Historical and future trends in global snow conditions – observed by remote sensing and forecasted by spatio-temporal modelling

• Main Author: Eyþórsson, Darri
• Other Authors: Sigurður Magnús Garðarsson, Umhverfis- og byggingarverkfræðideild (HÍ), Faculty of Civil and Environmental Engineering (UI), Verkfræði- og náttúruvísindasvið (HÍ), School of Engineering and Natural Sciences (UI), Háskóli Íslands, University of Iceland
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: University of Iceland, School of Engineering and Natural Sciences, Faculty of Civil and Environmental Engineering 2023
• Subjects: Snjóalög; Fjarkönnun; Loftslagsbreytingar; Reiknilíkön; Hnattrænar breytingar; Doktorsritgerðir; Arctic; Halda; Iceland
• Online Access: https://hdl.handle.net/20.500.11815/4473

Snow resources worldwide are undergoing extensive changes in response to widespread and rapid changing of the global climate. These resources are vital in many areas and changes to them have and will continue to impact human societies and ecosystems in cold regions. The research presented in this dissertation entails the assessment and comparison of historical trends in the climate and snow regimes and the projection of these trends until the end of the 21st century, under different emission scenarios. The results show that extensive changes have occurred to the frequency of Northern Hemisphere (NH) snow cover since the beginning of the 21st century, as estimated based on remote sensing data from the MODIS satellite instrument. The future evolution of NH snow resources was modelled for the period 1950-2100 for each of the 21 downscaled and bias corrected CMIP5 climate models for two emission scenarios (RCP45 and RCP85) using the Snow17 model. The simulations show that the Snow Cover Frequency (SCF) is in general projected to diminish substantially across the NH. However, the NH 1st April Snow Water Equivalent (SWE) is projected to increase slightly at the beginning of the period, driven by increased snowfall at high latitudes in the Arctic and then decline back to 1950-1975 levels under RCP45 and 10% under those given RCP85. These trends were analyzed specifically for Icelandic circumstances revealing a trend of increasing SCF in many parts of the country over the period 1930-2021, whereas the simulated results project a decrease in SCF across Iceland between 1950 to 2100. Snjóauðlindir víðsvegar um heiminn eru nú breytingum undiropnar í kjölfar hnattrænna loftlagsbreytinga. Þessar auðlindir eru mikilvægar víðsvegar og breytingar á eðli þeirra hafa haft og munu halda áfram að hafa áhrif á mannleg samfélög og vistkerfi á kvöldum svæðum. Rannsókn sú er birt er í þessari ritgerð fjallar um greiningu og samanburð á sögulegri þróun loftlags og snjós og gerð forspár um það hvernig væntar loftlagsbreytingar munu hafa ...