system
Given the following post, respond as if you're commenting on Reddit:
human
[Frozen] Can Elsa thaw natural ice?

When Elsa finally understands how love can overcome her fears, she manages to thaw the unnatural ice and snow that she accidentally created. But can she also thaw natural ice? For example, if she came across a lake that froze naturally during winter, could she unfreeze it? Perhaps more extreme, could she thaw a natural winter to create a magical summer?

Or is the "reverse ice magic" aspect of her powers exclusive to ice she herself created?
gpt
There doesn't appear to be any difference between the ice she forms and normal ice, with two exceptions. The first exception is when she creates living things out of ice and snow - they can control themselves (and the big guy can even manipulate his body to produce more ice.) The second exception is when her magic interacts with someone - it appears to begin a process that slowly chills the person before transforming them into ice in a single move.

Beyond those exceptions, there is no indication that her powers wouldn't be able to affect normal ice, or that the ice she forms is in any way different from normal ice. I'd say yes.

On the thawing a natural winter to create a magical summer, though, thawing the ice doesn't necessarily make things *warm*. It's cold because the sun is hitting that part of the earth at more of an angle (instead of more straight on,)  reducing the heat that it receives. She might be able to thaw a winter, but the cold temperatures would remain.  Arendelle was in summer during the events mentioned, and so removing the magical clouds allowed the sun's light to warm the area.