Rúna Magnússon

1 INTRODUCTION Arctic ecosystems are facing rapid warming and fundamental climatic changes. Air temperatures are increasing three to four times the rate of average global warming (AMAP, 2025; Rantanen et al., 2022), inducing changes in key ecosystem processes (Box et al., 2019).

2.2.2 Ring width measurement and chronology development Ring widths of shrubs from thaw ponds and shrub patches were measured and cross-dated earlier by Magnússon et al. (2020) for the purpose of age determination of shrubs. Samples from the Yedoma ridge were analysed according to the same protocol. Cross-dating of ring width series of individual shrubs was carried out separately per subsite to account for potential spatial variability in climate–growth associations.

To address the question weather heavy summer rainfall has a warming or cooling effect on ground temperatures in permafrost landscapes, and whether this may be related to climatological contrasts, we combined several methodological approaches. We first reviewed relevant literature on the topic to collect information about observed effects.