Temperatures in Greenland are the highest in 1000 years
Temperatures in Greenland are the highest in 1000 years
Recent high temperatures on the ice sheet in central and northern Greenland lies are unique, when compared to 1000 years of reconstructed climate conditions on the ice sheet.
This is the main message of a new scientific study based on numerous updated ice core data.
Niels Bohr Institute
University of Copenhagen
The climate of the last 1000 years reconstructed
In the last decade ice core researchers from the Alfred Wegner Institute and the Niels Bohr Institute have collaborated to update existing ice cores with information from the most recent decades. Hence, several missions have been flown to remote locations on the Greenland ice sheet in order to drill new cores at locations where ice cores had been drilled some 30 years ago.
This has been done in order to get ice and snow samples from the latest decades.
Comparing the water isotopic composition in the recent samples with similar records reaching a millennium back in time it is possible to reconstruct climate from year 1000 all the way up to 2011.
The new temperature reconstruction shows that the most recent decade in the cores are some 1.5 degrees warmer than the long-term average.
This warming is unique in the 1000-year perspective provided by the ice cores. Hence, it is clear that the signal of global warming has reached even the remote ice sheet locations in central and northern Greenland.
Rising temperatures and increase in meltwater from the inland ice sheet go together
The new study goes on to compare the reconstructed Greenland temperature evolution to melt-water run-off from the Greenland ice sheet, showing that temperatures and melt is closely related.
Hence, the increase in melt observed in recent decades is also likely to be unique in the past 1000 years.
Rising sea levels is the consequence
Associate professor Bo Møllesøe Vinther, who participated in the study describes its significance:
“The close relationship between higher temperatures and increasing melt of the Greenland ice sheet documented in the study, is of great concern given that Greenland warming is projected to continue due to continued emissions of greenhouse gasses.
Melt from the Greenland Ice Sheet must thus be expected to contribute more and more to sea level rise in the future”.
The new study has been published in the scientific journal Nature.
a, The NGT-2012 composite record of 11-year running mean d18O (black, left axis) and inferred temperature time series (right axis, Methods) from 1000 to 2011 (top panel). Light grey lines in the background display annual mean values. The thick red line highlights the extension of existing ice-core records to 2011 by re-drillings performed as part of this study. Estimated linear trends over the periods 1000–1800 (pre-industrial) and 1800–2011 are shown as dashed black lines. The number of firn cores contributing to the reconstruction is shown beneath as a brown line. The bottom panel shows the Arctic 2k temperature reconstruction record13 displayed as 11-year running mean values and as annual data and with dashed blue lines indicating linear trends, as for NGT-2012. The time series was extended to 2011 using HadCrut instrumental data70 (cyan line, Methods). b, Locations of the ice cores used for NGT-2012 (circles) and of nearby weather stations16 (black triangles; geographic map data obtained from the ‘rnaturalearth’ package for the software R). Site IDs are detailed in Extended Data Table 1. c, Comparison of the NGT-2012 11-year running mean temperature reconstruction (1871–2011, black) with Greenland meltwater run-off from MAR3.5.222 (R = 0.62, P < 0.01, n = 141; Methods and Extended Data Fig. 7). Grey shading indicates a ±40% uncertainty of the temperature reconstruction obtained from the range of plausible calibration slopes (Methods). All time series are displayed as anomalies relative to the 1961–1990 reference period (horizontal dashed lines).
Reference:
Hörhold, M., Münch, T., Weißbach, S. et al. Modern temperatures in central–north Greenland warmest in past millennium. Nature 613, 503–507 (2023). https://doi.org/10.1038/s41586-022-05517-z
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