By far the biggest threat to life on this planet is Capitalism. Other economic systems might require mass industrialisation, but what makes Capitalism so unique in this regard is the engine that drives it: Growth for growth's sake.
The need for ever-larger profit margins, ever expanding markets, ever higher GDP. All of our planet must be colonised, disrupted and turned into commodities, even past the point of irreversible destruction. If you care about the planet, you can't be a Capitalist.