Increasing evidence of an anthropogenic signal in drought variations on the river source areas of southeastern Tibetan Plateau

Although anthropogenic greenhouse gas emissions are widely regarded as the major cause of ongoing global climate change, isolating anthropogenic impacts on climate is difficult due to the internal variability of the climate system and the brevity of the observational record. Here we attempt to discern a human signal in recent climate change using a 400-year reconstruction of the self-calibrating Palmer Drought Severity Index for the southeastern Tibetan Plateau, where current warming is more pronounced than most other places. Our results highlight a trend towards progressively drier conditions, while the most recent drought and wetness events are ranked as the second most severe throughout the entire reconstruction. We conclude that anthropogenic influence on climate in this region, which is clearly detected at the end of the 20th century, will become stronger in the foreseeable future.