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Rising methane emissions from boreal lakes due to increasing ice-free days

2020; IOP Publishing; Volume: 15; Issue: 6 Linguagem: Inglês

10.1088/1748-9326/ab8254

1748-9326

Mingyang Guo, Qianlai Zhuang, Zeli Tan, Narasinha Shurpali, Sari Juutinen, Pirkko Kortelainen, Pertti J. Martikainen,

Climate change and permafrost

Abstract Lakes account for about 10% of the boreal landscape and are responsible for approximately 30% of biogenic methane emissions that have been found to increase under changing climate. However, the quantification of this climate-sensitive methane source is fraught with large uncertainty under warming climate conditions. Only a few studies have addressed the mechanism of climate impact on the increase of northern lake methane emissions. This study uses a large observational dataset of lake methane concentrations in Finland to constrain methane emissions with an extant process-based lake biogeochemical model. We found that the total current diffusive emission from Finnish lakes is 0.12 ± 0.03 Tg CH 4 yr −1 and will increase by 26%–59% by the end of this century depending on different warming scenarios. We discover that while warming lake water and sediment temperature plays an important role, the climate impact on ice-on periods is a key indicator of future emissions. We conclude that these boreal lakes remain a significant methane source under the warming climate within this century.