Increased winter runoff in Siberia modeled with tree rings as evidence
for the recent high rate of permafrost degradation
Abstract
The instrumental data shows 7%-20% increase in annual discharge of the
major Eurasian rivers like Ob, Yenisei and Lena between 1936 and 2018
(Wang et al. 2021). The trend has been attributed to increased
precipitation and permafrost thawing due to the temperature warming
(Walvoord, Kurylyk 2016). However, the instrumental data does not
provide the longterm scope of the trend. We modeled seasonal discharge
from tree rings for the Yenisei River upstream at Kyzyl gauge and found
a remarkable 80% upsurge in winter ‘ow (Nov-Apr) over the last 25
years, which is unprecedented in the last 214 years since 1784
(Panyushkina et al. 2021). In contrast, the annual discharge (Oct-Sept)
has only a 7% increase over the last 25 years and shows normal range of
variability since 1700 (Fig. 1). Water balance modeling with CRU data at
the Yenisei upstream indicates a significant discrepancy between decadal
variability of the gauged ‘ow and climate data after 1960 (Fig. 1). The
long-term buckhound of the changes in regional hydrology is successfully
assessed with tree-ring methods. The tree-ring networks in Eurasian cold
climates have a great potential to reconstruct spatial pattern of the
seasonal runoff and quantify the long-term impact of permafrost
degradation on the hydrological regimes in Siberia. We discuss the
impact of melting permafrost on the base ‘ow and enrichment of the
surface and groundwater interaction at the Yenisei River basin coupled
with the warming temperature and, more importantly, forest fires. Recent
increase in the frequency, size, and intensity of boreal fires scale s
of its impact on hydrology and permafrost in Siberia. This study
demonstrates the complexity of hydrological feedback in Siberia to the
Arctic Ampli:cation (AA). The adverse impacts of AA have been and will
remain the greatest for the health and socioeconomic of people living in
the Pan-Arctic and the geopolitics and macroeconomics of the global
society.