The influence of proglacial lakes on climate and surface mass balance of retreating ice sheets – An Investigation of the Laurentide and Fennoscandian ice sheets,13 ka BP

This study investigates how large proglacial lakes affected regional climate and surface mass balance (SMB) of retreating ice sheets during the last deglaciation. For this purpose we have modified the atmosphere model ECHAM6. The approach is here to limit the surface temperature of proglacial lakes to values below 4°C, while other lakes in ECHAM6 can freely evolve according to a mixed layer scheme.

As a first application we investigate the impact of proglacial lakes during the Allerød interstadial at 13 ka (ka is thousand years before present) with three atmosphere stand-alone experiments:

(i) with 13ka land surface boundary conditions (GLAC1d, Ivanovic et al., 2016) and a modern lake configuration

(ii) same as (i) but with additional lakes around the North American and Fennoscandian Ice Sheets

(iii) same as (ii) but the additional lakes are treated according to our proglacial lake approach.

Over the ocean we use boundary conditions taken from a 15ka coupled climate simulation. These three simulations were evaluated with respect to the regional climate response and the SMB was calculated using the diurnal Energy Balance Model (dEBM, Krebs-Kanzow et al., 2021). Preliminary results are indicating an overall positive effect of regular lakes, and in particular proglacial lakes, on the SMB of the great ice sheets over Northern America and Scandinavia during the Allerød interstadial.

 

References:

Ivanovic, R. F., Gregoire, L. J., Kageyama, M., Roche, D. M., Valdes, P. J., Burke, A., Drummond, R., Peltier, W. R., and Tarasov, L.: Transient climate simulations of the deglaciation 21–9 thousand years before present (version 1) – PMIP4 Core experiment design and boundary conditions, Geosci. Model Dev., 9, 2563–2587, https://doi.org/10.5194/gmd-9-2563-2016, 2016.

Krebs-Kanzow, U., Gierz, P., Rodehacke, C. B., Xu, S., Yang, H., and Lohmann, G., 2021: The diurnal Energy Balance Model (dEBM): a convenient surface mass balance solution for ice sheets in Earth system modeling, The Cryosphere, 15, 2295–2313, https://doi.org/10.5194/tc-15-2295-2021.