Influence of volcanic eruptions on Northern Hemisphere summer temperature over the past 600 years

A network of temperature-sensitive tree-ring-density chronologies provides circum-hemisphere information on year-by-year changes in summer warmth in different regions of the northern boreal forest1. Combining these data into a single time-series provides a good summer-temperature proxy for northern high latitudes and the Northern Hemisphere as a whole2. Here we use this well dated, high-resolution composite time-series to suggest that large...