Abstract

Both anthropogenic activities and climate change can affect the biogeochemical processes of natural wetland methanogenesis. Quantifying possible impacts of changing climate and wetland area on wetland methane (CH4) emissions in China is important for improving our knowledge on CH4 budgets locally and globally. However, their respective and combined effects are uncertain. We incorporated changes in wetland area derived from remote sensing into a dynamic CH4 model to quantify the human and climate change induced contributions to natural wetland CH4 emissions in China over the past three decades. Here we found that human-induced wetland loss contributed 34.3% to the CH4 emissions reduction (0.92 TgCH4), and climate change contributed 20.4% to the CH4 emissions increase (0.31 TgCH4), suggesting that decreasing CH4 emissions due to human-induced wetland reductions has offset the increasing climate-driven CH4 emissions. With climate change only, temperature was a dominant controlling factor for wetland CH4 emissions in the northeast (high latitude) and Qinghai-Tibet Plateau (high altitude) regions, whereas precipitation had a considerable influence in relative arid north China. The inevitable uncertainties caused by the asynchronous for different regions or periods due to inter-annual or seasonal variations among remote sensing images should be considered in the wetland CH4 emissions estimation.

Highlights

  • Variation in wetland CH4 emissions has been considered as a dominant factor in explaining the fluctuations in the atmospheric CH4 concentrations over the past two decades[4,5,10]

  • The inventory method does not reflect the spatial heterogeneity in regional wetland CH4 emissions and the effects of wetland area dynamics

  • As a result of a substantial wetland loss occurred between 1990 and 2000, in the Northeast region (NE) region, the wetland CH4 emissions in China significantly decreased during this period

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Summary

Introduction

Variation in wetland CH4 emissions has been considered as a dominant factor in explaining the fluctuations in the atmospheric CH4 concentrations over the past two decades[4,5,10]. Remote sensing data have been used to derive global inundated areas and wetland distributions[16,17,18] and to investigate the effects of changes wetland area on CH4 emissions[19]. Over the past three decades, a number of studies on CH4 emissions from natural wetlands in China have been conducted, but the estimation of wetland CH4 emissions through site-based measurement extrapolation is still preliminary due to the coarse data of wetland areas and distributions[20,21,22,23]. Based on remotely sensed wetland dynamics information (four periods: 1978, 1990, 2000, and 2008)[24], we used the process-based model of TRIPLEX-GHG with a full description of wetland CH4 emission processes[25,26] to quantify the effects of changing climate and wetland area on the regional CH4 budget in China

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