Research Interests

My research interests cover broad areas in present, past and planetary climates. We aim at studying fundamental and frontier problems of Earth and planetary climates. My philosophy is to treat the Earth climate as an integrated and dynamic system, which receives energy from solar radiation, dynamically evolves throughout fluid motions, and involves the interplay of the atmosphere and ocean with the interior of Earth. My approach to these problems is to combine observational data analyses, numerical simulations, and theoretical studies.

Present-day Climate

we focus on anthropogenic influences on the climate system. Specifically, we are interested in how changes in atmospheric compositions due to anthropogenic activity, such as greenhouse gases and stratospheric ozone, alter atmospheric thermal structures, lead to changes in atmospheric and oceanic circulations, and consequently cause global and regional climate changes.

The Hadley circulation is one of the most important atmospheric circulations. Its changes in strength and width have crucial impacts on redistribution of global energy and the hydrological cycle. Our series of works demonstrated that the Hadley circulation has undergone widening and weakening in the past few decades, due to global warming. The mechanism is that increasing greenhouse gases cause changes in vertical and horizontal temperature gradients, result in enhanced atmospheric stratification and weakened wave activity, and lead to the weakening and widening of the Hadley circulation. Associated with the widening of the Hadley circulation is poleward shifts of the subtropical dry zones, which impacts on human living environment, agriculture, and ecosystems in the adjacent extratropics.

Ozone depletion and recovery have been of great concerns by academic and public communities in the past few decades. The ozone layer not only absorbs utralviolet radiation but also has significant influences in tropospheric and surface climates. Therefore, studying ozone depletion and recovery and its climate effects has long been one of our research directions.  

Paleoclimate

We have great enthusiasms in deep-time climate evolution. Earth’s climate had experienced alternating hothouse and icehouse intervals in its 4.6 billion year history. Studying deep-time climate changes not only benefits reconstructing climate and life evolution in the past, but also helps our fundamental understanding the ongoing climate change at present.

Our research in paleoclimate has a wide span of the past, from the “Boring Billion” in the Mesoproterozoic, to the “Snowball Earth” in the Neoproterozoic, and to climate evolution of the Phanerozoic. We are interested in the mechanisms of climate evolution, especially the coupling of Earth’s different spheres and its implications to life evolution. In the recent few years, we focused simulating climates of the Phanerozoic, including changes of the global and regional monsoon system and continental evolution, deep-time hydrological cycle, atmospheric and oceanic circulations, plant evolution, marine biogeochemistry, weathering reactions, glacier-climate coupling, and quantitative relationships of geological proxies with climate conditions. We aim at a comprehensive understanding of the fundamental principle of the co-variations of the climate system, life, and coupling of different spheres.

Planetary Climate

Viewing Earth as a planet, we would be surprised how Earth has maintained its habitable environment, whereas Mars and Venus are uninhabitable. There is evidence showing that both Mars and Venus could have oceans in their early past. If so, Venus had experienced runaway greenhouse gas, and Mars had gone runaway freezing. Therefore, studying planetary climates and their habitability benefit our understanding Earth climate evolution.

Searching for Earth-like planets and extraterrestrial life has long been a great dream of Human Beings since the civilization. Our research in planetary climates and habitability includes planets of both the solar system and extra-solar planets. We extend our knowledge of Earth climate to studying planetary climate. We have done systematic simulations of planetary climates. These results provide the theoretical base for searching for habitable exoplanets.