Trees May Clean the Air But we Need New Ideas

  Do you see tree-lined streets and hear birds singing
when close your eyes and imagine your ideal home and ideal city?

People tend to describe the same things when asked to imagine their favourite place. The question is how to get from this image to reality. Simply adding natural elements like trees into urban environments may not be enough.

Trees help to reduce the impact of human activities and the surfaces of leaves absorb pollutants. Trees intercept airborne particles and absorb pollutants such as carbon monoxide, sulfur dioxide, and nitrogen dioxide. Trees also lower air temperature through respiration.

The size of trees and shrubs is a predictor of future trends in an area. While larger trees provide more ecosystem services like air quality than smaller trees, they are difficult to maintain in urban areas.  Space is often limited in urban areas and there is also risks involved in keeping large trees in backyards. This risk may even increase as we may expect more storms and higher wind speed in the future.

However, the benefits of trees is not straightforward and older trees grow slower and although they store significant amounts of carbon dioxide, they do not remove as much as they used to. When a tree is dying they also emit carbon dioxide CO2. Tree planting can be seen as more of a short-term fix and when trees die they release the carbon back. Thus, rather than acting like a sponge older trees create more of a balance.

Tree planting scheme has been a popular method to help combat climate change and reduce the effects of carbon dioxide. Yet, many of the trees that have been planted have been pines and eucalyptus trees. Although these fast-growing trees rapidly suck CO2 from the atmosphere, they do not support a rich biodiversity. We have to be careful when we plant trees so that we select native trees that support biodiversity.

A warmer climate may also change the way trees are growing, and extend the season of growth.  These factors may lead to more natural emission, which means that the need for a reduction of human contribution is even higher. We also need other ways to reduce our carbon footprint such as changes in our behaviour, and  new solutions and approaches to manufacturing and designing urban areas.Thus, to solve the issues related to both air pollution and the primary greenhouse gas, CO2, we also need to seriously look for alternatives.

Biomimicry or biometrics aims towards understanding how ecosystem functions and to see if it possible to restore those functions or to develop solutions that help to mimic those systems that have been developed for thousands of years.

Can we create building materials that clean the air and store carbon just like trees?

An interesting idea is to make building materials by mimicking sea shells. Sea shell absorb CO2 from their surrounding and they hold on to the carbon more long-term. Currently cement manufactures are busy trying to find solutions that means that the carbon emission from production of building materials is reduced – the cement industry is contributing at least 5 percent of global carbon dioxide emissions. For example, the Australian company Zeobond has develop E-concrete that forms at room temperature and no kiln is required in the production.

So perhaps we need to raise the ribbon and not only look for greener and more sustainable materials but also to develop materials that can hold on to carbon dioxide. We can also develop artificial trees that help to suck CO2 from the skies and maybe other dangerous substances. Even if these trees may lack some of the lovely features I associate with living trees, there is no need to plant biodiverse artificial trees. And I would not mind having this artificial tree inspired by the dragon blood tree in my back yard.



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