1 Introduction

Pre-industrial cities can be defined as ecological cities with low population and ones that have harmony between nature and humanity. In the process from the post-industrialization to the present, the balance between cities and the ecological system has deteriorated (Deniz, 2009). Moreover, with the development of the industry, people started to live in uncontrolled and unhealthy areas which lacked infrastructure and started to use fossil fuels. As a result, air pollution has occurred in cities while carbon emissions have been increasing, and the ecological footprint of cities has grown (Işıldar, 2012). Therefore, our carbon footprint, which makes up an important part of our ecological footprint, increased by 30% between 2000 and 2010. According to data in 2007, the world’s total ecological footprint was 18 billion global hectares (gha) or 2.7 gha per individual. Whereas, the biological capacity of the world is only 11.9 billion gha or 1.8 gha per individual. If it is to continue in this fashion, it is clear that we will need 2 planets in 2030 and 2.8 planets in 2050 (Pollard et al., 2010; Wackernagel et al., 2012). Today, the increasing ecological footprint both personally and in our world; for cities requires a transition to different city models such as eco-cities, sustainable cities, green cities, and many more. Improving the quality of life, reducing ecological footprints, and adapting to climate changes are essential steps for sustainable cities (Pauleit et al., 2017). Ecological footprint is a methodology used to determine these negative effects with numerical data, studies to reduce the ecological footprint are also gaining importance (ÇELİK & Handan, 2022). In addition, ecological footprint calculation methods provide a systems approach for natural resource accounting based on global, regional, local, and individual supply and demand (Mızık & Yiğit Avdan, 2020). The main factor in realizing the ecological transformation of the cities is the determination of their ecological footprint. Its definition in the literature also presents the total amount of bio-productive land and wetlands required to meet the vital necessities of a specific population and how much production area is needed by nature for human consumption (Lu & Chen, 2017). In addition, the ecological footprint calculation is made according to the demands of a society, that is, their consumption, and taking into account the resources that the ecosystem can meet. Demand or consumption calculation measures the plant or animal food consumed by the individual or society, the timber and forest products, the carbon dioxide emissions as a result of urban infrastructure, and fuel consumption. Calculation of available resources shows the biocapacity of a city or nation, production lands, forest lands, agricultural lands, livestock lands, settled lands, and marine areas. Accordingly, the ecological footprint; can be calculated for individuals, cities, regions, and planets (Boğaziçi University Climate Change and Policies Application and Research Center). Especially countries that make ecological footprint calculations can measure, track and manage the value of their ecological assets. Countries that define ecological footprints with all their components, causes, and consequences; can find ways to manage the risks of ecological deficit. Thus, they prioritize the protection of natural resources with policies that consider ecological boundaries. As a result, countries that prepare the ecological footprint balance sheet define their development goals by considering environmental sustainability and present their progress indicators in a comprehensive way (Wackernagel et al., 2012). Calculating the component footprints of regions in different land use characteristics within countries will provide a more accurate calculation of the country’s ecological footprint. If these evaluations can be made by calculating the ecological footprint within the scope of the countries, it is aimed to make them on an urban scale for the first time in this study.

2 Literature review

Studies on the ecological footprint calculation especially focus on determining institutional or national ecological footprint. Nonetheless, ecological footprint studies of cities are not many in number. Accordingly, in a study conducted in an educational institution, the institution’s footprint was calculated as 314 gha, and scenarios were designed to reduce this number (Gottlieb et al., 2012). In another study, the ecological footprint of the students of Sakarya University Engineering Faculty was calculated, and the ecological footprint differences of these students based on department, gender, age, and education were examined (Eren et al., 2016). In a different study, the ecological footprint of Mustafa Kemal University Faculty of Agriculture academics was calculated as 3.08 gha (Eren et al., 2017). In a study conducted on the scale of a city, it is predicted that Bei**g’s ecological footprint between 2016 and 2020 will be doubled compared to 1996–2015, increasing to 14.2 gha by 2020 (Liu & Lei, 2018). In another study, the ecological footprint value of Bahria and Gulraiz towns in Rawalpindi city, which is in Pakistan, was calculated. As a result of this study, it was seen that the urban population of these two regions consumes much more resources than the biological capacity of Pakistan (Rashid et al., 2018). As a result of the project on ecological footprint value and land use analysis for Calgary, Canada, in 2008, it was determined that the most important component that increased the ecological footprint by %85 in the residential area is the carbon footprint (The City of Calgary Land Use Planing and Policy, Ecological Footprint and Land Use Scenarios 2024). The compound-based method was used in the ecological footprint analysis study of the city of London, and the individual value was found to be 6.63 gha (Lyndhurst & Authority 2003). In International Footprint network study, Valletta, Athens, and Genoa were the cities with the highest ecological footprint values, ranging from 4.8 to 5.3 gha per individual. In the same study, the ecological footprint per individual in Tirana, Alexandria, and Antalya was determined to vary between 2.1 and 2.7 gha (Network, 2017).

This study, in which the ecological footprint and the ecological footprint components of the city of Sakarya are analyzed, aims to reduce the pressure on the ecological system by making the cities more compatible with nature.It also aims to contribute to the ecological transformation and sustainability of the cities. Sakarya province is a city that constantly receives immigration and a rapidly develo** agriculture and industry. Therefore, the city’s ecological footprint is growing rapidly. It is essential to calculate the ecological footprint and consider it in development plans to secure the city’s sustainability. In addition, this study has been an important study that will meet an important need since the ecological footprint values of the cities in Turkey are not certain. In the study, within this context, the ecological footprint of Sakarya province for the years 2010 and 2018 was calculated by using data from different areas such as fossil fuel usage, heating and transportation, food production, waste disposal and waste recycling, and built-up area usages. By the results gathered, realistic and local solutions have been proposed for Sakarya to become a sustainable and ecological city.

3 Material and methods

3.1 Study area

Sakarya province is located in the northwest part of Turkey at 29°57′ and 30°53′ east longitudes and 40°17′ and 41°13′ northern latitudes. Its acreage is 5,015 km2, and its altitude is 31 m. The rate of plains is 22% throughout the city. It’s most important river is the Sakarya River, and its most important valley is the Sakarya Valley. The province, where the Black Sea and Mediterranean climates both show their effects, is a transitional climate area. Winters in Sakarya are rainy and warm, while summers are hot. The annual average temperature is 15.35 °C, while the average precipitation is 800 mm. Forests cover an area of 204,708 hectares. Field crops and agricultural areas where vegetables and fruits grow cover approximately 50% of the province’s land (Fig. 1). Livestock is also widely practiced. Caused by the city’s development, agricultural and meadow pasture areas had decreased in size between 2010 and 2018 (Fig. 1). Non-agricultural areas, especially residential areas, had expanded during these periods (Environment & Directorate, 2017). The population was 872,872 in 2010 and 1,010,700 in 2018 (Turkish Statistical Institute 2019a). According to the migration data of the Turkish Statistical Institute for 2020–2021 Provinces, 5,230 arrived in Sakarya in 2020, 4,428 arrived in Sakarya, 8,147 arrived in Sakarya in 2021, and 4,392 outgoings the number of immigration are available (Turkish Statistical Institute 2020). Accordingly, the population of Sakarya Province is increasing rapidly, especially due to external migration. Therefore, it is a city whose ecological footprint is increasing every year.

Fig. 1
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Distribution of Sakarya city land by characteristics (Sakarya Provincial Directorate of Agriculture & Forestry, 2010, 2017)

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There are two methods for ecological footprint calculations: “composite” and “component-based” methods. The component-based method calculates the regional and organizational ecological footprint values, and the calculations are made with consumption and production data analysis (Klinsky et al., 2009). The NFA method (National Footprint Accounts), which is known as the component-based method in the literature, is the national scale ecological footprint calculation of human demand on natural resources according to land use types. Land use is taken into account in National Footprint Accounts (NFA), which is the method used in the ecological footprint analysis of countries or regions. Another method in which the ecological footprint is analysed according to consumption categories is the Consumption and Area Utilization Matrix (CLUM) method. In the CLUM method, product and service type data are used to calculate the amount of natural resources used. Therefore, CLUM is more suitable for calculating the footprint of small areas and organizations. In the ecological footprint calculation of a whole city, the NFA method based on land use was chosen as the method of this study because it is more suitable (Özsoy & Ahmet, 2016). According to this, the component-based ecological footprint method is considered more appropriate in a city-scale calculative study. In the component-based method, the main components are electrical energy use, heating and transportation using fossil fuels, food production, waste disposal and waste recycling, and land use for construction. The footprint values of each of these were collected to determine the ecological footprint value for Sakarya Province.

The formulas in the ecological footprint calculation with the component-based method are as follows:

$$ \begin{gathered} Ecological \,Footprint \,Affecting \,Production \,Area \hfill \\ = \left[ {\left( {\frac{Consumption\left( t \right)}{{Yield \left( \frac{t}{ha} \right)}}} \right)\;X \;Yield \,Factor \left( {\frac{wha}{{ha}}} \right)\;X\;Eq\imath ivalence \,Factor \left( {\frac{gha}{{wha}}} \right)} \right] \hfill \\ \end{gathered} $$
$$ \begin{gathered} Carbon \,Capturing \,Soil \,Area \,Ecological \,Footprint \hfill \\ = \left[ {CO2\left( t \right)CO2 - CRatio\left( {\frac{tC}{{CO2}}} \right)\; \times \;\frac{1 - Ocean \,Carbon \,Absorption \,Rate \,Per \,Ton}{{Forest \,Carbon \,Capture \,Rate \left( {\frac{tc}{{ha}}} \right)}}} \right. \hfill \\ \left. {\,\,\,\, \times \;Forest \,Equivalence \,Factor \,\left( {\frac{gha}{{ha}}} \right)} \right] \hfill \\ \end{gathered} $$
$$ \begin{gathered} {\text{Total \,Ecological \,Footprint (EFP)}} \hfill \\ { = }\,\left[ {\text{Ecological \,Footprint \,Affecting \,Production \,Area}} \right. \hfill \\ \left. {\,\,\,{\text{ + Total \,Ecological \,Footprint \,for \,Carbon \,Capturing \,Soil \,Area}}} \right] \hfill \\ \end{gathered} $$

It is important to note that the method for calculating the carbon dioxide (CO2) emissions resulting from consumption varies for each component. This distinction arises from the diverse nature of the consumed components. For example, the CO2 emissions resulting from a vehicle’s fuel consumption greatly differ from those resulting from residential heating fuel consumption. Nevertheless, when determining the total CO2 emissions, the calculation process remains uniform, aiming to establish the necessary carbon sequestration area to offset emitted CO2 (Klinsky et al., 2009). These carbon sequestration areas primarily include our oceans and forests. Essential carbon-related data, such as carbon absorption and capture rates, have been sourced from the International Energy Agency (Akıllı et al., 2008; Klinsky et al., 2009). To compute the footprint of a specific component in terms of global hectares, we employed equivalence factors, a unit of ecological production value found in the dataset of the International Footprint Network, to convert CO2 emissions into carbon (Table 1) (IEA, I 2019).

Table 1 Turkey equivalence/equivalence and yield factors (IEA, I 2019; Network, 2018)
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In summary, this study highlights the critical importance of ecological city planning, emphasizing the need to reduce ecological footprints through the adoption of sustainable practices, alternative energy sources, and innovative solutions. These measures are essential in mitigating the ecological impacts of urban expansion.

In the literature, only if the soil type and the area related to that soil are not known exactly, then it can be accepted that the area to be taken into account for ecological footprint calculations can develop in cultivation areas. In the case of an equality factor, the “infrastructure equivalence factor” is used to express the area as global hectares (IEA, I 2019; Network, 2018).

The leakage and loss rates pertaining to the footprint calculations, stemming from electricity dependence on fossil fuels, were sourced from the Department of Electrical Engineers. Data related to transmission system losses were obtained from the Turkish Electricity Transmission Anonymous Corporation. A study conducted by this institution in 2011 determined the annual average electricity consumption for a family of four in Turkey to be 3,036 kWh, a value consistently maintained for both years considered in this paper (Press Release of the Chamber of Electrical Engineers, 2018; Turkish Electricity Enterprises Turkish Electricity Enterprises Joint Stock Company 2019). Furthermore, the CO2 emission value per kWh for electricity generation in Turkey was extracted from the International Energy Agency’s dataset. The national electricity carbon intensity value (tCO2/toe) was converted to tCO2/kWh (1 toe = 11,630 kWh). The footprint value was subsequently computed utilizing these data.

The CO2 emission value for the footprint calculation resulting from the usage of natural gasses was obtained from the data of the International Energy Agency (IEA), and the national natural gas consumption values were obtained from the Energy Market Regulatory Board (EPDK) (Gas Electricity: Average Electricity Consumption Per Household in Turkey 2019; International Energy Agency, 2017). Turkey’s average natural gas consumption per household is 905 m3 (Natural Gas Market Sector Report, 2018). Turkey’s largest natural gas conversion power plant is in the city of Sakarya. For this reason, natural gas is used as fuel throughout the city (Atlas, 2023). Accordingly, it was assumed that all households consumed natural gas for heating purposes for both years and the average annual natural gas consumption was calculated with this assumption in mind. The data relating to the number of households comes from the Turkish Statistical Institute (TUIK) (Turkish Statistical Institute, 2019b). Based on these data, the footprint value was calculated.

To calculate the transportation-rooted footprint value, the total number of vehicles was acquired from the Traffic Registration Branch Directorate. We then determined the distances between the city center and various districts were determined by selecting the most optimal routes via Google Maps. This enabled us to compute the fossil fuel consumption associated with transportation. Notably, the “Smart Junctions” application, which was implemented by the Sakarya Province Municipality (SBB) as part of the 2019–2023 Sakarya Smart City Strategy and Action Plan project, involved the removal of signaling systems. This initiative significantly reduced waiting times and energy consumption at intersections, thereby eliminating the need to account for CO2 emissions resulting from vehicles’ stop-start processes in our study Sakarya Metropolitan Municipality: Press and Public Relations; News (2019).

In this study, we assumed that all cars were assumed use gasoline as their primary fuel type, while other vehicles opt for diesel as the most fuel-efficient option. We also made the assumption that each vehicle undertakes a daily round-trip from the district center to the city center throughout the year. To estimate the annual CO2 emissions per gram per kilometer, we obtained average CO2 emission values per kilometer categorized by vehicle fuel types were obtained from the Ministry of Industry and Technology. Based on the assumption that each vehicle travels an average of 15,000 km annually, we calculated the projected amount of CO2 emissions per kilometer was calculated and utilized this as our average value. Consequently, the average CO2 emission for gasoline vehicles was found to be approximately 215.12 g per kilometer, while diesel vehicles emitted roughly 207 g per kilometer (Göcen, 2012). Using this data, the annual carbon emissions for each individual vehicle were determined. These figures were extrapolated to calculate the total emissions across the province. Additionally, we applied an “uplift factor” was applied to account for carbon emissions stemming from the “indirect energy” requirements associated with vehicle and road manufacturing and maintenance operations. As there was no country-specific uplift factor available for Turkey, highest value reported in the literature was opted, which was 1.51% (Galioğlu, 2015). The footprint linked to fossil fuel-based transportation is thus expressed as an equivalent carbon sequestration land area.

For the footprint associated with food consumption, evaluations were conducted in two distinct categories: vegetable and animal consumption. Data on the production values, areas, and annual consumption per individual in Turkey for herbal products were obtained from the Turkish Statistical Institute (TUIK) (Turkish Statistical Institute 2019c; Turkish Statistical Institute, 2019d). The production quantities of animal products and pastureland data were sourced from the Sakarya Provincial Directorate of Agriculture (Sakarya Provincial Directorate of Agriculture & Forestry, 2010). Annual individual consumption values for animal-based products such as milk, eggs, red and white meat, and honey in Turkey were gathered from various sources, including the Economic Development Cooperation Organization, The National Milk Council Reports, the Egg Producers’ Association, and relevant literature (Data, 2017; Ökmen 2019; Industry Report, 2011, 2018; Union, 2018). The weight of an egg was assumed to be 100 g. Utilizing these values, the food consumption amounts and footprints for the province based on the city’s population were calculated.

Data related to the energy use footprint calculation stemming from waste and recycling processes were obtained from the Sakarya Province Municipality (SBB) and district municipalities (Guide, 2010). In 2010, the city collected a total of 161,000 tons of solid waste, and since recycling facilities were non-existent, these collected wastes were merely stored. Consequently, the ecological footprint resulting from recycling was not calculated for that year. However, in 2018, the city collected, separated, and recycled a total of 273,416 tons of solid waste in a newly established facility (Guide, 2010, 2018). These solid waste components were assessed across six categories: kitchen waste, paper, plastic, cardboard, metal, and garden waste. The amount of recycled waste was determined by these categories, and the footprint was subsequently calculated based on the emissions resulting from recycling. To calculate the transportation distance covered by the collected wastes from the districts to the landfill facility, we assumed the most suitable routes were determined using Google Maps. We also considered that each garbage collection vehicle transported waste to the landfill once every two days. Emission values for heavy vehicles per kilometer were obtained from the literature (Galioğlu, 2015). The footprint value was computed based on the carbon emissions associated with waste collection and storage processes.

Data on the built-up area values were obtained from Sakarya Province Municipality (SBB). Given that zoning plan implementations are designed to remain consistent for a period of 10 years, the built-up area values for both 2010 and 2018 were assumed to be identical. These total construction area values are provided into Table 2, overviews the total consumption, emissions, and waste figures.

Table 2 Data for the ecological footprint calculation of Sakarya city (Sakarya Provincial Directorate of Agriculture & Forestry, 2010; Press Release of the Chamber of Electrical Engineers, 2018; Turkish Electricity Enterprises Turkish Electricity Enterprises Joint Stock Company 2019; Gas Electricity: Average Electricity Consumption Per Household in Turkey 2019; International Energy Agency, 2017; Natural Gas Market Sector Report, 2018; Sakarya Metropolitan Municipality: Press and Public Relations; News (2019); Turkish Statistical Institute 2019c; Turkish Statistical Institute, 2019d; Data, 2017; Industry Report, 2011, 2018; Ökmen 2019; Union, 2018; Guide, 2010, 2018)
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4 Results and discussion

In Table 3, the total consumption values, emission values, and waste amounts obtained from the calculations made by using the data gathered from the relevant institutions for the years 2010 and 2018 are given.

Table 3 Total consumption, emission and waste values
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With the energy consumption stemming from fossil fuels, only the footprint of the carbon-capturing soil area is evaluated. Accordingly, to compensate for the CO2 emissions resulting from the annual electricity consumption of Sakarya province, the study has documented that a biological capacity of 279,069 gha for 2010 and 288,443 gha for 2018 is required (Tables 4, 5).

Table 4 Ecological footprint values of Sakarya city in 2010
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Table 5 Ecological footprint values of Sakarya city in 2018
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Based on the data given in Table 2, the total yearly natural gas consumption according to the number of houses that the city has was calculated as 603,332,730 million m3 for 2010 and 636,572,475 million m3 for 2018. Since the values that show how much CO2 is emitted by the combustion of one cubic meter of natural gas are constant, the value of 0.00185 t CO2 /m3 was kept the same for both years. It has been calculated that Sakarya Province needs a biological capacity of 287,683 gha in 2010 and approximately 303,532 gha in 2018 to compensate for the CO2 released due to the yearly use of fossil fuels for heating purposes (Tables 4, 5).

The study has discovered that a biological capacity of 197,690 gha for 2010 and 282,868 gha for 2018 is the requirement to compensate for the CO2 released due to the yearly transportation-based footprint, calculated by using the total amount of CO2 emissions from transportation (Tables 4, 5).

It has been determined that Sakarya province needs a biological capacity of 247,133 gha for 2010 and 198,918 gha for 2018 to compensate for the biocapacity consumption that occurs due to annual plant food production. It can be seen that Sakarya province needs 655,347 gha of biological capacity in 2010 and approximately 542,97 gha in 2018 to compensate for the biological capacity consumption that occurs due to annual animal food production. Ultimately, the final footprint value of Sakarya province that stems from food production is 247,788 gha for 2010 and 199,461 gha for 2018 (Tables 4, 5).

The amount of energy produced from 1 kg of organic waste (kWh) is 2.8 kWh in the footprint calculation resulting from waste and waste recycling processes (Galioğlu, 2015). This research has revealed that 55,213 gha of biocapacity for 2010 and 93,773 gha for 2018 are required to compensate for the CO2 released from wastes (Tablse 4, 5).

It has been revealed that around 58,412 gha of biocapacity is necessary every two years to compensate for the built-up area footprint throughout Sakarya. This productive area is being destroyed due to construction (Tables 4, 5).

In 2010, the ecological footprint value of Sakarya Province was 1,125,856 gha in total according to the ecological footprint values of the components that have been determined (Table 4). This value is 2,324,915,78 gha for Turkey in the same year (Network, 2019).

The ecological footprint value of Sakarya province in 2018 was 1,226,490 gha (Table 5). Also, the ecological footprint value of Turkey for the same year was 2,669,611,72 gha (Network, 2019).

The distribution of ecological footprint values that belongs to 2010 is shown in Fig. 2. It can be seen that the major components which make up the ecological footprint are the energy use and the fossil fuel use resulting from heating purposes. Since the use of fossil fuels is essential in the mentioned two components, it can be said that the ecological footprint, in general, originates from fossil fuels.

Fig. 2
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Percentage distribution of ecological footprint value of Sakarya city in 2010

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The distribution of ecological footprint values for 2018 is shown in Fig. 3. The major components which make up the ecological footprint value for 2018 are the energy use, transportation and fossil fuel use from heating. Also for this year, the ecological footprint generally originates from fossil fuels.

Fig. 3
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Percentage distribution of ecological footprint value of Sakarya city in 2018

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5 Discussion

Turkey currently holds the dubious distinction of having the highest ecological footprint among all countries globally. This footprint is growing at an alarming rate, driven by the increasing population and rising demands, which in turn pressurizes our natural resources (Özsoy & Ahmet, 2016). The ecological footprint of countries is imperative to determine as a crucial step towards ensuring environmental sustainability. However, the ecological footprint indicators for entire countries are an average derived from the characteristics of the various cities within the respective countries, each with its unique population and biological area features. Calculating the ecological footprint of cities with distinct characteristics separately would provide a more precise indicator for a country’s ecological footprint, enabling tailored measures to be formulated and implemented according to regional specificities. Identifying this ecological gap will facilitate the effective management of ecological assets, the implementation of necessary measures, and the transformation of cities into ecologically sustainable urban centers. As previously discussed, the dominant contributors to the ecological footprints within Sakarya Province are the consumption of fossil fuels in energy production, transportation, and heating. The study findings reveal that footprint values arising from fossil fuels are generally high, aligning with similar conclusions drawn from previous literature on the subject.

In 2010, Turkey’s ecological footprint amounted to 2,324,915.78 global hectares (gha) (Network, 2019). When comparing Sakarya Province’s ecological footprint with this figure, it becomes evident that it is approximately 0.005 times that of Turkey. Similarly, when examining the ecological footprint in 2018, it is approximately 0.004 times the national value.

Quantitative comparisons are challenging to make due to the scarcity of studies using the NFA method to calculate city-specific ecological footprints worldwide. This study is the only good practice example of local studies on this topic, being the first in Turkey to quantitatively calculate the ecological footprint of cities using the NFA method. Only, per capita footprint results were compared with two provinces. The ecological footprint per capita in Sakarya City is notably lower when compared to a major city like London. Additionally, when compared to Antalya Province, which has a population approximately two and a half times larger than Sakarya Province in Turkey, it is evident that the ecological footprint values are roughly 40% lower.

Furthermore, a comparison between the ecological footprint values in 2018 and 2010 for Sakarya indicates a decrease in the ecological footprint (Fig. 4). This reduction can be attributed to the rapid population growth due to immigration. It is assumed that the increase in population due to migration will increase the built-up area footprint, which is a component of the urban ecological footprint. Therefore, it is predicted that the increase in built-up area will be the cause of an increase in heat and energy consumption. Briefly, it can be said that an increase in the population will increase the number of components that have a negative impact on the Ecological Footprint.

Fig. 4
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Comparison of ecological footprint values of Sakarya city in 2010 and 2018

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To enhance the ecological footprint of Sakarya City, it is evident that efforts should primarily focus on reducing the footprint values of its components. As highlighted in the recommendations section of this study, the most critical components contributing to the ecological footprint increase in the city are energy consumption and transportation. Consequently, alternative solutions identified for these components should be implemented. The consumption of ecological resources should be evaluated on a resource basis, and the sustainability of each resource should be ensured as emphasized in the literature (Mızık & Yiğit Avdan, 2020).

The ecological footprint resulting from the use of fossil fuels in transportation stands as the most significant portion of our ecological burden. Furthermore, carbon emissions from fossil fuel use are the primary contributors to environmental harm, escalating the ecological footprint. Factors like industrial expansion, population growth, and increased consumption have been identified as the driving forces behind rising carbon emissions. Therefore, it becomes imperative to implement measures in alignment with these sources and alter consumption patterns to curtail carbon emissions. As recommended, transitioning to renewable energy sources as an alternative to fossil fuels for household energy and heating is of paramount importance. In this regard, generating electricity from the solid waste landfill presents a viable solution. With the current system, we can produce energy from waste that would suffice to meet the needs of approximately 16,000 households, equivalent to the energy consumption of 61,000 people. By scaling up this capacity, we can significantly reduce the ecological footprint and concurrently mitigate the escalating greenhouse gas emissions from the energy sector. It is estimated that adopting this waste-to-energy approach can reduce the ecological footprint per household by 0.1 gha, ultimately resulting in a reduction of 34.7 gha in the overall ecological footprint (Koç & Şenel, 2013).

6 Policy suggestions

When examining the ecological footprint of Sakarya city in both 2010 and 2018, it becomes evident that the most significant contributor to the ecological footprint increase across the province for both years is energy consumption, particularly the consumption of fossil fuels for heating and transportation. This underscores the critical need for the adoption of renewable and alternative energy sources and fuel options. While considering solar energy as an alternative source, it is important to note that the solar energy potentials in Sakarya may not suffice to establish a power generation facility for the entire province, as indicated by the GEPA (Turkish Solar Energy Potential Map). Furthermore, the initial investment costs associated with solar power plants are higher compared to other contemporary renewable energy options (Governorship & Directorate, 2010). Wind and geothermal energy sources are also available throughout the province, but their economic viability is limited, which make them more effective in smaller settlements like towns and districts. For instance, wind energy initiatives have begun in the Geyve district. Additionally, biomass energy holds promise as an alternative energy source that can contribute to the economy and environmental well-being. In terms of vegetative biomass, 29,279,814 tons of waste were generated in 2018 due to the pruning of field crops and fruit trees, with a total thermal value of 1,184,515,834 GJ/year, which is equivalent to 329,032,176,111 kWh of energy per year (Karabaş, 2019). This amount exceeds the energy consumption for both years and is more than sufficient for the province. Biomass energy appears well-suited for both electrical energy and heating. Notably, the initial investment costs for biomass power plants, especially when compared to solar power plants, are lower. Currently, energy production in Sakarya relies on natural gas thermal power plants, generating 15,416,000,000 kWh of energy annually. The annual production costs are $739,968,000 for biomass power plants and $554,976,000 for natural gas power plants (Kadir & Erdem, 2015; Koç & Şenel, 2013). This suggests that energy production with biomass power plants is 1.33 times more expensive; however, the utilization of a local, clean, and renewable energy source can offset this additional cost within a short period, contributing to long-term sustainability. In 2010, Sakarya had an individual ecological footprint of 1.29 global hectares (gha), while the individual ecological footprint for Turkey in the same year stood at 3.21 gha. By 2018, Sakarya’s individual ecological footprint had decreased to 1.21 gha, whereas Turkey’s individual ecological footprint for 2018 was 3.36 gha (Network, 2019). This comparison reveals that Sakarya’s ecological footprint in 2018 was only 0.36 times that of Turkey, indicating that if the current consumption rates persist among Sakarya residents, they will continue to exceed the province’s current biological capacity per individual. These findings underscore the pressing need to reduce fossil fuel consumption, particularly in transportation. It will be a significant step toward reducing the local ecological footprint. To achieve this goal, there should be a focus on clean energy vehicles and transportation system improvements. Enhancements in the transportation systems should include the expansion of the public transportation network, development of regional car park-to-city center public transportation services, promotion of vehicles with lower fuel consumption, encouragement of the widespread use of smart traffic applications and systems, and the establishment of pedestrian roads and lanes From Zero To Hero-Wise Energy Use Volunteering Scheme For Youngster (2023). Additionally, the increased use of bicycles and the adoption of public vehicles with lower emissions are activities that can make a substantial difference. For instance, the implementation of a rail system project has the potential to significantly reduce the carbon and ecological footprint by approximately 0.6 gha, according to our calculations (Özkaynak, 2020).

7 Conclusion

This study introduces a novel tool for achieving sustainability through ecological footprint calculations, serving as a valuable resource for individuals and decision-makers alike. Its primary objectives are to quantify the ecological footprint of the province, reduce its cumulative impact, and offer guidance for corrective actions through alternative ecosystem preservation methods. Particularly in the face of the escalating climate crisis, the study can form the foundation for both local and national planning aimed at establishing sustainable and resilient provinces.

The calculation of a province’s ecological footprint provides insight into the ecological strain caused by consumption patterns. This information, along with a historical record of ecological footprints, becomes a powerful tool for urban ecological transformation and footprint reduction efforts. By addressing each component contributing to the ecological footprint individually, these values can be continuously monitored, leading to well-planned remedial actions. Even small improvements in a single component can have a substantial positive impact on the overall ecological footprint of the city. The ecological footprint serves as a vital sustainability indicator, not only reflecting desires and needs but also guiding us towards a more sustainable path. To reduce the ecological footprint, it is imperative to bolster efforts aimed at incorporating sustainability contributions into the nation’s economy, drawing inspiration from global examples. Raising awareness on this issue and fostering a collective consciousness is vital to drive progress in reducing ecological footprints, following the lead of similar global initiatives. This is also inlined with the results from the current study. In this manner, we can take meaningful steps toward positively transforming our practices and ensuring a brighter future for all.