Ground subsidence effects on simulating dynamic high-latitude surface inundation under permafrost thaw using CLM5

Altug Ekici,Hanna Lee,David M Lawrence,Sean C Swenson,Catherine Prigent

doi:10.5194/gmd-12-5291-2019

Abstract

Abstract. Simulating surface inundation is particularly challenging for the high-latitude permafrost regions. Ice-rich permafrost thaw can create expanding thermokarst lakes as well as shrinking large wetlands. Such processes can have major biogeochemical implications and feedbacks to the climate system by altering the pathways and rates of permafrost carbon release. However, the processes associated with it have not yet been properly represented in Earth system models. We show a new model parameterization that allows direct representation of surface water dynamics in CLM (Community Land Model), the land surface model of several Earth System Models. Specifically, we coupled permafrost-thaw-induced ground subsidence and surface microtopography distribution to represent surface water dynamics in the high latitudes. Our results show increased surface water fractions around western Siberian plains and northeastern territories of Canada. Additionally, localized drainage events correspond well to severe ground subsidence events. Our parameterization is one of the first steps towards a process-oriented representation of surface hydrology, which is crucial to assess the biogeochemical feedbacks between land and the atmosphere under changing climate.

Highlights

Northern high latitudes experience pronounced warming due to Arctic amplification (Serreze and Francis, 2006)
In the original Community Land Model (CLM) parameterization, fh2osfc is calculated with a static microtopography index (Fig. S1) derived from a prescribed topographic slope dataset (Oleson et al, 2013)
The degradation of Arctic permafrost due to increased soil temperatures leads to the release of permafrost carbon to the atmosphere and further strengthens the greenhouse warming (IPCC, 2013; Schuur et al, 2008)

Summary

Introduction

Northern high latitudes experience pronounced warming due to Arctic amplification (Serreze and Francis, 2006). Temperature increase in the Arctic has been twice the amount of that in the tropics (Solomon et al, 2007). The abrupt increase in Arctic temperatures threatens to destabilize the global permafrost areas and can alter land surface structures, which can lead to releasing considerable amounts of permafrost carbon as greenhouse gases to the climate system (Schuur et al, 2008). Increased precipitation can accelerate the release of permafrost carbon in high latitudes (Chang et al, 2019; Grant et al, 2017). The main natural sources of CH4 emissions are from tropical wetlands; the contributions from high-latitude wetlands are increasing each decade (Saunois et al, 2016) with further thawing of permafrost

Methods

Results

Conclusion