Introduction

The fact that the effects of global climate changes experienced today have reached undeniable dimensions reveals the necessity of humanity to act collectively. It has made it important to preserve the current state and leave a habitable world for future generations. Countries, especially in limiting the excessive increase in greenhouse gas emissions, support the issue by organizing conventions, protocols, and studies aimed at measures in this direction through international bodies.

For this reason, steps have been taken to reduce carbon dioxide emissions, which have an 80% share of total greenhouse gas emissions [1]. In this context, the Montreal Protocol, dated 1987, is defined as the most successful and first multilateral agreement on the environment [2]. The turning point in terms of being the first global agreement to explicitly address climate change is the “Framework Convention on Climate Change” (UNFCCC), which was opened for signature at the United Nations Environment and Development Conference held in Rio, Brazil, in 1992.

Then, the Kyoto Protocol and the Paris Agreement (2016), which were established as a result of the “Third Conference of Parties” (COP3) held in Japan in 1997, are of great importance. The Kyoto Protocol has required countries to reduce the amount of carbon they emit into the atmosphere to the levels from 1990 [3]. The long-term goal of the Paris Agreement is expressed as keeping the global average temperature increase below 2ºC compared to the pre-industrialization period and as the continuation of global efforts to keep this increase below 1.5ºC [4]. The phenomenon of climate change occurs because of the increase in the amount of greenhouse gas emissions (GHG) due to human activities and changes in the natural greenhouse gas concentration [5]. The IPCC has strongly warned that failure to make “significant and sustained” reductions in GHG emissions will increase irreversible impacts [6]. Gases such as carbon dioxide (CO₂), methane (CH₄), and nitrous oxide (N₂O), which are among the GHGs and originate from humans, have seen serious increases in their amounts since pre-industrial times and are among the main reasons for climate change. The majority of these increases are caused by human activities, such as fossil fuel consumption, improper land use, and agricultural activities [7, 8]. The temperature increases caused by GHGs in the atmosphere depend on factors such as the heat retention properties of the gases, their amount in the atmosphere, and the residence time in the atmosphere [9]. In this sense, knowing the sources of GHGs, the distribution of emissions by sectors, the contributions of different regions and countries to these emissions, and the fluctuations in these emissions are of great importance to the fight against climate change [10]. All greenhouse gases cause climate change, albeit at different rates. However, CO₂ emissions are used as a measure of value in the struggle against climate change because of their high percentage density and their direct human origin.

At this point, seas and oceans protect the world from the negative effects caused by climate change by absorbing excess CO₂ in the atmosphere [11]. For this reason, the oceans are the part that needs the most work on the climate change problems caused by global warming. It is stated that the absorption rate of CO₂ released due to anthropogenic activities in the last twenty years by the oceans has increased to 20%-30% [12, 13]. Because of the large increase in the amount of GHGs, global air and sea surface temperatures have increased over the past century [14].

The most special of these seas is the Mediterranean, considering its socioeconomic and geostrategic location. Indeed, the Mediterranean region has been more affected by global warming than other parts of the world [15, 16]. The average air temperature in the Mediterranean region, which was 14.5ºC at the beginning of the 20^th century, increased to 16.5ºC in this period, and the temperature difference between these periods worldwide was 1.2ºC, in addition, the average summer temperature in the Mediterranean has increased by 2.5-3ºC in 120 years [17]. Because the Mediterranean Sea is a closed sea that warms up more easily than the oceans, seawater cools slowly. The Mediterranean Sea accumulates energy because of heating and spreads this energy into the atmosphere. This situation has caused temperature increases, decreased precipitation, and decreased soil moisture content. It even indirectly increased forest fires in Mediterranean countries [18].

For this reason, climate policies that include countries in this region have become even more important. Firstly, the control of exhaust gas emissions in the transportation industry, which has emerged with stricter public pressure, has brought to light the necessity of controlling emissions in all other sectors as well, as the demand for international trade has increased. According to the Global Sustainable Development Report [19] published by the UN on the subject, creating economic growth only by increasing the consumption of material goods is no longer valid at the global level, and if the predictions come true, global material use will increase from 89 gigatons (Gt) to 167 Gt between 2017-2060. Accordingly, it is stated that gas emissions which cause global warming, such as GHGs, will increase. The European Scientific Advisory Board on Climate Change, established by the European Climate Law, has recommended reducing EU emissions by 90-95% by 2040 compared to 1990 levels, based on a science-based assessment that considers both fairness and feasibility. The Board determined the EU’s greenhouse gas emissions budget (i.e. cumulative emissions) for the period 2030-2050, and it recommends keeping it at a limit of 11-14 Gt CO_2-eq, in line with limiting global warming to 1.5ºC (this temperature should never be exceeded or only limited and temporarily exceeded) [20].

These limitations are essential to reduce climate risks and achieve a sustainable future. In this context, the importance of EU policies regarding the protection of the environment and natural resources has increased gradually since the 1980s. Currently, EU nomination candidate Türkiye has already harmonized its environmental policies with EU environmental policies. With the process of harmonization with the EU acquis as a stronger motivation and norm, coordination and harmonization studies with the EU in environmental policies have started since COP 2001.

Ultimately, Türkiye became a member of the European Environment Agency in 2003. During the preparation of the UNFCCC, countries that were considered to have historical responsibilities in terms of GHG emissions in the atmosphere and were therefore required to make efforts to reduce emissions were called “developed countries” and were placed in the Annex-I List of the Convention. Among these countries, those with OECD membership are obliged to provide financial and technological support to developing countries and are included in Annex II of the Convention. For this reason, Türkiye, one of the founding countries of the OECD, is included in both Annex I and Annex II [21]. Therefore, in the five countries included in the study, countries have implemented some measures, whether domestic regulations, international agreements, or EU agreements, and their responsibilities and motivations in the titles are the same.

The Climate Change Performance Index (CCPI), which includes these five Mediterranean countries, is an independent monitoring tool for the climate protection performance of countries, published annually since 2005. This index aims to increase transparency in international climate policies and enables the comparison of countries’ climate protection efforts and progress [22]. With this index, the climate protection performance of the EU and 59 countries, which account for more than 90% of global greenhouse gas emissions, is evaluated in four categories: GHG Emissions, Renewable Energy, Energy Use, and Climate Policy [22, 23].

When the current situations of the five Mediterranean countries mentioned were evaluated using this index [22], for the GHG emissions of the countries, Spain, France, and Greece showed medium performance, and Italy and Türkiye showed low performance. Additionally, when compared to other countries evaluated within the scope of this index, Greece ranks 28th and Spain 18th as medium performers, Italy is ranked 44th and France 37th as low performers, and the last was Türkiye, placed 56th among the very low-performing countries. While they show different performances in the other three CCPI categories (renewable energy, energy use, and climate policy) when detailed within themselves, they differ from each other in the policies they follow. Greece shows medium performance in Renewable Energy, high performance in Energy Use, and low in Climate Policy. According to the previous year, change only occurred in Climate Policy. Also, Greece shows good performance in trend indicators in general. Italy shows low performance in Climate Policy and medium in Energy Use and Renewable Energy. Italy imports wood pellets in high quantities for the heating sector mainly. In the transport area, Italy lacks policies for the decarbonization of transportation.

Also, the fossil fuel policies of Italy are going backward. France has medium performance in the Climate Policy, low in Energy Use and Renewable Energy. The renewable energy target of France needs to be three times higher to comply with the Paris Agreement. After failing with the 2020 renewable energy target, France introduced the Renewable Energy Acceleration Bill, which is a legislative package that focuses on production with offshore wind energy. France has extended the life of its two coal plants, delaying the coal exit from 2023 to 2024. The other country is Türkiye. The country has a low performance in Energy Use, medium in Renewable Energy, and very low in Climate Policy. Türkiye for the GHG emissions announced 2053 as the net-zero target date. In four main CCPI categories, Spain shows medium performance. The country updated the National Integrated Energy and Climate Plan in 2023 and proposed a 32% GHG emissions reduction by 2030.

Trade connections between countries are getting closer with the developing globalization effect and contribute to economic development, but this situation brings with it various environmental problems, such as increasing carbon emissions, global warming, and climate change, as mentioned before [24]. Especially developing countries cause negative effects on environmental pollution and carbon emissions, depending on energy, raw material, and consumption needs for commercial needs and economic development [25]. The alarming increase in carbon emissions globally emphasizes the urgency of the transition towards sustainable and low-emission applications especially in industry [26]. In this context, all countries are responsible for reducing the carbon emissions they cause, and various studies are being conducted to evaluate this situation [27, 28].

One of the main determinants of this emission inventory of countries is the international movement of goods produced [29] in that country and sent abroad or transferred from another country to that country for various reasons, such as welfare. In this study, the effect of container volume, which is concrete evidence of consumption-based commercial goods movements and foreign trade inputs, on CO₂ emissions was investigated. The study focused on 5 countries that are commercially and geographically close to each other in the Mediterranean, which is one of the regions most affected by global climate change. Because recently, it is understood that in addition to global scale enterprises, small and medium-sized enterprises have also turned to container transportation for the import and export of raw materials, semi-finished products, and final products. And, The Mediterranean Region, which hosts these commercial attraction centers, is also one of the most important maritime trade areas where container trade takes place.

Data and Method

In this study, while the effect of container volume on CO₂ emissions was investigated, the cointegration relationship between the container volume handled and carbon emissions was examined. For this reason, panel data analysis, that is, a method for estimating economic relations using cross-sectional data of the time dimension, was used for the established econometric model. As an advantage over time series, more data was developed by considering five countries. The results were evaluated with a homogeneity test, horizontal cross-section dependence test, unit root test, Westerlund cointegration test, AMG panel-based prediction, and the Dumitrescu Hurlin panel causality test. The existence of cross-sectional data dependency can be explained as positive or negative shocks occurring in one country, while also affecting other countries. Accordingly, the relationship between the increase and decrease in container handling volume and the carbon emission level will help understand the role of these activities in the sample of Mediterranean countries.

Theoretical Framework and Data Descriptions

This article examines whether there is a relationship between container handling volume in TEU (20 Foot Equivalent Units) and CO₂ emissions of France, Greece, Italy, Spain, and Türkiye, which are located in the Mediterranean region and have an important place in world maritime trade in terms of container handling, based on annual data in the period between 2000-2019 with using panel data econometrics. These data, which are regularly provided in the World Bank database, are CO₂ emissions (metric tons per capita) and Container port traffic (TEU) data from World development indicators [30]. Emission data for this database is provided from Climate Watch Historical GHG Emissions prepared by the World Resources Institute. Handled container data is provided by UNCTAD (UN Trade and Development). In this analysis, the container handling amount (TEU) of the panel is the independent variable, while the dependent variable is CO₂ emission data.

All data are taken as a single column on an annual basis. Port container traffic data measures the flow of containers from sea to land transport modes and vice versa in twenty-foot equivalent units (TEUs), a standard-size container. The data relates to both international voyages and coastal shipping. Transshipment traffic is counted as two movements at the intermediate port (one for unloading cargo, the other for loading) and includes empty units. Emission values are created as total emissions with the agriculture, bunker fuels, energy, industrial process, land-use change - forestry, and waste statistics in the database and officially reported data.

When the Table 1 is examined, it is seen that the average CO₂ emission of the countries that were subject to the research between 2000-2019 was 6.09 M/T per capita, and the container handling volume was 6,879,854 TEU. In addition, it is understood that the CO₂ moderate value is 5.85 M/T per capita, and the container handling volume is 5,917,100 in terms of TEU. The maximum amount of CO₂ emissions of the five countries, which are chosen for the research, was detected as 9.44 M/T per capita, while the minimum carbon emission value was 3.093 M/T per capita. The maximum handling value in terms of container handling volume was 17,372,962 TEU, while the minimum value was 672,522 TEU.

In the first graph in Fig. 1, the X-axis shows countries (1: France, 2: Greece, 3: Italy, 4: Spain, 5: Turkey) and the Y-axis shows carbon emissions (CO₂ emissions, metric tons per capita). According to the graph, since 2000, there has been a decreasing trend in France for CO₂ emissions. In the other four countries, horizontal and vertical increases and decreases in different periods could be mentioned.

In the second graph in Fig. 1, the X axis shows countries, and the Y axis shows container port traffic. According to the graph, there has been an increasing trend in terms of container handling volume in TEU in Türkiye since 2000, and in the other four countries, the presence of horizontal and vertical increasing and decreasing trends in different periods.

Table 1.

Descriptive statistics of the series.

	CO2	TEU
Mean	6.091217	6879845
Median	5.853014	5917100
Maximum	9.441123	17372962
Minimum	3.039248	672522.0
Std. Dev.	1.626320	4069127
Observations	100	100

Fig. 1.

Graph for CO₂ emission, Container handling volume graph TEU.

Results

Conclusions

Recently, it is understood that in addition to global-scale enterprises, small and medium-sized enterprises have also turned to container transportation for the import and export of raw materials, semi-finished products, and final products. The Mediterranean Region, as one of the most important maritime trade areas where container trade is carried out, is increasing its strategic status day by day. With the increasing volume of trade in the region, at what rates does emission pollution increase or whether the measures are effective or not, these are some of the topics that public opinion and researchers are curious about. In this context, the research aims to determine whether there is a cointegration relationship between the container volume handled and carbon emissions in the context of France, Greece, Italy, Spain, and Türkiye, the countries in the Mediterranean, which is among the regions most affected by global climate change. In the analyses, due to the presence of cross-section dependence among the series subject to the research, the Westerlund test, one of the second-generation panels cointegration tests, was used, and it was determined that there was a cointegration relationship between the series regarding the carbon dioxide emissions of the relevant countries and the container handling volume in TEU between 2000-2019. Accordingly, it is seen that there is a co-movement and balance between the two series. In addition, the existence of cross-sectional data dependency can be explained as positive or negative shocks occurring in one country also affecting other countries. In addition, according to the results of Dumitrescu Hurlin Panel Causality Tests, the container handling volume in TEU in the entire panel is the cause of carbon emissions at a 1% significance level, however, carbon emissions are not the cause of container handling volume, which also coincides with the practice and the result supports the purpose of our study. According to AMG estimation results, a negative correlation was detected between the two series. Also, AMG estimation results performed based on the entire panel revealed that there was a negative relationship between container handling volume and carbon emissions at a statistically significant level of 5% (p-value: 0.037<0.05). Accordingly, although the container handling volume increases, the carbon emission level decreases, contrary to expectations. This situation is contrary to the traditional belief that increasing the volume of economic activities causes environmental pollution to the same extent. At least it is clear that container trade is not at the top of the list of factors causing carbon emission pollution.

It could be said that the climate policies have been implemented more concretely with the international agreements to which the countries participating in the study adhere and the increasing awareness of climate change. Because, according to all the determined criteria, including CCPI, the emergence of energy-saving technology and the conversion to renewable energy sources have a direct effect on reducing CO₂ emissions. In conclusion, it is clear that an increase in maritime trade does not lead to an increase in carbon emission pollution levels, and the implementation of more environmentally friendly policies does not slow down the cycle of economic progress and development in Mediterranean trade. Although more and more countries and industry organizations are committing to achieving net zero emissions, this transition still does not have a mass-binding regulation. Considering that the path to reaching Net Zero in terms of technology is still unclear in many sectors, the situation in maritime can be said to be on the right track as a more environmentally friendly transportation approach, fossil fuel-free or filtered shipping, and green port practices will yield positive concrete results. The IMO (International Maritime Organization) Marine Environment Protection Committee aims to reduce GHG emissions from ships by more than 50 percent in 2050. For this reason, IMO maritime transport, which has the sanctioning power in the sector, has asked ships to take Energy Efficiency measures (EEDI) to reduce GHG emissions into the atmosphere. In addition, it took a more active role in the EU and established DCS (Data Collection System) and wanted to detect and control the current situation by collecting information on the amount of CO₂ released into the atmosphere from ships and the energy efficiency of ships. Therefore, he asked them to make an Energy Efficiency Management Plan (SEEMP) for their ships in order to reduce GHG emissions into the atmosphere.

The fact that emissions are falling in the findings should be interpreted as the success of some such actions and stability in operation and should also be used to suggest a policy basis for achieving the Sustainable Development Goals proposed by the United Nations and reinforce initiatives such as the UNFCCC’s Race to Zero campaign. These results will provide a strong motivation for governments to create the necessary policies to reduce GHG emissions by showing that their economic progress will not be damaged. However, from now on, how the EU’s policy of granting the right to emit CO₂ in accordance with ETS (Emission Trading Systems) will change this situation should be addressed in future studies.