To whet your appetite and keep your writing fingers limber, take a good look at the photo, or let a prompt settle in your mind. Set a timer for a reasonable amount of time, be that five, fifteen, or thirty minutes. Then start writing.
Imagine that a group of sailors from the tropics sees a polar bear for the first time. What do they make of it? What happens next?
Write about the coldest time you can remember.
Write about the impact of climate change on an ecosystem.