which found strange blue rings in samples of trees and shrubs from the northern treeline in Norway. “Blue rings look like unfinished growth rings, and are associated with cold conditions during the ...

These eruptions likely cast a volcanic winter over the northern hemisphere, impacting the trees at Mount Iškoras in Norway, where the study was conducted. "Blue rings look like unfinished growth ...

These “blue rings ... Norway, where these plants battle harsh Arctic conditions. Here, at the northern limit of where trees can survive, they uncovered a natural record of historical cold events ...

Volcanic eruptions and cold summers leave lasting marks in the wood of northern trees, unlocking the secrets of past climate extremes.