The 1783–1784 CE Laki eruption in Iceland was one of the largest, in terms of the mass of SO2emitted, high‐latitude eruptions in the last millennium, but the seasonal and regional climate response was heterogeneous in space and time. Although the eruption did not begin until early June, tree‐ring maximum latewood density (MXD) reconstructions from Alaska suggest that the entire 1783 summer was extraordinarily cold. We use high‐resolution quantitative wood anatomy, climate model simulations, and proxy systems modeling to resolve the intra‐annual climate effects of the Laki eruption on temperatures over northwestern North America. We measured wood anatomical characteristics of white spruce (
The Laki eruption in Iceland, which began in June 1783, was followed by many of the typical climate responses to volcanic eruptions: suppressed precipitation and drought, crop failure, and surface cooling. In contrast to the observed cooling in 1784–1786, the summer of 1783 was anomalously warm in Western Europe, with July temperatures reaching more than 3 K above the mean. However, the winter of 1783–1784 in Europe was as cold as 3 K below the mean. While climate models generally reproduce the surface cooling and decreased rainfall associated with volcanic eruptions, model studies have failed to reproduce the extreme warming in western Europe that followed the Laki eruption. As a result of the inability to reproduce the anomalous warming, the question remains as to whether this phenomenon was a response to the eruption or merely an example of internal climate variability. Using the Community Earth System Model from the National Center for Atmospheric Research, we investigate the “Laki haze” and its effect on Northern Hemisphere climate in the 12 months following the eruption onset. We find that the warm summer of 1783 was a result of atmospheric blocking over Northern Europe, which in our model cannot be attributed to the eruption. In addition, the extremely cold winter of 1783–1784 was aided by an increased likelihood of an El Niño after the eruption. Understanding the causes of these anomalies is important not only for historical purposes but also for understanding and predicting possible climate responses to future high‐latitude volcanic eruptions.
more » « less- NSF-PAR ID:
- 10460695
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Journal of Geophysical Research: Atmospheres
- Volume:
- 124
- Issue:
- 13
- ISSN:
- 2169-897X
- Page Range / eLocation ID:
- p. 6770-6790
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Picea glauca ) trees from two northern Alaska sites. Earlywood cell characteristics of the 1783 ring are normal, while latewood cell wall thickness is significantly and anomalously reduced compared to non‐eruption years. Combined with complementary evidence from climate model experiments and proxy systems modeling, these features indicate an abrupt and premature cessation of cell wall thickening due to a rapid temperature decrease toward the end of the growing season. Reconstructions using conventional annual resolution MXD likely over‐estimate total growing season cooling in this year, while ring width fails to capture this abrupt late‐summer volcanic signal. Our study has implications not only for the interpretation of the climatic impacts of the Laki eruption in North America, but more broadly demonstrates the importance of timing and internal variability when comparing proxy temperature reconstructions and climate model simulations. It further demonstrates the value of developing cellular‐scale tree‐ring proxy measurements for paleoclimatology. -
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