Mass Starvation and mass migration due to the climate change
These are the two things that will severely affect every part of the globe in the next few decades. No one will care about why the animals are dying or getting smaller, or why storms are getting worse or why floods are happening .... millions of people will be moving into places where other people already live and people won't like that.
And we'll wonder why the world is degrading and why we are fighting one another.