When was the first recorded sign of glacial melt or global warming?

[AwesomeSeattlePerson]

I can't find anything to tell me. I need to know for my Independent Research Project, which is like a huge 8th grade project. My topic is glacial melt, so obviously i need to provide some background information on it. If anyone could give me links to any sites that would give any information like that i would greatly appreciate it.
Thank you so much in advance!