DNAmaster10

Exactly. Climate change we have the chance to mitigate, and very possibly prevent / reverse. The heat death on the other hand is not only just a theory as to how the universe might end, but also something that would likely be completely out of our control, assuming that humans even survive a fraction of the time until then. Most likely, there'll be something else that kills us first.

You do realize that the heat death of the universe would only likely take place in literally trillions and trillions and trillions of years time? Climate change is happening now.