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 ...

Blue rings found in the stems of trees and bushes in Norway point to a historic cold period in the late 1800s, but the exact cause of this climatic event remains unclear, scientists say.

A blue ring formed in 1902 in a tree in northern Norway. Credit: Image by Pawel Matulewski and Liliana Siekacz. Blue growth rings in woody plant stems indicate years when cells failed to lignify ...

Trees need a certain number of warm days in their growing seasons to grow properly; otherwise, the cell walls of new growth don't lignify properly, creating 'blue rings' that appear when wood samples ...

Scientists have been studying peculiar blue growth rings in the wood of trees and shrubs in Norway. The markings have provided a fascinating glimpse into the climate history of the late 1800s. These ...