title: Weakening of annual temperature cycle over the Tibetan Plateau since the 1870s.
abstract: The annual cycle of extra-tropical surface air temperature is an important component of the Earth's climate system. Over the past decades, a reduced amplitude of this mode has been observed in some regions. Although attributed to anthropogenic forcing, it remains unclear when dampening of the annual cycle started. Here we use a residual series of tree-ring width and maximum latewood density from the Tibetan Plateau >4,000 m asl to reconstruct changes in temperature seasonality over the past three centuries. The new proxy evidence suggests that the onset of a decrease in summer-to-winter temperature difference over the Tibetan Plateau occurred in the 1870s. Our results imply that the influence of anthropogenic forcing on temperature seasonality might have started in the late nineteenth century, and that future human influence may further contribute to a weakening of the annual temperature cycle, with subsequent effects on ecosystem functioning and productivity.
authors.affiliation: State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, 100093 Beijing, China.|Department of Geography, Justus Liebig University of Giessen, 35390 Giessen, Germany.
authors.forename: Jianping
authors.initials: J
authors.lastname: Duan
authors.affiliation: Department of Geography, Johannes Gutenberg University, 55099 Mainz, Germany.
authors.forename: Jan
authors.initials: J
authors.lastname: Esper
authors.affiliation: Swiss Federal Research Institute WSL, 8903 Birmensdorf, Switzerland.|Oeschger Centre for Climate Change Research, CH-3012 Bern, Switzerland.|Global Change Research Centre and Masaryk University, 61300 Brno, Czech Republic.
authors.forename: Ulf
authors.initials: U
authors.lastname: Büntgen
authors.affiliation: Chinese Academy of Meteorological Sciences, 100081 Beijing, China.
authors.forename: Lun
authors.initials: L
authors.lastname: Li
authors.affiliation: Department of Geography, Justus Liebig University of Giessen, 35390 Giessen, Germany.
authors.forename: Elena
authors.initials: E
authors.lastname: Xoplaki
authors.affiliation: Department of Geography, Justus Liebig University of Giessen, 35390 Giessen, Germany.
authors.forename: Huan
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, 100101 Beijing, China.
authors.forename: Lily
authors.initials: L
authors.lastname: Wang
authors.affiliation: National Climate Center, China Meteorological Administration, 100081 Beijing, China.
authors.forename: Yongjie
authors.initials: Y
authors.lastname: Fang
authors.affiliation: Department of Geography, Justus Liebig University of Giessen, 35390 Giessen, Germany.|Centre of International Development and Environmental Research, Justus Liebig University of Giessen, 35390 Giessen, Germany.
authors.forename: Jürg
authors.initials: J
authors.lastname: Luterbacher