In recent years, the threating effects of global warming-ranging from environmental damage to human health challenges- have attracted considerable attention of environmentalists and policy makers. Paris climate conference 2015 is considered a watershed mark in the context of combating global warming through reduction in GHGs (greenhouse gas emissions) backed by a serious pledge of international community, Glasgow Summit the most recent. Scientists believe that despite determined efforts on the part of governments spread over decades, the planet will not cool down as the threshold level of temperature set at 2°C will be missed. Furthermore, the projection that temperature will reach 30°C by 2050 warns about impending catastrophes including natural disasters (UNFCCC, 2018). Intergovernmental panel on climate change, IPCC (2007) mentions that developing countries will face decrease in their GDP by 2–4% and 10% by 2040 and 2100 respectively. The common global goal agreed by nations compels developed nations to transfer energy-efficient technologies to developing countries with the objective to combat CO2 emissions without compromising their economic development. The measures including environmental fund transfer from developed nations to low-income countries and transition towards renewable, sustainable, and clean energy will enable poor nations to participate in the global efforts to address environmental challenges (UNFCCC, 2015).
Despite its catastrophic implications, the global warming impacts are not uniform for all regions in the world, as few regions are more prone to these events due to many socio-economic factors including trade openness, level of development and financial performance. To protect environmental damage without compromising on increased human activity aimed at economic growth is a challenge for environmentalists and policy makers. Energy consumption is the crucial input in the production process in modern economy (Rafiq & Salim, 2009) and all the developments are in and around energy especially fossil fuel. According to an estimate, until 2025 energy consumption will grow at 1.1 and 3.2 percent in developed and developing countries respectively (Asif & Muneer, 2007). The contribution of fossil fuels in global energy demand is about 80–95%. This is alarming as fossil fuel consumption has huge damaging effect on the environment including air pollution, climate change and global warming (Nejat, Jomehzadeh, Taheri, Gohari, & Majid, 2015). Therefore, it is mandatory to use renewable, clean, and sustainable energy sources to grow economies without compromising the ecological footprint (Saidi & Omri, 2020). The share of renewable energy such as wind power, biomass, solar, hydropower, nuclear, tidal, and geothermal is increasing in total energy mix in industrialized countries due to rapid decrease in renewable energy technology costs (Bulut & Inglesi-Lotz, 2019). However, developing countries are struggling to exploit renewable energy sources to meet their energy demand and hence causing massive CO2 emissions which raises various concerns about global environmental conditions (WDI, 2018). The continuous increase in energy demand to power economic activities in developing nations has elevated pollution levels (Zafar, Ullah, Majeed, & Yasmeen, 2020).
In the light of energy economic literature, it is argued that renewable energy can help reduce CO2 emissions, ensure sustainable development, and enhance environmental quality (Bulut, 2017; Swain, Kambhampati, & Karimu, 2020) especially in developing countries (Shafiei & Salim, 2014). According to Fang (2011), policy makers expect that renewable energy can outweigh environmental challenges created by fossil fuel energy consumption and meet energy needs for economic development. Therefore, many countries have reshaped their energy policies to incentivize renewable energy through provision of investment and sectoral subsidies and other supports (Koçak & Şarkgüneşi, 2017). To draw meaningful conclusions and frame suitable policies regarding renewable energy, trade openness and financial development, we have selected the sample of low, middle, and high-income countries. We mention in this study that the impact of financial development, trade openness and renewable energy consumption on CO2 emissions is different across countries. Trade openness and economic growth are strongly correlated, and we are investigating whether trade openness and environmental quality are associated in the ensemble countries. In studies of environmental quality, the major concern has been the association between environmental quality and trade openness as later may affect environment positively (Ferrantino, 1997) or negatively (Khan, Weili, Khan, & Khamphengxay, 2021). Trade openness improves economic development but at the same time pollutes environment through export and import activities (Khan et al., 2021). Poor policies in developing countries fail to increase economic growth without rise in CO2 emissions. This study considers role of trade in determining CO2 emissions due to increase in global human activity and changing environmental standard. We expect that the trade effects on environmental quality are not uniform across countries but vary according to development level of a country.
This study also expects that like trade openness, financial development can have impact on environmental quality. A plethora of studies record the negative impact of financial development on environmental quality (Muhammad, Tiwari, & Muhammad, 2011) through different channels including foreign direct investment which enhances economic growth and subsequently increases energy consumption that causes global warming, reduction in financial cost because of development of the stock market that attracts new installations leading to increase in energy consumption, and consumerism based on easy and affordable loans that increase purchase of luxurious items (Ahmed, Kousar, Pervaiz, & Ramos-Requena, 2020). On the other hand, a handful of studies conclude that financial development improves environmental quality (Komal & Abbas, 2015; Tamazian & Rao, 2010) through the channel of increase in energy efficiency (Gokmenoglu, Ozatac, & Eren, 2015). This can be attributed to the easy provision of modern technologies that are environmentally friendly. Hence, it is believed that financial development is key to sustainable environment (Boutabba, 2014).The inconsistency in findings of the exiting empirical literature on financial development-environmental nexus requires further examination of the potential impact of financial development on environmental sustainability.
Therefore, a thorough investigation of the literature reveals several limitations to which we want to address in this study: first, the non-existence of a consensus on the possible outcomes of renewable energy, trade openness, financial development in the context of environmental pollution. For example, the impact of trade openness and financial development on CO2 emissions might be positive as well as negative (Abbas et al., 2020; Honma, 2015; Khobai & Le Roux, 2017; Solarin, Al-Mulali, Musah, & Ozturk, 2017). In addition to these contradictory findings, some studies reveal non-linearity/asymmetric association between the stated nexus (Ahmed et al., 2020). Second, as per our knowledge scarce literature exists that discusses the environmental implications of financial development and trade openness (Boutabba, 2014).Third, no empirical evidence can be found on the relationship of trade openness, financial development, and CO2 emissions worldwide. Therefore, this study contributes on the several fronts: First, the study used the quintile regression in addition to panel ARDL to account for the income level in explaining trade openness-financial development-CO2 emissions nexus. Furthermore, D-H causality test has been conducted to determine the direction of relationship between the variables. The quintile regression with its unique characteristics can handle outliers lying across percentiles of the data series while other regression techniques estimate mean effects, which usually overestimate, underestimate, or fail to detect significant dependencies (Binder & Coad, 2011). In addition, along with conditional distribution, the quantile regression help find more detailed and comprehensive relationship among the series (Zhang, Peng, Liu, & Tan, 2015).
Second, the study targets all groups of countries e.g., low, middle, and high-income countries to provide reliable insights for policy purpose as all the previous investigated relationships are either country specific (Ahmed et al., 2020) or region specific (Aruga, 2019). Third, long data ensures the credibility of estimation results that are essential for effective policy framework related to renewable energy in all group of countries. This study uses data from 1960 to 2019 that is significantly larger than any other data set used in previous empirical literature on the subject as (Ahmed et al., 2020) [1996–2018: Pakistan]; (Aluko & Obalade, 2020) [1985–2014: 35 SSA countries]; (Shobande & Ogbeifun, 2021) [1980–2014: 24 OECD countries]; (Li, Zhang, & Ma, 2015) [1980–2010: 102 countries]; (Ye, Khan, Wu, Shah, & Abbas, 2021) [1987–2020: Malysia].
Third, country specific studies have some constraints regarding estimation as these studies use time-series approaches (Baltagi, 2008). This demands a panel data study that allows the heterogeneity across economies and increases the estimation power by combining time-series and cross-sectional data. In addition, studies conducted on panel data can potentially handle limitations associated with time-series analysis. Finally, the previous empirical literature has yielded un-conclusive findings on CO2 emissions-renewable energy- trade openness- financial development nexus thus necessitating further analysis of the nexus. To our best knowledge, not a single study can be mentioned that investigates the dynamic impact of renewable energy, trade openness, and financial development on CO2 emissions globally.