Potential future methane emission hot spots in Greenland

Abstract

Climate models have been making significant progress encompassing an increasing number of complex feedback mechanisms from natural ecosystems. Permafrost thaw and subsequent induced greenhouse gas emissions, however, remain a challenge for climate models at large. Deducing permafrost conditions and associated greenhouse gas emissions from parameters that are simulated in climate models would be a helpful step towards estimating emission budgets from permafrost regions. Here we use a regional climate model with a 5 km horizontal resolution to assess future potential methane (CH 4 ) emissions over presently unglaciated areas in Greenland under an RCP8.5 scenario. A simple frost index is applied to estimate permafrost conditions from the model output. CH 4 flux measurements from two stations in Greenland; Nuuk representing sub-Arctic and Zackenberg high-Arctic climate, are used to establish a relationship between emissions and near surface air temperature. Permafrost conditions in Greenland change drastically by the end of the 21st century in an RCP8.5 climate. Continuous permafrost remains stable only in North Greenland, the north-west coast, the northern tip of Disko Island, and Nuussuaq. Southern Greenland conditions only sustain sporadic permafrost conditions and largely at high elevations, whereas former permafrost in other regions thaws. The increasing thawed soil leads to increasing CH 4 emissions. Especially the area surrounding Kangerlussuaq, Scoresby Land, and the southern coast of Greenland exhibit potentially high emissions during the longer growing season. The constructed maps and budgets combining modelled permafrost conditions with observed CH 4 fluxes from CH 4 promoting sites represent a useful tool to identify areas in need of additional monitoring as they highlight potential CH 4 hot spots.

A new dataset of soil carbon and nitrogen stocks and profiles from an instrumented Greenlandic fen designed to evaluate land-surface models

“…The studied fen (Nuuk fen) is located within the Nuuk Eco- (Geng et al, 2019). According to the classification of Glooschenko et al (1993) of Arctic and subarctic wetlands, Nuuk fen is in the low subarctic wetland region. The research station consists of a drainage basin of 32 km 2 situated at the head of a fjord.…”

Methane in Zackenberg Valley, NE Greenland: multidecadal growing season fluxes of a high-Arctic tundra

“…The relative increase ranges from +114 % to +171 % when considering the lower and upper 95 % confidence bounds; see Fig. 3 in Geng et al (2019).…”

“…Zackenberg Valley shows the potential for increased methane fluxes in the 21st century, as methane shows a positive correlation with temperatures (Geng et al, 2019), similar to the rest of Greenland and the Arctic (AMAP, 2017).…”

“…Modeling results show higher soil temperatures and a deepening of the AL in Zackenberg Valley in the future (Christiansen et al, 2008;Westermann et al, 2015). Increasing temperatures are expected to impact both positive and negative methane flux and surface erosion in the Arctic (Schuur et al, 2015;Geng et al, 2019;Oh et al, 2020), which is also likely for Zackenberg Valley. The emergence of several active erosion sites in Zackenberg Valley in recent years could be an initial step towards increased erosion activity during the 21st century.…”

A Structured Approach for the Mitigation of Natural Methane Emissions—Lessons Learned from Anthropogenic Emissions

“…Some thought-provoking statements are given, and a first categorization approach is performed in Figure 6. Emissions resulting from global warming, for example, from thawing permafrost or destabilizing clathrates [112][113][114][115], belong to this new category. In addition, wetlands are impacted by climate change due to changes in temperature and precipitation regimes [116] and emissions such as microseepage can be the result of anthropogenic actions, e.g., enhanced oil recovery [117] or fracking [118].…”