Even though the drought comes to the Divide three years after the death of John Bergson, the story picks up six years later. In the book, it states that, after three years the drought came and lasted for another three years.
I've read this book three times and just realized that the timeline doesn't add up.
In Part II, it has been 16 years since John Bergson died. Part I ended 6 years after his death, measured by the 3 years of success followed by 3 years of drought. Carl leaves at the end of these 6 years.
But when Carl returns, he says it has been 16 years since he has been gone.
Emil has also only aged 16 years since the start of the novel, from 5 to 21, so it isn't simply a typo at the start of Part II that could explain the gap being longer.