New research from LBS professor Lauri Arvola and colleagues shows that contrary to expectations, Finnish lakes on the whole have not become browner over a 101 year period (1913-2014). This is the first time that a comparison over such a long time period has been made.
The hue of the water has become browner in many lakes, but the opposite is true in others, and many have remained stable.
See this link for the publication:
And a Finnish language news article is here: