The human population? no.
Some civilizations on Earth? Sure. The "Western civilization" (for ex., the USA) is already in steep decline on all aspects (just like the Romans were around 1700 years ago).
There are no real Nuclear Tensions, at least, not to the level where the whole human race is at risk. Naturally, in some country that live in permanent election campaign, it is often easy to scare the voters by exaggerating the dangers.
The Doomsday Clock is an invention by a group dedicated to get attention for their cause. For a while, it was for nuclear disarmament. Not it is for environmental dangers.
Don't worry, global warming will raise the ocean levels and eventually get rid of about half the world population (lack of coastal habitat, lack of fields to grow enough food, redistribution of fish species = lack of food for humans, etc.). But the brunt of the effect will take more than a century.
A lot of people confuse a communist system, with the system that existed under the Communist Party in the USSR (after Stalin, the economic system of the Soviet Union was closer to a monopolistic capitalist system = the end-product of capitalism if it is allowed to continue unchecked).
A real communist system would resemble that described in the Acts of the Apostles. Obviously, this is something to be avoided by so-called "Christian countries" who prefer capitalism.
As to whether this communist system or any other would be better for the survival of the human race... who knows. So far, we seem to be able to multiply like lice, despite the system in place.
There has been at least two episodes in the "recent" human history (last 15,000 years) where the world population was on the brink of disappearance. In one case, we think the world population went down to mere thousands. And yet, we rebounded.
What we DO know is that with or without human-generated global warming, the conditions on Earth will no longer be suitable for human habitation in less than half a million years. Therefore, IF (a big if, considering the western world's selfishness) we want humans to continue beyond that, we better prepare to move. And that implies the need to practice "colonization".