EGU2020-3053
https://doi.org/10.5194/egusphere-egu2020-3053
EGU General Assembly 2020
© Author(s) 2020. This work is distributed under
the Creative Commons Attribution 4.0 License.

Late 20th century increase in northern Svalbard glacier-derived runoff tracked by encrusting coralline algae

Steffen Hetzinger1,2, Jochen Halfar3, Zoltan Zajacz4, Marco Möller5,6, and Max Wisshak7
Steffen Hetzinger et al.
  • 1Institut für Geologie, Universität Hamburg, Hamburg, Germany (steffen.hetzinger@uni-hamburg.de)
  • 2GEOMAR Helmholtz-Zentrum für Ozeanforschung Kiel, Kiel, Germany
  • 3CPS-Department, University of Toronto Mississauga, Mississauga, Canada
  • 4Department of Earth Sciences, University of Geneva, Geneva, Switzerland
  • 5Institute of Geography, University of Bremen, Bremen, Germany
  • 6Geography Department, Humboldt-Universität zu Berlin, Berlin, Germany
  • 7Senckenberg am Meer, Marine Research Department, Wilhelmshaven, Germany

The Arctic cryosphere is changing at a rapid pace due to global warming and the large-scale changes observed in the Arctic during the past decades exert a strong influence throughout the global climate system. The warming of Arctic surface air temperatures is more than twice as large as the global average over the last two decades and recent events indicate new extremes in the Arctic climate system, e.g. for the last five years Arctic annual surface air temperature exceeded that of any year since 1900 AD. Northern Spitsbergen, Svalbard, located in the High Arctic at 80°N, is a warming hotspot with an observed temperature rise of ~6°C over the last three decades indicating major global warming impacts. However, even the longest available datasets on Svalbard climatic conditions do not extend beyond the 1950s, inhibiting the study of long-term natural variability before anthropogenic influence. Ongoing climate trends strongly affect the state of both glaciers and seasonal snow in Svalbard. Modeled data suggest a marked increase in glacier runoff during recent decades in northern Svalbard. However, observational data are sparse and short and the potential effects on the surface ocean are unclear.
This study focuses on the ultra-high-resolution analysis of calcified coralline algal buildups growing attached to the shallow seafloor along Arctic coastlines. Analysis of these new annually-layered climate archives is based on the long-lived encrusting coralline algae Clathromorphum compactum, providing a historic perspective on recently observed changes. Here, we present a 200-year record of past surface ocean variability from Mosselbukta, Spitsbergen, northern Svalbard. By using algal Ba/Ca ratios as a proxy for past glacier-derived meltwater input, we investigate past multi-decadal-scale fluctuations in land-based freshwater contributions to the ocean surface layer. Our records, based on multiple coralline algal specimens, show a strong and statistically significant increasing trend in algal Ba/Ca ratios from the 1990s onwards, suggesting a drastic increase in land-based runoff at Mosselbukta. The drastic rate of increase is unprecedented during the last two centuries, directly capturing the impact of amplified surface air temperature warming on coastal high Arctic surface ocean environments.

 

How to cite: Hetzinger, S., Halfar, J., Zajacz, Z., Möller, M., and Wisshak, M.: Late 20th century increase in northern Svalbard glacier-derived runoff tracked by encrusting coralline algae, EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-3053, https://doi.org/10.5194/egusphere-egu2020-3053, 2020