> If we did that, meltwater water supply would essentially stop (in somewhere between 8 months and 2 years), everywhere on the planet

How? Why? Meltwater comes from the temperature difference between summer and winter, how does it have anything to do with this?

> Any variable that depends on the temperature delta that we depend on will rapidly become problematic if we stop accelerating global warming.

What variable depends on a temperature _delta_?

> Now I live in Europe. I don't expect water problems here (or only temporary).

We have water problems right now. Agriculture has problems, nuclear reactors have to shut down because of too warm(France) or missing (Romania) water. Dry forests leading to more fire.

> I know the theory behind green parties is "let's just stop doing what humanity is doing, and nature will save us".

I have never heard of this, I have a hard time that anybody relevant claims this.