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

<p>The ALBM model simulation data can be found in RCP4.5.zip and RCP8.5.zip. The lake information can be found in Lakefile.zip which is necessary for data analysis. File codes.zip contains the R and Matlab codes used to process raw model output, analysis processed data and make plots.</p>

<p>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<sub>4</sub> yr<sup>-1</sup> 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.</p>