Fig. 4.

STREC responses to volcanic eruptions. Dimensionless normalized 3-y composites, which are the result of the Superimposed Epoch Analysis showing summer temperature responses in Eastern Canada to the 10 strongest (A) and the 10 next strongest (B) volcanic eruptions of the last millennium deduced by ref. 9 (see SI Methods). Each 3-y composite is labeled with the year nearest to the eruption year (e.g., 0 stands for the 3-y composite composed of years 0, 1, and 2 from eruption). Confidence ranges (90%, 95%, 99%) are indicated by horizontal lines. Black and gray columns mark preeruption and posteruption composites, respectively.