Articles | Volume 8, issue 4
Clim. Past, 8, 1323–1337, 2012
Clim. Past, 8, 1323–1337, 2012

Research article 23 Aug 2012

Research article | 23 Aug 2012

Drastic shrinking of the Hadley circulation during the mid-Cretaceous Supergreenhouse

H. Hasegawa1,2,*, R. Tada1, X. Jiang3, Y. Suganuma1,4, S. Imsamut5, P. Charusiri6, N. Ichinnorov7, and Y. Khand7 H. Hasegawa et al.
  • 1Department of Earth and Planetary Science, the University of Tokyo, Tokyo 113-0033, Japan
  • 2Department of Natural History Science, Hokkaido University, Sapporo 060-0810, Japan
  • 3Chengdu Institute of Geology and Mineral Resources, Chengdu 610082, China
  • 4National Institute of Polar Research, Tokyo 190-8518, Japan
  • 5Department of Mineral Resources, Bureau of Geological Survey, Bangkok 10400, Thailand
  • 6Department of Geology, Chulalongkorn University, Bangkok 10330, Thailand
  • 7Paleontological Center, Mongolian Academy of Sciences, Ulaanbaatar 210351, Mongolia
  • *now at: Nagoya University Museum, Nagoya 464-8601, Japan

Abstract. Understanding the behavior of the global climate system during extremely warm periods is one of the major themes of paleoclimatology. Proxy data demonstrate that the equator-to-pole temperature gradient was much lower during the mid-Cretaceous "supergreenhouse" period than at present, implying larger meridional heat transport by atmospheric and/or oceanic circulation. However, reconstructions of atmospheric circulation during the Cretaceous have been hampered by a lack of appropriate datasets based on reliable proxies. Desert distribution directly reflects the position of the subtropical high-pressure belt, and the prevailing surface-wind pattern preserved in desert deposits reveals the exact position of its divergence axis, which marks the poleward margin of the Hadley circulation. We reconstructed temporal changes in the latitude of the subtropical high-pressure belt and its divergence axis during the Cretaceous based on spatio-temporal changes in the latitudinal distribution of deserts and prevailing surface-wind patterns in the Asian interior. We found a poleward shift in the subtropical high-pressure belt during the early and late Cretaceous, suggesting a poleward expansion of the Hadley circulation. In contrast, an equatorward shift of the belt was found during the mid-Cretaceous "supergreenhouse" period, suggesting drastic shrinking of the Hadley circulation. These results, in conjunction with recent observations, suggest the existence of a threshold in atmospheric CO2 level and/or global temperature, beyond which the Hadley circulation shrinks drastically.