Posted on April 12, 2018
Claudia Hartl, from the Johannes Gutenberg University in Mainz, Germany, stumbled across the impact while examining pines at Kåfjord near Alta. The dendrochronologist was collecting wood cores to build up a picture of past climate in the area. Severe cold and even infestation from insects can severely stunt annual growth in a stand, but neither of these causes could explain the total absence of rings seen in some trees dated to 1945. A colleague suggested it could have something to do with the Tirpitz, which was anchored the previous year at Kåfjord where it was attacked by Allied bombers. Archive documents show the ship released chlorosulphuric acid to camouflage its position. “We think this artificial smoke damaged the needles on the trees,” Dr Hartl told BBC News.