European hydroclimate response to volcanic eruptions over the past nine centuries

Abstract

The climatic aftermath of the 1815 Tambora eruption in Europe suggests that large volcanic eruptions can introduce environmental and societal consequences in this region. Here, we analyse the European summer hydrological response to 31 tropical and 44 Northern Hemisphere mid‐to‐high latitude eruptions over the past nine centuries, using a newly published reconstruction of global volcanism and a proxy record of hydrological conditions (Old World Drought Atlas) together with a superposed epoch analysis. Our results show a significant wetting response (at the 95% confidence level) for year 0 and year +1 after tropical eruptions, followed by a significant drying in year +2. Spatially, wetting occurs in northeast and southern Europe, while a drying response develops in central and northwest Europe. Both the wetting and drying responses are more significant for the group of eruptions with higher sulphate injection magnitudes than the eruptions with low magnitudes. Large high latitude eruptions tend to cause a drying response in western‐central Europe in year +2, which shifts south‐eastwards in years +3 and +4. Correcting for the effects of El Nino does not noticeably change the response patterns. The response to eruptions counteracts the hydroclimate response to global warming in some regions, e.g. the Mediterranean, but exaggerates is in others, such as central Europe. Our results verify previous modelling studies from a longer term proxy perspective, and illuminate potential effects of stratospheric geoengineering in Europe.

European and Mediterranean hydroclimate responses to tropical volcanic forcing over the last millennium

“…While postvolcanic spring and summer cooling is a consistent response both regionally (Figure S5) [ Esper et al , ; Luterbacher et al , ] and globally [ D'Arrigo et al , ; Stoffel et al , ], here we show that the hydroclimate response to volcanic forcing is much more spatially heterogeneous [e.g., Anchukaitis et al , ]. Posteruption hydroclimate anomalies (Figure ) over Europe and the Mediterranean resemble those caused by a negative phase of the EAP (Figures and a), with pluvial conditions over the western Mediterranean and drought conditions over northwestern Europe and the British Isles (Figures and ) [also see Büntgen et al , ; Gao and Gao , ]. A similar response is observed in a largely independent seasonal precipitation reconstruction (Figures S4 and S5) [ Fischer et al , ] and also simulated, albeit with slightly northward displaced anomalies, in volcanically forced mean May through September precipitation by the Community Earth System Model [ Colose et al , , Figure 4].…”

“…Our findings (Figures ) suggest that the hydroclimate response to volcanic forcing is consistent with this hypothesized weakening of the descending branch of the Hadley circulation and southward shift of storm tracks, causing springtime wetting over the western Mediterranean and spring and summer drying over northwestern Europe. Although this mechanism is largely consistent with that proposed by Gao and Gao [], we show that the OWDA primarily reflects spring through summer soil moisture (Figures and S1). Thus, it is unlikely that volcanically induced wintertime teleconnection anomalies, such as a positive winter NAO, play a dominant role in influencing the observed response.…”

Rogation ceremonies: a key to understanding past drought variability in northeastern Spain since 1650

“…This result is similar to that of a previous study using rogation ceremonies in the Iberian Peninsula, although it was based on individual and not regional drought indices (Domínguez-Castro et al, 2010). In addition, the normal conditions in the year of the Tambora eruption and the following year, and the increased drought intensity 2 years after the event, are in agreement with recent findings on hydroclimatic responses after volcanic eruptions (Fischer et al, 2007;Wegmann et al, 2014;Rao et al, 2017;Gao and Gao, 2017), although based on treering data only. In addition, Gao and Gao (2017) highlight the fact that high-latitude eruptions tend to cause drier conditions in western-central Europe 2 years after the eruptions.…”

Revisited Asian Monsoon Hydroclimate Response to Volcanic Eruptions

“…We use the cold tongue index (CTI), which is the average SST anomaly over 6°N–6°S, 180°E–90°W minus the global mean SST, as a measure of ENSO variability. The index is less influenced by both global warming and the short‐term cooling following volcanic eruptions and has been used in various studies (Gao & Gao, ; Iles & Hegerl, , 2015). The data are obtained from the Joint Institute for the Study of the Atmosphere and Ocean at the University of Washington (at http://research.jisao.washington.edu/data_sets/cti/).…”