@article {2792,
	title = {The positive net radiative greenhouse gas forcing of increasing methane emissions from a thawing boreal forest-wetland landscape},
	journal = {Global Change Biology},
	year = {2016},
	abstract = {At the southern margin of permafrost in North America, climate change causes widespread permafrost thaw. In boreal lowlands, thawing forested permafrost peat plateaus ({\textquoteleft}forest{\textquoteright}) lead to expansion of permafrost-free wetlands ({\textquoteleft}wetland{\textquoteright}). Expanding wetland area with saturated and warmer organic soils is expected to increase landscape methane (CH4) emissions. Here, we quantify the thaw-induced increase in CH4\&nbsp;emissions for a boreal forest-wetland landscape in the southern Taiga Plains, Canada, and evaluate its impact on net radiative forcing relative to potential long-term net carbon dioxide (CO2) exchange. Using nested wetland and landscape eddy covariance net CH4\&nbsp;flux measurements in combination with flux footprint modeling, we find that landscape CH4\&nbsp;emissions increase with increasing wetland-to-forest ratio. Landscape CH4emissions are most sensitive to this ratio during peak emission periods, when wetland soils are up to 10\&nbsp;{\textdegree}C warmer than forest soils. The cumulative growing season (May{\textendash}October) wetland CH4emission of ~13\&nbsp;g CH4\&nbsp;m-2\&nbsp;is the dominating contribution to the landscape CH4\&nbsp;emission of ~7\&nbsp;g CH4\&nbsp;m-2. In contrast, forest contributions to landscape CH4\&nbsp;emissions appear to be negligible. The rapid wetland expansion of 0.26\&nbsp;{\textpm}\&nbsp;0.05\% yr-1\&nbsp;in this region causes an estimated growing season increase of 0.034\&nbsp;{\textpm}\&nbsp;0.007\&nbsp;g CH4\&nbsp;m-2\&nbsp;yr-1\&nbsp;in landscape CH4\&nbsp;emissions. A long-term net CO2\&nbsp;uptake of \&gt;200\&nbsp;g CO2\&nbsp;m-2\&nbsp;yr-1\&nbsp;is required to offset the positive radiative forcing of increasing CH4emissions until the end of the 21st century as indicated by an atmospheric CH4\&nbsp;and CO2concentration model. However, long-term apparent carbon accumulation rates in similar boreal forest-wetland landscapes and eddy covariance landscape net CO2\&nbsp;flux measurements suggest a long-term net CO2\&nbsp;uptake between 49 and 157\&nbsp;g CO2\&nbsp;m-2\&nbsp;yr-1. Thus, thaw-induced CH4\&nbsp;emission increases likely exert a positive net radiative greenhouse gas forcing through the 21st century.},
	url = {http://onlinelibrary.wiley.com/doi/10.1111/gcb.13520/full},
	author = {Helbig, M and Chasmer, L and Kljun, N. and Quinton, W. and Treat, C. and O. Sonnentag}
}
