Abstract
AbstractWe provide an updated analysis of instrumental Greenland monthly temperature data to 2019, focusing mainly on coastal stations but also analysing ice‐sheet records from Swiss Camp and Summit. Significant summer (winter) coastal warming of ~1.7 (4.4)°C occurred from 1991–2019, but since 2001 overall temperature trends are generally flat and insignificant due to a cooling pattern over the last 6–7 years. Inland and coastal stations show broadly similar temperature trends for summer. Greenland temperature changes are more strongly correlated with Greenland Blocking than with North Atlantic Oscillation changes. In quantifying the association between Greenland coastal temperatures and Greenland Ice Sheet (GrIS) mass‐balance changes, we show a stronger link of temperatures with total mass balance rather than surface mass balance. Based on Greenland coastal temperatures and modelled mass balance for the 1972–2018 period, each 1°C of summer warming corresponds to ~(91) 116 Gt·yr−1 of GrIS (surface) mass loss and a 26 Gt·yr−1 increase in solid ice discharge. Given an estimated 4.0–6.6°C of further Greenland summer warming according to the regional model MAR projections run under CMIP6 future climate projections (SSP5‐8.5 scenario), and assuming that ice‐dynamical losses and ice sheet topography stay similar to the recent past, linear extrapolation gives a corresponding GrIS global sea‐level rise (SLR) contribution of ~10.0–12.6 cm by 2100, compared with the 8–27 cm (mean 15 cm) “likely” model projection range reported by IPCC in 2019 (SPM.B1.2). However, our estimate represents a lower limit for future GrIS change since fixed dynamical mass losses and amplified melt arising from both melt‐albedo and melt‐elevation positive feedbacks are not taken into account here.
Highlights
Recent research highlights increased mass loss from the Greenland Ice Sheet (GrIS) (Shepherd et al, 2020; Hanna et al, 2013a; Hanna et al, 2020; Bamber et al, 2018), and the ice sheet's response to anthropogenic global warming includes a non-linear effect of rising air temperatures on melt and runoff (Trusel et al, 2018)
Since Greenland summer temperature changes are crucial for affecting GrIS mass balance and global sea-level rise, we explore the relation between these parameters for both recent (1972–2018) and future climate conditions based on the output of a regional climate model (MAR) forced by the latest available (CMIP6) suite of global climate model (GCM) predictions
We present spatial patterns of Greenland temperature trends based on the MAR model output, which indicates the regional focus of the strongest warming
Summary
Recent research highlights increased mass loss from the Greenland Ice Sheet (GrIS) (Shepherd et al, 2020; Hanna et al, 2013a; Hanna et al, 2020; Bamber et al, 2018), and the ice sheet's response to anthropogenic global warming includes a non-linear effect of rising air temperatures on melt and runoff (Trusel et al, 2018). Trusel et al (2018) found a 250–575% increase in melt intensity at multiple ice-core sites in the Jakobshavn drainage basin on the west flank of the GrIS during 1994–2013, which corresponds with a period of strong global warming influence on Greenland surface air temperatures (Hanna et al, 2012). This analysis based on coastal AWS data is confirmed by plots from MAR comparing temperature differences for summer 2019 versus 2012, where only northernmost Greenland was generally warmer, by up to $2C, in 2019 (Figure 6).
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