Part 1:
Eric Fisk, Change in Average Temperature With Fahrenheit, used under CC BY SA 4.0 DEED https://creativecommons.org/licenses/by-sa/4.0/, https://en.wikipedia.org/wiki/Climate_change#/media/File:Change_in_Average_Temperature_With_Fahrenheit.svg.
Part 2:
I would ask them if they are just trying to site one article or if this is for a large research project. I would direct them to the learn how to cite tab on the library home page regardless. Based on the answer to the previous question, I would either direct them to zotero if ti as for a large project or zoterobib or google scholar if not. But I would always recommend double checking those software with the tools in the how to cite page as well.