This thesis examines Finland‘s transition from a solar based energy system to a fossil fuel based one, and the environmental consequences of this transition. The period under examination is from the beginning of the 19th century to the present, covering Finland's transition from a proto-industrial agricultural society to a --post- industrial| society. The theoretical starting point has been the environmental Kuznets curve hypothesis, which proposes that some pollution or measures of environmental degradation would follow an inverted U-curve related to incomes, increasing at low income levels and decreasing at high income levels. Based on the historical approach used in this thesis, two new explanations for the existence of an environmental Kuznets curve are added: 1) The severity of environmental degradation might itself create a turning point for the emissions, or in some cases fear of severe effects. 2) What at a first glance seems to be a genuine environmental improvement might just be a transformation of one environmental problem into another.  Some proponents of economic growth go as far as claiming that economic growth is a necessary condition for proper protection of the environment. This thesis turns the argument around, claiming that the causal connection goes in an opposite direction: proper environmental standards and conservation comprise a necessary condition for economic growth in the long run.  Finland industrialized by means of renewable, indigenous energy sources. The switch to imported fossil fuels in the 1960s led to exceptionally fast growth of carbon and sulphur dioxide emissions. The emissions of sulphur dioxide started to decline in the 1970s while the emission growth of carbon dioxide only slowed down. The initial decline of sulphur dioxide emissions was mainly a side-effect of changes in industrial processes rather than an outcome of a deliberate policy. Furthermore, anxiety about large and widespread damage to the forests was a major reason for active measures to decrease sulphur dioxide emissions since the mid- 1980s. Thus the emissions themselves provoked their downturn.  Quantitative calculations on the use of natural resources provide valuable tools, which can give new insights to old questions and raise new questions. Burning cultivation of peatlands, which has been neglected in historical research, was found to be the greatest source of carbon dioxide in Finland during the whole of the nineteenth century and at the beginning of the twentieth century. Another neglected occupation, the production of potash might have consumed as much wood during the 19th century as the production of tar.