The main goal of this study is to check the unit root properties of the ecological footprint and its six subcomponents-cropland footprint, grazing land footprint, fishing grounds footprint, forest land footprint, built-up land footprint, and carbon footprint-in 25 OECD (The Organisation for Economic Cooperation and Development) countries during the period 1961-2013. This study uses a new stationarity test with sharp and smooth breaks in the panel setting, developed by Bahmani-Oskooee et al. (2014). Empirical findings demonstrate that the fishing grounds footprint does not have mean-reverting behavior while the remaining ecological indicators display stationary properties under the assumption of both homogenous and heterogeneous long run variance. Therefore, if policymakers decide to decrease the size of the fishing grounds footprint, they will not face stiff resistance. In addition to the panel results, the univariate stationarity test results can also help policymakers in each country design effective emission reduction policies. (C) 2018 Elsevier Ltd. All rights reserved.