Climate change on the northeastern Tibetan Plateau during the past ~ 600 years inferred from peat pollen records

Abstract

A 600-year high-resolution pollen record from a peat core (FS-2010) on the Zoigê Plateau was obtained to reconstruct vegetation and climate changes on the northeastern Tibetan Plateau. Surface pollen data reveal that vegetation differences are reflected in different modern pollen assemblages. Fossil pollen data indicate that alpine meadow was the dominant vegetation type on the Zoigê Plateau during the Little Ice Age (LIA) from ~1400 to ~1900 AD. Pollen-based climatic reconstructions indicate climatic fluctuations during this period consistent with records from neighboring areas. Specifically, relatively “warm-wet” conditions persisted from ~1400 to ~1500 AD and ~1800 to ~1900 AD, but generally “cool-dry” conditions from ~1500 to ~1800 AD. The reconstructed temperature variations during the LIA (i.e., ~1400 to ~1900 AD) were attributed to variations in total solar irradiation. This study casts further doubt on the FG/MG (subalpine forest and shrub group/alpine meadow group) ratio as a reliable indicator of temperature reduction during the Current Warm Period (CWP; post ~1900 AD) due to significant anthropogenic impacts including deforestation and swamp drainage. The reconstructed patterns of precipitation in the Zoigê Plateau including Flower Swamp are shown to be contingent on variations in the strength of the Asian Monsoon.