Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | w.e. 1 − 1 n Island over ffi 0.36 m a ± 1.68 − , and A. Langlois 3,* er et al., 2014). In response to the ff w.e.) and 2 times as negative when com- , C. Zdanowicz , the Canadian Arctic Archipelago (CAA) is 1 1 N). In this paper, we measure historical and 2 1668 1667 − ◦ water equivalent (w.e.) for the 1952–2014 period, 1 − 0.19 m a , A. Royer ± 2 150 000 km ∼ 0.30 0.21 m a w.e. on the TNIC for the 1958/59–2014 period. More recently, − ± 1 − 0.37 , E. Berthier − 1 0.16 m a ± n Island, Nunavut, Canada), the small Grinnell and Terra Nivea ice caps have ffi 0.47 − This discussion paper is/has beenPlease under refer review to for the the corresponding journal final The paper Cryosphere in (TC). TC if available. Centre d’Applications et de Recherches en Télédétection, Université de Sherbrooke, Laboratoire d’Etudes en Géophysique et Océanographie Spatiales, Centre National de la Department of Earth Sciences, Uppsala University, Sweden previously at: the Geological Survey of Canada, Northern Division, Ottawa, Canada recent rates of area,borne elevation and and spaceborne mass datasets.areal changes of Results extent both show has ice that(GIC) decreased caps the extent by was using Terra reduced 34 in-situ, Nivea % bytion air- Ice 20 since % accelerated Cap since the at (TNIC) 1952. the late Forfor beginning both 50s, the of ice GIC while the caps, was the 21st rates of century. Grinnell area The Ice reduc- glacier-wide mass Cap balance Abstract In the far south of thesula Canadian (Ba Arctic Archipelago (CAA), onreceived the Meta little Incognita attention Penin- comparedevolution to can, the however, give much valuabletic larger information warming ice about at masses the lower further impact latitudes north. of (i.e. the Their 62.5 recent Arc- the TNIC has experienced an accelerated rate of mass loss of and between 2007 and 2014.1958/59–2007 This period rate ( is 5.6 times as negative when compared to the one of the majorcurrently glacier observed regions warming in in the2013; the world Kaufman Arctic et (Pfe (Vaughan al., et 2009), glaciers al.,mass have 2013; loss. recently experienced For Tingley an the and acceleration southern in Huybers, between their parts the of historical the CAA, (1963–2006) annual and thinning recent of (2003–2011) glaciers has periods doubled (Gardner et al., pared to the mass balance of other glaciers in the southern parts of Ba With a glacierized area of 1 Sherbrooke, Québec, Canada. Centre2 d’Études Nordiques, Québec, Canada Recherche Scientifique (LEGOS – CNRS,Toulouse, France UMR5566), Université3 de Toulouse, 31400 * Received: 16 February 2015 – Accepted: 2Correspondence March to: 2015 C. – Papasodoro Published: ([email protected]) 16 MarchPublished 2015 by Copernicus Publications on behalf of the European Geosciences Union. the 2003–2009 period. Agiven similar the calculated acceleration elevation in changes and mass the loss proximity. is suspected for the1 GIC, Introduction Area, elevation and mass changestwo of southernmost the ice caps ofCanadian the Arctic Archipelago between 1952 and 2014 C. Papasodoro The Cryosphere Discuss., 9, 1667–1704,www.the-cryosphere-discuss.net/9/1667/2015/ 2015 doi:10.5194/tcd-9-1667-2015 © Author(s) 2015. CC Attribution 3.0 License. 5 10 15 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 2–3 m ∼ ) and Penny 2 cult access to ffi 17 km south of the ∼ erent in situ geophys- 5900 km ff ∼ n Island region. ffi W) covers an area of 107 km ◦ W) is located n Island (Nunavut, Canada) is the ers from that of Way (2015) in the ◦ ff ffi (August 2014; this study) with a sim- C over the past 60 years, while mean ◦ C. Total annual precipitations reached 2 ◦ 24 N, 66.79 − ◦ N, 66.51 ◦ 1670 1669 200 mm). For both the GIC and TNIC, any present- 200 km northwest of the two ice caps) indicate that ∼ ∼ in 2009 (Gardner et al., 2011), making this region one 1 − 12 Gta ± 300 mm; rain: ∼ 92 − . In addition to the two major ice caps, Barnes ( ), the island is also covered by a number of isolated icefields and small 2 0.65–0.75 m water equivalent) was approximately equal to the rate of sur- 2 erential GPS) surveys. Our analysis di ff ∼ 6400 km Located in the southeast part of the CAA, Ba 500 mm (snow: 37 000 km ∼ snow; or face lowering by meltprobably in very summer close, (Zdanowicz, or 2007). slightly Hence below, the the present-day summit equilibrium of line the altitude (ELA). GIC is 2 Study area The GIC andsouth TNIC of (Fig. Iqaluit, 1) Nunavut. are The GIC located (62.56 on the Meta Incognita Peninsula, 200 km choice of photos, DEMs,ular, and we spaceborne, explored the remotely-sensed usePléiades data of satellites we sub-meter used. to resolution Inhomogeneously derive stereo distributed partic- pairs accurate ground obtained control DEMs points from andcessing (GCPs) the of for to new aerial the photogrammetric collect photos pro- archives.pattern accurate, We of place numerous regional our glacier and findings changes ining across the factors the context of CAA, of particular and the discuss relevance observed possible for climatic the forc- southernmost Ba (August 2014; this study)(a.s.l.). with On the the highest northeastconnects elevations side, to rising some the at outlet ocean. 800 glaciers The m extend TNIC above near (62.27 sea Frobisher level Bay, which summer temperatures ranged between 6∼ and 7 GIC. It covers an areailar of elevation approximately range 150 to km thecontinued GIC. presence Mercer of (1954) plateaumers suggested ice (2) three frequent factors caps low-level supporting on cloudinessstation the Meta and in (3) Iqaluit Incognita heavy (34 Peninsula: ma.s.l. snowfall. (1) Data and cool from the sum- weather day accumulation is likely only inrefreezing the of form of snow superimposed meltwater. ice,the Field i.e. ice summit observations formed in by of in winter GIC, situ 2003/04 and showed the no estimated firn net at winter snow accumulation there ( winter temperatures in this region averaged 2012). Over the entire2009, CAA, reaching the rateof of the mass main change contributors hasAntarctica to tripled (Gardner eustatic et between sea-level al., 2004 riseglaciers 2013; and for is Vaughan this thus et period, critical. al., after 2013). Greenland Continued monitoring and of CAA largest island of∼ the CAA (Andrews et al., 2002) and contains a total ice area of ( Nivea Ice Cap (TNIC) (Fig. 1).have Compared received to little Barnes scientific and attention Penny so ice far caps, (Andrews, GIC 2002). and Di TNIC ice caps such as the two southernmost ice caps, Grinnell Ice Cap (GIC) and the Terra ical measurements were carried out80s in by the teams 50s from (Blake, Cambridge 1953;1982, University Mercer, 1984). and 1956), Other the measurements and were University in conductedfrom of the in Colorado Bates the (Dowdeswell, College early (Maine, 90s USA) byogists a and scientific from the team Nunavut the Arcticthe Geological College. GIC In Survey (GNSS 2003/04, elevation of glaciol- measurements,measurements, Canada automatic stakes, weather etc.) carried station with installation, out theserving snow objective in site. to situ Consistent create prohibitive and measurements weather maintain on conditions a coupled long-term with ob- di the ice cap have ledis to a the recent cancellation of study the (Way,both 2015) project GIC which (Zdanowicz, and analyzed 2007). TNIC the since An the changingsat) exception 1950s rates imagery using of and historical areal digital aerial recession photographs, elevationthese satellite models of results (Land- (DEM). by In presenting the ations present comprehensive (1952–2014) study, analysis of we of supplement area, historical surfaceperiod elevation and 1952–2014. and This recent mass is fluctua- done forlaser by the combining altimetry GIC data and and from TNIC spaceborne opticalin over instruments stereo the (e.g., situ imagery), (di DEMs, airborne imagery (air photos) and 5 5 10 20 25 15 10 15 25 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 60 % between two Canadian National ∼ cients (RPCs), which ffi 1671 1672 30 % between each line and ∼ 10 %) were present during the two TNIC acquisitions (Fig. 2). < (Natural Resources Canada archives). In this study, we used 24 pho- Three stereoscopic pairs were acquired over our study area (Table 1): one for the Observations from various expeditions in the 50s revealed that the western margin allows geometric modeling withoutthe GCP. generation Those stereoscopic of pairs recentphotogrammetric were processing DEMs of used on the (1) historical both for aerial ice photos caps on3.2 the and GIC. (2) for Historical aerial GCP photos extraction forArchives the aerial photos covering the GIC were obtained through the Air Photo Library tos acquired at the end ofEagle the ablation IX season, Cone on 21 524 andflight camera 22 altitude August type was 1952. 16 A with 000 Williamson ft awith (4879 focal an m). The length overlapping photos of coverage are 152.15 of distributed mm in was 3 parallel used flight and lines the photos of a same line.ble, mainly On due these to images, the thequality late surface of summer texture acquisition detail of date. compared the Thesewere to GIC used photos, later for is exceptional the in series clearly extraction their visi- (1958 ofto historical onwards) the elevations Canadian taken on Digital from the Elevation GIC higherthe Data and latter, (CDED), altitudes, were especially given thus in numerous preferred the artefacts accumulation contained area. in 3.3 Historic Canadian Digital Elevation DataHistoric (CDED) CDED provided atquired a for the scale two ofaerial ice photos 1 : acquired caps. 50k during These (Natural summersric elevations 1958 Resources and and were referenced Canada) 1959. to created Raw were the by elevations Canadian ac- are stereo-compilation Gravitational orthomet- Vertical of Model of 1928 (CGVD1928). Acquisitions were made atgree the of end texture of due theticularly to ablation true a season for more the to humidThereby, present ensure surface this images, a (Berthier since is maximum and the de- a Toutin,2010). ice 2008). Each caps good This image were qualitative is was nearly provided par- primary winter with snow concern Rational free. Polynomial about Coe the ice caps’ fate (Pelto, free while a few clouds ( GIC (3 August 2014)26 and August two 2014 for for the the western TNIC part). (14 The August stereoscopic pair 2014 covering for the the GIC eastern is cloud- part and 3.1 Pléiades stereoscopic images Launched respectively on1A 17 December and 2011 1Bon and satellites glaciers 2 have and Decemberet thus, recently 2012, al., for the shown 2014). mass The Pléiades their twoprovide balance satellites panchromatic high calculations follow and the potential (Wagnon multispectral same ettion, imagery for near-polar at i.e. al., sun-synchronous DEM a 0.7 orbit 2013; m very and extraction Both Berthier for high satellites panchromatic ground have spatial and independent resolu- matic 2.8 stereoscopic m capabilities. band for The images multispectral fact deriveda that images the from clear (Astrium, panchro- advantage Pléiades 2012). on satellitesthat a a are glacier large coded surface radiometric in (especially rangeration provides accumulation 12 (Berthier better area), et bits contrast al., given and represents 2014). the limit the fact risk of image satu- of the GICwhen was compared relatively to stable,near photographs but both from that ice 1897 caps outlet (Mercer,100 in glaciers years the 1954, and were early that 1956). 80s shrinking both MorainesLittle indicated ice moderately studied Ice that caps were the Age probably main cold2002). at retreat climate their Dowdeswell dated (1982) interval largest from estimated areal (Muller, the extent thatWatts 1980; last during the Bay Dowdeswell, the outlet 1982, extended glacier 1984; much ofanother Andrews, further the outlet glacier GIC out to that a the calves south few into of centuries the earlier, ice cap but was also advancing. 3 reported that Data 5 5 10 25 15 20 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er et al., 2014) ff 65 m and a spacing of ∼ high-precision Real-Time ® erences). ff , which corresponds to a base-to-height ◦ 1674 1673 erences and their standard deviation (SD) were previously ff erent time periods, namely a few months before (April 2007) and af- ff glacier between 21 Arctic CDED maps tiles and ICESat laser altime- ff erent dates. We used the raw vectors from the 1 : 250k Canadian National ff pulse-derived corresponds to field-of-view with a diameter of 172 m between each footprintfrom (Schutz et their al., original 2005). Topex ICESatvided Poseidon elevations by were ellipsoid the converted to Nationalwas the Snow used WGS84 for and absolute ellipsoid Ice coregistrationa on Data using few ice-free Center. tools selected terrain, The dates while pro- (Table the entire 1)the data were dataset ice collected used caps. (2003 during for recent to elevation 2009) change calculations over 3.6 In-situ GPS measurements In April 2004, a teamelevation profiles from at 50 the m Geological horizontal intervals Survey using of a Trimble Canada measured three surface ice cap contour was usedthe for orthorectified 1999, panchromatic while Pléiades wefor manually image. four digitized For di the the 2014 TNIC, margin outlines from were derived Kinematic (RTK) GPS system onand the at southeast, west the andusing front northwest a of sides of fixed an the basewere outlet GIC, subsequently station glacier processed on with (Zdanowicz, the a 2007).Positioning Canadian geodetic Center System Data for benchmark (PPS) Remote acquisition monument, Sensing’s to Precise wastransects and were obtain made used GPS for an recent positions elevation accuracy changecalculated calculations. using of It Precise is Positioning a System known and that fewbe referenced elevations to cm. assumed the equal For GRS80 to ellipsoid this can the WGS84 paper, ellipsoid those (sub-mm di 3.4 ASTER DEM Products derived from thelogical ASTER satellite studies mission (e.g., haveorder been Frey widely to et used calculate al., for auct glacio- 2012; recent AST14DMO) Nuth mass generated and from balanceThis Kääb, an DEM rate was 2011; ASTER for automatically derived stereo Das the fromviewing) pair bands TNIC, et that 3N have acquired we an al., (nadir-viewing) intersection on and used angle 2014). 3B 3 ofratio a (backward- 27.6 In of August DEM 0.6 2007. (prod- (Fujisada etspacing of al., 30 2005). m The and rawpoints elevations from DEM are two was orthometric di provided to with theter an (November EGM96 2007) horizontal geoid. the Using grid ASTER 57(SD) acquisition, ICESat on we the assessed ice a cap verticalavailable for precision for this of the ASTER 2.5 GIC m DEM. at Due the to end cloud coverage, of no the3.5 ASTER ablation DEM season. was ICESat altimetric points Surface elevation profiles (GLA14, Release 634)timetry collected System by (GLAS) the onboard Geoscience ICESat Laser were Al- acquired (Zwally et al., 2002). Each laser 3.7 Glacier outlines Various datasets have been usedend to of extract the the ablation areal seasonferent extent (August–September). dates of For were the the used. two GIC, Thehistorical ice three 1952 caps aerial outline datasets was at photos. from derived the The dif- manually Randolph from Glacier the Inventory orthorectified (RGI 3.2; Pfe try points and were2009). reported Here, to CDED be weresurrounding 0.3 ice-free used and elevations (1) 6.2 m, were ascaps respectively used historical (see (Beaulieu for Sect. elevations and the 4.3). for Clavet, absolutewere Artefacts the coregistration manually located for deleted TNIC in both using and theelevations. ice the (2) accumulation Those derived areas the artefacts hillshade of in werelikely the order less due TNIC to pronounced to exclude CDED than the obviouslyused for poor false to contrast the generate and GIC the low CDED. CDED texture and of were the 1958/59 aerial photos that were The average elevation di calculated o 5 5 25 15 10 15 25 20 10 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect ff n Island region ffi 20 % of the ice cap outline), we used ∼ . No interpolation was performed to fill data 1676 1675 Low culties, especially for archive photos (Barrand et al., ffi cient number of ICESat points, we report here the vertical culty, Pléiades derived products (DEM and orthoimage) ffi ffi ective technic for glaciology studies, particularly used for ter- ff ective GCPs for photogrammetry purposes in mountainous or polar re- ff and the DEM detail to Collecting e Since the ice-free zones on our Pléiades DEM were not large enough to calculate an The following steps of DEM extraction were repeated for the 3 Pléiades stereoscopic rain reconstruction prior to the modern2009). satellite A era (Fox 1952 et DEM Nuttall,a 1997; of Barrand mathematical the et model al., GICdistortions compensating was (PCI for created Geomatics, both using 2013). OrthoEngine.followed terrain to The This compute variation typical the software model and photogrammetric and uses inherent thereby procedure solving was camera the least-square then bundle adjustment. gions remains one of the main di (SD), highlighting theshown precision to consistency be on mostly correlatedhere. glacier with surfaces. slope. This A similar accuracy vertical was precision is4.2 thus expected Aerial photos DEM generation Photogrammetry is an e 2009). To overcome this di elevation accuracy with a su precisions obtained in recent glaciologicalmeasured studies. an For example, accuracy Wagnon ofDEM. et 1 al. Berthier m (2013) et (SD) al. on (2014) a also glacier obtained surface an in accuracy Himalaya ranging using between Pléiades 0.5 and 1 m gaps so thatDEMs the were resulting geocoded with DEMs a do pixel size not of contain 4 m. interpolated elevations. Finally, the pairs. First, we collectedwell-distributed 20 TPs tie was found points to (TPs)ages improve providing outside the increased and relative coverage orientation 6 (Berthierfollowing between on et processing the al., the parameters two 2014). ice were im- For used cap.Mountainous the in Collecting DEM extraction, OrthoEngine: the the relief type was set to latter bias can besuch easily as ICESat. corrected on ice-free terrain with a good reference dataset, Topographic Data Base asthe the interpretation 1958/59 of boundary. Given thecluded the 1999 in anomalies margin the perceived from glaciera in the 30 extent), RGI m we 3.2 resolution ratherwas (i.e. Landsat manually snow manually 5 covered digitized image traced terrain acquired the fromthe in- on ice an on-demand August cap ASTER AST14DMO 1998. orthoimage margin product,orthorectified The using (15 while panchromatic August m Pléiades the 2007 of images 2014 limit resolution) (East margin and provided was West). with extracted To decrease from the the e of cloudiness on the Pléiades orthoimages ( 3.8 Meteorological and sea ice records In order to quantify changes in the regional climate of southern Ba a Landsat 8 panchromaticThe uncertainty (15 m assessment of of the resolution) outlines image is also briefly presented acquired in in Sect. August 4.4.3. 2014. The Pléiades DEMs2013. were No generated GCP were usingprovided available the with for the the OrthoEngine images. geometric modulePléiades Adding correction DEM, GCP of so does but we Geomatica not only relied improve allows on the reducing the vertical RPCs the precision vertical of bias the (Berthier et al., 2014). The over the period coveredIqaluit in weather our station study, for air 1950–2014the temperature). (http://climat.meteo.gc.ca/ records eastern This were is Canadian the retrieved Arcticthan station from a in with the few decades. the Furthermore, most seaStrait continuous ice were covered obtained records area from of extending the the(http://www.ec.gc.ca/glaces-ice/). Canadian back Hudson Ice Strait more Service and archives Davis for the 1968–2014 period 4 Methods 4.1 Pléiades DEM generation 5 5 25 20 15 10 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , X set ff . The gen- Y 0.1 m, while an average − and 2.15 m in X erences over ice-free terrain (Nuth and erences measured outside the ice cap ff ff ect of geoid variations (CGVD1928 and ff 3.29 m (ICESat below in elevations) and a SD 1678 1677 − set of ff . TPs residuals were 1.84 m in Z set measured over the ice-free terrain was ff ) of ice-free terrain near the ice caps (Fig. 2). This corridor coincides with set was below 1.5 m in each case, suggesting that the absolute coreg- 2 ff erence of about 0.64 m was measured over the ice cap, probably due to and 2.68 m in ff Y erent laser overpass periods (autumn 2003 to winter 2007), and the 2014 Pléi- 20 km ff ∼ Furthermore, the two independently coregistered Pléiades DEM of the TNIC (14 and Validation of the resulting DEM (before coregistration) against 76 ICESat points on 1000 ICESat points over ice-free zones. All other DEMs were then 3-D coregistered the CDED tile encompassing the two∼ ice caps was first coregisteredto with the approximately corrected CDED, independently forreferenced each ice to cap the and WGS84 the corrected ellipsoid. datasets To were evaluate the corrections consistency, the o elevation di the thinning between 14 andcoregistration 26 using August. the These corrected results CDED prove the DEM. robustness of the4.4 3-D Elevation changes and mass balance4.4.1 calculation Elevation changes along ICESat andFor GPS both tracks ice caps, recentfrom elevation di changes were measured betweenades 6 DEMs. ICESat tracks, For theApril GIC 2004 only, in elevation situcompute changes GPS a were transects glacier-wide and also mass thements balance calculated 2014 from since between those Pléiades (i) the recent DEM. theyand elevation We changes are (ii) did measure- sparse not GPS attempt and andlimited to data only some were cover of available a to the apply small ICESat a fraction seasonal data of correction. were Nevertheless, the acquired those two recent at ice the caps end of winter and 26 August) werecorresponding subtracted o in order to analyze the overlapping zone (Fig. 2). The EGM96 vs. WGS84) was negligible for such small zones. istration was well conducted and that the e of 4.96 m. Moreover, the SD of the elevation di over ice-free terrain between eachwere corrected verified. DEMs However, and onedistributed corresponding must and ICESat interpret limited points these number of resultsterrain. ICESat The carefully points o given (less the than sparsely 100) over moderate to hilly 4.3 DEM adjustments and coregistrations DEM coregistration is of primarybalance importance calculation before (Nuth performing and anyrelation Kääb, DEM-based between aspect, 2011). mass slope This and 3-D elevation di coregistration method uses the limited number of cloud-free ICESatrect shots (less coregistration than between 100 the for Pléiades each ice DEM cap) and so ICESat that was a di- not possible. Instead, were used to collectsurrounding GCPs. ice-free For terrain, each 3 aerialgraphic to stereoscopic or 7 model geomorphologic GCPs partially structures were covering visibleaerial collected on the photographs. both outside the In the Pléiades ice ordercollected orthoimage cap to as and on the strengthen stereo topo- GCP, the i.e.of mathematical 39 was model, stereo identified GCPs every in werestereoscopic GCP all collected model possible was resulting were aerial in collected photographs. 106of dispersedly. the A For GCPs. photogrammetric the Also, total block 6 and models covering to situatedwere only 10 in the collected TPs ice the in cap per middle (no order aerial stablebundle to terrain), adjustment, only connect the TPs them resulting to2.74 residual m the averages in of photogrammetric all block. the After GCPs the were final 2.85 m in between the Pléiades DEMwas and the 13.8 m, 1952 while DEMGIC (coregistered 16.5 m area together, see was was Sect. measured extractedtexture-less 4.3) accumulation on with areas. data the gaps ice concentrated cap. at Quantitatively, 66 the % highest of elevation the in the Kääb, 2011) using ICESat as reference. Theridor Pléiades ( images only included a small cor- ice-free terrain showed a mean o erated global DEM was geocodeddata with gaps a was grid performed. resolution of 10 m and no interpolation of 5 5 15 20 25 10 15 20 25 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , , t (3) d avg t d M/ . H/ no value avg t d erential DEM w.e.), d ff 1 H/ − is the time interval t ∆ (raw elevation change rate t is the mean elevation change d H H/ ∆ ) after dividing by the interval time. t d erent DEMs in order to calculate glacier- (Huss, 2013). For the sake of readability, ff H/ 3 − 1680 1679 is the area of the elevation band. Hypsometry is of the corresponding elevation band. Total volume i A H w.e.) as also demonstrated in Gardner et al. (2011). 1 − and i ) was then assessed by summing volume changes from all V 100 m) was found between the two elevation products. Applying 0.01 ma < < ρ , (2) ) as follows: · , (1) ) n ) t i avg ∆ V A t · · d ), or elevation change rates (d d i A ( H H H/ ∆ = d ( is the density constant of 850 kgm is the average between initial and final ice cap areas and corresponds to an elevation band of 50 m, = i ρ i A n avg t X t d d were binned into 50 m elevation bands and averaged after applying a three sigma = 0.1 m) and probably underestimated uncertainty for the elevation change averaged Finally, the area-averaged specific geodetic mass balance rate (ma The coregistered DEMs were first subtracted in order to obtain maps of elevation On the other hand, spatial autocorrelation between the ASTER 2007 and Pléi- The elevation change rate averaged over the entire ice cap (glacier-wide), d M/ H/ H V ± assuming that elevation errors werethat 100 % takes into correlated. account This both is the a2012) highly conservative correlated and CDED approach the elevation errors possible (Gardnerfacts et errors and al., associated low to coverage at the higher aerial altitudes). photos-derived DEM (i.e.ades arte- 2014 DEMs was analyzedchange on uncertainty ice-free in terrain to thecorrelation better distance recent ( characterize mass the balance elevation standard estimation principles on of error the propagation( TNIC. (e.g., A Zemp low et auto- al.,over 2013), the we entire found ice a cap. very Consequently, low it was instead conservatively assumed that the The main sources oftainties in uncertainty the in elevation change ourto measurements, mass the convert ice balance volume cap retrieval to limitsuncertainty are and mass was the related assumed changes. density equal to used For totered uncer- historical the DEMs SD (GIC measurements, over 1952–2014: stable elevation 13.8 m; terrain change TNIC between 1958–2007: the 9.6 m; two TNIC coregis- 1958–2014: 9 m), resulting from coregistered DEM subtraction) was distinguished from d the area-averaged specific geodeticafter mass simply balance referred rate as mass (Cogley balance et or al., glacier-wide 2011) mass4.4.3 balance. is here- Accuracy assessment was calculated as follows: d where where between the two DEMs. In the following sections, d change for an ice cap (d was then calculated as follows: d elevation changes along selected tracks are useful to complement the di d filter to exclude outlierspixels were assigned (Gardner to et the mean al., d 2012; Gardelleelevation et bands al., ( 2013). The based on the 1 :the 250k oldest CDED DEM (1958/59) used while in thethe the ice DEM calculation. cap used Sensibility limit to tests isbalance have derive conform shown calculation the to that ( the hypsometric the year analysis choice of has of a very low impact on the mass changes (d d analysis described below. 4.4.2 DEM derived elevation changes andThe mass geodetic balances method was applied usingwide the di elevation changes andeach mass calculation. balances. The following steps were performed for measured at elevation band where 5 5 25 15 20 10 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 1 ± is − avg 1 t − 6.7 d 0.003 a − for the 2 ± 1 H/ − 0.19 ma a 2 1 % of each ± 0.10 − < 0.02 km 0.9 ± − , a rate 5.6 times 1 − 0.05 km maps), revealing an between 1958/59 and ± 0.59 t 1 d − − was conducted over the . Similar patterns of his- ) for the two ice caps are 1 H/ t t 1.69 − 2 % of each ice cap extent) d d 0.40 ma − between 1958/59 and 2007), < ± H/ H/ 1 − 0.22 ma for the GIC and ± 1.97 . On the GIC, the surface thinning 1 0.19 ma 1 − − , a less pronounced rate when com- − ± 0.3 1 2.5 m for the ASTER DEM), assuming measured between 1958/59 and 2007. − − ± 0.22 ma as a function of elevation are shown in 1 was − ± 0.56 t d − 0.1 ma 0.25 ma avg 0.9 t − 1682 1681 H/ ± d − 0.25 ma 1 %). The total uncertainty of 3 % was used for ± H/ 1.1 0.22 ma < − ± 0.44 ) was experienced on the northeast outlet glaciers be- for the GIC. For the GIC, the 2014 areal extent is about 1 − 1 0.35 − was assigned to the density factor when converting from − − 3 a − 2 1 ma − < 60 kgm between 2007 and 2014 vs. 0.04 km ± 1 ± 1 m for the Pléiades DEM and between 1952 and 1999, whereas a rate of − ± are observed for both ice caps (Fig. 6 and d 1 − t 1.37 a between 2007 and 2014 vs. d − 2 1 − H/ 0.40 ma ± erence in extent was obtained ( 1.7 3 %) km The historical (1952–2014) glacier-wide averaged elevation change rate (d We estimated an error of 3 % for the ice caps outlines. This represents a synthesis On the GIC, a comparison of recent and historical d Elevation change rates sharply decreased in the recent years for both ice caps. On ff − ± ( measured for the TNIC betweenbeen 1958/59 significantly and more 1998. negative TheseTNIC since rates and 1998/99 of reaching area change have volume change to mass change (Huss, 2013). 5 Results 5.1 Area changes Areal changes measuredshown for in Grinnell Fig. and 2. Terra The Nivea GIC ice has caps experienced a since rate the of 50s area are change of 20 % smaller than during1958/59 and the 2014. 50s, while the TNIC area has shrunk by 34 % between 2007). merged in situ GPS pointsis and the ICESat only transects from recentrestricted March–April period to 2004 4 with (Fig. transects. 4). aabout One This reasonable the should coverage note seasonal of that height the given fluctuation, whole the no ice limited correction information cap available was although applied to account for the but is also unambiguously( observed in the upper sections of the accumulation area for the TNIC invations the above lower 250 ma.s.l., altitudes the (i.e.compared thinning the rate to outlet is the glaciers consistently GIC, in more at negative the for an peripheries). the average For TNIC, of ele- 0.40 ma pared to TNIC that experienced a rateaverage of surface lowering reaching as negative than the rate of 5.2 Elevation changes Maps of historical andpresented recent elevation in change Figs. rates 3–5Figs. (d 4–6. and trends of d torical d was similar for alla outlet stronger glaciers lowering between ( 1952tween and 1958/59–2007 2014 (Fig. 5, (Fig. upper 3) left while map). for thethe TNIC, TNIC, the recent (2007–2014) d The acceleration of the thinning rate is particularly strong at lowermost altitudes ( for the GIC was measured at of both the areas of possible image interpretation errors ( uncertainty for the elevation changesuncertainties was ( equal to the quadraticthat sum (i) of the the elevation twothe errors DEMs two are DEMs fully are correlated independent. within each DEM and that (ii) errors of and the impact of the image resolution used for outlines delimitation ( ice cap extent). Sincewere the mainly related ice to caps thecap. were snow-covered The surfaces not (i.e. error covered snow attributed patches) byanalysis to around made debris, each the between interpretation ice the image Pléiades errors resolutiondi and was Landsat 8 established derived from outlines, a for which comparison a small mass balance estimation as wellparable as to for area results change presented analysis.an in This uncertainty uncertainty Paul of is et com- al. (2013) and Winsvold et al. (2014). Finally, 5 5 25 20 10 15 20 10 15 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) ± 1 − ). As 1 0.47 culties − was up − ffi t d 0.36 ma H/ ± 0.19 ma November). The ± 1.68 > − ) when compared to 1 0.30 − − ected by film distortions ciency of using Pléiades ff erent periods with a mass ffi ff 1 m) in order to collect a suf- 5 m (1-sigma confidence level) 1.47 ma < − ∼ 2–3 m in average were obtained after w.e. was measured on the GIC. The ∼ 1 16 m for the TNIC) is likely at least partly − ∼ cult to exploit due to the logistical di 1683 1684 ffi 0.21 ma ). 1 ± − 0.37 − 0.25 ma − 11 m for the GIC and of ∼ erence in elevation change between 2003 and 2014 for the two ice caps 65 m in average) than the transects on the TNIC. ff w.e. This long-term average encompasses two di ∼ n Island to verify the coherence of results and get a more complete picture of 1 − ffi erent elevation acquisition periods of 1952 and 2014 (August) and 2004 (March– Additionally, the elevation changes measured between ICESat same-track transects ff involved in the field collection oflatitude accurate or and high well-distributed altitude GCPs inhere, regions. the however, Field we remote GCPs took high were advantage(0.7 lacking of m) for the and the very the two high vertical ice resolution precision caps of of studied the the Pléiades derived imagery DEM ( 6 Discussion 6.1 Pléiades as a tool forIn photogrammetric many GCPs regions collection ofa the potential world, vast gold archives minechange of for of historical glaciologists aerial glaciers in photographs andDEM order represent generated ice to from caps depict these (e.g., aerial themass photographs Soruco losses multi-decadal allows in et volumetric comparing order al., historicalations. to and 2009; put However, recent Zemp these in a data et longer-term remain al., perspective di 2010). the The recent glacier mass vari- ficient number of GCPson for the well-defined adjustment features of thatand the were the stereo-model. GCPs old clearly were aerial identifiable collected photos. on GCP both residuals the of Pléiades imagery the block bundle adjustment, andwas a measured DEM with precision of a fewfactory ICESat result points given available that over ice-free the terrain. aerial This photos is used a here satis- were a di that could not be corrected. Our results demonstrate the e April). For the 203and points 2014 where (points elevation superposed measurements with are black available dots in on 1952, the 2004 Fig. 4), the recent d stereo-images to collect accuratephotographs GCPs in for remote photogrammetric environments. processing of old aerial 6.2 Comparison to other studies Our estimates of shrinkage forfrom the Ba GIC and TNICthe can pattern be of compared glacier with changes other across studies this vast region. previously discussed (Sect. 5.2), theof GIC its has mass likely loss experiencedmated since, a given 2004. similar the However, acceleration no lack reliable ofthe recent comprehensive 2000s coverage mass for (i.e. balance this either ice could altimetry cap. be data esti- or DEM) in to 6 times morethe negative 1952–2004 for period the ( 2004–2014 period ( loss 5.6 times greaterwhen for compared the to period the 2007–2014 period 1958/59–2007 (mass (mass balance: balance: and Pléiades DEM are shown inof Fig. 7. annual This analysis elevation reveals (1)and changes a very (2) between similar variability heterogeneous both but ice coherent seasonal caps fluctuations during (March the 2003–2007 interval 2014, a mass balance of 5.3 Mass balances Mass balances for both ice caps are summarized in Table 2. Between 1952 and absolute di (total thinning of explained by the factaltitudes ( that ICESat transects covering the GIC are located at higher 0.16 ma historical mass balance for the TNIC (1958/59–2014) was more negative at 5 5 10 15 20 25 20 15 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) 2 n Is- 16 % 6.6 to N, ex- ffi − C) and ◦ ◦ ± 0.14 − erences in hyp- ) over this similar ff (135 to 120 km w.e) between the 2 1 1 − − a 2 8.5 km ± 0.12 ma ± 0.36 km for 1952–1999 (131.8 − erent between the three studies, 1 ff N, excluding the Penny Ice Cap) − N) are unfortunately too discontin- ◦ 0.76 a ◦ ), while the GIC areal extent reduced 2 − 2 9.9 to 173.2 ), while our own results give a nearly n Island glaciers (North of 68.6 2 ± ffi erence is likely due to di ff 7.5 km 0.05 to C between 1958–2007 (mean: ◦ 1685 1686 0.003 km ± ± (196.2 ± 1 50 year long SAT record from Iqaluit shows that − 0.20 a > 2 0.10 − − ). Results of Way (2015) are superposed in Fig. 8 (lower (197 to 169 km 2 erence which Gardner et al. (2012) attribute to the higher 1 ff w.e between 2005 and 2011 (Gardner et al., 2012). The erent spatial resolutions and acquisition dates of the data n Island is the decline in summer sea ice cover in this re- − n Island (South of 68.6 ff a 0.02 km ffi C), relatively to the 1950–2014 mean. Climate records from ffi 1 2000 ma.s.l.) of the Penny Ice Cap. The comparatively larger ◦ 2 − ± 0.9 km ∼ ± n Island, the 0.59 w.e., a di ffi 1 − 0.66 km − 0.12 ma ). Way (2015) recently reported that between 1973 and 2013, the TNIC − 2 ± erences in size and to the hypsometry of the ice caps, but also possibly to ff since 1968; Tivy et al., 2011). In the Hudson Bay – Hudson Strait – Foxe 1.08 1 0.12 ma 6.3 km − − ± ± On southern Ba Sharp et al. (2014) reported rates of areal change for the TNIC between 1958 and An important factor that likely contributed to the accelerating rate of glacier reces- Gardner et al. (2012) estimated that the average mass loss rate of all glaciers and 0.52 2007–2014 (mean: 0.58 uous to allow quantificationare of probably SAT close changes toseparated on those by Meta observed 17 km, Incognita in they did Peninsula, Iqaluit.mass not but Although experience loss these the the (Figs. same GIC historical 3–5), and rates and of TNIC shrinkage are part and only of the di stations further south (ex: Resolution Island, 61.5 sometry, which strongly influences(Oerlemans the response et of al., glaciers 1998;at to Davies slightly a et higher given al., altitude climate 2012; thanpared forcing Hannesdottir the to et TNIC, 68 % al., with for 2014). 77mass % the The balance, of TNIC, as GIC its and our lies area is observations above confirm. therefore 600 expected ma.s.l., to com- havesion a on slightly southernmost less negative Ba gion (Fig. 8b and c),decade one of the steepest observedBasin across region, up the to entire 70–80 CAA %and of (up the to autumn sea surface ice decline air has temperatures been attributed (SAT), to respectively, warmer wind spring forcing accounting for summer temperatures increased by 0.72 mass loss rates experienced bycribed the to GIC di and TNIC in the past half-century can be as- 6.3 Regional context and climatic factors The accelerating recession of glaciershas and ice been caps ascribed across to theperiod, CAA warming a in situation Surface recent that decades Atmosphericeastern results Temperatures Arctic from (SAT) that during a enhances sustained this advectionet atmospheric of al., warm circulation 2011). air pattern This from situation inof the has the northwest led the Atlantic to eastern (Sharp warmer, longerbalance CAA, summer (Weaver, 1975; melt Hooke and et periods al., this on 1987;et glaciers Koerner, largely al., 2005; 2012). Sneed accounts et al., for 2008; Gardner their increasingly negative mass local climatic factors, as described below. estimated mass loss− rates on Pennyelevation Ice range (up Cap to between 2003 and 2009 is lower at land at elevations betweenning 400 acceleration and 1100 (Sneed ma.s.l., etrate recently al., of experienced 2008; a Dupont strong et thin- al., 2012), resulting in a mass loss identical figure of periods 1957–2006 andmated 2003–2009. over This similar acceleration periodscluding is the for more Barnes northern than Ice Ba twice Cap). that The esti- Barnes Ice Cap itself, located on central Ba 2000 of up to period. For the GIC,reported however, by the Sharp shrinkage etnegative rate al. as of (2014) our over own the period figure 1958–2000 of is three to four times as increased by almost 4 times (i.e. our results agree withindisparities the could error be barscaps, explained when as by given. well We the as hypothesize interpretationsource by that (Paul of the et those al., snow di small 2013). patches around the ice ice caps on southern Ba panel). Hence, even though the results are slightly di 126.9 by 18 % (134.3 to 110 area decreased by 22 % (199.1 to 154.8 5 5 10 25 20 15 20 25 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ) n ± 1 − ffi 0.05). Ca 0.30 ◦ − N), where p < ◦ 0.05) since the w.e. (1958/59– 1 w.e. (1952–2014) − 1 p < ( ect that results from − ff 1 after 1992 ( − 1 − 0.16 ma daya ± 0.21 ma ◦ daya 1 ± ◦ ∼ 0.47 − 1.2 0.37 − ∼ 1688 1687 over the period 1984–2006, and probably faster 1 − a 2 − er somewhat from that of Barnes Ice Cap (70 ff n Island (Gardner et al., 2012). ffi 0.8 Wm ≥ Charles Papasodoro acknowledges support from the Fond Québécois de w.e., a rate 5.6 times as negative as the mass balance of 1 − ; Hocheim and Barber, 2014). A direct consequence of the sea ice retreat in w.e. measured between 1958/59 and 2007. This is also twice as negative as 1 − 1 0.36 ma − ± Ca ◦ The 2007–2014 mass balance on the TNIC is among the most negative multi-annual Historical glacier-wide mass balance has been Results showed that the extent of the TNIC is 34 % smaller in 2014 when compared The air temperature record from Iqaluit (Fig. 8a) shows that while the sum of positive 1.68 after the mid-1990s whenresulting sea positive ice radiative decline forcingdownwelling accelerated is solar (Matsoukas expected flux to et is be al., atmelt largest its 2010). rates on annual in The glaciers maximum, mid-summer of and when Meta this Incognita the has Peninsula likely in enhanced recentdegree-days surface decades. (PDD) in July in this region increased by the average mass balance obtainedin between the 2003 southern and part 2009 of Ba for other larger ice caps observed in the southernSouth-East mid-latitudes Alaska (Trüssel (Willis et al., et 2013). al.,of This similarity 2012; maritime underlines Berthier low-elevation the ice strong et bodies sensitivity latitudes al., to and 2009) the in or currently polar in observed regions climate (Hock change et at mid- al., 2009). In the case of the southern Ba glacier-wide mass balances measured to date, comparable to other negative trends 0.19 ma Recherche en Nature et Technologies (FQRNT) fellowship program and the Centre d’Études since the beginning of the 21st century. for the GIC and2014). slightly more The negative mass for− TNIC balance at measured for the TNIC between 2007 and 2014 was Island, the ice cap wastagea is rapid decline probably in due summer to sea a ice regional coverAcknowledgements. warming in partly this region. explained by to end of the 50s’2014. extent, Both while ice the caps have GIC also had experienced shrunk strong by acceleration nearly of their 20 % shrinkage between rates 1952 and 7 Conclusion This paper highlighted historical and recentfor trends in the area, elevation two and mass southernmostIce changes Cap ice (GIC) caps anddatasets of the and Terra the uses Nivea an Ice Canadian original Cap approachmetric Arctic where (TNIC). processing ground Archipelago, of Our control old points the analysis aerial for is photographs Grinnellades the are photogram- based stereo-images. derived on from multiple sub-meter resolution Pléi- the balance (Hocheim and Barber, 2014).immediately The retreating south sea of ice cover Meta inlarly Incognita Hudson large Strait, Peninsula, rise has in beencover mean accompanied minimum, SAT and by during the a rate autumn particu- of months autumn (SON) warming during between 1980 or and after 2010 the (0.15 sea ice is estimated to have been(0.05 three times greater than the mean between 1950 and 2010 this sector has been to increasemated the average net rate solar of flux received at the sea surface at an esti- relatively cool 1960s–70s, this rate increased to PDD recorded at Iqaluitin also increased April in or SeptemberTNIC May. and These October, in but observations recent not decades suggestautumn, noticeably possibly may that linked be increased to due2014). melt the This in later rates situation part freeze-up would on di in tothe GIC Hudson a lengthening Strait and of lengthening (Hocheim the of andevents melt Barber, the (Dupont season melt was et season attributedmay al., to in have 2012). more a clear frequent With illustration early of the spring the current thaw Arctic warming recession amplification of e the GIC and TNIC, we changes in surface albedochanges and over surface land and heat sea exchange (Serreze brought and about Barry, 2011). by cryospheric 5 5 20 15 25 10 10 15 20 25 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | n ffi n Island, Arctic, Vol. 6, 167 pp., 1953. ffi 1690 1689 n Island, N.W.T., Canada, unpublished MA Thesis, University of Colorado, Boulder, ffi n Island, USGS Professional Paper 1386-J-1, J162–J198, 2002. ffi Island, N.W.T., Canada, Arctic Alpine Res., 16, 311–320, 1984. Monitoring the melt seasoning active length and of passive, thedoi:10.1002/hyp.9382 microwave 2012. Barnes remote Ice sensing Cap data, over Hydrol. the Process., 1979–2010 26,737, 1997. 2643–2652, period us- IEEE T. Geosci. Remote, 43, 2707–2714,, doi:10.1109/TGRS.2005.847924 2005. from satellite data: methods, challenges,,doi:10.1016/j.rse.2012.06.020 and results, 2012. Remote Sens. Environ., 124, 832–843, over the Pamir-Karakoram-Himalaya duringdoi:10.5194/tc-7-1263-2013, 2013. 1999–2011, The Cryosphere, 7, 1263–1286, ley, J. G., Braun, C., andin Labine, the C.: Canadian Sharply Arctic increased Archipelago, mass Nature, loss 473, from 357–60, glaciers doi:10.1038/nature10089, and 2011. ice caps son, P.,Kaser, G.,Möller, M., Nicholson, L.,and and Related Zemp, M.: Terms, Glossary IHP-VII ofNo. Technical Glacier 2, Documents Mass UNESCO-IHP, Paris, Balance in 114 pp., Hydrology 2011. No. 86, IACSin Contribution the Wrangell Mountains,imagery, J. Alaska, Glaciol., USA, 60, from 283–293, doi:10.3189/2014JoG13J119, airborne 2014. laser altimetryglacier and response satellite stereo toCryosphere, atmospheric 6, warming, 1031–1048,, doi:10.5194/tc-6-1031-2012 northern 2012. Antarctic Peninsula, 1988–2009,Bay, Ba The Colorado, 169 pp., 1982. Ba Toulouse, 2012. timizing photogrammetric DEMs for glacier volumederived change ground-control assessment points, using laser-scanning J. Glaciol., 55, 106–116, 2009. ICESat, Photogramm. Eng. Rem. S., 75, 81–86, 2009. elevation changes in North-West112, Canada 2443–2454, and, doi:10.1016/j.rse.2007.11.004 2008. South-East Alaska, Remote Sens. Environ., guelen Islands (49S,doi:10.1029/2008JF001192, 2009. 69E) between 1963 andsiokas, M., 2006, Ruiz, L., J. Pálsson,evation F., Belart, Geophys. changes J. derived M. Res., from C., Pléiades and2291, sub-meter 114, Wagnon, doi:10.5194/tc-8-2275-2014, stereo P.: Glacier images, 2014. F03005, topography The and Cryosphere, el- 8, 2275– Fox, J. A. and Nuttall, A.-M.: Photogrammetry as a researchFujisada, tool, H., Bailey, Photogramm. G. Rec., B., 15, Kelly, G. 725– G., Hara, S., and Abrams,Frey, M. H., J.: Paul, ASTER F., DEM and performance, Strozzi, T.: Compilation of a glacier inventory for theGardelle, western Himalayas J., Berthier, E., Arnaud, Y., andGardner, Kääb, A. A.: S., Region-wide Moholdt, G., glacier Wouters, mass B., Wolken, balances G. J., Burgess, D. O., Sharp, M. J., Cog- Dupont, F., Royer, A., Langlois, A., Gressent, A., Picard, G., Fily, M., Cliche, P., and Chum, M.: Cogley, J. G., Hock, R., Rasmussen, L. A., Arendt, A. A., Bauder, A., Braithwaite, R. J., Jans- Das, I., Hock, R., Berthier, E., and Lingle, C. S.:Davies, 21st-century B. increase J., in Carrivick, glacier J. mass loss L., Glasser, N.Dowdeswell, F., J.: Hambrey, Debris transport M. paths and J., sediment flux and through the Smellie, Grinnell ice J. cap, Frobisher L.: Variable Dowdeswell, J.: Late quaternary chronology for Watts Bay Area, Frobisher Bay, Southern Ba Astrium: Pléiades Imagery User Guide, Airbus Defence and Space,Barrand, Geo-Information N. Services, E., Murray, T., James, T. D., Barr, S. L., and Mills, J. P.:Instruments and methods op- Beaulieu, A. and Clavet, D.: Accuracy assessmentBerthier, E. of and Canadian Toutin, T.: digital SPOT5-HRS digital elevation elevation data models using and the monitoring ofBerthier, glacier E., Le Bris, R., Mabileau, L., Testut,Berthier, L., E., and Vincent, Rémy, C., F.: Magnússon, Ice E., wastage Gunnlaugsson, on Á. the Þ., Ker- Pitte, P., LeBlake, W.: Meur, Studies of E., the Ma- Grinnell Glacier, Ba Andrews, J. T., Holdsworth, G., and Jacobs, J. D.: Glaciers of the Arctic Islands. Glaciers of Nordiques (CEN) for an internshipthe at GIC LEGOS were (Toulouse, France). conducted The with 2003/04tical field the support surveys able from on assistance the ofthe Geological J. Nunavut C. Survey Research Lavergne of Institute. andCanada) Canada, D. C. Scott, assisted Kinnard, the F. and with Polar Savopol, logis- Continental the C.was Shelf GPS Armenakis support Project, data and by and P. reduction Sauvé theFrench and (Geomatics Space Natural photogrammetric Agency Sciences analysis. (CNES) This through andthe the research Engineering Geological ISIS Research Survey and TOSCA of Councilfree programs Canada of of (Pléiades charge (field Canada, data) thanks and campaign). by respectively by ASTER to the the and GLIMS Landsat program data (NSIDC) and were USGS. obtained References 5 5 20 30 15 25 10 15 20 25 10 30 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ect , V., ff ć a, K. R., ff n Island, unpublished ffi en, S., and Winsvold, S.: On the accu- ff 1692 1691 , V., and Dyurgerov, M.: Mountain glaciers and ice caps ć er, W. T., Kaser, G., Ligtenberg, S. R. M., Bolch, T., Sharp, M. J., Hagen, J. O., ff n Island, Canada, M.S. thesis, University of Colorado, Boulder, Colorado, 211 pp., 1980. n and Bylot Island glaciers to sea level rise over the past half century, The Cryosphere, ffi ffi er, W. T., Arendt, A. A., Bliss, A., Bolch, T., Cogley, J. G., Gardner, A. S., Hagen, J.-O., ff Rastner, P., Raup, B.dolph H., Glacier Rich, Inventory: J., adoi:10.3189/2014JoG13J176, Sharp, globally 2014. complete M. inventory J., of and glaciers, the J. Glaciol., Randolph 60,ICESat consortium: Mission, 537–552, The Geophys. Res. Ran- Lett., 32, L21S01, doi:10.1029/2005GL024009, 2005. synthesis, Global Planet. Change, 77, 85–96, 2011. treme melt on Canada’s Arcticdoi:10.1029/2011GL047381, ice caps 2011. in the 21st century, Geophys. Res. Lett., 38,Dowdeswell, L11501, J. A., Gardner, A.Wyatt, S., F.: Recent Mair, glacier D., changes Wang, in L., the Williamson, Canadian S. Arctic, N., in: Global Wolken, Land G. Ice J., Measurements and racy of glacierdoi:10.3189/2013AoG63A296, 2013. outlines derived from remote-sensing data, Ann. Glaciol.,tions, The 54, Cryosphere, 4, 171–182, 67–75, doi:10.5194/tc-4-67-2010, 2010. Hock, R., Kaser, G., Kienholz, C., Miles, E. S., Moholdt, G., Mölg, N., Paul, F., Radi quantifying glacier thickness2011, change, 2011. The Cryosphere, 5, 271–290, doi:10.5194/tc-5-271- Schmeits, M., Stroeven, A.the response P., van of glaciers de to Wal, climate R. warming, Clim. S. Dynam.,Konovalov, W., 14, Wallinga, 267–274, V., 1998. J., Bris, andA., Zuo, R. Z.: Rastner, Le, Modelling P., Mölg, Raup, N., B., Nosenko, Scharrer, G., K., Nuth, Ste C., Pope, A., Racoviteanu, doi:10.3189/002214356793701910, 1956. Ba Miller, G. H., Otto-Bliesner,verses B. long-term L., arctic Overpeck,2009. J. cooling, T., Science, and 325, Vinther, B. 1236–1239, M.:, doi:10.1126/science.1173983 Recent warmingAnn. Glaciol. re- 41, 417–423, 2005. of Arctic sea-ice extent oncloud the data for absorbed 19832007, (net) Atmos. solar2010. Chem. flux Phys., at 10, the 777–787, surface, doi:10.5194/acp-10-777-2010, based on ISCCP-D2 PhD Thesis, McGill University, Montreal, Canada, 150 pp., 1954. Ba 6, 1103–1125,, doi:10.5194/tc-6-1103-2012 2012. Hock, R., Pfe van den Broeke, M.level rise: R., 2003 and to Paul, 2009, F.: Science, A 340, 852– reconciled 857 estimatevolume, doi:10.1126/science.1234532 of 2013. and glacier mass contributionsAge changes to maximum sea of in southeast the,doi:10.5194/tcd-8-4681-2014 2014. late Vatnajökull 19th ice century cap, to Iceland, 2010, from The the Cryosphere Little Discuss., 8, Ice 4681–4735, around Antarctica make,doi:10.1029/2008GL037020 a 2009. large sea-level rise contribution, Geophys.Arct. Antarc. Res. Alp. Lett., Res., 46, 36, 66–83, 2014. 17, mass balance, velocity, and surfaceCan. profile J. along Earth a flow Sci., line 24, on 1550–1561, Barnes 1987. Ice Cap,The 1970–1984, Cryosphere, 7, 877–887, doi:10.5194/tc-7-877-2013, 2013. Schutz, B. E., Zwally, H. J., Shuman, C. A., Hancock, D., and DiMarzio, J. P.: Overview ofSharp, the M., Burgess, D. O., Cogley, J. G., Ecclestone, M., Labine, C., and Wolken, G. J.: Ex- Serreze, M. C. and Barry, R. G. Processes and impacts of Arctic amplification: a research Sharp, M., Burgess, D. O., Cawkwell, F., Copland, L., Davis, J. A., Dowdeswell, E. K., Pfe PCI Geomatics: OrthoEngine User Guide,Pelto, Richmond M. Hill, S.: Ontario, Forecasting Canada, 2013. temperate alpine glacier survival from accumulation zone observa- Oerlemans, J., Anderson, B., Hubbard, A., Huybrechts, P., Johannesson, T., Knap, W. H., Nuth, C. and Kääb, A.: Co-registration and bias corrections of satellite elevation data sets for Paul, F., Barrand, N. E., Baumann, S., Berthier, E., Bolch, T., Casey, K., Frey, H., Joshi, S. P., Matsoukas, C., Hatzianastassiou, N., Fotiadi, A., Pavlakis, K. G., and Vardavas, I.: The e Mercer, J. H.: The physiography and glaciology of southernmost of Ba Koerner, R. M.: Mass balance of glaciers in the Queen Elizabeth Islands, Nunavut, Canada, Gardner, A. S., Moholdt, G., Cogley, J. G., Wouters, B., Arendt, A. A., Wahr, J.,Hannesdóttir, Berthier, H., Björnsson, E., H., Pálsson, F., Aðalgeirsdóttir, G., and Guðmundsson, S.: Area, Hock, R., de Woul, M., Radi Hocheim, K. P. and Barber, D. G.: An update on theHooke, ice R. climatology L., of the Johnson, Hudson G. Bay system, W., Brugger, K. A., Hanson,Huss, B., M.: Density and assumptions Holdsworth, for converting G.: geodetic Changes glacier volume in change toKaufman, mass D. change, S., Schneider, D. P., McKay, N. P., Ammann, C. M., Bradley, R. S., Bri Mercer, J. H.:Muller, The D. S.: Grinnell Glacial geology and and Quaternary history Terra of southeast Nivea Meta Incognita Peninsula, ice caps, J. Glaciol., 19, 653–656, Gardner, A., Moholdt, G., Arendt, A., and Wouters, B.: Accelerated contributions of Canada’s 5 5 20 25 30 15 10 25 30 10 15 20 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | n Island, Canada, ffi en, K., and Zhang, T.: Observations: ff 1694 1693 n Island, N.W.T., Canada) mass balance for the five budget ffi er, M., and Larsen, C. F.: Rapid thinning of lake-calving Yakutat ff Patagonian Ice Field, South America,doi:10.1029/2012GL053136, between 2012. 2000 and 2012, Geophys. Res. Lett., 39, 17, way from repeat inventories,2014. The Cryosphere, 8, 1885–1903,10.5194/tc-8-1885-2014, doi: Research Institute, NationalCanada, Glaciology 2007. Program, Geological Survey ofReanalysis Canada, of Ottawa, multi-temporal aerialComparison images of glaciological of and Storglaciären,doi:10.5194/tc-4-345-2010, 2010. volumetric Sweden mass (1959–99) balances, – The Part Cryosphere, 2: 4,Moholdt, 345–357, G., Mercer, A., Mayer,Vetter, C., H., Joerg, Elvehøy, H., P. C., and Jansson, Andreassen, P.,ment Hynek, L. series, B., M.: The Fischer, Reanalysing Cryosphere, A., glacier 7, Escher- mass 1227–1245, balance doi:10.5194/tc-7-1227-2013, measure- 2013. Hancock, D., Harding, D.,Thomas, Herring, R.: T., ICESat’s Minster, laserGeodyn., B., 34, measurements Quinn, 405–445, of doi:10.1016/S0264-3707(02)00042-X K.,2002. polar Palm, ice, S., atmosphere, Spinhirne, ocean, J., and and land, J. cryosphere, in: Climate Change 2013:Group The I Physical to Science the Basis, Fifthedited Contribution Assessment by: of Report Working of Stocker, theNauels, T. Intergovernmental F., A., Panel on Qin, Xia, Climate D.,UK Y., Change, and Plattner, Bex New V.. G.-K., York, NY, and USA, Tignor, 317–382, Midgley, M., 2013. P. M., Allen,Gilbert, Cambridge S. A., University K., Dumont, Press, Boschung, M.,mass Cambridge, Shea, balances J., of J. Mera M., and Pokalde7, Stumm, glaciers 1769–1786, D., (Nepal doi:10.5194/tc-7-1769-2013, and Himalaya) 2013. since Pokhrel, 2007, B. The K.: Cryosphere, Seasonal and annual Arctic 68, 1,, doi:10.14430/arctic4461 2015. years 1969 to 1974, Arctic Alpine Res., 7, 279–284, 1975. from Space: Satellite Multispectral Imaging ofKaab, Glaciers, A., edited Raup, by: B. Kargel, H., J. S., and Bishop, Leonard, M. G., P., Springer-Praxis, 205–228,Cap, 2014. Arctic Canada, over2008. the past two decades, Geology, 36, 71,, doi:10.1130/G24013A.1 1963 and,doi:10.1029/2008GL036238 2006 2009. in theprecedented Cordillera in the Real, past 600 years, Nature, Bolivia, 496, 201–205, Geophys., doi:10.1038/nature11969 Yackel, J. 2013. J.: Res. Trends andon Lett., variability the Canadian in 36, Ice summer Service116, sea Digital C03007, L03502, ice Archive,, doi:10.1029/2009JC005855 1960–2008 cover 2011. and in 1968–2008, the J. Geophys. Canadian Res., ArcticGlacier based and the collapse of161, the doi:10.3189/2013J0G12J081 , Yakutat Icefield, 2013. southeast Alaska, USA, J. Glaciol., 59, 149– ray, T., Paul, F., Ren, J., Rignot, E., Solomina, O., Ste Wagnon, P., Vincent, C., Arnaud, Y., Berthier, E., Vuillermoz, E., Gruber, S., Ménégoz,Way, R.: M., Multidecadal Recession of Grinnell and Terra Nivea Ice Caps, Ba Weaver, R. L.: “Boas” Glacier (Ba Willis, M. J., Melkonian, A. K., Pritchard, M. E.,Winsvold, and S. Rivera, H., Andreassen, A.: L. Ice M., and loss Kienholz, from C.: Glacier the area Southern and length changesZdanowicz, in C.: Nor- Glacier-Climate Studies on Grinnell Ice Cap – Final Research Report, Nunavut Zemp, M., Jansson, P., Holmlund, P., Gärtner-Roer, I., Koblet, T., Thee, P., and Haeberli, W.: Zemp, M., Thibert, E., Huss, M., Stumm, D., Rolstad Denby, C., Nuth, C., Nussbaumer, S. U., Zwally, H. J., Schutz, B., Abdalati, W., Abshire, J., Bentley, C., Brenner, A., Bufton, J., Dezio, J., Sneed, W. A., Hooke, R. L., and Hamilton, G. S.: ThinningSoruco, of the A., south dome Vincent, of Barnes C., Ice Francou, B.,Tingley, M. P. and and Huybers, Gonzalez, P.: Recent J. temperatureTivy, extremes A., F.: at Howell, Glacier high E. northern decline latitudes L., un- Alt, between B., McCourt, S., Chagnon,Trüssel, B. L., R.Crocker, Motyka, R. G., J., Tru Carrieres, T., and Vaughan, D. G., Comiso, J. C., Allison, I., Carrasco, J., Kaser, G., Kwok, R., Mote, P., Mur- 5 5 10 15 20 25 20 30 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | H H , absolute H ) H 1 − H 0.21 0.17 0.19 0.36 ± ± ± ± 0.37 0.48 0.30 1.68 − (mw.e.yr − − − H H Recent d Historical mass balancecoregistration and d Historical and recent mass balances and d 34 29 1696 1695 Pléiades DEM Pléiades DEM 21–22 Aug 1952Nov 2003, MarMar 2004, Mar 2006, 2005,glacier) Nov Nov 2005, 2006 and Apr 2007 (on part) Historical mass balance and d (East part) Apr and Nov 2007 (on glacier) Evaluation of ASTER DEM 1958/59–2007 CDED and ASTER2007–2014 DEM 21 ASTER DEM and derived DEM CDEDICESat points Whole laser periods outside glacier 6 Sep 1958 Absolute coregistration Absolute coregistration In-situ GPS pointsPléiades DEM Apr 2004 3 Aug 2014Pléiades DEM 14 Aug 2014 (West part) and 26 Aug 2014 Recent d Historical and recent mass balances and d ICESat pointsASTER DEM Whole laser periods outside glacier 3 Aug 2007 Absolute coregistration Recent mass balance and d Historical and recent glacier-wide mass balances for both ice caps. Elevation datasets used in this study with the acquisition date and the purpose of their Ice capGrinnell Elevation data set Photogrammetry Acquisition dateTerra Nivea CDED Purpose 6 Sep 1958 (West part) and 4 Aug 1959 (East Ice capGrinnell Time interval DatasetTerra Nivea 1952–2014 1958/59–2014 Photogrammetric CDED DEM and and Pléiades DEM 36 Data voids (%) Mass balance Table 2. Table 1. use for each ice cap. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1698 1697 Historical and recent area changes for both ice caps. Pléiades orthoimages of the Terra Nivea Ice Cap (14 Au- (c) (b) Pléiades orthoimage of the Grinnell Ice Cap (3 August 2014) superposed by Study area. Figure 2. (a) extents from 1952, 1999 and 2014 gust 2014 on the East1958/59, side 1998, and 2007 26 August andsented 2014 2014. on by The the the overlapping West black side) area dashed superposed between polygon. by the extents two from orthoimages is repre- Error margin for each measured area is 3 %. Figure 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1700 1699 ) on the Grinnell Ice Cap between March–April 2004 ) on the Grinnell Ice Cap between August 1952 (Aerial 1 1 − − Elevation change rates (ma Elevation change rates (ma (ICESat and In Situhistorical GPS (1952–2004) points) and and recent August (2004–2014) 2014contiguous rates of with (Pléiades elevation the DEM). changes 1952 along Bottom DEM the right 203 (represented graph points as shows black dots on the map). Figure 4. Figure 3. photo DEM) and August 2014 (Pléiades DEM). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Historical (1959–2007) and (d) Elevation change rates on the Terra Nivea (c) ) on the Terra Nivea Ice Cap between 1958/59 1702 1701 1 − Elevation change rates on the Terra Nivea Ice Cap between (b) Elevation change rates (ma Historical elevation changes measured for the Grinnell (1952–2014) and the Terra Figure 6. Nivea (1958/59–2014) ice caps forchange each measurement 50 m uncertainty elevation determined band. in The Sect. error 4.4.3. margin is the elevation Figure 5. (a) (CDED) and 2007 (ASTER). 1958/59 (CDED) andIce 2014 Cap (Pléiades between DEM). 2007recent (ASTER) (2007–2014) and averaged 2014 elevationNivea Ice changes (Pléiades Cap. for DEM). The error eachin margin Sect. 50 is m 4.4.3. the elevation elevation change band measurement on uncertainty determined the Terra Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Anoma- (b, c) Black lines are changes for the Terra Nivea Ice Cap. (d) 1 − 1.6 myr ∼ − 1704 1703 erences measured between Pléiades (2014) DEM and ICESat ff for the Grinnell Ice Cap and 1 − 1.1 myr ∼ − Annual anomalies in total positive degree-days (PDD) recorded between May and Recent elevation di in area extent offrom Way the (2015) GIC areet and al. represented the (2014). by TNIC, the 1952–2014, gray from lines Fig. and 2 the (this white study). square Areal dot extents is from Sharp lies in total sea iceHudson covered Strait area and during Davis theService. summer Strait For and (respectively), region autumn 1968–2014. boundaries, (25 Data see June–19 provided November) Tivy by over et the al. Canadian (2011), their Ice Fig. 4. November at the Iqaluit weather station, 1952 to 2014. Vertical scale is inverted. Figure 8. altimetric points. Only thetrend complete lines ICESat indicate the tracks mean available rateand for of equals elevation both changes along ice these caps two were ICESat reference used. tracks The Figure 7. Transects location for each ice cap is shown on the inset maps (right side).