Can't really help you about climate stuff but as for the whole map, here's a few comments:
Your lines are way too much pixellated, it looks too computer bad generated. That's weird that you have this kind of thing with tablet drawing I think. The transitions between areas and terrains are too harsh and the colors behind them go over the lines all the time. Some rivers doesn't make so much sense since they start from nowhere. You should first work on those things to improve the overall look of your map imho