Another scorching summer - what lessons can we learn from Singapore and Freetown to cool our cities?
Mark Coates FCIHT, FCInstCES
Trusted Advisor | Digital Leader | Stewardship | Change Agent | Strategic Theorist | Subject Matter Expert | Commercial Leader | Researcher | Author |
UK readers might not believe this with the drab summer and looking out of the window this morning but researchers at Copernicus say it is increasingly likely 2024 is going to be the warmest year on record.
This comes off the back of a record-breaking 2023 which was the previous warmest year since global records began in 1850.
Indeed, last year marked the first time on record that every day of the year was at least 1°C or more above the 1850-1900 pre-industrial level. The Copernicus data says that close to 50% of days were more than 1.5°C warmer than the 1850-1900 level, and two days in November were more than 2°C warmer, the first time that’s ever happened.
The Coates household doesn’t have the sophisticated global satellite monitoring capability of Copernicus.
However, after our last two summer holidays in Europe the expert researchers in the Coates household – comprising of my daughter, my fiancée and me – can confirm that it reached and exceeded “bloody scorching” on our temperature gauges for the past two years running.
Our holiday in August 2023 saw us face four days of temperatures above 40 degrees in Lazise on Lake Garda so this summer that we decided to drive from Oxfordshire to Castillon-du-Gard where we thought it would be a bit cooler.
It was, marginally, but we still faced 40-degree temperatures and even without this conclusive proof from the Coates household I think the majority of us can agree that the world is getting warmer.
This matters.
The implications of living in a warmer world are worrying.
Every year The World Economic Forum surveys around 1,500 global experts for the Global Risks Perception Survey.
Two-thirds of respondents said “extreme weather” (66%) was the top risk facing the world in 2024.
While extreme weather was seen as the second-most severe risk over the two-year time frame behind online misinformation and disinformation, extreme weather was ranked the number one issue over the ten-year time horizon.
According to experts, the top four risks over the long-term are all environmental. After extreme weather the top four features critical changes to Earth systems, biodiversity loss and ecosystem collapse and natural resource shortages.
What are the impacts of climate change?
A major impact of climate change on biodiversity is the?increase in the intensity and frequency of fires, storms and periods of drought. According to the UK Health Security Agency the impacts of drought on society include loss of crops and livestock, increases in food prices, water shortages and mass migration.
In recent months I have been researching a new White Paper with British Water on surface water flooding due to be launched in September.
In general, climate change is causing summers to be hotter and drier and winters to be wetter.
However, there are very important exceptions to this rule, and this is when much of the damage is being caused by climate change.
It is the extremities of climate change which is inflicting the most damage on places and infrastructure.
Many of the most extreme flooding events are taking place in the summer months.
This is because hot air can hold more moisture (The Clausius–Clapeyron relation - for every 1℃ of warming, the atmosphere can hold 7% more moisture).
So warmer air leads to more intense rainfall and increases the chances of flooding.
In July 2021 London suffered surface water flooding from three extreme rainfall events in less than two weeks. The floods caused the closure of eight tube stations for a day and two hospitals. Whipps Cross Hospital was one of these and had to evacuate 100 patients after a power failure. The insurance data company, Perils, has estimated that insurance and reinsurance industry losses for the flooding between 12th-14th July alone reached ￡281m.
In August that year New York along with eight other states were hit by Hurricane Ida.
Its peak of 80mm of precipitation per hour was almost double the 38-50mm of rain per hour capacity which can be handled by New York’s sewer system.
CoreLogic estimated that Ida caused an estimated $16-24 billion in flooding damage in the Northeastern United States which includes New York, New Jersey, Pennsylvania, Maryland, and Connecticut.
As this damage shows climate change is causing the most expensive challenges in cities where property prices are higher and where nowadays most people live.
According to the 2020 US census. urban areas, now account for 80% of the U.S. population.
In Europe almost three quarters (73%) live in urban areas, with 42% in cities and 31% in towns and suburbs.
Urban areas also experience higher temperatures than rural surroundings as buildings and roads absorb heat, this is exacerbated in areas with tall buildings and narrow streets and motor vehicles adding to the heat.
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These factors create what is known as the urban heat island effect, which is most pronounced during the night, when temperatures in urban areas can be up to 10°C higher than in rural areas as buildings and roads release heat during the night.
How can we make our cities more resilient to climate change?
Here we come to one of my favourite types of infrastructure: nature based solutions and green infrastructure.
Planting trees is one of the most common ways to reduce heat stress with the shade provided by trees able to reduce urban heat by between 5 and 8 degrees according to UK-based organisation Trees for Cities.
Going further than this to plan urban forests is also being used in cities such as Seoul, Melbourne, Milan and Barcelona.
Milan has a target to plant three million new trees by 2030 while Barcelona has a 20-year masterplan to plant more trees and diversify the city’s tree population , which includes increasing the city’s tree cover by 5%,?so that 30% of the city’s surface area is covered by trees).
According to the conclusion of the British report “Benefits of green infrastructure” (2010, Forest Research), installing more green infrastructure has a positive effect on life expectancy and improves mental and physical health due to the psychological and physical benefits arising from the physical and social activities undertaken by people in contact with nature. This reduces risks to mental health, circulatory problems, obesity, etc., with consequent savings in public health expenditure.
Cities with higher aspirations on tackling climate change are also investing to create more living, green roof spaces.
Singapore has been working on a greening blueprint of the city since 1992.
Since 2009 under its Skyrise Greenery Incentive Scheme, Singapore pays property owners up to 50% of the cost of installing green rooftops and facades. This amounts to up to $200 a square meter for roofs and $500 a square meter for vertical plantings,?according to the government .
One of the stated goals in the Sustainable Singapore Blueprint is the creation of?200 hectares?of rooftop greenery by 2030, enough room to fit around 280 football pitches.
Manfred Koehler, President of the World Green Infrastructure Network, states ‘green surfaces are less expensive than tiled roofs in the long run because they last longer.’
Singapore is blessed in this respect that because of its settled climate which is not subject to seasonal changes, the weather conditions are ideal for plant growth and not much re-planting is required.
Re-planting and maintenance of this is a much bigger challenge for most Western cities.
Mayors of 41 cities worldwide have signed up to the C40 Urban Nature Accelerator goal to have a target of 30-40% of built-up city surface area consisting of green spaces like parks or streets lined with trees, or permeable spaces to absorb water and prevent flooding by 2030.
A report on the progress the C40 cities have made so far showed 43% of cities had reached the target by 2023 with 23% going beyond the 40% target.
One of the most incredible examples of achievement from the C40 cities campaign has happened in Freetown in Sierra Leone.
In August 2017, Sierra Leone suffered the worst natural disaster in its history. A colossal mudslide, caused by days of torrential rain, engulfed the streets on the edge of Freetown, killing 1,141 people.
After becoming Mayor in May 2018 Yvonne Aki-Sawyerr OBE pledged to take action and in January 2020 launched a campaign called #FreetownTheTreeTown.
In 2021, the city secured US$ 1.8 million from the World Bank and Global Environment Facility to implement the campaign, aiming to plant, digitally track and grow 567,000 trees to reduce the risk of floods, landslides, coastal erosion and extreme heat.
Freetown's efforts were recognised in 2022 when the city was 15 cities recognised in the Bloomberg Global Challenge, receiving US$ 1 million.
According to C40 Cities as of December 2023, 977,000 trees have been planted, more than 1,000 green jobs created, and approximately US$ 3.25 million mobilised.
Going forwards Freetown plans to plant, track and grow an additional 10 million trees by 2030.
This is hugely encouraging to hear.
I’d love to write a blog exploring green infrastructure further in the coming weeks and months.
If anyone has any contacts with the World Green Infrastructure Network or the team’s leading on green initiatives in Freetown and Singapore I’d love to speak with them and find out more.
Stay safe and stay cool this summer where ever you are.
NB: Several temperature records have been broken recently:?
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2 个月So glad you highlighted the wonderful work trees do in our cities. Anyone who's sat under a tree in a park knows what a refuge from the summer heat they provide. However, I hate seeing how many of these trees are planted - squashed in too closely with no after care. Or how developers cut down mature trees instead of incorporating them into their plans. It takes approx 20 years to reach the bio benefits a mature tree provides. They need aftercare and that should also be considered into the green infrastructure plans.