CO₂ evasion from boreal lakes: Revised estimate, drivers of spatial variability, and future projections

Abstract

Lakes (including reservoirs) are an important component of the global carbon (C) cycle, as acknowledged by the fifth assessment report of the IPCC. In the context of lakes, the boreal region is disproportionately important contributing to 27% of the worldwide lake area, despite representing just 14% of global land surface area. In this study, we used a statistical approach to derive a prediction equation for the partial pressure of CO (pCO ) in lakes as a function of lake area, terrestrial net primary productivity (NPP), and precipitation (r = .56), and to create the first high-resolution, circumboreal map (0.5°) of lake pCO . The map of pCO was combined with lake area from the recently published GLOWABO database and three different estimates of the gas transfer velocity k to produce a resulting map of CO evasion (FCO ). For the boreal region, we estimate an average, lake area weighted, pCO of 966 (678-1,325) μatm and a total FCO of 189 (74-347) Tg C year , and evaluate the corresponding uncertainties based on Monte Carlo simulation. Our estimate of FCO is approximately twofold greater than previous estimates, as a result of methodological and data source differences. We use our results along with published estimates of the other C fluxes through inland waters to derive a C budget for the boreal region, and find that FCO from lakes is the most significant flux of the land-ocean aquatic continuum, and of a similar magnitude as emissions from forest fires. Using the model and applying it to spatially resolved projections of terrestrial NPP and precipitation while keeping everything else constant, we predict a 107% increase in boreal lake FCO under emission scenario RCP8.5 by 2100. Our projections are largely driven by increases in terrestrial NPP over the same period, showing the very close connection between the terrestrial and aquatic C cycle.

The Net Landscape Carbon Balance—Integrating terrestrial and aquatic carbon fluxes in a managed boreal forest landscape in Sweden

“…Boreal mires are commonly net CO 2 sinks (Nilsson et al, 2008;Peichl, Öquist, et al, 2014), but in contrast to forests, they act as net sources of CH 4 (Abdalla et al, 2016;Nilsson et al, 2001Nilsson et al, , 2008. In addition, lakes and streams are significant CO 2 and CH 4 sources in the boreal region (e.g., Hastie et al, 2017;Wik, Varner, Anthony, Macintyre, & Bastviken, 2016). Consequently, the overall landscape-atmosphere exchange of GHGs is strongly dependent on these sink and source components within the boreal forest landscape.…”

Arctic‐Boreal Lake Dynamics Revealed Using CubeSat Imagery

“…Their areal extents fluctuate seasonally and interannually in response to regional water balance, fluvial inundation, and surface-groundwater interactions. Furthermore, because Arctic-Boreal lakes are net sources of CO 2 and CH 4 (Hastie et al, 2018), fluctuations in lake area impact freshwater trace gas emissions to the atmosphere (Bastviken et al, 2011;Raymond et al, 2013). Furthermore, because Arctic-Boreal lakes are net sources of CO 2 and CH 4 (Hastie et al, 2018), fluctuations in lake area impact freshwater trace gas emissions to the atmosphere (Bastviken et al, 2011;Raymond et al, 2013).…”

Where does the river end? Drivers of spatiotemporal variability in CO2 concentration and flux in the inflow area of a large boreal lake

“…A lot of scientific effort has been dedicated to CO 2 flux dynamics in boreal aquatic ecosystems (Rantakari and Kortelainen ; Einola et al ; Teodoru et al ; Weyhenmeyer et al ; Denfeld et al ). The boreal forest region is considered as one of the most important carbon (C) sinks on land; however, the high density of inland waters in this landscape counteracts this terrestrial C sink (Intergovernmental Panel on Climate Change [IPCC] ; Verpoorter et al ; Lauerwald et al ; Hastie et al ). A large source of uncertainty in CO 2 emission from these systems arises from the period of ice‐melt in spring and early summer.…”