What you leave out is the "if". People observe trends to see where society is headed in 10, 20, 50, or 100 years. There's a certain amount of confidence that, if dangerous trends are identified and addressed in a timely manner, the worst consequences can be avoided.
There is a political motivation for this.
Not really. It's more like preaching to the choir. Ideas which run counter to the "people are great, we can do anything" narrative don't usually reach people predisposed to reject what they see as "pessimism".
... or that the trend of honey bees is now starting to turn the corner.
And where did you hear that?
Are there any optimistic progressives?
I'm not a "progressive" but I think it's stupid to refuse on principle to believe or even consider bad news. One shouldn't be a doctrinaire optimist or a committed pessimist — it's more constructive to marshal the facts, weigh the evidence, and decide on a case by case basis.