Dangerous development: how German forests flipped from taking up CO₂ from the atmosphere to becoming a major net source of CO₂, around 2018.
Main cause: the spruce bark beetle, propelled by storms, drought, and hot summers (see Robbie Andrews' thread on Bluesky: https://bsky.app/profile/robbieandrew.bsky.social/post/3lmykty2njs2o).