Methane emissions associated with the conversion of marshland to cropland and climate change on the Sanjiang Plain of northeast China from 1950 to 2100 1State Key Laboratory of Atmospheric Boundary Layer Physics and Atmospheric Chemistry, Institute of Atmospheric Physics, Chinese Academy of Sciences, Beijing 100029, China
18 Dec 2012
2The State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China
Received: 17 Mar 2012 – Published in Biogeosciences Discuss.: 24 May 2012 Abstract. Wetland loss and climate change are known to alter regional and global
methane (CH4) budgets. Over the last six decades, an extensive area of
marshland has been converted to cropland on the Sanjiang Plain in northeast
China, and a significant increase in air temperature has also been observed
there, while the impacts on regional CH4 budgets remain uncertain.
Through model simulation, we estimated the changes in CH4 emissions
associated with the conversion of marshland to cropland and climate change
in this area. Model simulations indicated a significant reduction of 1.1 Tg yr−1
(0.7–1.8 Tg yr−1) from the 1950s to the 2000s in regional
CH4 emissions. The cumulative reduction of CH4 from 1960 to 2009
was estimated to be ~36 Tg (24–57 Tg) relative to the 1950s,
and marshland conversion and the climate contributed 86% and 14% of
this change, respectively. Interannual variation in precipitation (linear
trend with P > 0.2) contributed to yearly fluctuations in CH4
emissions, but the relatively lower amount of precipitation over the period
1960–2009 (47 mm yr−1 lower on average than in the 1950s) contributed
~91% of the reduction in the area-weighted CH4 flux.
Global warming at a rate of 0.3 ° per decade (P < 0.001) has
increased CH4 emissions significantly since the 1990s. Relative to the
mean of the 1950s, the warming-induced increase in the CH4 flux has
averaged 19 kg ha−1 yr−1 over the last two decades. In the RCP
(Representative Concentration Pathway)
2.6, RCP 4.5, RCP 6.0 and RCP 8.5 scenarios of the fifth IPCC assessment
report (AR5), the CH4 fluxes are predicted to increase by 36%,
52%, 78% and 95%, respectively, by the 2080s compared to 1961–1990
in response to climate warming and wetting.
Revised: 07 Nov 2012 – Accepted: 21 Nov 2012 – Published: 18 Dec 2012
Citation: Li, T., Huang, Y., Zhang, W., and Yu, Y.-Q.: Methane emissions associated with the conversion of marshland to cropland and climate change on the Sanjiang Plain of northeast China from 1950 to 2100, Biogeosciences, 9, 5199-5215, doi:10.5194/bg-9-5199-2012, 2012.