On the progressive side of the political spectrum, it is assumed that with an increasing acknowledgment of the reality of climate change will come default support for a progressive Green New Deal agenda. There is, however, another possible outcome of the far-right abandoning climate denial: Avocado Politics, green on the outside, brown(shirt) on the inside. 
In the words of Nils Gilman, "The strong state demanded by right-wing environmentalists will not be one that is liberal, tolerant, or inclusive but rather one that prioritizes the welfare of the native-born and ethnically pure while enforcing punitive restrictions against foreigners, immigrants, and the ethnically impure."
A Green/Far Right alliance has sprung up in Austria which calls not just for 100% renewable energy, but also banning Islamic headscarves and detaining asylum seekers. The El Paso and Christchurch shooters both centered their manifestos around ecological justifications for their mass murders. 
There is a deep intellectual history for these ideas going back to Social Darwinism and beyond. The founder of the term "Ecology" Ernst Haeckel also invented the term Lebensraum which the Nazis used to justify their destruction of the peoples of Eastern Europe. In America, up until the 1990s, the Sierra Club was one of the fiercest anti-immigrant organizations in America. 
Nils offers a sweeping history and analysis of the phenomenon of Avocado politics and cautions progressives that catastrophist language may have unintended and unfortunate consequences.