Just playing with the OP
I define Soviet Cold War "victory" reversing OTL results- USA economically and politically collapses, all allies go over the hill to neutrality or ally with USSR ca 1990.
My assumption is that the Brezhnev-era policies continue, emphasizing production at the expense of the environment though the kind of USSR that could economically and politically outlast the USA would be unrecognizeable as the USSR 1950-1990.
Yellowstone blowing up and the US yielding the geopolitical field to the USSR by default's another POD.
USSR environmentally screws itself with massive Central Asian desertification reducing already lame crop yields. (One could argue it was marginal land planted with the wrong crops and all the Arctic river diversions, Aral Sea canals, etc causing even more havoc chasing ever more marginal yields as irrigation water gets saltier, more soil dries out and blows away in dust storms, etc)
Industrial areas of Eastern Europe (DDR, CS, Poland, Hungary) become polluted even more than OTL making acid rain effects on forests much worse and Baltic Sea near dead-zone by 2000.
Overfishing by Soviet, Norse, Japanese, and Chinese factory ships obliterates edible fish stocks by 2015. This screws up marine ecologies something fierce and leads to an edible protein crisis for Oriental nations.
How much they switch to chicken, pork, and other more-readily-raised protein sources is a matter of grave concern.
In essence I see the inefficient cluster-%^&$ of Soviet agriculture creating ever-bigger-problems for themselves and the world.
Overall global consumption of resources in a Soviet cold war victory would most likely be less, but it depends on how much the former West produces for themsleves and the Comecon "market".
Nevertheless, global warming due to the massive release of GHGs is still ongoing. IDK how much population growth would occur under this scenario.
The global cultural effects of triumphant Soviet Communism might act as a massive brake on 3rd World population growth as contraceptives and abortion become much more available, more women work, and more reliance on state supported education, child care, etc vs traditonal familial patterns in Southern Asia, sub-Saharan Africa, and Latin America take hold.
Lately the problem confronting the world isn't just population growth, it's per capita resource consumption that's also been exponentially increasing in Brazil, India, Nigeria, South Africa, Indonesia, and China.
Good news, OTL 2.5 billion people are living better but consuming 7-10X the resources aspiring to Western middle-class consumption patterns (eating more meat, personal transportation vs mass transport, having more gadgetry needing more power to support as well as ample food, medical care, and education) than they did as dirt-poor peasants two generations back.
ITTL, there's not as much to aspire to as far as lifestyle goes, but it's still a major shift from a largely self-sufficient agrarian peasant economy to the industrialized Soviet model.
All this just begs the question of how big a hurry is the developing world to get to Soviet standards of living?
Also, the Soviets weren't unaware of the damage their policies were causing. By the 1970's there was a lot of criticism of the effects, but by and large, the folks in charge were far more interested in results now than effects later. During WW2, AKA Great Patriotic War that made sense.
However as the WWII generation died off or became irrelevant to policymaking, more environmentally progressive policies might be formulated and enacted. The question is would they be enforced?
The Soviets continued the Russian tradition of lovely laws that were arbitrarily enforced, ignored, etc according to whatever exigencies a particular apparatchik felt like doing that very instant.
The change had to be felt throughout society in every segment for folks to demand, enforce, and obey such laws/policies/directives.