Modeling the carbon dynamics of terrestrial ecosystems in Northern Eurasia during the 21st century

Zhiwei Zhang, Purdue University

Abstract

Global warming concerns our society, and one of the most challenging scientific questions is specifically how the global climate will change. Greenhouse gases (e.g., CO2 & CH4) have been recognized as playing a significant role in climate change. In order to analyze climate change, it is important to know what carbon fluxes and pool sizes are now, and how they are going to change in the future. In this project, I use a process-based biogeochemical model, the Terrestrial Ecosystem Model (TEM) to quantify the major greenhouse gas (CO2 & CH4) exchanges in the region of Northern Eurasia in the late 20th (1970-2000) and 21st century. I use a 31-year historical climate dataset from 1970 to 2000, and also data from six MIT Integrated Global System Modeling Framework (MIT-IGSM) simulation climate scenarios and four Intergovernmental Panel on Climate Change (IPCC) SRES simulation climate scenarios from 2001 to 2100 to examine carbon changes (CO2 & CH4) in this region. I compare these ten simulation scenarios through a sensitivity and uncertainty analysis. For the late 20th century, the terrestrial ecosystems in this region are estimated to emit CH4 at a rate of 22 Tg CH4 yr-1 (1 Tg = 1012g), while the net sink of CO2 is about 0.09 Pg C yr-1 (1 Pg = 1015g). The region, therefore, is estimated to emit 0.22 Pg CO2 equivalent greenhouse gases into the atmosphere, given the assumption that a greenhouse effect of 1 g CH4 is equivalent to that of 25 g CO2 on a weight basis. Large discrepancies in model estimations are found for different climate change scenarios in the 21st century. Greenhouse gas emissions in the region are predicted to increase up to 58 Tg CH 4 yr-1 and 3 Pg CO2 yr-1 by the end of 21st century. I also find that, under the IPCC A1FI scenario, the region has the largest emissions of these greenhouse gases, and becomes a carbon source, while the IPCCB1 scenario provides the most conservative estimates relative to the other scenarios.

Degree

M.S.

Advisors

Zhuang, Purdue University.

Subject Area

Ecology|Environmental science

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