The uncertain climate footprint of wetlands under human pressure

Last modified: 
August 30, 2016 - 8:45am
Type: Journal Article
Year of publication: 2015
Date published: 04/2015
Authors: Ana Petrescu, Annalea Lohila, Juha-Pekka Tuovinen, Dennis Baldocchi, Ankur Desai, Nigel Roulet, Timo Vesala, Albertus Dolman, Walter Oechel, Barbara Marcolla, Thomas Friborg, Janne Rinne, Jaclyn Matthes, Lutz Merbold, Ana Meijide, Gerard Kiely, Matteo Sottocornola, Torsten Sachs, Donatella Zona, Andrej Varlagin, Derrick Lai, Elmar Veenendaal, Frans-Jan Parmentier, Ute Skiba, Magnus Lund, Arjan Hensen, Jacobus van Huissteden, Lawrence Flanagan, Narasinha Shurpali, Thomas Grünwald, Elyn Humphreys, Marcin Jackowicz-Korczyński, Mika Aurela, Tuomas Laurila, Carsten Grüning, Chiara Corradi, Arina Schrier-Uijl, Torben Christensen, Mikkel Tamstorf, Mikhail Mastepanov, Pertti Martikainen, Shashi Verma, Christian Bernhofer, Alessandro Cescatti
Journal title: Proceedings of the National Academy of Sciences
Volume: 112
Issue: 15
Pages: 4594 - 4599
ISSN: 0027-8424

Significant climate risks are associated with a positive carbon–temperature feedback in northern latitude carbon-rich ecosystems, making an accurate analysis of human impacts on the net greenhouse gas balance of wetlands a priority. Here, we provide a coherent assessment of the climate footprint of a network of wetland sites based on simultaneous and quasi-continuous ecosystem observations of CO2 and CH4 fluxes. Experimental areas are located both in natural and in managed wetlands and cover a wide range of climatic regions, ecosystem types, and management practices. Based on direct observations we predict that sustained CH4 emissions in natural ecosystems are in the long term (i.e., several centuries) typically offset by CO2 uptake, although with large spatiotemporal variability. Using a space-for-time analogy across ecological and climatic gradients, we represent the chronosequence from natural to managed conditions to quantify the “cost” of CH4 emissions for the benefit of net carbon sequestration. With a sustained pulse–response radiative forcing model, we found a significant increase in atmospheric forcing due to land management, in particular for wetland converted to cropland. Our results quantify the role of human activities on the climate footprint of northern wetlands and call for development of active mitigation strategies for managed wetlands and new guidelines of the Intergovernmental Panel on Climate Change (IPCC) accounting for both sustained CH4 emissions and cumulative CO2 exchange.

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