Actually, humans were involved but from a distance – not directly. Humans were responsible as a result of industrialization.
The clear signs of industrialisation can be found even in very remote lakes, thousands of kilometres from the nearest city. The research is based on studies of sediment from 36 lakes in the USA, Canada, Greenland and Svalbard, Norway. The researchers have analysed how the chemical composition of the sediment has changed over the centuries.
The cause is nitrogen.
Nitrogen is an important nutrient for plants, but overuse in more intensive farming can lead to pollution.
It appears that remote areas of our planet are not entirely remote.
Remote Wilderness Polluted by Humans