Greenland Ice Sheet surface mass balance 1870 to 2010 based on Twentieth Century Reanalysis, and links with global climate forcing

Abstract

[1] We present a reconstruction of the Greenland Ice Sheet surface mass balance (SMB) from 1870 to 2010, based on merged Twentieth Century Reanalysis (20CR) and European Centre for Medium-Range Weather Forecasts (ECMWF) meteorological reanalyses, and we compare our new SMB series with global and regional climate and atmospheric circulation indices during this period. We demonstrate good agreement between SMB annual series constructed from 20CR and ECMWF reanalyses for the common period of overlap and show statistically significant agreement of long-term modeled snowfall with ice-core-based accumulation data. We analyze variations in SMB for the last 140 years and highlight the periods with significantly increased runoff and decreased SMB since 1870, which have both been enhanced in the period since 1990, as well as interannual variations in SMB linked to Greenland climate fluctuations. We show very good agreement of our SMB series variations with existing, independently derived SMB series (RACMO2) variations for the past few decades of overlap but also a significant disparity of up to $200 km 3 yr À1 in absolute SMB values due to poorly constrained modeled accumulation reflecting a lack of adequate validation data in southeast Greenland. There is no significant correlation between our SMB time series and a widely referenced time series of North Atlantic icebergs emanating from Greenland for the past century, which may reflect the complex nature of the relationship between SMB and ice dynamical changes. Finally, we discuss how our analysis sheds light on the sensitivity and response of the Greenland Ice Sheet to ongoing and future global climate change, and its contribution to global sea level rise.

Surface mass balance model intercomparison for the Greenland ice sheet

“…Unlike the previous three atmospheric models, the approach taken by Hanna et al (2011Hanna et al ( , 2005Hanna et al ( , 2002Hanna et al ( , 2008 referred to here as ECMWFd does not model the atmosphere over Greenland. Instead ERA-40 and operational analysis surface air temperature, precipitation and surface latent heat flux are downscaled by bilinear interpolation from the original resolution of 1.125 • latitude × 1.125 • longitude to a 0.5 • × 0.5 • grid.…”

“…The GC-Net data however remains independent. The ECMWFd version used here is described in Hanna et al (2011). A further RCM for the GrIS, HIRHAM5 , is not considered here as estimates are only available over the period 1989-2009, forced by ERA_INTERIM.…”

Oxygen isotope ratios in the shell of <i>Mytilus edulis</i>: archives of glacier meltwater in Greenland?

“…Current global warming causes accelerated melting (Andresen et al, 2012;Howat et al, 2005;Rignot and Kanagaratnam, 2006), resulting in increased runoff since the early 1990s (Box et al, 2006;Hanna et al, 2011) and significantly contributing to global sea level rise (IPCC, 2007;Krabill et al, 2000;Price et al, 2011). The natural variability in GrIS mass balance over time is reconstructed by means of modelling studies, using instrumental data (covering the most recent decades) and proxy data (Alley et al, 2010;Israelson et al, 1994).…”

Evaluating Model Simulations of Twentieth-Century Sea-Level Rise. Part II: Regional Sea-Level Changes

“…The constant contribution is estimated following Gregory et al (2013a). It is computed as the opposite of the mean Antarctic and Greenland SMB over the period 1971-90 as both ice sheets are assumed to be close to mass balance during this period (Rignot et al 2008;Hanna et al 2011;Gregory et al 2013a). The resulting contribution of ice sheet dynamics mass loss to the twentieth century sea level change is small (7 6 5 mm at global scale; Part I) and the associated pattern with its uncertainty is shown in Figs.…”