I didn't respond to that particular point because you are erroneously conflating saving with investing. Inflationary currencies gear economies towards 'growth' which is understood to be good but, without guidance / direction, this leads to frivolous spending, bubbles, and massive waste. How is this good for the environment?
With a somewhat deflationary currency, an 'investment' worth putting money into has to be worth more than the money is appreciating in value. This cuts the fat as you have to be more picky as an investor, and banks have to be more picky as a lender. However, right now there is virtually no reason to save in this sense, you must throw your money at assets like equities or real estate to keep your purchasing power. You must feed the machine, so to speak.
I think you'll find your argument on the wrong side of history when it comes to saving the planet from climate change. We need a drastic reduction in general consumption and waste while we work to reverse the damage we have done and find much more efficient means of production. We aren't going to get that without a total reversal of monetary policy, alongside strong fiscal incentives for climate conservation. It is far-fetched, but possible for a cryptocurrency to achieve this.