Biodiversity SOS: Can green roofs help tackle the crisis?

Climate Change and Sustainability October 06, 2021

We asked green roof and ecology expert Dusty Gedge for his views on creating more sustainable urban landscapes.

As the scale of worldwide habitat loss becomes clear, the biodiversity crisis is gaining more attention on the global stage. With COP26 fast approaching and next year’s UN biodiversity conference edging into view, we at RSK want to lead the debate and inform solutions on the most important topics of the day. This is why we have called together experts in the biodiversity and ecology fields to share their opinions on how to tackle the crisis in our Green Dialogues webinar titled “Can we rewild land in our inner cities?” on 7 October.

In advance of the webinar, we asked panellist Dusty Gedge, President of the European Federation of Green Roof and Living Wall Associations and founder of Livingroofs.org, to share his knowledge on how green roofs can be successfully used to tackle the biodiversity crisis.

  1. Why are green roofs so important for increasing biodiversity in urban settings?

In our towns and cities, where space is at a premium, green roofs are an excellent way to transform what would be unused grey and lifeless areas on the tops of buildings into havens for wildlife. As more green roofs have been installed over the years and the industry has developed, their biodiversity quality has improved greatly. Most green roofs that are installed on buildings today are extensive ones that include excellent habitats for encouraging all sorts of wildlife, especially invertebrates. Given the global decline in insect populations, this is really important. Key research in the UK and Switzerland has shown that, by designing a green roof specifically with invertebrates in mind, it is possible to actively increase their overall ecological value.

Green roofs offer many other sustainability benefits – they can be designed as amenity spaces and then can help with climate change adaptation by increasing water attenuation and building performance. In cities with periods of heat stress such as London, they can help with cooling buildings as well as with mitigating air and noise pollution. Plus, they are much more attractive!

  1. London, UK, has been a leader in implementing green roofs. What have been the key elements of its success?

The key to London’s success is that, since the 2008 London Plan, there have been specific policies requiring the use of green roofs in new developments. This has led to a 17% annual increase in green roof area; London is now at 2.5 m2 of green roof per citizen, which is on a par with many cities around the world. London actually now has far more square metres of green roof per citizen than Toronto, Canada, which is often cited as a leader in green infrastructure.

As increasing numbers of developments have green roofs, the development industry in London has been able to see the benefits of green roofs from both the biodiversity and economic perspectives. Green roofs make better developments and more attractive homes, and sale values reflect this!

  1. What are the benefits for city dwellers of increasing biodiversity and how can we monitor these?

During the global pandemic, people have been constrained in where they can go because of lockdowns and restrictions on movements, but they have still sought out wildness wherever possible. Humans are instinctively attracted to nature and the last 18 months have shown how better access to natural spaces has all sorts of benefits for wellness. There are also the wider sustainability gains that make our cities more comfortable places to live in as the climate changes and we see more episodes of extreme weather such as flooding, high winds and periods of high temperatures and droughts.

There are lots of opportunities to monitor the benefits through citizen science and social networks. The only issue is that many of the more formal ecological assessments for monitoring biodiversity are adapted from those for the rural perspective. What is necessary for more accurate monitoring is bespoke urban ecological assessments that can encompass the full range of benefits in an urban setting.

  1. Do you have a favourite biodiversity project in London?

I have a couple! The first one is the European headquarters of Nomura Bank, which has transformed its simple sedum green roof into a wildflower one. This has been done by working with a local charity to grow the native wildflowers that young people have then planted on the roof. They also have a beekeeper who monitors the roof for wild bees and other wildlife. It is a great example of a corporate company engaging with biodiversity and using its green roof to not only celebrate plants but also make lasting benefits for young people. There can be strong links between biodiversity and wider corporate social responsibility agendas.

My second favourite London project is Ikea in Greenwich. I had a blank slate to work with and create the store’s green roof. I used seed that I had personally collected from all over Kent and south-east London. It is an interesting development, as it features five different green roofs, most of which are open to the public, despite it being a retail store. This is a model that Ikea also has in other countries. My part of the roof shows that we do not have to use commercial systems that are not as diverse and interesting in terms of rewilding. It is possible to recreate habitat and species combinations that are very appropriate to their location. And that linnets have been found on that roof is a particular bonus for me, as their numbers are in serious decline.

What needs to happen to keep up the good progress on increasing biodiversity in our urban landscapes?

It always comes down to policy. There are some really interesting ideas potentially coming through on green infrastructure and biodiversity in urban areas in the new environment and planning bills. The concept of biodiversity net gain in particular means that green infrastructure is increasingly going to be underpinning planning policies. What needs to happen next is to expand the ambition for green roofs to become policy requirements across all local authority areas, as this is not permitted under the current planning guidance, the National Planning Policy Framework. If we can normalise extensive green roofs across more developments in this country, we can make sure that urban areas are part of tackling the biodiversity crisis while also giving people who live in the cities access to all the sustainability and wellness benefits.

“Can we rewild land in our inner cities?” webinar

Join us on 7 October for the third webinar in our Green Dialogues series on rewilding in the city in which we will seek the opinions and expertise of leaders in the rewilding movement. Dusty Gedge will be joined in the discussion by Stephanie Wray, Managing Director of RSK Wilding, Sabine Hoefnagel of Rewilding Europe and Elliot McCandless, Communications Manager of the Beaver Trust.

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