The degree to which warming of the planet will alter Asia's water resources is an important question for food, energy, and economic security. Here we present geological evidence, underpinned by radiometric dating and dendrochronology, and bolstered by hydrological modeling, indicating that wetter-than-present conditions characterized the core of the inner Asian desert belt during the Little Ice Age, the last major Northern Hemispheric cold spell of the Holocene. These wetter conditions accompanied northern mid-latitude cooling, glacier expansion, a strengthened/southward-shifted boreal jet, and weakened south Asian monsoons. We suggest that southward migration of grasslands in response to these wetter conditions aided the spread of Mongol Empire steppe pastoralists across Asian drylands. Conversely, net drying over the 20th century has led to drought that is unprecedented for the past ~830 years, and that could intensify with further heating of the Asian continent.
Bibliographical noteFunding Information:
We are grateful to the Comer Science and Education Foundation (CSEF), the Quesada Family Fund , and the Lamont Climate Center for support. Putnam received generous support from a Lamont-Doherty Earth Observatory Research Professorship, the Lenfest Foundation, and the CSEF. We thank Zhisheng An, Weijian Zhou, and Minlu Fu for generous support in China. John Chiang, David Battisti, and Tanzhuo Liu, provided helpful insights into the hydroclimate dynamics of Asia. We thank Chris Atwood for constructive discussions about the history of the Mongol Empire. Tanzhuo Liu and Beizhan Yan assisted with translations. Yanbin Lu, Zhenkun Wu, Fred Quesada, and Hayley, Peter, and Kerri Wolcott assisted with fieldwork. William Fitzhugh and an anonymous reviewer provided insightful comments that led to an improved paper. This is LDEO contribution #7943.
- Asian hydroclimate
- Asian monsoon
- Lop nor
- Mountain glacier
- Taklamakan desert
- Tarim basin