Until approximately mid last century, economists had traditionally analyzed the economy as something independent of the environment. There were no environmental constraints in terms of the use of energy or natural resources. So for their analyses, there were unlimited resources and environmental externalities did not suppose costs for agents and for the economies. This might had happened because of the lack of awareness due to the dimension of the global economy at that time. The global resources and energy needs at the period before the two world wars was not big enough to think that natural resources are scarce. Regarding the effects of pollution on human heath, although known, there were not considered important enough compared to progress, as they thought was mostly affecting working class (not middle class yet).
Whatever the reason, environmental economics, ecological economics, natural resources management, industrial ecology, political ecology, and other academic disciplines related to the economy, society and environment are still young. However, it is naïve nowadays to think that the environment does not affect economic activities and that the economic activities does not affect the environment in multiple ways. There is a huge corpus of theoretical and empirical work, coming from all natural sciences and social sciences that support it.
Related to this, scientists have been alerting us during at least the last four decades that there is no doubt on the existence of an anthropogenic climate change, i.e. caused by human activities. There is a huge consensus among the scientific community on this issue. GHG emissions need to be cut right now. It is a survival issue for our specie. However, some politicians, probably influenced by petrol lobbies, seem to deny it. Climate change is a non-evident to human eye, complex problem. It is easier to believe in quick and easy-to-understand things, but even though we do not deeply understand quantum mechanics, we do not deny Einstein’s work if scientists say it works.