Greenland climate change: from the past to the future

(a) Map of Greenland showing11 the ice sheet extent (white), schematized surface oceanic currents affecting Greenland climate (red arrows, warm surface currents; dashed blue arrows, cold surface currents; EGC: East Greenland Current; WGC: West Greenland Current; B‐LC: Baffin‐Labrador Current), the largest towns and settlements (yellow circles) as well as ice core drilling sites (orange circles). (b) Zoom on Greenland.

(a) Greening of the Arctic. Satellite observations of Arctic sea ice reduction (indicated by the trend in the percentage of open water) and tundra vegetation productivity (indicated by the MNDVI, modified normalized difference vegetation index). Trends are calculated from 1982 to 2010 using a 10 km resolution, updating earlier data.12 (b) Zoom on Greenland.

Current Greenland warming in the perspective of natural climate variability and future projections. (a) NorthGRIP ice core δ¹⁸O (‰), a proxy of Greenland SAT14 at a 20 year resolution (grey) and multi‐millennial binomial smoothing (red) as a function of time (years before 2000 AD); the orbital forcing, which is the main external driver of glacial–interglacial trends, is illustrated by the 70°N June insolation (W/m²). Red areas highlight the interglacial periods and the blue area highlights the last glacial period; the green area indicates the instrumental period. The 25 Dansgaard–Oeschger events are numbered. (b) Estimate of southern GrIS23 SAT anomalies during the current interglacial period (°C, with respect to the last millennium) (gray, 20 year resolution; red, millennial trend) based on a stack of ice cores and a correction for elevation changes23 and a comparison with the instrumental SAT record from southern Greenland updated to 201013 (black, 10 year resolution). The SAT level of the decade 2001–2010 is displayed with a horizontal dashed black line. The 2010 anomaly is displayed as a filled diamond. The vertical rectangles illustrate the succession of human occupations of Greenland, from archeological data (see text). The red area illustrates the current interglacial period, and the green area the instrumental period. The rate of SAT change during the abrupt warming, approximately 8200 years ago, is also indicated (2.5°C per century). (c) Meteorological records from southern Greenland based on a stack of meteorological data updated to 201013 (thin black line, annual data; thick stair steps, decadal averages). The data are compared to the MAR regional climate model results for the south‐west Greenland coastal area, forced by ERA‐40 (green) and ERA‐interim (orange) boundary conditions from 1958 to 2010.7 Data are displayed as anomalies from the 1960–1990 period, which is 0.5°C above the average data for the last millennium as displayed in panel (b). The 2010 SAT anomaly is highlighted as a filled diamond. An example projection is given using MAR forced by the ECHAM5 A1B projections (red line, annual values; red stair steps, decadal values). This corresponds to a warming trend of 4.7°C per century.

Cumulative updated4 anomalies of major mass balance components of the GrIS, 1990–2010, and GRACE gravimetry estimate of mass loss, vertically offset for clarity. Abbreviations are explained in the legend. SMB data from RACMO2 RCM.4 GRACE data courtesy of I. Velicogna and J. Wahr.

(a) Observed and projected permafrost degradation in Zackenberg 1900–2080 based on down‐scaled climate model (HIRHAM RCM) data. Projections are given for two vegetation types: wetland (brown), heath (green), and two scenarios: a 2°C global warming over 100 years (filled symbols) and 2.4°C over 60 years (open symbols). Running means over 10 years are shown as solid lines. (b) Active layer and permafrost total soil organic carbon observed for two vegetation types, wetlands (open symbols) and heath (filled symbols),89 and (c) Ammonium concentrations in melt water, for two vegetation types, wetlands (open symbols) and heath (filled symbols).89

(a) Schematic representation of environmental changes recorded by the Igaliku lake sediments100,102,103: (A) water quality estimated from diatom assemblages, (B) soil erosion rates estimated from the minerogenic and organic inputs into the lake and controlled by a set of geophysical, geochemical, and ecological parameters including magnetic susceptibility, titanium content, bulk organic matter geochemistry, and diatom valve concentration, (C) vegetation history from pollen and nonpollen palynomorphs analyses, and (D) archeological periods. Limited impacts of Norse agriculture are reflected by indicators of clearance and sheep grazing, as well as by the persistence of introduced species. Modern agriculture is marked by clearance, soil erosion, and the onset of the first mesothropic phase of the last 10,000 years; (b) Photograph of Norse apophytes (Rumex acetosa—Taraxacum sp) on a medieval archeological site in south Greenland (source: E. Gauthier, 2007).

(a) Probabilistic estimate of the rate of SAT change over the course of stadial–interstadial events, with a duration longer than 60 years. Data are represented as a probability density function (%) as a function of the rate of SAT change (°C per 100 years), calculated from the published uncertainties on event duration and magnitude (see Table 2). Color codes reflect the CO₂ concentration (as an indicator of the back ground climate) during events (from blue, concentrations between 200 and 215 ppmv; orange, 220–230 ppmv; brown, 230–240 ppmv; and red, 240–260 ppmv). The black line displays the mean probability density, calculated from the 11 studied events). There is a tendency for having slower rates of temperature rise (DO20, DO22, DO23, DO25, BA) under ‘warm climate’ background. DO 22 appears to be very close to a ‘mean’ event. (b) Rates of changes for future climate in RCP4.5 and RCP8.5 projections. Simulations from 13 models or model versions have been considered (NorESM1‐M, MRI‐CGCM3, MPI‐ESM‐LR, MIROC‐ESM, MIROC‐ESM‐CHEM, MIROC, IPSL‐CM5A‐LR, inmcm4, HadGEM2‐ES, CSIRO‐Mk3, CNRM‐CM5, CCSM4, CanESM2, and HadGEM2‐ES). Results are displayed in terms of cumulative frequencies within the 13 models.

Illustration of the impact of a large GrIS meltwater flux (>0.1 Sv) on global climate projections using the IPSL CM4 model.3 SAT (top) and precipitation (bottom) changes for 2× CO₂ (averaged over years 450–500)168 with respect to the preindustrial control simulation when including (right) or not (left) the impact of GrIS meltwater flux. A strong reduction in the AMOC induces a reduced warming in the north Atlantic but enhanced warming in the southern hemisphere tropical Atlantic, resulting in a southward shift of the Inter tropical Convergence Zone. Such a migration may have strong impacts on tropical precipitation distributions. This type of behavior has been found in a multi‐model ensemble for modern conditions and appears to be robust under global warming conditions.161