Recent atmospheric drying in Siberia is not unprecedented over the last 1,500 years

Abstract

Newly developed millennial δ¹³C larch tree-ring chronology from Siberia allows reconstruction of summer (July) vapor pressure deficit (VPD) changes in a temperature-limited environment. VPD increased recently, but does not yet exceed the maximum values reconstructed during the Medieval Warm Anomaly. The most humid conditions in the Siberian North were recorded in the Early Medieval Period and during the Little Ice Age. Increasing VPD under elevated air temperature affects the hydrology of these sensitive ecosystems by greater evapotranspiration rates. Further VPD increases will significantly affect Siberian forests most likely leading to drought and forest mortality even under additional access of thawed permafrost water. Adaptation strategies are needed for Siberian forest ecosystems to protect them in a warming world.

Figure 1

A 1,489-year δ¹³C chronology from larch tree-ring cellulose was constructed based on annually cross-dated samples (n = 48). Individual tree measurements used to verify the range of variability of each tenth-year (T1, T2, T3, T4 and T5) are marked with circles of different colors.

Figure 2

Annually resolved (grey line) and smoothed by a 41-year Hamming window (black line) July VPD reconstruction over the period from 516 to 2004. The Early Medieval Period (EMP), Medieval Climate Anomaly (MCA), Little Ice Age (LIA) and the Recent Period (RP) for northeastern Yakutia (C-IND) are indicated in blue and red rectangles.

Figure 3

Spatial correlation maps of VPD reconstructed data versus gridded maximum July temperature (a) and July evapotranspiration (b) for the available period 1979–2004, respectively.