I've asked this question before: Does anyone know with certainty what the temperature and climate around the Earth is supposed to actually be?

If we don't know that, how can we be sure whether the planet is supposed to be warmer, colder, air more oxygen-rich, air more nitrogen-rich, more humid, more dry, or anything else? Does mankind in its arrogance really believe it can keep the climate of the planet fixed at any static level? And if so, why? Do we know whether it is more harmful to the planet to keep it environmentally stationary level?

The polar bear population is getting smaller because heir environment is shrinking. Well, there was a time when there were no polar bears, or several oher species, and many species ceased to exist over the last few thousand years.