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

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.

Declining greenness in Arctic-boreal lakes

“…The continental-scale shifts in lake greenness, and their links to large-scale climatic changes, are not necessarily surprising, since temperature and precipitation patterns have been shown to shape other lake properties, such as dissolved organic carbon concentrations ( 94 ) and patterns of greenhouse gas (GHG) emissions ( 95 ). Yet our observations have several important implications for water quality, primary productivity, and GHG emissions.…”

“…Also, stronger stratification in deeper lakes may starve pelagic phytoplankton of nutrients, causing reduced primary production ( 113 ). However, large lakes comprise only ∼1% of the lakes in this study and are likely to already be contributing less methane due to greater methane oxidation in the water column and lower sediment organic substrate availability ( 95 ).…”

Validation and Sensitivity Analysis of a 1‐D Lake Model Across Global Lakes

“…Based on previous studies using ALBM (Guo, Zhuang, Tan, et al, 2020;Tan et al, 2015Tan et al, , 2017, we calibrated nine parameters related to lake sediment properties (solid particle thermal conductivity, k s ; solid particle heat capacity, c ps ; sediment porosity, pi; solid particle density, ρ s ), radiative transfer (light extinction coefficient, feta), turbulent heat and momentum fluxes (wind shielding factor, wstr; turbulence diffusivity scaling factor, ktscale; bulk heat transfer factor, hwt), and snow density (ρ n ), respectively. Detailed explanation and value ranges for each parameter can be found in Table 1.…”

“…Therefore, it is of great scientific and societal importance to understand the historical and future climate change impacts on lakes and modeling is a powerful tool. Moreover, accurate modeling of lake thermodynamic properties and processes is essential for simulating lake carbon dynamics, such as CO 2 and CH 4 emissions, of which lakes have been identified as an important source (Bastviken et al., 2011; Guo, Zhuang, Tan, et al., 2020; Prairie et al., 2013; Saunois et al., 2016; Tan & Zhuang, 2015a, 2015b).…”

Arctic-Boreal Lake Phenology Shows a Relationship between Earlier Lake Ice-Out and Later Green-Up

“…Paleolimnological records from the Siberian Arctic verified that warmer, ice-free summer conditions were linked to the intensified aquatic primary productivity [14] and earlier ice-out with recent warming has been linked to earlier phytoplankton blooms and an earlier season start [15]. Arctic and boreal lakes are key players in global carbon cycles, and changes in the onset and duration of the ice-free growing period could alter their net contributions to carbon fluxes [16]. However, other studies show that impacts of climate on lake productivity are community-specific [17], and the relative influence of catchment versus climate processes on lake productivity remain an active area of research [18].…”