Filtering out new accounts would set a tremendously dangerous precedent. There are many rather prolific, insightful, and level-headed users here that prefer creating new accounts for each thread they engage with in order to reset karma and enforce privacy. Rather than fuel animosity behind the veil of anonymity, these users are trying to preserve the instinctive behavior of out-group participants and even under-represented experts to engage with intellectually honest criticism when the signals of authority such as identity and karma are missing.

The problem you're seeing here isn't due to anonymity, but rather self-selecting hostile interactions by participating with front page news as soon as posted. This is typical of HN and really any technically-bent social media, where the first to interact are typically the most outspoken and inflammatory regardless of identity visibility, with the rational high-quality debate trickling in once the topic starts significantly eroding in popularity.

I'd also be happy with banning climate change denial here, similar to how I assume Holocaust denial would be treated. Climate change is an existential threat to our planet and everything on it. There is no debate to be had. The science is in. Denialism of climate change is just as legitimate as Holocaust denial, which is to say, not at all legitimate.