Simulated methane emissions from Arctic ponds are highly sensitive to warming

Abstract

Abstract. The Arctic is warming at an above-average rate, and small, shallow waterbodies such as ponds are vulnerable to this warming due to their low thermal inertia compared to larger lakes. While ponds are a relevant landscape-scale source of methane under the current climate, the response of pond methane emissions to warming is uncertain. We employ a new, process-based model for methane emissions from ponds (MeEP) to investigate the methane emission response of polygonal-tundra ponds in northeastern Siberia to warming. MeEP is the first dedicated model of pond methane emissions which differentiates between the three main pond types of the polygonal-tundra, ice-wedge, polygonal-center, and merged polygonal ponds and resolves the three main pathways of methane emissions – diffusion, ebullition, and plant-mediated transport. We perform idealized warming experiments, with increases in the mean annual temperature of 2.5, 5, and 7.5 ∘C on top of a historical simulation. The simulations reveal an approximately linear increase in emissions from ponds of 1.33 g CH4 yr−1 ∘C−1 m−2 in this temperature range. Under annual temperatures 5 ∘C above present temperatures, pond methane emissions are more than 3 times higher than now. Most of this emission increase is due to the additional substrate provided by the increased net productivity of the vascular plants. Furthermore, plant-mediated transport is the dominating pathway of methane emissions in all simulations. We conclude that vascular plants as a substrate source and efficient methane pathway should be included in future pan-Arctic assessments of pond methane emissions.

Assessing methane emissions from paddy fields through environmental and UAV remote sensing variables

“…Additionally, we leveraged GDD as an agroclimatic measure to gauge the growth impact and calculate CH4 emissions. The significance of GDD in predicting CH4 emissions has been underscored by previous studies (Rehder et al, 2023;Rößger et al, 2022), given its direct influence on methanogenesis activity (Stams et al, 2019;Xu et al, 2022). In the realm of remote sensing predictors, the GRVI median holds significant importance.…”

Thermal Regime of High Arctic Tundra Ponds, Nanuit Itillinga (Polar Bear Pass), Nunavut, Canada

“…Changes in ground thaw can alter drainage patterns and water storage in ponds (Young and Woo, 2003;Rehder et al, 2023).…”

“…As the permafrost thaws to deeper soil layers or is completely thawed, the perched water table may be lowered, resulting in drier surface soils, and then this can lead to substantial carbon loss. But in other areas, ground collapse can fill with water to form ponds and wetlands enhancing methane losses (Moonmaw et al, 2018;Rehder et al, 2023).…”

“…This can influence pond thawing rates and maximum thaw depths. Permafrost degradation can also cause expansion or shrinkage of wetland areas and warming associated with permafrost thaw could also turn wetlands into sources of carbon that increases greenhouse gas emissions to the atmosphere (Moonmaw et al, 2018;Kreplin et al, 2021;Rehder et al, 2023). Wrona et al (2016) argue that while temperature is a key driver in ecological processes in tundra ecosystems, it is hydrological interactions that mediate the climate responses of tundra ecosystems.…”

“…to dry out over summer seasons with vascular plants encroaching, suggesting that in the long-term, certain ponds may shift into wet or dry meadow features (see Fig. 14), which may eventually alter greenhouse gas emissions (Rehder et al, 2023), snowcover receipt, and evapotranspiration rates as shifts in vegetation have done elsewhere (Morison et al 2023).…”