Passage: The use of dendrochronology, or tree-ring dating, has provided scientists with high-resolution records of past climate variability long before the advent of instrumental records. The width of a tree's annual growth ring is influenced by environmental factors, primarily temperature and precipitation during the growing season. In temperature-limited environments, such as the high-latitude boreal forests or alpine treelines, wider rings generally correspond to warmer summers. By cross-dating samples from living trees with preserved wood from older structures or subfossil logs found in lake sediments, researchers can construct multi-millennial chronologies. However, some studies have noted a 'divergence problem' in recent decades: in some northern regions, tree growth has become less sensitive to rising temperatures than historical patterns would predict. This phenomenon suggests that other factors, such as moisture stress or changes in the timing of snowmelt, may be becoming the primary limiting factors. This divergence complicates the use of tree-ring data for reconstructing the full magnitude of recent warming relative to past natural cycles.