Why do we care if anmails are being killed

Lack of diversity.

Explanation:

Lack of diversity is not a good effect of global events such as climate change and ocean acidification. This means the less animals in the ecosystem, the less it will thrive and (generally speaking) less enjoyment for humans in the future. If cows went extinct you wouldn't have the burger you had yesterday, or if chickens went extinct you wouldn't be enjoying those chicken nuggets you had 2 minutes ago. Hope this helps.

he will find out what went wrong or happened and how.

i may be wrong but i think your answer is flashback