(2016a), who measured emission-line lags in the H and Mgii emission lines in 15 of the brightest, relatively low-redshift sources in our sample using the rst year of SDSS-RM spectroscopy alone (i.e., no photometric data were used).Li et al. (2017) also measured composite RM lags using a low-luminosity subset and the rst year of spectroscopy. Image credit: Grier et al. (2017) Based on the first year of data, we measured black hole masses for 44 quasars. These quasars are much farther away than most of the other active galaxies that have been reverberation-mapped. This is the largest sample of measurements ever to be done at once.
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Abstract
The IPCC 2013 Wetlands Supplement provided new guidance for countries on inclusion of wetlands in their National GHG Inventories. The United States has responded by including managed coastal wetlands for the first time in its 2017 GHG Inventory report along with an updated time series in the most recent 2018 submission and plans to update the time series on an annual basis as part of its yearly submission to the United Nations Framework Convention on Climate Change (UNFCCC). The United States followed IPCC Good Practice Guidance when reporting sources and sinks associated with managed coastal wetlands. Here we show that intact vegetated coastal wetlands are a net sink for GHGs. Despite robust regulation that has protected substantial stocks of carbon, the United States continues to lose coastal wetlands to development and the largest loss of wetlands to open water occurs around the Mississippi Delta due mostly to upstream changes in hydrology and sediment delivery, and oil and gas extraction. These processes create GHG emissions. By applying comprehensive Inventory reporting, scientists in the United States have identified opportunities for reducing GHG emissions through restoration of coastal wetlands that also provide many important societal co-benefits.
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Data availability
Some of the data that informed this analysis are included in the US Greenhouse Gas Inventory (see previously published studies5,6). Other data can be made available upon request to the corresponding author (S.C.).
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Acknowledgements
We are grateful to the Coastal Blue Carbon Working Group, Restore America’s Estuaries, the NOAA, the USGCRP and the EPA for support and technical input as part of this process. This is contribution number 9 of the Sea Level Solutions Center at the Institute of Water and Environment, Florida International University.
Competing interests
The authors declare no competing interests.
Author information
S.C. and T.G.T. led the process for including coastal wetlands in the US Greenhouse Gas Inventory with technical input from T.W. and with help from A.E.S.-G., N.H., B.B. and L.S.-B. S.C., A.E.S.-G. and T.G.T. wrote this manuscript with help from T.W.
Correspondence to Stephen Crooks.
Supplementary information
Supplementary Information
Supplementary Discussion, Supplementary Tables 1–2, Supplementary References
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