Unfrozen lakes

Yes, there was a time when these pools of life froze during winter, to be reborn again as soon as the sun started shinning more and more.

Especially in light-limited regions, spring means life. Blooms of tiny organisms scattered all over to serve as pillars of the food web. They are the base of all forms of life, no matter to which trophic level you assign yourself. Whether you are a vegetarian, or an architect, every single living creature depends on primary producers.

With CC, less and less lakes freeze. Spring comes earlier. Winter comes later. The cycle is broken. 

Now it is just a matter of time until they are extinct.