How trees are cooling our cities
A well-known phenomenon is how warm our cities are compared to their rural counterparts. This
difference can be great, with some studies suggesting it can be 1-3͘͘͘͘͘ ̊C hotter in the city, whilst others
say it is anywhere up to 10 ̊C warmer. These higher temperatures can lead to further negative
impacts on our environment, through higher energy bills as people frantically attempt to cool down
in the metropolitan heat, with air conditioning and fans.
This phenomenon is often referred to as an ‘Urban Heat Island,’ and happens in our cities for a
number of reasons. The combination of densely situated insulated buildings, energy released from
residents going about their day and mass sky scrapers, city structures, pavements and car parks all
trapping heat throughout the day, slowly releasing at night all lead to rising temperatures with no
means of escape.
difference can be great, with some studies suggesting it can be 1-3͘͘͘͘͘ ̊C hotter in the city, whilst others
say it is anywhere up to 10 ̊C warmer. These higher temperatures can lead to further negative
impacts on our environment, through higher energy bills as people frantically attempt to cool down
in the metropolitan heat, with air conditioning and fans.
This phenomenon is often referred to as an ‘Urban Heat Island,’ and happens in our cities for a
number of reasons. The combination of densely situated insulated buildings, energy released from
residents going about their day and mass sky scrapers, city structures, pavements and car parks all
trapping heat throughout the day, slowly releasing at night all lead to rising temperatures with no
means of escape.
So how are we going to cool down our cities? City wide renovations? The latest scientific discovery?
Simpler than that: trees.
Now obviously, when you sit in the shade of a tree you are out of the sun, and your body
temperature cools. But this is just one of the many ways in which trees can cool down their
surrounding area. One such way is evapotranspiration (it’s not as complicated as it sounds).
Evapotranspiration is when rays from the sun hit the leaves on the trees, and the heat evaporates
the water in the leaves. That’s it. It’s just a tree sweating. But as this process needs energy in order
to take place, it therefore takes out some of the energy that would have been used to heat the air.
It’s like natures air conditioning.
Aside from this are other immediate benefits such as cooling down buildings, which have been
shown to decrease the cost of air conditioning by 20-30% for a detached house, another plus for
being environmentally (and financially) friendly. Trees can also lead to better water management
within our cities, improving the quality of the water by taking in and filtering rainwater and stopping
water from just running off our pavements and hard surfaces.
They also improve our health. Trees take in horrible air pollutants and carbon dioxide in the
atmosphere and push out oxygen, meaning the air we are breathing is cleaner and better for the
environment. Amongst all these factual positives, trees make for lovely scenery. They increase
biodiversity, creating habitats for animals, and reduce noise pollution, which I am certain will aid a
city dwellers restful sleep. There really is no end to the pros of these plants.
A recent study has suggested that in order to get all the cooling benefits from trees, the canopy
needs to cover at least 40% of the surrounding area. If you were to look at your road from above,
trees would cover at least 40% of the map. Meaning we need to plant an awful lot of trees. Want to
be part of the solution? Join us, Be Carbon Negative, and our pledge to give 100% of our profits to
planting trees, offsetting your carbon input.
Simpler than that: trees.
Now obviously, when you sit in the shade of a tree you are out of the sun, and your body
temperature cools. But this is just one of the many ways in which trees can cool down their
surrounding area. One such way is evapotranspiration (it’s not as complicated as it sounds).
Evapotranspiration is when rays from the sun hit the leaves on the trees, and the heat evaporates
the water in the leaves. That’s it. It’s just a tree sweating. But as this process needs energy in order
to take place, it therefore takes out some of the energy that would have been used to heat the air.
It’s like natures air conditioning.
Aside from this are other immediate benefits such as cooling down buildings, which have been
shown to decrease the cost of air conditioning by 20-30% for a detached house, another plus for
being environmentally (and financially) friendly. Trees can also lead to better water management
within our cities, improving the quality of the water by taking in and filtering rainwater and stopping
water from just running off our pavements and hard surfaces.
They also improve our health. Trees take in horrible air pollutants and carbon dioxide in the
atmosphere and push out oxygen, meaning the air we are breathing is cleaner and better for the
environment. Amongst all these factual positives, trees make for lovely scenery. They increase
biodiversity, creating habitats for animals, and reduce noise pollution, which I am certain will aid a
city dwellers restful sleep. There really is no end to the pros of these plants.
A recent study has suggested that in order to get all the cooling benefits from trees, the canopy
needs to cover at least 40% of the surrounding area. If you were to look at your road from above,
trees would cover at least 40% of the map. Meaning we need to plant an awful lot of trees. Want to
be part of the solution? Join us, Be Carbon Negative, and our pledge to give 100% of our profits to
planting trees, offsetting your carbon input.