Institute of Tibetan Plateau Research of the Chinese Academy of Sciences scientists showed that global warming has suppressed shrub recruitment in Greenland and Tibetan Plateau. The study has been published in PNAS.
Researchers assumed that warming-triggered tipping points related to cold biomes are very likely to occur in the Arctic Region. This includes Greenland and alpine regions in the Tibetan Plateau. These two regions are characterized by similar cold-adapted shrubs.
Shrub recruitment is a highly sensitive indicator of climate and environmental change. Shrub recruitment is a key component of vegetation dynamics beyond forests. It can perform as an indicator of the tipping point of cold biomes.
The researchers from ITP/CAS, University of Arizona, Instituto Pirenaico de Ecología and University of Cambridge have used two long-term shrub recruitment datasets of 2,770 samples from the Tibetan Plateau and Greenland. The samples dated back to 1871 to identify trends in shrub recruitment.
The study proves that the shrub recruitment time series well captured the tipping points in some Arctic and Tibetan shrub communities. In Greenland and the Tibetan Plateau, shrub recruitment reached tipping points around 1961–1970 and 1930–1940. Shrub recruitment has been steadily declining, since then.
This decline is related to warmer and drier climates across the Tibetan Plateau and Greenland. It is associated with a stronger summer El Niño Southern Oscillation and Atlantic Multidecadal Oscillation.
The study shows that the optimal climate for shrub recruitment has already passed in two remote and ecologically important cold regions. This offered an early warning signal of a phase shift in shrub communities. Scientists want to further understand the effects of warming on shrub-dominated cold biomes. So, they need more datasets to show changes in shrub recruitment over a longer time scale.