Global sea-level contribution from Arctic land ice: 1971–2017

Abstract

The Arctic Monitoring and Assessment Program (AMAP 2017) report identifies the Arctic as the largest regional source of land ice to global sea-level rise in the 2003-2014 period. Yet, this contextualization ignores the longer perspective from in situ records of glacier mass balance. Here, using 17 (>55°N latitude) glacier and ice cap mass balance series in the 1971-2017 period, we develop a semi-empirical estimate of annual sea-level contribution from seven Arctic regions by scaling the in situ records to GRACE averages. We contend that our estimate represents the most accurate Arctic land ice mass balance assessment so far available before the 1992 start of satellite altimetry. We estimate the 1971-2017 eustatic sea-level contribution from land ice north of ∼55°N to be 23.0±12.3 mm sea-level equivalent (SLE). In all regions, the cumulative sea-level rise curves exhibit an acceleration, starting especially after 1988. Greenland is the source of 46% of the Arctic sea-level rise contribution (10.6±7.3 mm), followed by Alaska (5.7±2.2 mm), Arctic Canada (3.2±0.7 mm) and the Russian High Arctic (1.5±0.4 mm). Our annual results exhibit co-variability over a 43 year overlap (1971-2013) with the alternative dataset of Marzeion et al (2015 Cryosphere 9 2399-404) (M15). However, we find a 1.36× lower sea-level contribution, in agreement with satellite gravimetry. The IPCC Fifth Assessment report identified constraining the pre-satellite era sea-level budget as a topic of low scientific understanding that we address and specify sea-level contributions coinciding with IPCC Special Report on the Ocean and Cryosphere in a Changing Climate (SROCC) 'present day' (2005)(2006)(2007)(2008)(2009)(2010)(2011)(2012)(2013)(2014)(2015) and 'recent past' (1986)(1987)(1988)(1989)(1990)(1991)(1992)(1993)(1994)(1995)(1996)(1997)(1998)(1999)(2000)(2001)(2002)(2003)(2004)(2005) reference periods. We assess an Arctic land ice loss of 8.3 mm SLE during the recent past and 12.4 mm SLE during the present day. The seven regional sea-level rise contribution time series of this study are available from AMAP.no.

Freshwater Export in the East Greenland Current Freshens the North Atlantic

“…For both sources (EGC and land ice) it is unclear how this has been distributed further in the North Atlantic: if it has remained in the boundary current system encircling the subpolar gyre or whether an exchange with the interior has taken place. While the FWT in the EGC returned to normal levels in 2014–2015, the FW input from Greenland and Arctic glaciers and ice caps is expected to increase in a warmer climate and increasing ocean temperatures (Box & Colgan, ).…”

Spread of Svalbard Glacier Mass Loss to Barents Sea Margins Revealed by CryoSat‐2

“…The Arctic is one of the most rapidly warming areas of the planet (AMAP, 2017b), in part due to the polar amplification of climate change (Serreze & Barry, 2011). This has resulted in pan‐Arctic glacier mass loss, dominated by increased surface melting (Box et al., 2018; Gardner et al., 2011; Larsen et al., 2015; Noël et al., 2017). The Norwegian high Arctic archipelago of Svalbard lies at the confluence of cold air masses from the Arctic, and warm, humid air masses from the Atlantic (Hagen et al., 1993).…”

Firn cold content evolution at nine sites on the Greenland ice sheet between 1998 and 2017

“…The Greenland ice sheet, the greatest fresh-water reservoir in the Northern hemisphere, is losing mass at an accelerating rate as a response to climate warming in the Arctic (Vaughan and others, 2013). This mass loss is responsible for a 0.46–0.76 mm per year rise of global mean sea level in the last decades, or 15–30% of the observed contemporary sea-level rise (Box and others, 2018; WCRP Global Sea Level Budget Group, 2018; Nerem and others, 2018). Roughly half of the current ice-sheet mass loss stems from surface melt and subsequent meltwater runoff, both of which increased during recent decades (van den Broeke and others, 2016).…”