Author: davidoclubb

(Spoiler – yes – and with a lot of strategic thought and hard work could be far nicer than our towns and cities of today. They could be glorious 🌟🏴󠁧󠁢󠁷󠁬󠁳󠁿 Read on to find out how 👇)

Summary of suggestions

For any urban area of Wales 🥵 under high or very high extreme heat risk 🥵

• Review double yellow line areas with a view to incorporating trees where they do not interfere with road safety (incorporating SUDS or other low-level green infrastructure if trees would cause significant street use risk)
• Prohibit the removal of trees with Tree Preservation Orders for the purposes of facilitating or enabling new developments
• Assess every street for the potential to integrate new trees, focusing on streets that are furthest from existing green space first
• Remove 10% of on-street parking places on streets that are not currently suitable for urban trees, to enable street furniture and trees to be integrated
• Local authorities be required to set ‘shade standards’
• Build a community movement to reshape gardens to be part of the solution

Lessons from southern Europe

If summer 2023 has shown us anything it’s that the impacts of climate change, so long felt as theoretical issues for far-off lands, are coming closer.

2023 is likely to be the hottest year on the planet since records began. Sadly, it’s likely to be one of the coolest years in the 21st century, because the additional energy we’re capturing in the biosphere due to greenhouse gas emissions is at a record high, and is accelerating.

The evidence provided by geological studies enables us to put this level of atmospheric carbon dioxide into the context of the last several thousand years, which helps us consider why the ‘anthopocene‘ is a reality.

Parts of southern Europe this year experienced temperatures as high as 47°C. We are altering our ecosystem to the extent that we are risking, at certain times of the year, temperatures at which it becomes impossible for humans to live in the absence of actively cooled structures.

Perhaps even more fundamental to humanity is that high temperatures can dry out soil and vegetation, greatly increasing the likelihood that fires will take hold and spread, releasing huge amounts of carbon back into the atmosphere, and devastating local ecosystems on a local or regional scale.

Once the soil ecosystems are significantly degraded, it is more difficult for ecosystems to recover, risking a downwards spiral in nature and habitat, unless active measures are taken to protect and enhance nature.

I remember in 2010 attending a conference in Poland where a German agronomist claimed that if southern Italy received 13 fewer days of rain annually, it would become a semi-desert and would be impossible to farm.

It seems that this was indeed a relevant warning; 13 EU member states have since declared that they are affected by desertification.

The travails of the river Po are illustrative of more challenging times for Mediterranean countries; the river nearly ran dry in 2022, but the rainfall in May 2023 caused widespread flooding, and stagnant water after the event risked rotting the roots of 50 million fruit trees and huge swathes of land used for wheat production.

With overall global temperatures increasing, we should use southern Europe as an example of what might come to us in the years and decades ahead. Our latitude gives us advanced warning of future impacts but it is only of use if we actually learn, and prepare ahead of time.

What temperatures are plausible in Wales?

In order to properly prepare ourselves, and our infrastructure, for the likely impacts of heating, we should assess the approximate range of temperatures under consideration.¹

Current models show that Wales will experience an additional 1.34°C of average heat by . However, the records tumbling on an annual basis point to something far more serious; the likelihood of extremes of weather are significantly greater than the average temperature increase would suggest. As the Met Office puts it:

extremes of temperature are changing much faster than the average temperature.

The same Met Office report points out that the 2022 heatwave would happen once every 528 years in the absence of human-induced climate change, and is now likely every 3.4 years.

By 2060, under scenarios that assume reductions in carbon emissions (that do not seem that likely under current political and economic systems), the 2022 heatwave would be considered an average year, and by 2100, it would be a cool year.

The lifespan of green, blue and grey infrastructure in Wales takes us, roughly speaking, to the period 2050-2100. Trees can take decades to reach maturity. Hard infrastructure has a design life of decades. It would therefore be prudent to start examining what can be done now to prepare for regular summer temperatures of 40-50°C, particularly in urban environments which face additional challenges in maintaining habitable temperatures.

Green infrastructure can alleviate heating, and also plays a role in mitigating climate change. A recent Public Health Wales report highlights the impact that climate change will have on health and well-being in Wales:

Public Health Wales NHS Trust (PHW) recognises that climate change is one of the most significant threats of the century, endangering physical health, mental health and wellbeing. It threatens all areas of life that impact our ability to achieve and maintain good health.

Public Health Wales

Heat, and overheating, is a constant theme in the Public Health Wales report, emphasising why this topic needs adressing with some urgency.

Why are urban areas particularly susceptible to summer overheating?

There are a number of factors that exacerbate heating in urban areas. These include:

• Hard, dark surfaces absorb and the radiate heat back into urban areas
• High population density in urban areas increases the amount of heat-generating activities per unit area. Air conditioning cools single buildings or vehicles but adds another heat load to the external environment
• Urban areas typically have less vegetation than rural areas. Plants provide shade, and also evapotranspiration to cool the surrounding areas
• Buildings can modify air flow, trapping or releasing warm air to surrounding areas

The BBC has a tool to determine how likely your home and neighbourhood is to suffer from extreme heating. Counter-intuitively, even rural towns like Machynlleth could experience high urban heating in their town centres, and should also consider green infrastructure interventions where possible, although cities will experience heat outcomes that are more complex and challenging to resolve.

Research shows that urban areas furthest from green space are those most inhabited by people of low income or from ethnic minority communities. If Wales is to deliver on its socio-economic duty (equality of outcome for all), we should prioritise the hottest urban areas for urgent action to increase green infrastructure and natural shade.

Shade as the solution?

The most immediate solution to overheating in buildings is air conditioning. Which certainly treats the symptom in that particular building, but exacerbates the problem of climate change (uses electricity and other raw materials in manufacture and use), and increases heating outside the property by ‘dumping’ the heat into the urban environment.

A more holistic solution is to shade our urban areas.

Urban shade is provided by buildings and trees. Buildings provide temporary respite from heat by providing shade, but they generally absorb the heat and re-emit into surrounding areas, raising overall heat levels. Trees and other green infrastructure provide shade and additional cooling through evapotranspiration. Although the built environment could certainly be improved to provide more shade and allow greater air flow, by far the biggest improvement in urban shade would be to greatly increase the urban canopy by planting more trees and providing greater protection for existing trees.

Urban trees provide a huge range of benefits, as described in the image below. They are the focus of the solution I propose for urban heating in Wales. The reason for focusing on them now is because they take a long time to mature, with the benefits increasing as they grow; and because the co-benefits of urban trees are so compelling.

Wales was the first country in the world to map the canopy cover of its urban trees. The data helps enable evidence-based discussions about what additional interventions should take place to improve green infrastructure and urban shading. Kudos to Natural Resources Wales for that!

The most recent data (2019) gives a figure of 16.4% for mean urban canopy cover. So around 1/6 of Wales’ urban spaces in 2019 were provided with direct canopy cover from trees. This figure is a marginal increase from 2013 (16.3%) which was itself a slight decrease from the 17.0% figure of 2009.

Worryingly for those who would like to see more natural shade, the prognosis is not good:

Whilst there has been little change in canopy cover between 2013 and 2019, the number of trees over this period have decreased overall and the figures show an ageing population of urban trees which is not being replenished.

Tree Cover in Wales’ towns and cities; update 2020²

(Water as the solution)

Although this blog post focuses on using trees to create shade, it’s also worth pointing out that water bodies contribute to urban cooling. Which is why Cardiff Council deserves credit for their scheme to open up some of the old canal that used to run through the city.

Suggestions to prepare Wales’ urban areas for a hot future

Protect what’s already there

I understand from somebody within the woodland sector that trees with Tree Preservation Orders are routinely consented for destruction when planning applications come before local authorities. If true, this makes a mockery of the Tree Preservation Order purpose, and runs contrary to a number of Welsh Government priorities.

Given the life-threatening nature of likely future heating, I propose that trees with Tree Preservation Orders in any urban area indicating extreme heat risk are not eligible for removal for the purposes of enabling new developments.

Assess existing ‘hot spots’ for potential new trees

Given the urgency provided by the Climate Emergency, and the trend of a reduction in the number of urban trees, an active Wales-wide programme of creating new urban trees would seem to be a no-brainer.

Using modelling to highlight ‘extreme heat’ areas, sites should be identified to install new trees where the current risk is greatest, and where the future benefit will be maximised. Where streets are not currently suitable for siting trees, 10% of on-street parking should be removed in order to enable new trees and integrated street furniture to be embedded.

Assess double-yellow line areas for integrating new green infrastructure

I’ve noticed a number of areas near where I live that have double-yellow lines, and have become more or less functionless from the streetscape perspective. If that’s the case in ‘my’ part of Cardiff, it’s likely replicated to a certain extent across other urban areas.

I understand that they are likely to be restricted for parking to enable better views around corners, but perhaps some of them might be suitable for integrating street furniture and/or trees or other green infrastructure, instead of having to remove on-street parking?

Shade standards for at-risk urban areas

Local authority areas in Abu Dhabi, Tel Aviv and Arizona have set shade standards to enable urban living in hot environments.This sort of future thinking should be integrated in urban areas in Wales which are categorised as ‘at risk’ from extreme heat.

Abu Dhabi’s Public Realm Design Manual calls for “continuous shade” for 80% of primary and 60% of secondary walkways, shaded rest areas at regular intervals and 100% shade coverage for all formal play structures in public parks. Tel Aviv’s Shade Planning Guidelines recommend continuous shade on 80% of public streets, paths and walkways, and 50% shade in school playgrounds.

Nature.com

Community and street-level participation

Although some of the levers for the urban green infrastructure revolution rightly lie with local authorities, Welsh Government, Natural Resources Wales and other large organisations, the full potential of our urban areas will only be realised when we tap into an empowered and educated community.

A signifcant contribution to the change in streetscapes towards more green infrastructure could be delivered from those domestic properties that have front gardens. It’s something I’m implementing myself – fruit trees to give partial shade in summer but allow most of the light through in winter. Wisteria, hops, jasmine, grapes and other climbers to provide some natural shading, again just during the warmer months.

I can imagine programmes of street-level activity for domestic properties to be carried out nation-wide in urban areas targeted as at risk for urban heating.

This grass-roots activity could be supported by water companies (for helping with water body cleaning and reducing combined sewer overflow), local authorities, health boards (improved well-being will reduce future health expenditure) and Welsh Government (supports many outcomes). I’m also a fan of land value taxation; this system could help increase revenue from areas that already benefit from excellent green infrastructure, in order to support areas at risk of extreme heating.

Organisations or concepts such as Natural Neighbours, National Park Cities, and Transition Towns and Transition Streets, show some possibilities for engaging people, communities and organisations with the possibilities of their local built environment.

Existing nature or conservation organisations such as Coed Cadw, RSPB, WWF Cymru, Friends of the Earth Cymru, the National Trust and a myriad of other organisations, some represented through Wales Environment Link, could perhaps play a role in helping build this movement.

Civic and community organisations would be very valuable participants, bringing their specialist local knowledge, as well as sector-specific understanding not necessarily available to environmental organisations.

Who’s doing urban trees well?

• When I used to work in the woodland sector, the Red Rose Forest was widely recognised as a pathfinder in this sector. It has now been rebranded as Manchester’s City of Trees
• Urban Forest – a community organisation in south Manchester looks interesting

Non-heating issues

Some of the interventions suggested also have wider benefits. For example, urban trees, in addition to providing cooling:

• Look nice
• Improve mental health and well-being just by being part of the townscape
• Improve air quality by scrubbing particulates and harmful gases
• Remove and store greenhouse gases
• Reduce the cases of childhood asthma
• Provide a habitat for many non-human species
• Reduce rainwater run-off (by 2% per 5% increase in tree cover), and thereby the risk of flash (pluvial) flooding perspective

Urban trees can be integrated with street furniture to provide huge amenity to a wide range of residents and visitors. Street furniture, particularly shaded furniture, is a key enabler for people to participate in urban life if they experience challenges in walking, are carrying shopping, engaging with young children etc.

Caveats

The suggestions made in this blog post are provided in the luxury of not having to bear in mind any policy, legal, financial or practical implications for implementing them.

There are likely a myriad of challenges to implementing them, not least with educating people about the reason for changes in the streetscape, keeping trees alive in urban areas, removal of parking to allow street furniture and/or trees, removal of leaves in the autumn etc.

The suggestions are made as a way to stimulate discussion about ways in which the objective of liveable urban areas in Wales by 2100 can be provided that give the maximum climate, nature and health benefits.and community benefit.

Could 50°C in the towns and cities of Wales be liveable?

I believe that the answer to this is a resounding ‘yes’ – but it will take a lot of strategic vision, and a genuine approach of reinventing our urban areas as places where nature and the built environment work in harmony.

I can see a future for Wales’ towns and cities which is far more liveable than our urban spaces today, even pricing in big challenges arising from climate change. These towns and cities will be designed to address heat and heavy rainfall using natural solutions as the default, with other built ‘hard’ structures only where nature is not able to deliver all the solution. Our towns and cities could be truly wonderful places to live and visit.

I look forward to working with others to make the vision a reality.

Footnotes

1. This is, of course, an inexact exercise, complicated by the non-linearities inherent in a complex system. For example, we don’t yet know how much the Atlantic Meridional Overturning Circulation (AMOC) will weaken this century, or whether it will collapse completely. If it does, it may offset some of the ‘generic’ heating impacts of climate change. The subsequent shift of heat to the south pole could massively increase ice cap melt, raising sea levels and rendering the population centres of Wales – and neighbouring cities in England uninhabitable, except, I guess, by marine creatures. ↩︎
2. Full reference “Hodges, C. 2020. Tree Cover in Wales’ Towns and Cities: update 2020 – Updated information to help us understand canopy cover to better plan and manage our urban trees. Report No: 465, 26pp, Natural Resources Wales, Bangor (Gwynedd).” ↩︎

Additional resources

• Woodlands for Wales action plan (2023); Welsh Government
• Tree cover in Wales’ towns and cities; update 2020; Natural Resources Wales
• Trees and Design Action Group