Nonlinear rise in Greenland runoff in response to post-industrial Arctic warming

The Greenland ice sheet (GrIS) is a growing contributor to global sea-level rise1, with recent ice mass loss dominated by surface meltwater runoff2,3. Satellite observations reveal positive trends in GrIS surface melt extent4, but melt variability, intensity and runoff remain uncertain before the satellite era. Here we present the first continuous, multi-century and observationally constrained record of GrIS surface melt intensity and runoff, revealing that the magnitude of recent GrIS melting is exceptional over at least the last 350 years. We develop this record through stratigraphic analysis of central west Greenland ice cores, and demonstrate that measurements of refrozen melt layers in percolation zone ice cores can be used to quantifiably, and reproducibly, reconstruct past melt rates. We show significant (P < 0.01) and spatially extensive correlations between these ice-core-derived melt records and modelled melt rates5,6 and satellite-derived melt duration4 across Greenland more broadly, enabling the reconstruction of past ice-sheet-scale surface melt intensity and runoff. We find that the initiation of increases in GrIS melting closely follow the onset of industrial-era Arctic warming in the mid-1800s, but that the magnitude of GrIS melting has only recently emerged beyond the range of natural variability. Owing to a nonlinear response of surface melting to increasing summer air temperatures, continued atmospheric warming will lead to rapid increases in GrIS runoff and sea-level contributions.Ice-core-derived melt records reveal that atmospheric warming has recently intensified Greenland ice-sheet surface melt and runoff to levels that are exceptional over at least the last 350 years.

[1]  J. Wallace,et al.  Tropical forcing of the recent rapid Arctic warming in northeastern Canada and Greenland , 2014, Nature.

[2]  X. Fettweis,et al.  Atmospheric and oceanic climate forcing of the exceptional Greenland ice sheet surface melt in summer 2012 , 2013 .

[3]  A. Dyke,et al.  High Arctic Holocene temperature record from the Agassiz ice cap and Greenland ice sheet evolution , 2017, Proceedings of the National Academy of Sciences.

[4]  Xavier Fettweis,et al.  Reconstructions of the 1900–2015 Greenland ice sheet surface mass balance using the regional climate MAR model , 2016 .

[5]  Axel Schweiger,et al.  Influence of high-latitude atmospheric circulation changes on summertime Arctic sea ice , 2017 .

[6]  Jonathan M. Lees,et al.  Robust estimation of background noise and signal detection in climatic time series , 1996 .

[7]  R. Alley,et al.  Characterization and formation of melt layers in polar snow: observations and experiments from West Antarctica , 2005, Journal of Glaciology.

[8]  M. Evans,et al.  Early onset of industrial-era warming across the oceans and continents , 2016, Nature.

[9]  H. Fischer,et al.  Representativeness and seasonality of major ion records derived from NEEM firn cores , 2014 .

[10]  Ed Hawkins,et al.  Time of emergence of climate signals , 2012 .

[11]  Jennifer A. Francis,et al.  Has Arctic Sea Ice Loss Contributed to Increased Surface Melting of the Greenland Ice Sheet , 2016 .

[12]  Ian M. Howat,et al.  On the recent contribution of the Greenland ice sheet to sea level change , 2016 .

[13]  E. Cook,et al.  Last millennium Northern Hemisphere summer temperatures from tree rings: Part II, spatially resolved reconstructions , 2017 .

[14]  Kenneth C. McGwire,et al.  An integrated system for optical imaging of ice cores , 2008 .

[15]  J. Walsh,et al.  A database for depicting Arctic sea ice variations back to 1850 , 2017 .

[16]  Xavier Fettweis,et al.  Estimating the Greenland ice sheet surface mass balance contribution to future sea level rise using the regional atmospheric climate model MAR , 2012 .

[17]  J. McConnell,et al.  A Method for Continuous (239)Pu Determinations in Arctic and Antarctic Ice Cores. , 2016, Environmental science & technology.

[18]  C. Bretherton,et al.  The Effective Number of Spatial Degrees of Freedom of a Time-Varying Field , 1999 .

[19]  W. Ebisuzaki.  A Method to Estimate the Statistical Significance of a Correlation When the Data Are Serially Correlated , 1997 .

[20]  Kevin E. Trenberth,et al.  Atlantic hurricanes and natural variability in 2005 , 2006 .

[21]  Xavier Fettweis,et al.  Greenland Ice Sheet Surface Mass Loss: Recent Developments in Observation and Modeling , 2017, Current Climate Change Reports.

[22]  W. T. Pfeffer,et al.  Thermal tracking of meltwater retention in Greenland's accumulation area , 2012 .

[23]  Michael E. Schlesinger,et al.  An oscillation in the global climate system of period 65–70 years , 1994, Nature.

[24]  J. Box,et al.  The implication of nonradiative energy fluxes dominating Greenland ice sheet exceptional ablation area surface melt in 2012 , 2016 .

[25]  Edward Hanna,et al.  Ice-sheet mass balance and climate change , 2013, Nature.

[26]  Michael M. Herron,et al.  Climatic signal of ice melt features in southern Greenland , 1981, Nature.

[27]  J. Box,et al.  Abrupt shift in the observed runoff from the southwestern Greenland ice sheet , 2017, Science Advances.

[28]  X. Fettweis,et al.  Decreasing cloud cover drives the recent mass loss on the Greenland Ice Sheet , 2017, Science Advances.

[29]  Xavier Fettweis,et al.  Evidence and analysis of 2012 Greenland records from spaceborne observations, a regional climate model and reanalysis data , 2012 .

[30]  S. Lhermitte,et al.  Modelling the climate and surface mass balance of polar ice sheets using RACMO2 – Part 1: Greenland (1958–2016) , 2017 .

[31]  E. Mosley‐Thompson,et al.  Greenland meltwater storage in firn limited by near-surface ice formation , 2016 .

[32]  M. Curran,et al.  Suppressed ion chromatography methods for the routine determination of ultra low level anions and cations in ice cores. , 2001, Journal of chromatography. A.

[33]  J. Kahl,et al.  20th-Century Industrial Black Carbon Emissions Altered Arctic Climate Forcing , 2007, Science.

[34]  M. Sharp,et al.  Recent melt rates of Canadian arctic ice caps are the highest in four millennia , 2012 .

[35]  Hans-Peter Marshall,et al.  Ice Core Records of West Greenland Melt and Climate Forcing , 2018 .

[36]  Keith R. Briffa,et al.  Extending Greenland temperature records into the late eighteenth century , 2006 .

[37]  Takao Kameda,et al.  Melt features in ice cores from Site J, southern Greenland: some implications for summer climate since AD 1550 , 1995, Annals of Glaciology.

[38]  M. R. van den Broeke,et al.  Clouds enhance Greenland ice sheet meltwater runoff , 2016, Nature Communications.

[39]  Edward Hanna,et al.  Greenland Blocking Index 1851–2015: a regional climate change signal , 2016 .

[40]  A. Grinsted,et al.  Persistence matters: Estimation of the statistical significance of paleoclimatic reconstruction statistics from autocorrelated time series , 2012 .

[41]  James Stephen Marron,et al.  Advanced Distribution Theory for SiZer , 2006 .

[42]  Nerilie J. Abram,et al.  Acceleration of snow melt in an Antarctic Peninsula ice core during the twentieth century , 2013 .

[43]  Aslak Grinsted,et al.  Nonlinear Processes in Geophysics Application of the Cross Wavelet Transform and Wavelet Coherence to Geophysical Time Series , 2022 .

[44]  Richard B. Alley,et al.  Rise in frequency of surface melting at Siple Dome through the Holocene: Evidence for increasing marine influence on the climate of , 2008 .

[45]  Edward R. Cook,et al.  SPATIAL REGRESSION METHODS IN DENDROCLIMATOLOGY: A REVIEW AND COMPARISON OF TWO TECHNIQUES , 1994 .

[46]  Neil L. Rose,et al.  Anomalously weak Labrador Sea convection and Atlantic overturning during the past 150 years , 2018, Nature.

[47]  M. R. van den Broeke,et al.  A tipping point in refreezing accelerates mass loss of Greenland's glaciers and ice caps , 2017, Nature Communications.

[48]  X. Fettweis,et al.  A daily, 1 km resolution data set of downscaled Greenland ice sheet surface mass balance (1958–2015) , 2016 .

[49]  K. Anchukaitis,et al.  Tropical sea surface temperatures for the past four centuries reconstructed from coral archives , 2015 .

[50]  Ian Baker,et al.  Climate change and forest fires synergistically drive widespread melt events of the Greenland Ice Sheet , 2014, Proceedings of the National Academy of Sciences.

[51]  Xavier Fettweis,et al.  Surface mass balance model intercomparison for the Greenland ice sheet , 2012 .

[52]  E. Mosley‐Thompson,et al.  Changes in the firn structure of the western Greenland Ice Sheet caused by recent warming , 2015 .

[53]  L. Thompson,et al.  Reconstructed changes in Arctic sea ice over the past 1,450 years , 2011, Nature.

[54]  J. McConnell,et al.  Continuous ice-core chemical analyses using inductively coupled plasma mass spectrometry. , 2002, Environmental science & technology.

[55]  Myoung-Jong Noh,et al.  An improved mass budget for the Greenland ice sheet , 2013 .

[56]  K. Steffen,et al.  July 2012 Greenland melt extent enhanced by low-level liquid clouds , 2013, Nature.

[57]  Karen E. Frey,et al.  Divergent trajectories of Antarctic surface melt under two twenty-first-century climate scenarios , 2015 .

[58]  M. Winstrup,et al.  Timing and climate forcing of volcanic eruptions for the past 2,500 years , 2015, Nature.

[59]  X. Fettweis,et al.  Brief communication "Important role of the mid-tropospheric atmospheric circulation in the recent surface melt increase over the Greenland ice sheet" , 2012 .