Reply on RC1

Philippa Higgins

doi:10.5194/cp-2021-171-ac2

Abstract

Much of our knowledge about the impacts of volcanic events on climate comes from proxy records. However, little is known about the impact of volcanoes on trees from the Southern Hemisphere. We investigated whether volcanic signals could be identified in ring widths from eight New Zealand dendrochronological species, using superposed epoch analysis. We found that most species are good recorders of volcanic dimming and that the magnitude and persistence of the post-event response can be broadly linked to plant life history traits. Across species, site-based factors, particularly altitude and exposure to prevailing conditions, are more important determinants of the strength of the volcanic response than the species. We then investigated whether proxy selection impacts the magnitude of post-volcanic cooling in tree-ring based temperature reconstructions by developing two new multispecies reconstructions of New Zealand summer (December–February) temperature. Both reconstructions showed temperature anomalies remarkably consistent with studies based on instrumental temperature, and with the ensemble mean response of climate models, demonstrating that New Zealand ring widths are reliable indicators of regional volcanic climate response. However, we also found that volcanic response is complex, with positive, negative, and neutral responses identified – sometimes within the same species group. Species-wide composites thus tend to underestimate the volcanic response. The has important implications for the development of future tree ring and multiproxy temperature reconstructions from the Southern Hemisphere.

Highlights

Emissions from large volcanic eruptions are a key source of temperature and hydroclimate variability on interannual to decadal time scales (Iles et al, 2015; Robock, 2000)
We investigated whether volcanic signals could be identified in ring widths from eight New Zealand dendrochronological species, using superposed epoch analysis
4.1 Volcanic responses recorded by New Zealand trees Previous studies have not identified significant volcanic responses in Southern Hemisphere tree rings (Krakauer & Randerson, 2003; Palmer & Ogden, 1992) or in the temperature reconstructions based on them (Allen et al, 2018; Cook et al, 1992)

Summary

Introduction

Emissions from large volcanic eruptions are a key source of temperature and hydroclimate variability on interannual to decadal time scales (Iles et al, 2015; Robock, 2000). As few large volcanic eruptions have occurred during the instrumental era, much of our knowledge about volcanic impacts on climate, regional and global temperature, comes from proxy records (Tejedor et al, 2021). These records are predominantly high altitude or high latitude tree-ring proxies from the Northern.

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