Synergy between nutrients and warming enhances methane ebullition from experimental lakes

Abstract

Lakes and ponds are important natural sources of the potent greenhouse gas methane (CH4), with small shallow waters identified as particular hotspots(1,2). Ebullition (bubbles) of CH4 makes up a large proportion of total CH4 flux(3,4). However, difficulty measuring such episodic events(5) makes prediction of how ebullition responds to nutrient enrichment and rising temperatures challenging. Here, the world's longest running, mesocosm-based, shallow lake climate change experiment was used to investigate how the combination of warming and eutrophication (that is, nutrient enrichment) affects CH4 ebullition. Eutrophication without heating increased the relative contribution of ebullition from 51% to 75%. More strikingly the combination of nutrient enrichment and experimental warming treatments of +2-3 degrees C and +4-5 degrees C had a synergistic effect, increasing mean annual ebullition by at least 1900 mg CH4-C m(-2) yr(-1). In contrast, diffusive flux showed no response to eutrophication and only a small increase at higher temperatures (average 63 mg CH4-C m(-2) yr(-1)). As shallow lakes are the most common lake type globally, abundant in highly climate sensitive regions(6) and most vulnerable to eutrophication, these results suggest their current and future contributions to atmospheric CH4 concentrations may be significantly underestimated.

Published in

Nature Climate Change
2018, volume: 8, number: 2, pages: 156-160
Publisher: NATURE PUBLISHING GROUP

SLU Authors

• Audet, Joachim

  • Department of Aquatic Sciences and Assessment, Swedish University of Agricultural Sciences
    
  • Aarhus University

Global goals (SDG)

SDG13 Climate action

UKÄ Subject classification

Climate Research

Publication identifier

• DOI: https://doi.org/10.1038/s41558-017-0063-z

Permanent link to this page (URI)

https://res.slu.se/id/publ/93844