I don't think I've ever heard of anyone advocating degrowth or depopulation in the UK. We're more into increasing renewable energy.
Some of the hard core environmentalists don't like nuclear energy, and they do tend to be more on the left side of politics.
https://www.theguardian.com/environment/2017/jul/12/want-to-...
The concluding statements say:
"Chris Goodall, an author on low carbon living and energy, said: “The paper usefully reminds us what matters in the fight against global warming. But in some ways it will just reinforce the suspicion of the political right that the threat of climate change is simply a cover for reducing people’s freedom to live as they want.
“Population reduction would probably reduce carbon emissions but we have many other tools for getting global warming under control,” he said. “Perhaps more importantly, cutting the number of people on the planet will take hundreds of years. Emissions reduction needs to start now.”
Seems reasonably balanced to me.
The reduction of population would probably work but it would take too long, is terrifying to me. *Edit* "WILL" take too long is even scarier.
IMHO People are the best hope we have for innovating and solving the situation we find ourselves in, anyone preaching depopulation as a answer should be intensely scrutinized for what other beliefs they hold regarding final solutions.