The impact of economic development on the environment is researched. The development of Russian regions is analyzed and their compliance with the environmental Kuznets curve is verified. It is shown that the group of regions with high share of the mining sector, which have high per capita gross regional product and environmental impact, significantly shifts the parameter estimates. At the same time, the dynamics of certain regions in the 2000s corresponds to the environmental Kuznets curve. The relationship between economic and environmental indicators is investigated for the Russian Federation and for Republic of Karelia, and models are developed that describe this interaction. The impact of modernization on the dynamics of environmental indices is showed. The causes behind the reduction of emissions into the air in Karelia and their rise in Russia at large in the 2000s are identified.