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Table 1. Information on the variables used
Symbol Category Variables Description and measurement Source
EF Dependent variable Ecological Footprint Ecological Footprint vs Biocapacity (gha per Global Footprint Network
person) (2025)
REN Dependent variable Renewable energy Quadrillion Btu EIA (2025)
GDP Independent Income GDP per capita (constant 2015 USD) World Bank (2025)
variable
GDP2 Independent Income Squared GDP per capita (constant 2015 USD) World Bank (2025)
variable
NREN Independent Fossil energy Quadrillion Btu EIA (2025)
variable consumption
TO Independent Trade openness The ratio of total exports and imports to GDP World Bank (2025)
variable
URB Independent Urbanization Urbanization (% of total population) World Bank (2025)
variable

Table 2. Descriptive statistics
Stat. EF REN GDP GDP2 NREN TO URB
Mean -0.16 0.28 6.93 48.17 2.74 3.52 3.39
Median -0.21 0.28 6.91 47.83 2.70 3.69 3.39
Max. 0.08 1.32 7.64 58.42 3.24 4.02 3.58
Min. -0.38 -0.34 6.28 39.39 2.25 2.74 3.24
Std. Dev. 0.16 0.52 0.44 6.15 0.32 0.39 0.10
Skew. 0.08 0.45 0.10 0.16 0.07 -0.44 0.21
Kurt. 1.48 1.91 1.68 1.69 1.59 1.83 1.80
J-B 3.22 2.75 2.46 2.50 2.76 2.97 2.23
(0.20) (0.25) (0.29) (0.29) (0.25) (0.23) (0.33)

Values in parentheses indicate probability value.

lower in India. Understanding the impact of TO on environmental degradation is considered important for
Indian economic policies. In this context, TO was added to model (1). In model (2), the focus is on the
relationship between REN and GDP and GDP2. Because of the high correlation between NREN and REN,
the NREN variable was not included in the model. Rapidly increasing urbanization in India can also lead to
environmental consequences. In this context, the relationship between renewable energy and urbanization
can become important. Therefore, the TO variable was added to model (2) to form an empirical model. In
both models, the natural logarithm of the variables was taken. Mishra et al. and Mishra et al. suggested
[54]
[53]
that consistent and reliable findings were achieved by taking the natural logarithmic transformations of the
variables. Therefore, it is stated that the models lead to more consistent and robust results. The relevant
models are expressed as

where t indicates the sample period of 1990-2022. In both models, the constant terms are indicated as β
10
and β , respectively. In model (1), where the EKC hypothesis will be tested, β , β , β , and β indicate the
14
20
13
11
12
elasticity coefficients of GDP, GDP2, NREN, and TO, respectively. In model (2), where the RKC hypothesis