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Abstract How forests respond to accelerated climate change will affect the terrestrial carbon cycle. To better understand these responses, more examples are needed to assess how tree growth rates react to abrupt changes in growing‐season temperatures. Here we use a natural experiment in which a glacier's fluctuations exposed a temperate rainforest to changes in summer temperatures of similar magnitude to those predicted to occur by 2050. We hypothesized that the onset of glacier‐accentuated temperature trends would act to increase the variance in stand‐level tree growth rates, a proxy for forest net primary productivity. Instead, dendrochronological records reveal that the growth rates of five, co‐occurring conifer species became less synchronous, and this diversification of species responses acted to reduce the variance and to increase the stability of community‐wide growth rates. These results warrant further inquiry into how climate‐induced changes in tree‐growth diversity may help stabilize future ecosystem services like forest carbon storage. 

Abstract Here, we present a 420‐year‐long winter lake level reconstruction for Lake Erie based primarily on temperature‐sensitive tree‐ring chronologies from Alaska, Oregon, and California. This well‐verified model explains more than 51% of the variance in winter lake levels over a 131‐year calibration period (1860–1990) and shows strong decadal fluctuations related to changes in sea surface temperatures in the North Pacific and the North Atlantic, which alternate in terms of their relative influence. Decadal variability is superimposed on a persistent secular lake level rise that began in the mid‐1900s coinciding with a growing influence of the Atlantic sector. In the context of the last 420 years, the instrumental period experienced extreme lake levels, with the lowest over the entire record during the Dustbowl and the highest in 2020. Fluctuations in Lake Erie water levels are primarily determined by climate, and their variability greatly impacts the region's infrastructure and ecosystems. 

Abstract Reconstructing how biota have responded to fast‐paced warming events in the past can help predict their responses to rapid climate changes in the future. Here we suggest that natural communities located near glaciers are useful laboratories for this purpose as they experienced climate changes accentuated by past ice‐margin fluctuations. By reconstructing an Alaskan glacier's position over a 166‐year period and measuring the periglacial air temperatures over the last 3 years, we estimate that the adjacent temperate rainforest episodically cooled and warmed by 0.5–0.7°C/decade. These rates of change exceed most historical warming trends measured elsewhere on Earth and are comparable to the rates of climate warming predicted for the next century. The ring‐width responses of yellow‐cedar trees growing at varying distances from the ice edge illustrate the potential for using periglacial ecosystems to predict how forests may respond to rapid warming in the future. 

Abstract Two large volcanic eruptions contributed to extreme cold temperatures during the early 1800s, one of the coldest phases of the Little Ice Age. While impacts from the massive 1815 Tambora eruption in Indonesia are relatively well‐documented, much less is known regarding an unidentified volcanic event around 1809. Here, we describe the spatial extent, duration, and magnitude of cold conditions following this eruption in northwestern North America using a high‐resolution network of tree‐ring records that capture past warm‐season temperature variability. Extreme and persistent cold temperatures were centered around the Gulf of Alaska, the adjacent Wrangell‐St Elias Mountains, and the southern Yukon, while cold anomalies diminished with distance from this core region. This distinct spatial pattern of temperature anomalies suggests that a weak Aleutian Low and conditions similar to a negative phase of the Pacific Decadal Oscillation could have contributed to regional cold extremes after the 1809 eruption.