Nature

Nature isn't cruel, it is simply indifferent.

Consider any prey animal, say a gazelle.  It lives its life just fine until one particular unremarkable day when it is caught and eaten.  Perhaps it has even been chased before and escaped but its immaterial to nature.  One day while trying to flee it gets brought down, killed and eaten.

Similarly nature treats most of its creations the same way.  You eventually will become fodder for other life.  Even if you don't die violently, you most likely decompose and be consumed.

Unless of course you get buried under volcanic ash or get mummified.

People have taken greater control of this process than any other creature on the planet, finding way to fend off certain diseases and survive certain disasters.  We can even predict when some are coming.

Unfortunately we are also by all the evidence the cause, or at least the contributor, to some.

We have carelessly introduced or removed things into nature on an unprecedented scale.

It isn't a new phenomena we have been doing it since we started slash and burn agriculture.

Still it is only in the industrial age that we started to dig up carbon and re-release it into the atmosphere.

It took millennia for that carbon to become coal, oil, natural gas and remove it from the environment.  We are reversing the process at breakneck speed.

Nature will adjust, it always has.  We weren't always around and we may be returning to a state that doesn't support our survival.

Nature doesn't care.