Amateurs are the people who do something for the love of it, without getting paid for it. I get paid for doing what I love, so don't get to be called an amateur*. One of my favorite amateurs on climate is Jan Schloerer. He was active in the Usenet group Sci.environment in the 1990s, and wrote a number of articles on climate for nonprofessionals. A number of excellent articles. He ok'd my posting them to my personal web site (I used to be on radix.net) and I'm now, finally, moving my personal site to www.grumbinescience.org.
Two of the great things about Jan as an amateur writer on climate was that he wrote for other people who also were not professionals, and that he paid a lot of attention to what was in the scientific literature, citing thoroughly where data and conclusions came from. Therefore, even though it's 15-20 years since he wrote the articles, they remain relevant and correct as far as they go. Good job Jan!
On a different side, Jan is (was? nobody I know has heard from him in years) a very caring person. When the US government shut down in the 1990s, he knew that I was working for it, so not being paid. He offered to help me out financially if needed. Fortunately it wasn't. But he is/was the kind of person who speedily thought about the possibility that I could be in some difficulty, and offered help immediately if it might be needed.
Jan's articles (I'm not sure I have the most recent versions, so any errors are mine, not his, and the formatting is all my fault -- to be fixed Real Soon Now; updates will be coming):
How we know humans are the source of the CO2 increase
Readings on climate change
CLIMAP -- the climate mapping project (1970s-early 1980s)
* Well, on my oceanography/glaciology/... work. On other things I am indeed an amateur. I hope in my amateur activities to approach Jan's level.