Geo-biosphere Interactions Across the Tibetan Plateau In Response to Climate Change

The high-elevation Tibetan Plateau encompasses ~2.5 million km³ and represents a major orographic barrier that influences global atmospheric circulation. Precipitation and glacier melt in the mountain regions surrounding the plateau are a water resource for more than 1.4 billion people. Over the Cenozoic, the rise of the plateau surface induced dramatic regional changes in the atmosphere, biosphere, cryosphere, and hydrosphere. Present-day global warming has significantly impacted the interactions between these different spheres in ways we are only beginning to understand.

This presentation investigates how past and present climate change have impacted the Plateau’s permafrost, hydrology, and ecosystems. This is done using atmospheric general circulation models and a compilation of existing climate, hydrologic, cryosphere, biosphere, and geologic studies documenting environmental change from decadal and glacial-interglacial timescales back to the middle Miocene. Results indicate that warmer and wetter periods in the geologic past led to a flourishing of plateau ecosystems. However, recent anthropogenic-induced warming and wetting of the plateau have led to the opposite effect and degradation of many plateau ecosystems in former permafrost environments.  This contrast in environmental ‘health’ between the geologic past and the present day is interpreted to result from anthropogenic disturbances of plateau environments via changes in grazing practices.

Looking towards the future, two pathways are identified that could lead to either favourable greening or unfavourable degradation and desiccation of plateau ecosystems. Both paths are plausible, given the available evidence. The key to which environmental pathway future generations experience lies in what if any, human intervention measures and management strategies are implemented.

Related references:

Ehlers, T. A., Chen, D., Appel, E., Bolch, T., Chen, F., Diekmann, B., Dippold, M. A., Giese, M., Guggenberger, G., Lai, H.-W., Li, X., Liu, J., Liu, Y., Ma, Y., Miehe, G., Mosbrugger, V., Mulch, A., Piao, S., Schwalb, A., Thompson, L. G., Su, Z., Sun, H., Yao, T., Yang, X., Yang, K., and Zhu, L.: Past, present, and future geo-biosphere interactions on the Tibetan Plateau and implications for permafrost, Earth-Science Reviews, 234, 104197, https://doi.org/10.1016/j.earscirev.2022.104197, 2022.

Li, J., Ehlers, T. A., Werner, M., Mutz, S. G., Steger, C., and Paeth, H.: Late quaternary climate, precipitation δ18O, and Indian monsoon variations over the Tibetan Plateau, Earth and Planetary Science Letters, 457, 412–422, https://doi.org/10.1016/j.epsl.2016.09.031, 2017.

Mutz, S. G., Ehlers, T. A., Werner, M., Lohmann, G., Stepanek, C., and Li, J.: Estimates of late Cenozoic climate change relevant to Earth surface processes in tectonically active orogens, Earth Surface Dynamics, 6, 271–301, https://doi.org/10.5194/esurf-6-271-2018, 2018.