Climate change affects landscape architecture

Climate change causes the following extreme situations in Estonia

There is a general trend towards more extreme temperature fluctuations (both severe cold and heatwaves), and these extremes are becoming more frequent (for example, during winter, the temperature may fluctuate from 0°C to -15°C in a single day and then back to 0°C, and in summer from +15°C one day to +30°C the next).
Droughts are becoming more common, with longer dry periods mainly in spring and summer.
Winters are becoming softer. This has various effects. On the one hand, warm tempearatures means more water instead of snow and ice, and as the ground is partially thawed and partially frozen, and does not absorb additional precipitation so well, leading to soil erosion. On the other hand, it leads to a drough in the spring, as there are no ice and snow that would gradually moisten the ground. The lack of water in spring causes great stress to urban greenery and increases maintenance costs due to the extension of the watering period. Species adapted to a certain length vegetation period and need a rest in winter do not survive frequent temperature fluctuations, mild winters, and without the necessary winter rest period, they may weaken and die.
Increase in heavy rainfall events (cloudburts). This means a huge amount rain falling down at once, which the ground cannot absorb (infiltrate) all at once, resulting in floods and soil erosion.
Warming climate creates favorable conditions for the more successful spread of invasive species, which may compete with local species (e.g., some ornamental plants become invasive, such as knotweed) and may also become a threat to human health (e.g., pathogens).

Why is it so difficult to understand that we need to adapt to climate change?

1. The impact is long-term and not immediate

Climate change brings about gradual changes that may be difficult to notice in the short term. For example, warm, snowless Christmases have become common in recent years, but we remember from our childhood that such warm winters were rather rare. Changes in air quality are not visible and not so easily sensible, especially since this deterioration occurs step by step and not all at once.

2. The impact seems intangible

Climate change affects various areas of life, where it may not be obvious to be related to climate change. The effects are indirect and complex, and the connections to climate change are not clearly identifiable. Highlighting local impacts illustrates the effects very well. For example, in Estonia, autumn storms that cause a lot of damage have become more frequent. The direction of stormy winds has changed compared to the past, causing trees to break and even roofs of buildings to be torn off. Trees are affected by the twisting force of the wind, as they are not accustomed to such wind direction during their growth and the wood tissue breaks.

3. Preventive and mitigating measures are abstract

As the impact is not immediate but long-term, and the effects of climate change are difficult to understand, the ways to prevent and mitigate it are also difficult to grasp. It is important to understand what can be done at the individual level and what can be done at the organization and state level. To make the need to adapt to climate change more understandable, it is important to focus on practical examples, local impacts, and explanatory work on how one could contribute to mitigating the effects of climate change. For example, excel landscape design can protect communities from extreme weather conditions such as wind corridors, the impact of cloudburst events and heavy rains and storms, and heatwaves.

Climate change significantly affects the daily work of a landscape architect

Recognition of green infrastructure as an important and necessary component to mitigate the harmful effects of climate change. A shift in society’s mindset is needed to recognize green spaces as part of green infrastructure with equal importance to road networks and/or utility networks. It’s time for green infrastructure to shed its ‘garnish’ image as merely fulfilling an aesthetic function, as it has been seen so far. Green spaces (including street greenery, parks, and green corridors) play a significant role in regulating climate change-related impacts: heat island effect, devastating impact of storms, reduction of air pollution and flood damage, erosion, and loss of habitats. Key here is to choose plant species that are resilient to different types of stress: heat and drought, winds, temporary extreme water condtions, as well as thrashing by winds and storms.

Sustainable planning. Increasing urban building density, planning green infrastructure as a continuous system (reduces erosion, preserves habitats, and increases rainwater buffering), ensuring accessibility, and densifying public transport networks support walking and cycling, increase the use of public transport, and likely reduce dependence on car travel. This reduces carbon dioxide emissions and improves the efficiency of various resource uses.

Adapting to climate change. All designers (not only landscape architects) must consider extreme weather phenomena: storms, temperature extremes (including heatwaves), and increasing heavy rains. Adaptation requires smart design and adjustment of green areas, making them more flexible and resilient. Such adaptation-driven solutions are led by landscape architects due to their fundamental knowledge.

Considering the risk of flooding. With the increase in heavy rains, floods are becoming more likely, which can cause a variety of damages. There is a need for measures that ensure the functioning of infrastructure, such as collecting, delaying (holding), and gradually infiltrating rainwater.

Landscape design can reduce the impacts and damages caused by climate change

1. Improving air quality

Trees and greenery binds carbon dioxide and releases oxygen, thereby reducing the amount and impact of greenhouse gases. Trees and greenery reduce air pollution, such as the amount of dust and soot in the air. Evergreen trees and shrubs are more effective because they also function in winter when deciduous woody plants are bare. Dust and soot are captured by the leaves so they do not float in the air no longer.

2. Reducing the impact of flooding caused by cloudburst events

As rainwater drainage systems have limited capacity, increasing water volumes cause various problems. Smart planning can collect and direct rainwater in a way that prevents flooding. For example, guidelines have been developed in the form of a , showing what possibilities are available in our climate conditions for delaying and locally infiltrating large amounts of rainwater.

In general, such smart local infiltration systems support the functioning of the water cycle, the recharging of surface water and groundwater. Impervious surfaces (e.g., roads, parking lots, and building ground) do not allow water to seep in, and the proportion of so-called ‘desert areas’ increases because water is diverted to rainwater drainage systems and then into some waterbody (lake or the sea), but it is not infiltrated into the ground at its source as it happens in natural areas. Through green spaces and infiltration areas, water seeps back into the ground, ensuring the continuity of the water cycle.

3. Reducing heatwaves and the heat island effect

Trees and greenery have a cooling effect for several reasons – on the one hand, trees provide shade, and the temperature is always lower in the shade than in full sun, and on the other hand, water always evaporates from the surface of leaves, lowering the local temperature. Large trees and shrubs provide better shade than small ones. Therefore, it is always preferable to preserve existing large trees because a small tree will take 10 years to reach dimensions that start to noticeably affect the area’s microclimate. Therefore, green areas, especially large trees, are of great importance for human health and well-being. Street trees and green areas provides shade for cyclists and pedestrians on their daily journeys, especially important for elderly people who are particularly sensitive to high temperatures. The heat island effect also affects our pets – summer hot asphalt burns the pads of our four-legged friends, and asphalt shaded by trees provides cooling relief for them too. Structuring parking lots with trees and greenery is also important, as it provides shade for cars, and it is much more pleasant to get into a cool car. Structuring parking lots with trees and greenery also helps to infiltrate rainwater locally, thereby improving the water cycle.

Water bodies also have a cooling effect on hot summer days. Smartly planned areas act as rainwater reservoirs and allow the collected water to be gradually infiltrated into the ground. Such areas cool the air and local microclimate during the hot summer, as evaporation from surfaces lowers the surrounding air temperature.

4. Protection from storm and strong winds

Outdoor spaces can be combined with trees and greenery (especially large trees and shrubs, and evergreen trees and shrubs) to block wind corridors and reduce the twisting effect of winds. This way, damage to property (e.g., uplifting of the roof of a building) and wind throw in green spaces and urban areas can be reduced.

5. Energy savings

Trees and greenery around a building reduces the possibility of wind corridors. The presence of evergreen tree groups around a building means less energy spent on heating in winter, as it mitigates the wind chill effect. In summer, trees and greenery provides shade from the sun, reducing the energy spent on cooling. An existing large tree is always better than several new and still small trees. The wind-shading and cooling effect of a large tree is immediate and does not require waiting for small trees to grow over the years.

Sources:

1. Rainwater solutions suitable for the Estonian climate (original title Eesti kliimasse sobivad sademeveelahendused). 2021. Merle Kuris, Gen Mandre, Valdo Kuusemets, Alar Mik.
Link: https://urbanstorm.viimsivald.ee/wp-content/uploads/2021/08/urbanstorm-teavik_EST_veebifail-1.pdf

2. Handbook of rainwater solutions suitable for the Estonian climate (original title Eesti kliimasse sobivate säästvate sademeveelahenduste käsiraamat). 2022. Gen Mandre, Valdo Kuusemets, Merle Kuris.
Link: https://urbanstorm.viimsivald.ee/wp-content/uploads/2023/03/SUDS_kasiraamat_digi.pdf

3. The nature of climate change (original title Kliimamuutuste olemus). 26.09.2022. Kliimaministeerium.
Link: https://kliimaministeerium.ee/rohereform-kliima/kliimamuutused#prognoos

4. Impact examples in Estonia (original title Mõju näiteid Eestis). 07.05.2021. Eestimaa Looduse Fond.
Link: https://www.kliimamuutused.ee/pohjused-ja-tagajarjed/tagajarjed/moju-naiteid-eestis

5. A guide for planning green infrastructure and network (original title Rohevõrgustiku planeerimisjuhend). 2018. Riin Kutsar, Pille Metspalu, Kaile Eschbaum, Siim Vahtrus, Kalev Sepp.
Link: https://loodusveeb.ee/sites/default/files/inline-files/rohev6rgustiku-planeerimisjuhend_20-04-18.pdf