Throughout history, the world's population has lived in rural areas by and large. In the 1800s, at least 90% of the world's population lived in the countryside, while the urban population constituted less than 10%. With the development of trade, people switched to urban life as cities became centers of trade.
As industrial production became widespread, migration multiplied and people moved to areas with more production, establishing new and large settlements.
Especially with the Third Industrial Revolution, rapid urbanization began and today, 54% of the world's population lives in cities. By 2050, the world's urban population is projected to rise to 66%.
At the heart of mass migration lies the anxiety of a comfortable life with transportation, communication, education and health being the most obvious reasons for this. This puts pressure on the area where people migrate to, as the resources are limited but the number of people looking to take advantage of them increases every day. While cities offer people the chance to live a more comfortable life at the same time they create local, regional and universal problems that are difficult to solve.
Population growth and rising income levels are another source of problems. In our country, the population has increased by 50% in the last three decades from 55 million to 83 million. In the same period, developments within the country, where national income per capita increased by about four times, also led to an increase in consumption. This excessive consumption has undoubtedly put pressure on the environment.
Currently, cities consume 75% of natural resources globally and are responsible for 50% of the waste generated while also producing on average 70% of the world's greenhouse gas emissions.
Of course, cities should address needs, such as food, housing, clean air, water and waste services but additionally should provide green spaces where citizens can go to be healthy, take a break and refresh.
Silent Killer: Air Pollution
One of the major environmental problems we face today is air pollution. According to the World Health Organization (WHO) data, 8 million people die each year from air pollution-related causes.
Air pollution is an important environmental problem for Turkey, too. While developments designed to reduce pollution such as the spread of natural gas, the advancement of technology, the spread of public transport and alternative means of transport have been implemented and lowered pollution levels to some degree, pollution caused by public transport, in particular, continues to add to the issue.
The main factor affecting air pollution levels is vehicle density. According to the Turkish Statistical Institute (TurkStat) data, the number of vehicles on the streets in 1990 was 4 million, 8 million in 2008, 23 million at the end of 2019 and has reached 25 million currently. As with the population, about 20% of vehicles are in mega-city Istanbul.
A project carried out by Hacettepe University on behalf of Ministry of Environment and Urbanization revealed that about one-third of these vehicles are over 16 years old and equipped with old technology. This makes the application of green walls, which are becoming more and more common in the world, more attractive and necessary in order to prevent air and noise pollution caused by heavy vehicle traffic.
Refreshing green spaces
According to WHO assessments, the green space per person should be 9 square meters (97 square feet) for a healthy life. However excessive densities occur in some regions that can pose a number of difficulties for green space production.
The new garden trend was developed in order to prevent such problems in several developed megacities such as New York, Melbourne, London and Paris, in order to alleviate the increased air pollution to some extent and to enable people to relax spiritually.
With the concentration of population density in certain regions within the scope of commercial activities, the space problem has become important in the world, and vertical growth has been achieved by developing multi-story buildings for housing. Vertical agriculture (multistory garden applications), which is also a new application in the agricultural sector which is gradually decreasing due to climate change and soil erosion, is becoming increasingly popular today.
Vertical gardens began emerging in the 1970s but now new types of green spaces are being cultivated that can be put to many different applications. Whether it be a rooftop garden, vertical garden, green or living wall, leading cities around the world including New York, Melbourne, London and Paris are incorporating a bit more nature into their concrete landscapes.
These gardens' most important trait is that they do not require additional space and are usually cultivated on unutilized rooftops or external wall surfaces. Even public transport stops, such as train stations, and the tops of the vehicles themselves are being used to increase the green view.
Benefits at hand
These gardening practices, which have been in our lives for the last 50 years, offer environmental benefits such as preventing air and noise pollution and reducing global greenhouse gas emissions, and economic benefits such as energy savings and reducing possible health costs.
Moreover, they act as a kind of filter for important air pollutants released from exhausts. According to research, a 60-square-meter garden wall can filter 40 tons of harmful gasses and 15 kilograms (33 pounds) of heavy metals. They also contribute to the air quality by absorbing harmful volatile organic compounds.
According to a 2012 article in the Environmental Science & Technology magazine published in the U.S., green wall applications on roads in the canyon structure (with buildings or walls on both sides) reduce harmful dust (PM10) by up to 50%. Again, similar results were obtained in studies conducted under an article published in ScienceDirect in 2016, where green wall applications were seen to prevent air pollutants by 24%-61%.
One of the important effects is the prevention of greenhouse gases. The greenery functions as a swallow space for greenhouse gases that lead to global warming. A living wall of only one square meter removes 2.3 kilograms of carbon dioxide gas from the air, while they also give 1.7 kilograms of oxygen to the environment, which is our source of life.
A study conducted at the Royal Melbourne Institute of Technology, the largest university in Australia, also stated that if green walls are constructed correctly they can act as an ecological buffer, preventing both air and noise pollution. The study's results show that green walls can combat up to 63% of carbon emissions, which would contribute to the fight against climate change.
One of the important benefits is the reduction of noise. Vegetation in vertical gardens allows the noise from vehicles to be dispersed in multiple directions, rather than reflected directly in one. It acts as a kind of noise barrier by dampening it within itself. Up to 40% noise reduction can be achieved depending on the selected plant type and planting frequency.
Vertical gardens also absorb the sunlight, stabilizing the temperature in the region and preventing the formation of heat islands in city centers, one of the major problems caused by global climate change. They also absorb the energy in the environment through plant sweat. However, if it is applied to the external wall of a building, it keeps the building cooler in summer and protects it against adverse weather conditions such as winds in winter, thus contributing to energy saving.
According to the report of the ninth National Roof and Facade Conference held in 2018, the studies carried out by the National University of Singapore showed that reducing the temperature of a building by only one degree leads to as much as 5% in energy saving. Likewise, according to the evaluations of the American Society of Landscape Architects (ASLA), which has a history spanning 120 years, green walls contribute to energy efficiency by 23% like green roofs and rooftop gardens and can reduce temperatures by up to 10 degrees.
In addition, they are more aesthetically pleasing in appearance and provide relief for people as well as acting as the natural habitat for species of birds and insects. In this way, they help promote biodiversity, which is one of the major environmental problems facing the world today.
On the other hand, research shows that they also increase productivity in business environments as cleaning the air eliminates complaints such as headaches, eye irritation and fatigue caused by air pollution – allowing employees to feel more energetic. They also provide relief by reducing stress.
Watching a green space for 3-5 minutes is known to improve blood pressure, heart rhythm, muscle tension and brain activities. According to relevant research, a green working office increases productivity by 15%. Amazon Towers in Seattle hosts 40,000 plants of 400 different species while the Desjardins building in Canada’s Quebec province is home to the world's largest living wall with a height of 65 meters, housing 11,000 plants.
The 800-square-meter entrance surface of the iconic Musee du quai Branly – Jacques Chirac in Paris has been adorned with 15,000 plants. Paris has a target of covering 1 million square meters of roadside wall, roofs and façades of buildings facing main streets with greenery.
As part of the Bosco Verticale (Vertical Forest) project, 800 trees and 15,000 plants were planted on the balconies and rooftops of two 111-meter-high buildings in downtown Milan, overwhelmed by air pollution, bringing both fresh air and making it a beautiful site. Additionally, as part of the project, thousands of bird and insect habitats have been created in the center of the city, which has been landlocked by concrete.
A living wall was created in the passenger boarding hall at London’s Heathrow Airport, Europe's busiest airport, to create a healthy environment for passengers. In the section called Garden Gate, seven panels with an area of 4.5 square meters were created, each containing 240 plants.
The motivation to create the gate was customer satisfaction. Passengers reported 47% satisfaction prior to the living wall which increased to 72% once the wall was up and operating healthily.
Likewise, studies carried out by the U.K.'s Birmingham and Lancaster Universities in 2012 revealed that adding more green life to the streets could prevent air pollution by 30% on a cumulative basis. According to British experts, green walls reduce NO2 emissions by 40% and particulate matters by 60%.
In this respect, walls on both sides of a busy main road that runs through London have been converted into green walls. It is reported that a four-meter square wall can produce the same effect as 275 trees. It is predicted that a portion of the £500 million budget allocated for the development of the green infrastructure of the city will be designated to the development of living walls in areas with heavy traffic.
Mexico City, the capital of Mexico, launched the initiative in 2018, covering columns on the roads with heavy traffic and the walls around the roads with green vegetation. The aim is to prevent vehicle-induced air pollution while beautifying the city.
More than 1,000 columns were covered with greenery and living material in an area exceeding 54,000 square meters and the project is expected to meet the oxygen needs of 25,000 people while absorbing 27,000 tons of harmful gases and about 6,000 tons of dust annually.
Great efforts are being made both on a local and national front to increase green areas per capita in our country. As part of its vision project for 2023, the Ministry of Environment and Urban Planning aims to bring 81 million square meters of green space to 81 provinces with the project of national gardens greatly contributing to this goal.
According to the municipal data, as a result of the investments made by the capital Ankara in the last 25 years, the green area per person has reached 20 square meters, marking a 10-fold increase with this figure standing at 6-7 square meters per person in Istanbul and 4-5 square meters in Izmir, another important big city of Turkey. Keeping this value in mind, when we look at other world metropolises, it is around 3 square meters in Tokyo, 5 in Barcelona, 10 in Paris and 23 in New York.
These values are not the same for the entire province and differ in parts. According to international assessments, woodlands, green vegetation on roadsides and green spaces on private property (including the gardens of public buildings) are not included in these values.
Therefore, due to space limitations, vertical and rooftop gardens are becoming a matter of greater importance with Turkey creating the necessary regulations in 2013, bringing the issue to legal ground.
The amendment to the Planned Areas Type Zoning Regulation paved the way for the building gardens on rooftops. Given the numerous benefits of green spaces such as air quality, energy saving, temperature balance and contribution to biodiversity, this regulation is of great importance.
However, we cannot say that rooftop gardens and vertical gardens have become very common in our country.
Municipalities are implementing green initiatives especially in megacities such as Ankara, Izmir and Istanbul where local governments are cultivating roadside wall gardens in areas with heavy traffic.
Caring for a wall or rooftop garden is very simple as they require minimal interference as they are designed with an internal irrigation system but do need an annual pruning, some fertilizer or, when called for, the removal of harmful pests. The walls offer numerous ecological, economic and mental benefits, with municipalities decorating the panels with figures derived from recycled plastic - both reducing maintenance costs and decorating the area.
Istanbul municipality's move
Istanbul Metropolitan Municipality (IBB) administration is taking an odd position after it previously stopped investments in advanced biological treatment plants with a membrane system that would bring with it a new era in wastewater management in Istanbul, saving a lot of money. The 55,000-square-meter green wall application, which offers countless benefits, unfortunately, faces a massacre.
Developing and growing vegetation is being removed and replaced by graffiti using a synthetic chemical paint. The IBB claims the move is due to the walls' high cost as well as pollution caused by the chemicals used in the care of these areas. However, the plants used for the vertical gardens are no different from those in other public parks and gardens and are subject to the same care and chemicals.
People continue to visit public parks, even bringing their children, and do not experience any side effects from the pollutant chemicals used on the plants, so why should the case for the roadside be any different? Moreover, plants in public parks and gardens are prone to vandalism whereas vertical gardens on roadsides are not.
The graffiti process in these areas has negative environmental effects with an average of 11,000 to 15,000 liters of paint being used, meaning at least 5-10 tons of volatile organic compounds will be released into the air. In addition to destroying the benefits of green vegetation, volatile organic compounds are formed as a result of the painting that emits compounds into the air, which are extremely harmful to health. When these compounds interact with NO2 gas released from vehicles it causes the formation of ground-level ozone, which is extremely harmful. Ground-level ozone, whose effects will gradually increase with hot weather, puts those with respiratory conditions such as asthma at great risk.
Colorful graffiti is more likely to distract drivers with dark colors absorbing more solar energy than concrete would, causing temperatures to further rise. The murals decompose faster due to sunlight and other meteorological factors and therefore will inevitably need to be renewed – an inevitable financial burden that eliminates the benefits the vertical gardens offered.
The destruction of a beneficial, functioning system – instead of utilizing the one million square meters of available wall in Istanbul – highlights the lack of planning that has gone into the move.
In our world where the effects of global warming are increasing day by day as heat islands emerge and high air pollution make city centers more uninhabitable the importance of greenery per square meter increases. Environmental investments should increase rather than eliminating the existing ones.
As we have always said, the environment is an issue that cannot be politicized. Since all environmental investments will prevent health costs, we consider a healthy environment a form of preventive medicine. In this respect, we call on the authorities to do their duty. Let us not destroy the refreshing living walls but rather increase their number as it will benefit us all.
*Deputy minister at the Republic of Turkey's Ministry of Environment and Urbanization, chief climate change envoy