things do only one thing very well. Right. And that's a really important thing. Green roofs provide multiple benefits, not single benefits. So a solar panel produces energy. That's what it does. Yes. But a solar panel on a green roof produces energy and you've got all those other environmental benefits.

I think it's just such an important subject, urban biodiversity and urban greening, I think Gary called it. You know, just this idea of bringing the countryside, you know, into the cities. And that has to be good for wellbeing, doesn't it? And families. So families is an important part of what we're trying to do at the Water Roo as well. So it's all about aligning the economy, the ecology with everyone. And family has to be a part of that, and green spaces can only help, you know, help families too, can't it? I spoke with Jenny Bailey.

Jenny Bailey, yes.

Yeah, and I'm going to be doing a podcast with her, with her—

what is it again?

The Tales from the, you know, Tales from— with her Tales from the Countryside.

Well, I mean, I gave a lot of advice to it. It's a story about A Hairy Footy Flower Bee and the Black Red Star Stars in it. And I write— it's a rather lovely book actually, it really is lovely.

Yes, so it's beautiful that that's bringing all of this together as well, you know. Businesses are interested in this as much as the public sector, probably more so.

Well, I mean, I think it's starting to change. I mean, the main reason most people, most businesses have green roofs, because there's an obligation in the planning system, certainly in London. But what's very interesting this year, and I've noticed it already, most financial real asset companies have got to report on nature. It's a mandatory duty. And I get— I go into a lot of banks and legal firms and, you know, a lot of people up in the city. And this year I've noticed they're going, 'Dusty, nature, it's really hit the business.' And our green roof, this is really interesting. So I think what's going to happen is I think businesses are going to start recognizing that this is not just something they have to— they're obliged to do through, you know, the national government or the, you know, the Greater London Authority, that actually it's a mechanism for them to report on nature, that they're actually doing something meaningful on their own building.

Right, brilliant. Well, that's great news, and it's got to be good for employee well-being, hasn't it? You know, just nice to have a green roof to go to.

Yeah, well, I mean, there's a little conflict there, if I may, Paul, because what happened is, for whatever reasons, a lot of what happened in the United Kingdom has come from my laptop. From my laptop, it was Gary's laptop, or it's right, you two.

I've got the two main guys on my podcast, so I've done well.

A lot of ecologists say is, oh, you know, these green roofs, they're for biodiversity, so people shouldn't go on them. And I go, well, why? So there's a roof I go onto at 202 Bishopsgate. I can't remember which company's in it. I used to do a tour there on Open Square weekend. I remember once doing the tour and 7 of the people worked in that building and they didn't even know they had a green roof. And I said to them, would you like to come and sit out on this roof and have a cup of coffee? They said, we'd love to. I said, but you're happy? I mean, this roof looks like Dungeness. Right. If, if a roof is accessible, all of a sudden it has to be private and lawn. Yeah, I know.

This is—

there's a video I want to do soon because I'm going to sort of tell viewers I've got this YouTube channel, I'm doing all these videos. I went to a restaurant roof in Zurich last year while I was there. It's just a wild, what they call alluvial gravel wildflower meadow. Right, right. Yeah, nothing. It was just wild, and it's right in the center of Zurich. Now, if that was in England That would have bamboo, lawn, and privet hedge on it, right?

Yeah, yeah. And I think there's— it'd be great if more people could, I think anyway, you know, start promoting the idea of wildflowers and wild gardens and getting everyone to, you know, not think that it has to be manicured to be, um, to be livable. Well, I hope you're a great fan of No Mow May because I'm a massive fan of No Mow May, June, July, August, September, October. Yeah, so what about the challenges then? Let's, let's, uh, you know, the challenges of implementing urban biodiversity.

Specific what we want in terms of urban biodiversity is we want, you know, native wildflowers, native pollinators, and native birds. And, um, certainly what I do, mainly what I do, I mean, I do other stuff at ground level, but But, you know, in terms of roofs, what we need to do is get a lot of our, you know, lovely— the oxeye daisies, the viper's buglosses, the bird's-foot trefoils, all what we call calcareous wildflowers onto our roofs. And, you know, within that, if people are going to have access to it, you could add some non-native but good for wildlife. You know, bamboo is non-native, but it's got no use to wildlife. So we want plants that have got use to wildlife. And we're slowly moving there. And there's one roof I should talk about, really. Yeah, so this is at the Museum of the Home, which is viewable as you go into the museum or from above the DLR. And I was asked to design this roof. It's not really what I normally do because it's what is known as a semi-intensively green roof, and they wanted it to represent what the Museum of the Home is about. So I've got a friend of mine, David Matzdorff, who lives up in Islington, who's just Mad Yucca Man, and he just plants all these mad plants from around the world, you know, not native. And, you know, Museum at Home wanted something like that, so I designed this reef using yuccas and aloes and curry plant. And, you know, I'm quite pleased with it because actually when you look at it, you go like, this is really quite interesting. But it's underplanted with the London Wildflower Mix, which we use on Green Rivers. And people said to me, you know, that's really great, Dusty, because you've got these mad yuckers sticking out. And then you've got all these, you know, the Echeverias and the, you know, the self-heal and the whatever. So, you know, there's a combination. There's a way of doing this that, you know, can give aesthetics. But for me, and I think Gary would agree because Gary's more like that, is it's the function first, not the form. Let's Yeah, function. What, what is it functionally there to do? Deliver for biodiversity. So let's get that right.

And it sounds to me, you know, from what you were saying a little bit earlier, that people can set these green roofs up and kind of leave them.

Well, that's what happens most of the time— out of sight, out of mind. But I think, you know, what's interesting, you go to places like Berlin, you've got a lot of social housing where the residents can come to these native meadows. Yeah, look at them, and they're allowed to sunbathe on them. And there's a little rule, so some may be somewhere differently, but they're not allowed to have— so it's all— it's very German. What you find in Germany is really nice meadow roofs, which are my type of roof, but they're maintained properly, they're installed properly, and then they enjoy them.

An unkept green roof still meets some requirements of whatever green roofs are meant to be doing there?

Only if it's done properly.

Still going to need to be maintained though?

It's still going to be minimal maintenance, I'd green roof, because it's not like a normal meadow at ground level. It's not— it doesn't need mowing every year. What it needs is a bit of an annual weed for essentially woody plants, because you don't want woody plants on the green roof.

How often are these roofs just left like that then? How often is a project just to have a green roof up there as opposed to a nice living space?

Well, I mean, the majority of green roofs in most cities in Europe are what are known as extensive green roofs. Which really aren't roof gardens or parks. The issue in countries like the UK is because they're out of sight, out of mind, people aren't installing them as good as they should be.

That's the issue. Right. And what's the consequence of them not installing them as good as they should be?

You know, they get— they're not as diverse and they're not not as florally rich. But that's going to change because essentially from November, I think it is, biodiversity net gain comes in, which is legislation. And in a city, about the only way you're going to get biodiversity net gain, and it will be in, in an inner city, is green roofs. And they're going to have to monitor those for 5 years. And I know that because I wrote the metric for BMV. Yeah, so I'm already saying to some of these developers, I said, like, you know, you're going to have to be really, really careful about what you purchase, because if you're going to have to monitor that and it's not installed properly, you know, you're going to have some issues. So you're going to have to up your game, you know.

So issues being?

Well, if it doesn't deliver for biodiversity in terms of the metric, right, it's not—

that's the issue. Yeah. And how is that going to be measured?

Well, there's 10% Well, I have a process to measure biodiversity net gain on green roofs, but you know, that's a commercialism that I have. But essentially, somebody's going to have to go up there and say whether it meets the metric, you know, physically or remotely, like my company Genshin does. But you know, what that means is, so I specify a lot of roofs, and then for whatever reason, they ask me to come and, you know, basically inspect them and tick them off. I go back and I say, that's not what I specified.

Okay, so have they changed it? What would typically—

I don't want to go into there, but it could be the system. I think this is going to be better, and he's convinced them. But if you do that with biodiversity net gain and you use an inappropriate system, you're going to fail. Well, that's good. You've lost money.

That's going to cost a lot. Yeah, we're going to You know, we need those things done properly, don't we? Just tell us a little bit about your company then, please, Dusty.

I'll give you the background to it. So from about— because we set up this policy in 2008, and we knew by about 2010 there was about, I don't know, 200,000 square meters of green roofs in London. Well, you know, I wanted to know how many green roofs were installed. So I'm not joking, I physically, every summer in 2015 till 2020, mapped all the roofs of London on Google Maps. It took me all the whole week. I mean, right, I'm completely sad. I'm a real sad, yeah. So I have to meet a mate of mine, and he said to me, you know, we could do that remotely using satellite. So we set up the company initially to remotely map green roofs, and we're doing lots of work for local authorities across the United Kingdom. I'm in fact about to publish a league table of the United Kingdom because I mapped 34 of the cities. And that's now moved— well, it was always intended to move to be able to remotely assess a green roof in terms of biodiversity net gain. But we're also now doing that out in the wider countryside, so we can map habitats. And we're currently working with Plantlife to map and verify whether our AI is really good at identifying, you know, certain habitats, because characteristics. What we're very good at is identifying different grasslands, which often ecologists get wrong as well. So gentian, it's a smart meter for nature, as we like to call it.

Smart meter for nature. How do you spell gentian?

Gentian is a French— well, it's an alpine flower. G-E-N-T-I-A-N. Okay, it's an alpine flower, and we have a couple of French speakers in our company who I think they were the ones who decided.

Are birds returning to cities when there are green roofs? I mean, going back to your bird story, I guess.

There's a lot of black redstarts in London. I mean, I can't be absolutely certain, but the story that I tell— I've got a video on my YouTube channel coming out in the next 3 months— the linnet, basically the linnet is this small finch that, you know, was once really common. The Victorians, it did have a bit of a collapse because Victorians got into caging it, and then that got banned. But, um, you know, it's, it's, it's, it's a very pretty— but it's not like a goldfinch. Everybody goes, oh, goldfinches. Then it's a kind of a little bit boring. But I've got a book of finches that I bought when I was a young, you know, teenager. It was written in 1953. The linnet, common, absolutely common, right? Common, common. It's quite a famous book by Eric Sims. For bird watchers out there. In my lifetime, the linnet population's collapsed, right? Okay, because of intensive agriculture. So in the early days when I was doing all this bird watching professionally, I, I was actually the official bird watcher for the, for the dome back in 1999, 1998, '99, 2000, 2002. So I did all the bird surveys around the dome, and there were about 6 to 10 pairs of linnets on the dome area, right? Peninsula, the whole peninsula. Yeah, yeah. Now, for whatever reason, there's a roof that I've been heavily involved with the last 5 years, and on that roof— that roof has been completely seeded by seeds that I've collected from around Kent and Southeast England. That roof in 2020 had 20 linnets feeding on it. Right, right. There are now more linnets on the Greenwich Peninsula than there was 23 years ago. And that's because every single new development on the Greenwich Peninsula, which is a lot of developments, all have green roofs, and the linnets are using the green roofs to feed on. That is— that when I stand up in front of— I do a lot of public speaking— that nearly makes me cry because that's really—

that's brilliant. That is— that really said That goes to show. And then, and then all everything that follows from that, you know, kids looking out of their windows seeing those birds. Yeah, you know, what do they need to do to go get themselves a green roof besides contacting yourself?

Well, the first thing is be very careful when you go on to Google and don't buy the lightest system possible, which is what everybody does, and then in the heatwave it dies. So I have said I've got another little thing called greenrooftraining.com, which is a A complete guide to a DIY green roof on a shed, a garage, an extension, and it explains all the structural implications, the waterproofing implications, and it tells you, right, you can go for that, but if you want a really good green roof and look out of your bathroom and clean your teeth and enjoy it, do it like this.

Okay, can you give us 2 or 3 things to think about, or, you know, in terms of what they might learn on your course?

Well, it's an online guide, it's not a course. Okay. Essentially, you want to have at least 10 centimeters of substrate. We call it substrate, which is a stony aggregate. Yeah, you need that much. If somebody says to you, oh, we can give you the lightest green roof, you know that that's not what you want. Yeah, okay. It's not good in the green roof, you know, in terms of vegetation. Light means good from a structural engineering point of view, not from another point of view. So that's a good point. Go 10 centimeters and, you know, get it built by a contractor using our guide so that it's done well. And then what you want to do is you want a mix of sedums and wildflowers. But people say, oh, I want one of those sedum roofs, don't I? You go, no, you want a mix of sedum and wildflowers. Flowers, and then you'll really get a lot of joy out of it.

Let's get on to the other half of this, which is, you know, maintaining them, looking after them afterwards. Well, I mean, is it just like any garden then, I suppose?

I mean, the beauty of a green roof is they're so low maintenance if they're done well. You don't really have to worry about it. And, you know, okay, now last summer— I'm not into irrigating because actually plants are quite good at bouncing back So one of the problems last year was that it's the grass that goes yellow and it's grass that sets on fire. There was a while— and it's slightly— there is— this is relevant. So there was a wildfire near here. I went next day and all over where the wildfire was, all the wildflowers were still alive. They were green because they're deep-rooted. Okay, so it's grass that wants So, you know, the great thing about a green roof is you generally don't put grass on it, so it takes longer to die off, but it will. But the beautiful things about wildflowers are, is they will bounce back. If you irrigate something too much, once you stop irrigating, everything's going to die because they get used to the drug. So try not to put too much water on your roof.

Okay, that's a good tip. Really, I like that tip.

Lean and mean. The main thing is, you know, to keep things as native as possible, which is not stopping putting non-natives in, but do things which are good. And the other thing is, what's important in a garden is to have, you know, it's a bit technical, this is have wildflowers which have different sizes of sepals, right? So long sepals, sepals which long-tongued bees could go into. And then you have things like daisies which have really tiny sepals, so the short-tongued can. So you want— diversity is best. Diversity is right.

Okay, get rid of your lawn. Get rid of the lawn. Yeah, absolutely. Yeah, there's a lawn near me, they've just let it grow wild, you know, it looks great. And just so that they— so everybody knows that they've done it deliberately, they've sort of just mowed around the outside, you know, the circumference, you know, the perimeter.

I get told off on social media for being— somebody told me you're the lawn Gestapo, Dusty. And I go like, I don't like lawns.

Well, I think we have a problem with everything being too manicured, don't we? This is it, you know, it's everything's too neat and tidy, which just doesn't help nature.

You know, I walk around when we have an intense summer storm, I walk around and see all these downpipes coming from people's houses and they just pour them onto the street and all that rainwater is going into the, you know, the sewage system. And you go, yeah, in parts of Germany and parts of actually United States of America, you're the polluter, you've got to do something about it. Yeah, right. So, you know, one of the things you can do is like when you've got downpipe, you could run your rainwater through a rain garden and have like storage. So they're like temporary wetlands that, you know, They're not breaking the drainage route, they're just there. And you have these lovely rain gardens. And Gary and I wrote a guide on this a few years ago. But you just go rain gardens, there's hundreds of sites in America which tell you how to do it. I've got 40 videos I'm slowly making of different aspects of the work that I've done over 25 years. And that's what I want to do is I want to communicate. I'm trying to move away from being Mr. Policy Guru, Design Guru, because consultancy is a funny old game. I used to be an entertainer. I want to kind of bring my knowledge and my entertainment skills to the fore because I feel I've got some stories to tell.

I think absolutely, if you can bring your entertainment skills alongside your technical understanding and expertise, that's an absolute winner, isn't it? Dusty, I really want to say thank you. Really appreciate your time and helping to educate us and, you know, the audience. And yeah, thank you again.

Not at all, Paul. Thanks for inviting me.