Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1 erent ff Discussions The Cryosphere , and L. Schirrmeister 3 , I. Fedorova 1 1496 1495 ¨ unther , F. G 2 , G. Grosse 1 This discussion paper is/has beenPlease under refer review to for the the journal corresponding final The paper Cryosphere in (TC). TC if available. Alfred Wegener Institute for Polar and Marine Research, Telegrafenberg A43, Geophysical Institute, University of Alaska Fairbanks, 903 Koyukuk Drive, Fairbanks, Arctic and Antarctic Research Institute, Otto Schmidt Laboratory for Polar and Marine (Anisimov and Reneva, 2006; Zimovwater et and land al., surface 2006; energy Schuur balances et (Osterkamp al., et al., 2008) 2009), and which changes may in influence Yedoma landscapes. 1 Introduction Climate warming in mostresulted northern in high-latitude widespread permafrost warmingdegradation regions of during (ACIA, permafrost, 2004) the last has andmafrost few also, decades soils in (Romanovsky some and et cases, al., sediments permafrost 2010). is Thawing accompanied of by per- the release of old organic carbon Further thermokarst development in existingthat basins is have restricted already to undergone underlyingdeposits deposits thaw, formed compaction, after and initialmental old lake stages carbon drainage. of thermokarst mobilization, Therefore, andfor and landscape a future units to distinction is permafrost between necessary degradation to develop- assess and the carbon potential release due to thermokarst in Siberian sensing and geoinformation techniques.thermokarst The lakes morphometry on Yedoma and uplands,basins spatial thermokarst are distribution lakes analyzed, of in andcal basins, possible context and dependence is thermokarst upon considered. reliefon Of position these Yedoma and uplands thermokarst cryolithologi- alter stages,study developing ice-rich thermokarst area permafrost lakes compared the tofor most, 20.0 % developing but large occupied areas occupy by of only thermokarsting thermokarst basins. 2.2 distances % on to The Yedoma of uplands future degradational the is potential features limited and due to delta shrink- channels that foster lake drainage. Distinctive periglacial landscapes havedeposits formed in (Ice late-Pleistocene ice-richthermokarst Complex) permafrost basins of alternate withthermokarst Northern ice-rich stages Yedoma Yakutia, in uplands. Ice Siberia. We Complex investigate deposits di of Thermokarst the Lena lakes River Delta and using remote Abstract The Cryosphere Discuss., 5, 1495–1545,www.the-cryosphere-discuss.net/5/1495/2011/ 2011 doi:10.5194/tcd-5-1495-2011 © Author(s) 2011. CC Attribution 3.0 License. 1 14473 Potsdam, Germany 2 AK 99775-7320, USA 3 Research, Beringa st. 38, 199397 St. Petersburg, Russia Received: 19 April 2011 – Accepted:Correspondence 28 to: April 2011 A. – Morgenstern Published: ([email protected]) 16 MayPublished 2011 by Copernicus Publications on behalf of the European Geosciences Union. Spatial analyses of thermokarst lakesbasins and in Yedoma landscapes ofDelta the Lena A. Morgenstern 5 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | erent ff ects on the ecology, ff E) is situated in the continuous per- ected landscapes (Osterkamp et al., ◦ ff N; 126 ◦ 1498 1497 ected large areas in arctic lowlands with ice-rich permafrost ff ects of relief position and cryolithological context, and (3) to deduce the ff To estimate future carbon release from Yedoma areas due to thermokarst it is nec- The classical works of Soloviev (1959, 1962) and Czudek and Demek (1970) de- Thermokarst is one of the most obvious forms of permafrost degradation in arc- a late-Pleistocene accumulation plainraulakh ridges, in which the now form foreland the of third the Lena Delta Chekanovsky terrace and (Grigoriev, Kha- 1993) (Fig. 1). techniques, (2) to analyzecidate the any spatial e distribution ofpotential these extent of lakes future and thermokarst basins, evolution and in the elu- study area. 2 Study area and regional setting The North Siberian Lenamafrost River Delta and (73 tundra zone. It features Ice Complex deposits on insular remnants of study we provide a basisrich for quantifying permafrost potential thermokarst by evolution answering inmay Siberian develop the in ice- question the study of area,race where an with area and its which Ice to comprises Complexstages the what deposits. third in extent Lena The lake River thermokarst specific Delta and objectives ter- basin are: development (1) based to assess on di remote sensing and geoinformation Recent studies of modernon thermokarst thermokarst lakes activity by detecting inKravtsova broad-scale Yedoma changes and landscapes in Bystrova, thermokarst have lake 2009).tween focused area thermokarst (e.g., lakes However, on Yedoma thus uplandsgeneration and thermokarst, far thermokarst and they lakes have in not have basins addressed not of these older- distinguished complex thermokarst be- basins. essary to assess thelandscapes impact of under thermokarst climate processes scenarios on the that evolution predict of significant permafrost Arctic warming. In this and smaller remnant thermokarstunder lakes. thermokarst Repeated lakes cycles andlake of drainage subsequent permafrost can permafrost lead degradation aggradationcompanied to after by multiple full modifications cycles or of ofhydrostatic secondary partial initial pingos in thermokarst basin-and-lake the within morphometry basin basins (Katasonov, and 1960; ac- Romanovskii, the 1961; growth Soloviev, 1962). of drain partially or completely. The remaining basins feature steep slopes, flat bottoms, As these thermokarst lakes grow, they eventually coalesce with neighboring lakes or lake basins have been investigatedthe on North a broad Slope scale of using Alaska satellite (Frohn et remote al., sensing 2005). on scribe the development(Siberia). of In thermokarst this region in withsubaerial conditions. a Ice continental Only Complex after climate, initial thermokarst depositsevolving ground starts thermokarst subsidence in to does basins water develop Central that accumulate under inthe are Yakutia the wet termed polygonal “alasses” tundra atrich of a deposits the more is represented developed North by stage. Siberian ponds and lowlands, In circular evolving lakes thermokarst that completely in fill ice- their basins. 2007; Zona et al., 2009;ance Karlsson et in al., permafrost 2010) or regionsmethods as by (Payette indicators et analyzing of al., a changes changing 2004;Bystrova, in water Smith bal- 2009). lake et area al., The using 2005;lakes highest Riordan remote-sensing in et Yedoma methane or al., emissions Yedoma-like 2006; sediments from Kravtsova (Walter and et arctic al., lakes 2006). are Drained reported thermokarst for years ago, thermokarst a (Romanovskii et al.,rich 2000; deposits Walter (Ice et Complex)(Schirrmeister of al., et the al., 2007). Yedoma 2011b). Suiterich were Yedoma Today, In thermokarst uplands deposited in lakes the in this and late Northerngeomorphology, region. basins hydrology, and Thermokarst Siberia Pleistocene, alternate local has with climate such important of ice- e 2000; ice- a Grosse et al., 2011).as Various recent sources studies of have investigated carbon thermokarst lakes release to the atmosphere (Zimov, 1997; Walter et al., 2006, 2009). tic landscapes. Thermokarstforms is result defined from as the thawing theEverdingen, of 2005). process ice-rich by permafrost During which or a the characteristic phase melting land- of of massive global ice warming (van about ten to twelve thousand atmospheric processes via a feedback mechanism (Chapin, 2005; Schuur et al., 2008, 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ecting the Lena ff E) (Fig. 1) serves as 0 03 ◦ N; 126 0 23 ◦ 1500 1499 image mosaic of the Lena River Delta (Schneider et al., 2009) + Within the study area, Kurungnakh Island (72 The modern outlines and surface patterns of the third terrace are the result of ca. geomorphological main terrace, excludingAmerika-Khaya the islands. bedrock We outcrops also of excluded the lakes Sardakh and and basins at the boundary of the (a.s.l.). 3 Data and methods 3.1 Remote-sensing data and processing A Landsat-7 ETM served as thetent basis of for the Lena mapping Delta the Ice thermokarst Complex. lakes We and defined this basins extent within as the all areas ex- of the third basin. Pingos have formedbasin in surface and some diameters of of the up basins, to 150 with m heights (Grigoriev,a 1993). up key to site 30 m fortectonically above more the uplifted detailed investigations. western delta This island and is has the elevations easternmost of part up of to the 55 m above sea level diameter) are strongly dissected by60 m delta above channels the and adjacent reachmicrorelief river elevations with of level. small more ponds. Yedoma than meters. uplands Thermokarst are If lakes characterized can their byoften polygonal reach water dissected diameters table by of small is thermo-erosional several belowseveral kilo- gullies hundreds the (Fig. of surrounding 3). meters Basin Yedoma forBasin surface, diameters single floors range their forms are from to rims mainly tens flat are lakes of with that kilometers ice-wedge for are polygons, coalesced polygon mostly forms. ponds, remnants and thermokarst of the initial large thermokarst lake that formed the the early Holocene (Kaplina2009). and Thermokarst Lozhkin, lakes and 1979;the basins study Romanovskii area. are et depressed Individual al.,the into and islands. sometimes the 2000; networked flat Kaplina, Thermal thermo-erosional Yedomahigh uplands erosion channels relief drain of is gradient fostered of by the high third ice terrace; these contents small in islands the (a Yedoma few and tens the of kilometers in greatly influenced the landscapes in this region since the Bølling-Allerød and during since the mid-Holocene (Schwamborn et al., 2002b). Thermokarst processes have Delta the boundary isunit located is represented below by the depositsdepressions. river covering Deposits the level of Ice (Grigoriev, the Complex 1993).consist and Holocene of deposits cover The brownish-black, exposed of cryoturbated Holocene on thermokarst siltyand top sand are with of characterized numerous the by small smaller Ice ice peatcomposed Complex wedges. inclusions of unit Deposits cryoturbated of thermokarst silty depressionsand sands, are contain numerous syngenetic ice plant wedges remains, about and 3 to peat 5 inclusions, m12 000 wide yr (Schirrmeister of et permafrost al., 2003). degradation and of deltaic processes that have been ongoing range in Ice Complexboundary deposits between (1.1 the toseveral lower 32.5 tens wt and %). of upper meters, TheDelta units likely vertical (Schwamborn due varies position et to within of al., neotectonicin the 2002b). the block the study movements sharp In height a area the range by western of 15–25 Lena up m Delta to above this river boundary level is (a.r.l.), whereas found in the Eastern Lena The cryostructure of the sandyGravimetric section ice is content is mostly between massive 20 withtent and some is 40 small wt between % ice 1.0 and wedges. and totalIce 5.4 organic wt Complex carbon %. (TOC) deposits con- The that uppertween accumulated Pleistocene 44.5 unit during and is the 17 formed ka).a middle by high polygenetic It and gravimetric consists late ice of content Weichselianice peat, (38 (be- in silty to the 133 sand, form wt andwedges %). of peaty can The be paleosoil ice ground several layers bands, ice meters with occurs veins, wide as and and segregated up small to ice 20 m lenses. tall. Very TOC large content exhibits syngenetic a ice wide Pleistocene main units and aet Holocene al., unit (Schwamborn 2003, et 2011a;vial, al., 2002b; interbedded Wetterich Schirrmeister medium-to-fine-grained et and al.,paleo-Lena silty 2008) River sands (Fig. during deposited 2). thesome by a early lower The meandering Weichselian parts lowest period unit the consists (between sands of 100 include flu- and plant 50 ka). remains and In alternate with peaty layers. The stratigraphical composition of the third terrace can be divided into two late- 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | TM 4.6. In TM 30 m). The pixel-based × ected by cloud cover was ff a liated data sets were assigned 2 ffi (16 times 30 m 2 1502 1501 N UTM zones. The UTM meridian is situated in ◦ ect on the circularity index because it is based on ff N and 52 ◦ N. Kurungnakh Island and a ◦ N, because the larger areal percentage belongs to this zone. ◦ N with the geodetic datum WGS 1984 because this was the original ◦ 30 m spatial resolution of the Landsat data has to be taken into account for × ects on morphometric calculations the data sets were separated along the UTM Because the lakes were extracted from raster data and vectorized without smoothing, Mapping of all features was performed in the Universal Transverse Mercator (UTM) Basins were manually digitized along their upper margins at the scale of 1:30 000. To extract all water bodies automatically, we applied a grey-level thresholding on The Landsat scenes covering the Ice Complex extent show a medium water level ff an object of thelake same circularity area cannot with a reach complex the outline. value of In consequence, 1 the for pixel-based a perfect circle and will always have the 30 m morphometric analyses. Star and Estes (1990)cell recommend size, using a one conservative sixteenth raster minimum the lake size size for of analyses the ofand the minimum orientation shape mapping metrics of circularity unit. main index,outline axis elongation Therefore, of to index, we the be set lakes 14 400 the area has m and a perimeter. strong An e object with a smooth outline will have a shorter perimeter than were calculated (Table 1).ject’s The shape deviates circularity from index aject is perfect has a circle. (a) measure Values of angated. approaching how irregular A 0 strongly or square indicate an has complex thataxis/minor a ob- an outline, axis) value ob- (b) and of orientation 0.785. includes ofellipse The islands, major with calculations or axis an of area refer (c) the to equal elongation is to the index very that axes (major of of elon- the a object best-approximated being analyzed. meridian into a westernits original and UTM an Zone eastern 51 completely part. to Zone 52 The western part was3.2 re-projected to Morphometric analyses For all lakes andity basins, index, elongation morphometric index, variables orientation including of area, major axis, perimeter, and circular- the coordinates of centroids projection Zone 52 projection of the Landsat250 km mosaic. and covers The thethe study 51 center area of has thee a Lena large Delta E–W and extent crosses of Kurungnakh about Island. To minimize distortion lake was assigned abasin (Fig. location 3). attribute that had the value on Yedoma uplands or in The transition between Yedoma surface andable basin slopes in is the visually clearly Landsat distinguish- to data one due of to two categories: betteractivity, whereas single drainage coalesced basins of basins are consist slopes. distinct ofto basins at Each lateral formed lake least basin by expansion two in local was basins the thermokarst thatconnected assigned past. have via Basins merged narrow that due drainage are channels locatedwere adjacent but treated to have each retained as other their separate and original features; morphometry each was assigned to the category single. Each channels. The resulting data set wasprocessing converted and into vector analyses polygons. were Subsequent9.3 performed data and using its the spatial data GISreferred analysis software to toolbox. package as In ArcGIS the lakesactually following for ponds. all reasons extracted water of bodies readability are even though smaller water bodies are eastern part). Anreplaced by Ice a Complex subset of area a of Landsat scene about from 140 5band km August 2000 5 (path of 130,these row the 9). mid-infrared Landsat wavelengths water data bodiesable are using from strong the other absorbers, easily land imageatmosphere distinguish- cover reflectance processing types values software (Morgenstern ofmoved ENVI et 0 all al., to water 2008a). 0.1 pixels were related All defined pixels to as with drainage water. top-of- channels, small We streams, manually re- and river delta action. The manual mapping wastem done (GIS). using The a desktop resulting Geographical vectorand Information layer Sys- expert was advice then given modified by using M. our N. own Grigoriev field (personal knowledge communication,situation 2009). in summer (26 July 2001 in the western part, 27 July 2000 in the central and Ice Complex whose original morphology has been directly influenced by fluvial-deltaic 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 16.0 erent ff TM ice-wedge poly- erences between ◦ ff and existing thermokarst ◦ 2 ≥ 5 to correct for the influence of the × usually no polygons exist, but hummocks ◦ 2 ≥ 1504 1503 better drainage would prevent water accumulation and re- ◦ 2 4.8 with a kernel size of 5 ≥ TM ¨ unther, 2009). The DEM has a horizontal resolution of 5 m and a vertical During a field campaign in summer 2008, the relief characteristics and lake bathyme- Detailed field observations in combination with DEM analyses in Eastern Kurung- We used the high-resolution DEM to analyze the relief position of thermokarst fea- Statistical analyses of the resulting dataset were performed using the SPSS For each basin we determined the number of lakes per basin, the sum of lake area, lakes and basins fromraster the was area target-oriented above filtered the using 17 aDilate m combination filters reference of of plane. the ENVI morphological Thesystematic Erode resulting undulating and surfaces binary of theuplands. DEM, which occurred mainly on the flat Yedoma tries were investigated in detailin in the one south thermokarst of basin Kurungnakh with Island three (Morgenstern large lakes et located al., 2008b; Ulrich et al., 2010). initiation, i.e. at slopes strict lake formation.development within To the calculate limits the of theassuming area remaining that prone Ice new Complex lakes to on would Kurungnakhland potential predominantly Island, form surfaces, new and on we thermokarst poorly drained, subtracted lake flat all Yedoma up- areas with a slope of and 20 m a.r.l. Forto calculation 17 m purposes a.s.l. in the17 All m GIS lakes contour we and line set basinsstratigraphical the are whose unit. height considered floors of to are the have partially boundary their or base completely in belownakh the the Island fluvial revealed sands that ofgons in occur, the whereas areas lower in with areasare with a slope prevalent. negligible slope We of also interpret 0 this to threshold 2 as the relief condition for thermokarst relief of the whole Lena Delta Ice Complex. tures and, in particular, their positionto in Schirrmeister relation to et the al. twoboundary (2003) sedimentary units. between and Ice According Wetterich Complex et deposits al. and (2008) underlying we fluvial assume sands that lies the between 15 average coarse to extract terrain information in the detail needed for analyzing the thermokarst from digitized 1:200 000 topographic maps. The spatial resolution of these maps is too the subgroups lakes onuplands vs. Yedoma single uplands basins, we vs. applied lakes the in rank-based Mann-Whitney-U basins test. 3.3 and lakes Relief on analyses Yedoma on Kurungnakh Island For Kurungnakh Island, aALOS high-resolution PRISM Digital satellite Elevation image Modelavailable stereo (DEM) (G triplet based (acquisition on date an accuracy 21 September of 2006) 5.8 m. was For the rest of the study area, elevation information was derived and basin centroids were calculated in the same way assoftware. for lakes An in basins. explorativevealed data non-normal analysis distribution (EDA) fortests and for all subsequent the variables. analyses. Kolmogorov-Smirnov test Therefore, In order we re- to used test non-parametric for morphometric di and the percentage oftroid lake and area. the The angle distance formedto between the by line basin moving between counter-clockwise centroid the from andsingle centroids the lake basins were E–W cen- calculated (Table reference 1). to axis assessby Centroid the the position distances length of were of lakes normalizedsizes. within the by major In dividing basin addition, the axis pingosCorona distance to were satellite allow mapped comparison data as between and point basins topographic objects of maps. on di the Distances basis of and Landsat angles and between pingos index between subpopulations ofnot between the lakes data and set basins,index as is are the therefore only basins used legitimate werebecause as manually visual among an estimations digitized. additional lakes, of The measure the but they elongation basins and generally (especially do should in not give the have meaningful category complex results outlines. single) reveal that lower values than digitized basins of the same shape. Thus, comparisons of circularity 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 2 to 2 218) show = 2 , which 144) re- n 2 35 000 m = n = 14 400 m ) with a total area ≥ 2 . 2 that are considered for 2 , respectively), and more 2 14 400 m ≥ or 20.0 % of the study area (Ta- on the third Lena Delta terrace 144) was categorized as single. 14 400 m 2 2 = ≥ n 296) and single basins ( = ) and 98.6 % of the third terrace area n 2 , respectively). Figure 4 shows the study and 362 300 m 2 2 200 000 m ering frequencies (Fig. 6). Lakes on Yedoma er significantly from lakes in basins ( ff ff 1506 1505 ≥ ) lakes. The frequency distributions of the ma- 2 296) di = n 200 000 m ≥ ected by thermokarst. Lakes on Yedoma uplands account for erence between the major orientation of smaller (14 400 m ff 425) shows a peak in the WNW direction. This indicates an ff = di erences for all morphometric variables (Table 6). Lakes on Yedoma n ◦ ff ( 2 , respectively) and have a smoother shoreline (Table 5). Frequency 2 within the study area (Table 2). Thus, at a 30 m pixel resolution 5.2 % of ); the remaining areas consist of exposed bedrock (Morgenstern et al., ) and of larger ( 2 2 2 erent picture with a more pronounced NNE direction, but also two peaks directed to Frequency distributions of the major axis orientations for all lakes Tests between lakes on Yedoma uplands ( Lakes on Yedoma uplands ( Frequency distributions of area values for all water bodies in the study area show Thermokarst basins cover a total area of 337.7 km ff a major orientation peak in(Fig. the 6). WNW direction In andwere a a found minor previous to peak study, inlected exhibit all the distribution lakes a NNE of direction major majorand NNE axis 200 orientation 000 orientations m (Morgenstern forapproximately lakes et 90 with al., areas 2008a).200 between 000 m 14 400 A m se- jor axis orientation of singlethe basins WNW show direction, a opposite major the peak orientation in of the NNE all and lakes a minor peak in uplands have a much strongersingle prevailing basins orientation are in more the frequently WNWparison oriented direction; of in in the the contrast, morphometric NNE direction.in characteristics basins, Table between 5 and lakes shows single on a basins. Yedoma com- uplands, lakes di the WNW and NW. veal significant di uplands are, on average, much smallernitude; than the single basins area (byelongated. median about one Orientation equals order shows of 35 000 the mag- m and same one major in the peaks WNW for direction, both but with groups, di one in the NNE in their morphometric characteristicson except Yedoma uplands for are, the on elongation average,and index smaller than (Table 67 4). 900 lakes m in Lakes basinsdistributions (median of lake orientationdirection on and a Yedoma minor uplands peak in show the a NNE direction major (Fig. peak 6). in Lakes in the basins show WNW a slightly regions (Grosse et al.,ments (Downing 2008) et or al., 2006). in more general patterns throughout other environ- respectively). strong skewness towards lowerabundant values, than large because lakes small (Fig.morphometric water 5). analyses However, bodies lakes still are cover 93.8 much %their of number more the is whole small lake (514 area,for vs. because most 2327 even of though for the theship whole lake water between area. body lake population) This surface they is account area consistent and with areal the frequencies specific patterns found in of the various relation- Ice Complex ble 3). Of theSingle 169 basins basins cover mapped, acentage the than much majority do smaller ( coalesced arealof basins the extent, (20.2 % study but and area showa 11.7 is %, much a a respectively). lower higher proportion lake Finally, of 22.2 area % total per- area than do thermokarst basins (2.2 % and 20.0 %, (1711.6 km 2008a). We detected 2327 waterof bodies 88.3 (minimum km one pixel, 900the m Ice Complex extenttion, is 1509 covered water with bodies arethough open situated they water. on are Yedoma much Of uplands morearea the and abundant, than 818 total lakes lakes are on water in in Yedoma body basins uplandsarea basins. (37.4 cover with popula- Even a and all smaller thermokarst 50.9 km total lakes and basins mapped. 4.1 Area calculations and morphometric characteristics The study area, i.e.is the 5.8 % mapped Ice of Complex, the covers Lena an Delta area of area 1688.1 (29 km 000 km 4 Results 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 453, . . The 0 224 m, 2 = = r that is not ◦ . 3 − (Fig. 12). This means that 3.9 and 2.3, interquartile 2 = 0.57), mostly in the NNE and = , or 28.1 % of the Kurungnakh Island 2 01 for single basins). Lakes in basins are 0.24, max . 0 = 1508 1507 ≤ p . The TOC reservoir of this volume amounts to , or 39.6 % of the key study area. Thermokarst 3 2 212, . 0 = r ected by thermokarst or thermal erosion where new thermokarst could ff 07 Pg) as calculated following the method described in Strauss et al. (2011), . 0 19.0 and 22.1 for all basins and for single basins, respectively). Correlation be- = 598 m; normalized distances: min = 01 for all basins and . = 0 The area of Kurungnakh Island above 17 m a.s.l. with slopes of 0 to 2 Based on the ALOS PRISM DEM, the deposits above the 17 m reference plane In the study area 34 pingos were mapped, the majority situated in coalesced Table 7 compares the characteristics of permafrost relief, thermokarst lakes, and Basins have a low lake area percentage (median Bathymetric data from six lakes in the study area suggest that lakes on Yedoma ≤ and corresponds to an average organic carbon inventory of 24included kg C in m the thermokarstonly features 33.7 % amounts of to the area 87.4uplands within km the una limits of Ice Complexpotentially deposits start represents to flat Yedoma develop. However,of we existing are lakes aware close that to lateralthese slopes thermokarst slopes may expansion result as in well. reworking of Ice Complex deposits along 17 m level. approximately represent the remaining Iceposits Complex was deposits; the calculated volume to70 of Mt these be ( de- 2.9 km total thermokarst area.area This (Fig. amounts 10). to The 73bottoms) km surfaces of have these subsided thermokarst to featurescalculation the (lake is base very water of conservative level the because andwith it Ice basin does surfaces Complex not deposits above take into or theunfrozen account lower. 17 lakes ground) m and This that basins contour areal also linefluvial reached sands. the that boundary should This between is haveALOS Ice illustrated formed PRISM Complex in taliks deposits DEM Fig. and (bodies 11, that which of is shows situated a above profile 17 line m derived a.s.l. from while the the lake floors reach the The mapped extent oftotal the area key of study thermokarston (i.e., area Kurungnakh all on Island thermokarst Kurungnakh islakes basins Island and and 102.8 basins is km lakes that 259.5 intersect on km or Yedoma are uplands) situated below the 17 m isoline cover 71 % of the 4.2 Relief analyses of Kurungnakh Island from topographic maps aremaximum lower in Ice the Complex thickness. easternage part, Khardang while but Island featuring do has the not a largest seem very basin proportional sizes low by lake to far. areathermokarst percent- basins (24ated vs. at ten distances in ofmax single several hundreds basins). of metersSSW In from directions the single (Fig. basin 9). basins, centers pingos (min are situ- basins between major islandswestern of part the study ofKhardang Island, area. which the experienced separate Islands studyIce block Complex of uplift area thickness (Grigoriev, the varies 1993). greatly show tectonically-uplifted the Maximum between western the higher islands, and but maximum eastern shows parts similar relief ranges of in the heights, study area. especially Maximum basin depths as inferred uplands are deeper thana 30 lakes m in deep thermokarst basinslake basin. (Fig. 2, Maximum and 8). recorded 4.0 depth m is fora Lakes lake 3.6 large 1, m 3. part for 2, Lake of lake 4 the 1, andsituated is basin 4.2 on floor. also m 3 Yedoma uplands located for Its are and in maximum reach situated recorded aand depths depth thermokarst in Dorozhkina, of is basin, 12.5 2000). 8.1 but and m. it 9.0 Lakes m, covers 5 respectively and (Pavlova 6 are range tween basin area and lake areap percentage was found to benot slightly regularly positive situated ( in basinnorthern centers, but and are southern shifted directions towards (Fig. basin 7). margins, mostly in 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | . This is 2 30 m ≥ ected by fluvial erosion as it is nowadays ff 1510 1509 ect of thermal erosion on the areal extent of thermokarst ff ´ e and Burn, 2002). Within the Lena River Delta, the third terrace features ˆ ot ected by thermokarst and thermal erosion to be more than 50 %; for the area ff ected area to be 78 %. In contrast, in the present situation small remnants of the former coherent Ice Com- ff ical network. The limitingis e also reflected in a lower lake area percentage in regions of higher relief energy, started to form simultaneouslybetween Yedoma with uplands, thermokarst the basins, development andarea of delta of channels. an thermokarst Consequently, increasing lake the forced formation relief growing was lakes gradient to little drain; limited hence,kilometers by large each thermokarst the were lakes hydrological able with to networks diameters form. that of several plex plain have been elevateddevelopment of above thermal a erosion and dynamic the river connection of delta Yedoma uplands environment, to fostering the hydrolog- the massive thermokarst development in thisuated region about hundreds 12 of ka kilometers agoKaplina, the to 2009). coastline the was north The sit- study oflation area its plain was present where not location Ice2011a). part Complex (Bauch The of deposits et terrain a were presumably al., was river distributed 2001; in not delta, widely the as but delta a (Schirrmeister context of et (Schwamborn a et al., broad al., 2002b), accumu- and thermo-erosional gullies probably (by about one order of magnitude).ceeds Taken total together lake with area, the fact this thatsizes suggests total in that basin the thermokarst area past. lakes ex- After havemainly drainage, reached basins by much can secondary greater undergo thermokarst expansion lakes throughboundaries in lateral indicates erosion the that basins. this process Theter cannot smoothness drainage account of for of single substantial the basin arealargely initial increase a lake, af- result which of suggestslarge-area the that first thermokarst the lake lake size that development of formed. were these more We basins therefore suitable is conclude in indeed that the conditions past. for During the a 5.2 Areal constraints on thermokarst development Modern lakes on Yedoma uplands are, on average, much smaller than single basins of Cape Mamontov Klyk west of the Lena Delta, Grosse et al. (2006) calculated the area a due to thermokarst, whichthermokarst is lakes 22.2 % and of drained the2005), basins and study cover on area. a the Barrow combined Peninsula Inour 72 area Alaska, % study of (Hinkel area on et 46.1 cannot the al., % be 2003). North (Frohnalso considered The et plays Slope undisturbed remaining an Yedoma al., 77.8 surfaces important % as of role thermalIsland in erosion show Ice that Complex only degradation. 33.7 % Theis of results the in from island Kurungnakh the area is same undisturbedother range flat portions Yedoma as surface. of This results thethe of Ice previous Bykovsky Complex remote-sensing-based Peninsula accumulation studies east plain that of cover in the the Lena Laptev Delta, Sea Grosse region. et For al. (2005) calculated the for potential thermokarst evolution intecting Ice thermokarst Complex lakes deposits by thatthermokarst is remote-sensing potential solely methods for based would this on therefore study de- study deduce area. area a exceeds However, the the high total totalto current basin our lake area calculations. area mapped This by adds in a a our substantial high percentage factor to of the four, area according of Ice Complex degradation erage (Hinkel et al., 2005) orcoverage the (C Tuktoyaktuk Peninsula in arctic Canadathe with lowest 30 % lake lake areaof percentage 30 (Morgenstern m per et pixel al., didthat not 2008a). small allow ponds small The significantly ponds Landsat contribute to totheir resolution be the detected. OLE lake study Grosse coverage of et site, Ice al.calculated which Complex (2008) 13.3 areas. is showed % For lake part coverage of includingstill the all a standing westernmost small water portion percentage bodies of of of our the whole study study area, area. they An assessment of the area available 5.1 Thermokarst extent in the study area Lakes cover 5.2 %tundra of regions the like the study western area; arctic coastal this plain of coverage Alaska is with low about 20 compared % lake to cov- other arctic 5 Discussion 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | s is about 30 m (Grig- ff 1512 1511 erent areas of permafrost aggradation and subsidence, etc. Bosikov (1991) suggested that the lake area percentage of basins is an indicator of ff thermokarst lakes drained the taliks and basin deposits gradually refroze, permafrost a few thousand years2008). (Anisimova, 1962; Consequently, Schwamborn Ice et Complexlakes have al., deposits undergone underneath 2002a; taberal first-generation Westtion, development, and thermokarst including and Plug, ice compaction, loss,may organic resulting refreeze carbon in again deple- after aground lake diagenetically ice, drainage. altered, are Portionsa thawed possibly of stage sediment conserved corresponding Ice which underneath to Complex stageturity deposits, smaller 2 and including lake in developed Fig. basins a 13,such that deep before basins talik they drained exist reached in (Kaplina, at full the 2009). thermokarst study ma- area However, as only inferred a from small basin number sizes. of After first-generation fluvial sands with aing gravimetric ice significant content thermokarst of subsidenceof 20 below to a the 40 Ice first-generation %, Complex thermokarst tootalik base. low lake naturally to Even has will allow if expand not for the belowa yet continu- it. floor talik reached several A the tens thermokarst of Ice lake meters Complex a deep base, few in meters cold, its deep ice-rich will permafrost develop over several hundred to have already completely thawed(stage the 3 Ice in Complex Fig. depositsuated 13). within just their Soloviev basin above (1962) footprint theour also Ice study describes area Complex Central approximately Yakutian base. corresponds basinof to floors the Therefore, Ice sit- basin we Complex floors thickness,our assume marks and analysis that the the of basin position position of the depththe the in relief Ice Ice on Complex Complex Kurungnakh basehigher base. Island, and (Fig. This where lake 11). is lake surfaces confirmed bottoms and In by are basin our situated floors study at are area, located the a sediments few underlying meters the Ice Complex are poor and thus thermokarst-resistantlustrates thermokarst sand evolution unit in the belowThe specific the maximum stratigraphical Ice Ice context of Complex. Complex theoriev, thickness study 1993) observed Figure area. and at 13 coastal possibly il- depths blu of reaches up about to 30 48 m m are on common, so Khardang the Island majority of (Table first-generation 7). thermokarst lakes Basin can be explained by the stratigraphy of the study area, in particular the relatively ice- to result in therequired substantial for further subsidence large of secondary the thermokarst lake or lakes basin to floor develop that in would be existing basins. This the complex basindi floor morphology with drainage channels,5.3 pingos, lake terraces, Stratigraphical constraints on thermokarst development The low lake area percentageuplands in occurs, lake basins level indicates falls thatply to if to the drainage elevation the of of basinto lakes the on cannot drainage its Yedoma sill. lead margins. Further to Subsequent water further thermokarst sup- water evolution level in rise the or basins does to not the seem infilling likely of the basin therefore, less probable in coalescedin than in coalesced single basins basins. (24) Theof total is pingos, number therefore, much of might pingos higher alsoHowever, than it indicate is in the beyond single the evolutionary scope stage basinsmore of of irregular (10). this shapes thermokarst study of basins. to The lakes further in occurrence investigate basins this compared hypothesis. to The lakes on Yedoma uplands reflect the evolutionary stage of thermokarstbasins basins would in have Centralsmaller a Yakutia. Younger basins higher thermokarst are lake younger,than area they larger should basins. percentage In tend than our tobasins study old area have exhibit we basins. a found a an higher oppositefact higher lake Assuming correlation. results area lake However, that from single percentage area athese better percentage basins connection compared have of often to coalescederosional coalesced basins coalesced channels. into to The basins. broad the water accumulation valleys, hydrological that which network; is This drained required for through renewed thermo- lake growth is, which has experienced an additionaltween block uplift the (Grigoriev, largest 1993), the basinshas discrepancy and been be- an the abrupt smallest changea in lake change thermokarst area resulting conditions, from percentage from better large-scale suggests drainage to that and very thermal there limited, erosion. especially in the uplifted western part of the study area (Table 7). On Khardang Island, 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1514 1513 ect of thermokarst development varies depend- ff erences between thermokarst on Yedoma uplands and thermokarst ff 33 % less carbon than those Ice Complex deposits that never thawed. Ice erent potential for ground subsidence due to thermokarst is also supported by ff ∼ erent depths of lakes on Yedoma uplands vs. lakes in basins (Fig. 8). While the ff On Kurungnakh Island, at least 71 % of all thermokarst lakes and basins have The di subsided to the Ice Complex base. Here, the Ice Complex deposits have thawed labile, carbon than dosame second-generation time thermokarst the lakes potential in forlakes the existing development that basins. of are new At thermokarst able the established lakes, to connection especially of large form the extensive basins taliks toof the before basin drainage they sediments. system also drain, Taberites,with allows is lake for ground the very sediments, ice erosion limited. and that Holocenethus aggraded A eliminating peat during the well- horizons refreezing basis can together formatter future be thermokarst of removed development. the from In basin the this sediments basin case, is the floor, transported organic to the fluvial system. refrozen taberal Ice Complexcontain deposits beneath drainedComplex Holocene on thermokarst Yedoma uplands lakes hassitive a to high potential ground thermokarst icedeveloping development on content; Yedoma in uplands therefore, thus a it have warming a is higher climate. very potential to sen- Thermokarst mobilize older, lakes and more acter, and environmental processesforming than thermokarst underneath lakes thermokarst inphysical lakes existing and on basins. biochemical Yedoma processes Taliks uplandsture in and the enable the Ice the composition Complexyears. activation of deposits, organic of altering matter The their that sediments struc- possess had in the been characteristics basins, conserved of for however, theuplands. thousands have very These of already ice-rich di permafrost been ofin reworked the basins and surrounding also Yedoma do have not implications for the carbon cycle. Walter et al. (2007) report that These findings emphasize thating the e on whether itolder-generation takes thermokarst. place onlands Newly have undisturbed developing a stronger plain thermokarst transformative impact surfaces lakes on or permafrost on sediments, in landscape Yedoma char- existing up- basins of 5.4 Impact of future thermokarst development the di former (lakes 5 and 6)4 m reach deep. depths Lake of 4 12 illustrates m,was an the fully intermediate latter developed. stage. (lakes It 1 Theabove partly to the exposed drained 3) Ice before basin are thermokarst Complex floor no baseprocess more is (Fig. and than reached situated 11). its at The present 30 depthat remaining m of the lake 8 a.s.l., Ice continued m. which Complex the The base. present is thermokarst lake well floor is situated directly veins and wedges penetrates thesein horizons the of taberal basin and sediments, lake which sedimentsdeposits and are (Kaplina, syngenetic, epigenetic due 2009; to peat Wetterichable accumulation, et in second-generation the al., thermokarst, alas 2009). therefore,the are lower Favourable two conditions provided resemble for only the consider- underlying in fluvial the sands top in terms horizon; of low ground ice content. compacted, partly deformed,lower and ice refrozen. content than These didbe the several so-called meters original taberites thick. Ice havebeen Complex Taberites in calculated a (between to a 20 much be thermokarst to 2.3nal basin 40 m Ice on wt thick, %), Complex assuming Kurungnakh (Ulrich and a Island et can totalhave have al., ice similar 2010). content ground Refrozen of ice lake 90 contents sedimentsis vol overlaying (20 formed % the by to in taberites silt 40 the and origi- wtIce %). peat Complex layers (up The with to top very 200 horizon high wt (i.e., ground %), ice alas and content deposits) can similar reach to thicknesses that of of 5 the to 7 m. A system of ice however, does not reach the amountcumulated included over in several initial tens Icedeveloped of Complex in deposits thousands thermokarst which of ac- basins years. canground be ice Permafrost divided content sediments into (Kaplina, three that 2009;The main lowest have Wetterich horizon horizons et represents with al., the varying 2009) former Ice (stages Complex 4 sediments, and which 5 were in thawed, Fig. 13). formed accompanied by ground ice aggradation. The renewed ground ice content, 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ≥ er between in situ ff ) surround large thermokarst ◦ ects should intensify with growing ff shift in orientation from smaller to larger ◦ ect from wave-induced erosion (abrasion) ff ect of solar insolation dominates that of wind 1516 1515 ect on orientation than does solar insolation, ff ff ected by thermokarst, mainly by lateral growth ff are available for the initiation of new thermokarst lakes ◦ can also be a ◦ ´ e and Burn, 2002; Hinkel et al., 2005); however, authors investigat- ˆ ot ) are oriented mainly in the WNW direction whereas larger lakes ( 2 ect of solar insolation is also implausible. However, if main summer wind ff ) and single basins have major orientation peaks to the NNE. Several hy- 2 at some time during the Holocene. Second, the strength of the orienting forces ◦ erent orientation-driving forces than are larger lakes. Despite several decades of re- ects. This is physically not plausible, as wind e ff ff lake area. tion as the mainin factor major for summer lake wind orientation. directionimportant during A e the possible Holocene. explanation Under coulddirection our be second remained a hypothesis stable, change an a changein in the its wind e direction tomain the wind establishment direction of or wind-drivenin vice currents versa smaller at might right lakes be angles windwhile possible. to has in the Our a larger third lakes stronger hypothesis ande e implies in that basins the e Hussey, 1962; C ing orientation and directedComplex evolution deposits of discuss thermokarst solar lakes insolationet and al., (e.g., basins 2010) Soloviev, and 1962; in erosion Boytsov, Siberian due 1965;(e.g., to Ice Kuznetsova, wave Ulrich activity 1961). in The the first direction of of prevailing our summer winds three hypotheses would rule out solar insola- by 90 may have changed with growingdi lake size. Third,search, smaller there lakes is may still a be debateareas dominated about where by which lake factors control orientation thermokarst doesAmerican lake not orientation Arctic follow in underlying Coastal relief Plain,to structures. preferential prevailing On summer erosion the wind of North directions duebeen the to lake proposed wind-driven shores and currents and at agrees wave right activity well has angles with current main wind directions (e.g., Carson and to 200 000 m 200 000 m potheses can be proposed toforms. explain First, this if 90 it is truelakes that and smaller single thermokarst basins, lakes the have external not orienting existed as forces long may as have larger changed their direction indicate a general deviation from round and regular forms. Smaller lakes (14 400 study area are notrace as (Morgenstern elongated et al., as 2008a), the the oriented descriptive lakes statistics of of circularity the and second elongation Lena Delta ter- investigate the extent to whichoping the remaining thermokarst, Ice or Complex by isin thermal degraded existing by abrasion basins, newly due or devel- by to thermal the erosion. expansion of5.5 thermokarst lakes Oriented thermokarst development The lateral growthgeneration thermokarst of in thermokarst existingfrom basins lakes morphometric did and and not orientation proceed the uniformly, analyses. spatial as can Even development be though of seen lakes second- and basins in the important contributors to the degradationthermal of abrasion Ice of Complex deposits. lakelies. Key shores Mobilization, processes transport, and are and thermal transformationthawing of erosion and organic in ground matter di retrogressive subsidenceinvolving valleys slope in processes or local and gul- thermokarst flowing water. lakes It and will the thus be lateral of dynamics interest in future work to because these areas allowslopes ponding of of water more and thanof ground 2 existing subsidence. thermokarst The lakes. areasper In with slopes some of Yedoma cases uplands. pondinghere, However, extensive of thermokarst because water activity lateral can is also not growthparts possible occur will of on the lead up- slope. tolakes or Many drainage belong of when to the the thermo-erosionalIsland, steeper valleys indicating lake slopes that that reaches (5 cut lateral across the to sediment the transport 20 lower surface and of mass Kurungnakh wasting processes are also position of old organic matter.derneath If most we of assume the that remaining fully-developed 29 talikscompletely % have degraded of existed Ice thermokarst un- lakes Complex and depositsIsland. basins, in thermokarst up has Areas to outside 39.6 %base existing of with thermokarst the slopes lakes area of of and Kurungnakh up basins to above 2 the Ice Complex completely and have been exposed to biogeochemical processes such as the decom- 5 5 25 15 20 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | er- ff N, data from ◦ E 126.5 ◦ on Kurungnakh Island revealed 2 er significantly from those of lakes in ff 10 000 m ≥ 1518 1517 erent evolutionary conditions. However, the di ected by thermokarst, and total thermokarst basin ff ff ¨ unther, 2009). Following the solar radiation hypothesis, the NNE The inconsistencies of lake and basin orientation patterns in the study area over Lakes in basins are not situated in the centers of the basins, but are shifted mainly A change detection study for all lakes Yedoma uplands. Furtherto thermokarst the processes underlying in ice-poor existing fluvial basins sands and, are in limited the due case of basins where permafrost but the factors and processesstudy responsible area for oriented remain thermokarst unclear. development Conditionsthermokarst in more the in suitable the to the Icesuch development Complex development of will deposits large-area be ofity further our of limited study newly-developing in thermokarst area to areabasins have existing and existed and degradational depth features in thermo-erosional in like the valleys thermokarst thetial as past; future. for well considerable The as thermokarst proxim- toOn activity delta Kurungnakh on Island, channels Yedoma 33.7 uplands reduces % before the of drainage the poten- occurs. total area is vulnerable to future thermokarst on characteristics of lakes onbasins Yedoma or uplands single basins, di reflectingences di between the two lakeclassifying types lakes are on not Yedoma clear-cut uplandsdicators and in and do a lakes GIS. not in Thermokarst allow basins lakes for based and automatically single on basins morphometric show in- oriented morphometries, 6 Conclusions Large parts of the studyarea area exceeds are a total thermokarststages of lake thermokarst area complexity byYedoma have uplands, a been (2) distinguished factor in single of(3) this basins four. coalesced study: basins with Three (1) with residual lakes developmental residual and on and second-generation second-generation lakes, lakes. and The morphometric conclusions about oriented thermokarst development. space and time, asdevelopment described in the above, Yedoma landscapes do of not theat Lena allow present. River the Delta to cause be of clearly elucidated oriented thermokarst single basins in the study area does not permit using pingo position to derive robust similar to the position ofern lakes directions in basins; from pingos the are basin also shifted centers in (Fig. northern 9). and south- However, the low number of pingos in at the sidesdrainage, of residual active lakes thermokarst inIf development basins thermokarst (Romanovskii, remain development proceeded at 1961).has unidirectionally the been over sides observed After the for of Kurungnakh whole partial Islandsituated recent study over predominantly thermokarst the area, in last activity. one as 40 direction yr,clustered lakes only distribution in from of basins lakes the should in basin be basinsrectional center. therefore factors The does such bi-directionally not as support solar hypothesesof of insolation the unidi- and main prevailing axes. summer It winds is in interesting the to direction note that the position of pingos in single basins is hypothesis of orientation duelakes to of prevailing Kurungnakh winds Island in over the the direction last 40 of yr. majortowards axes for northern the andprofiles southern result margins from (Fig. directional 7), basin indicating evolution. that asymmetrical Thermokarst basin lakes are often deeper ation rates for afor thermokarst south-facing basin basin on slopes. Kurungnakhfacing Island slopes Rates (Ulrich showed for et the al., west-facing highestonly 2010). slopes acceptable values Solar if exceeded insolation a rates as summerthe for the cloud-cover afternoon single east- regime orienting were with factor consistently to isorological higher be thus station cloudiness observed on in on Stolb Kurungnakh Island1955–1991) Island. near show Kurungnakh pronounced Wind Island southern data (72.4 windriod from directions and the for three mete- the peaks whole forthe the observation ESE, period pe- and of one positive from temperatures, the one NNW from (Morgenstern the et S, one al., from 2008a). This would support the the directional growth ofriod lakes of in about the 40 yr(SSW-facing) NNW (G slopes direction of during the the lakesafter investigated and noon time basins and pe- should therefore receive be maximum preferentially energy eroded. shortly The results of modeling solar radi- 5 5 25 15 20 10 25 15 20 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , doi:10.1002/ppp.407 , 2005. orts of all German and Rus- ff , 2005. , 2005. doi:10.1002/ppp.509 ¨ 1520 1519 usslein-Volhard Foundation. G. Grosse was sup- ¨ oßler, and P. Ivlev. ALOS PRISM data used for DEM erent developmental stages of thermokarst and landscape ff doi:10.1126/science.1117368 We thank M. N. Grigoriev for his advice on enhancing the map of the Ice doi:10.1016/j.rse.2005.04.022 ´ e, M. M. and Burn, C. R: The oriented lakes of Tuktoyaktuk Peninsula, Western Arctic coast, erentiate between the di Academy of Sciences, Yakutsk, 176 p., 1993 (in Russian). images in remote sensing ofcoast, periglacial Permafrost geomorphology: Periglac., 16, an illustration 163–172, from the NE Siberian 97, 116–126, 2388–2397, 2006. lakes and drained thaw lake basins on the North Slope of Alaska, Remote Sens. Environ., Canada: A GIS-based analysis, Permafrost Periglac., 13,lowland relief, 61–70, Quaternary Res., 1, 103–120, 1970. ell, W. H., Kortelainen,abundance and P., Caraco, size distribution N. of F., lakes, Melack, ponds, and J. impoundments, M., Limnol. Oceanogr., and 51, Middelburg, J. J.: The global Rupp, T. S.,Euskirchen, Lynch, E. A. S., H., Hinzman,Walker, Schimel, D. L. A., J. D., and P., Jia, Welker,Science, Beringer, J. 310, G., M.: J., 657–660, Ping, Role Chapman, C.-L., of W. Tape, land-surface L., K. changes D., Epstein, in Thompson, Arctic H. summer C. E., warming, D.2002. 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NoDeveloping old thermokarst organic lakes carbon on willteration Yedoma be uplands of Ice directly have Complex the mobilized deposits from highest anddi these Yedoma impact landscapes. areas. on Therefore, it the is al- units necessary in to order to assess the degradation of very ice-rich permafrost due to thermokarst, has aggraded during the Holocene, due to the thin layers of ice-rich alas sediments 5 5 30 25 15 20 10 25 20 10 15 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , erent regions of ff , 2005. doi:10.1002/ppp.656 doi:10.1002/ppp.532 ected terrain types in the periglacial Lena- ff ce, ESA, Noordwijk, Netherlands, available at: ffi 1522 1521 ¨ , 2008b. orster, J., Hammarlund, D., Jackowicz-Korczynski, M., ´ en, P.: Quantifying the relative importance of lake emis- , 2011. , 2004. , 2006. , 2010. based ondoi:10.1029/2005JG000150 1950–2002 remotely sensedand images, the New J. 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29 ], 1 = equal equal = 1 ], ] m² ] m ] ∞ ∞ ∞ [0;359.9] ° ° [0;359.9] range range axes [0; [0; [0;179.9] ° ° [0;179.9] [0; 1] perfect circle perfect possible value value possible 2 ) ) basin minor axis length [1; , 2006. / perimeter / ths ths and orientation of major axis for lakes major basin axis length doi:10.1126/science.277.5327.800 / area × ² ² = 1 [0; , 1] π × 1525 1526 Major axis length Distance between basin and lake [0; 1] 4 , 2009. perimeter lake centroids (counter-clockwise) = = = / , 2009. area ) and the distance between basin and x x β π angle between E-W reference axis and the distance thedistance axisand reference E-W between angle (counter-clockwise centroids lake and basin between GIS output GIS output GIS = distance between basin and lake centroids / major / centroids andlake basin between distance = angle between E-W reference axis and major axis axis major axisand reference E-W between angle (counter-clockwise) axislength = 4 x x 4 = = major axis length / minor axis length axis length / minor length axis major = [1;

) ) β doi:10.1126/science.1128908 ) and major axis (counter-clockwise) α ted ted for lakes and basins. Major and minor axes leng y as for basins. basins. as for y ) ) Angle between basin Angle between E–W reference axis [0;359.9] Elongation index axis ( Normalized centroid distanceand lake centroids ( centroids Orientation of major Angle between E–W reference axis [0;179.9] AreaPerimeterCircularity index GIS output GIS output [0; [0; α orientation of major axis major of orientation ( angle between basin and and basin between angle ( centroids lake area area perimeter normalized centroid centroid normalized distance circularity index index circularity elongation index index elongation

doi:10.1029/2009GB003487 doi:10.1016/j.palaeo.2009.05.002 Overview of morphometric variables calculated for lakes and basins. Major and minor Science 312, 1612–1613, bauer, S. F., andtable Lipson, manipulation D. A.: experiment inGB2013, Methane fluxes the during Alaskan the Arctic initiation tundra, of Global a Biogeochem. large-scale Cy., water 23, Chapin, M. C., Trumbore, S.,by Pleistocene and carbon, Tyler, S.: Science, 277, North 800–802, Siberian lakes: a methane source fueled sky, V. V.: Eemian and Latesequences Glacial/Holocene at palaeoenvironmental records the from Dmitry73–95, permafrost Laptev Strait (NE Siberia, Russia), Palaeogeogr. Palaeocl., 279, Illustration Variable Calculation Possible value

Table 1. Overview of morphometric variables calcula wa same the calculated but were here, shown arenot illustration variable calculation Zona, D., Oechel, W. C., Kochendorfer, J., Paw, U. K. T., Salyuk, A. N., Olivas, P. C., Ober- axes lengths and orientationthe of same major way as axis for for basins. lakes are not shown here, but were calculated Zimov, S. A., Schuur, E. A. G., and Chapin III, F. S.: Permafrost and the global carbon budget, Table 1. Zimov, S. A., Voropaev, Y. V., Semiletov, I. P.,Davidov, S. P., Prosiannikov, S. F., Chapin III, F. S., Wetterich, S., Schirrmeister, L., Andreev, A. A., Pudenz, M., Plessen, B., Meyer, H., and Kunit- 1 1 2 5 10 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 2 14 400 m ≥ ) uplands 2 169 144 25 1528 1527 All basins Single basins Coalesced basins 2327 1509 818 514 All lakes Lakes on Lakes in All lakes minimum one Yedoma basins pixel (900 m ) 50.9 26.9 24.0 2 ) 88.3 37.4 50.9 82.8 ) 337.7 133.0 204.7 2 2 Area calculations for thermokarst basins on the third Lena Delta terrace (except Area calculations for water bodies on the third Lena Delta terrace (except bedrock Area (km Percentage of study area 5.2 2.2 3.0 4.9 N N Area (km Percentage of study areaTotal lake numberSum of lake area (km Total lake area as aof percentage total basin area 20.0 15.1 818 7.9 20.2 263 12.1 11.7 555 Table 3. bedrock islands). Table 2. islands). Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | and 2 14 400 m ≥ erences between ff 369 001 . . 3 − are shown in brackets. 2 erences between the two lake ff 724 469 0 . . 0 shorelines outlines − 14 400 m < 176 000 0 . . 5 index index of major axis 1530 1529 − 017 000 0 . . uplands 5 Area Circularity Elongation Orientation 296 (1509) 218 (818) 144 − Lakes on Yedoma Lakes in basins Single basins ))) 33.7 35 000) 65 800) 14 2 400 482 200 (37.4) (2700) (2 482 200) (8100) 67 2 900 112 300 49.1 (900) 210 300 (2 112 300) 14 (2700) 600 (16 200) (50.9) 7 706 600 (900) 1 096 200 362 300 133.0 20 400 2 2 2 2 2 Median 0.48 0.41 0.93 Median 1.55 1.58 1.29 Minimum 0.12 0.07 0.74 Minimum 1.03 1.04 1.02 Maximum 0.70 0.70 0.98 Maximum 6.19 8.07 2.02 Total (km Median (m Mann-Whitney-UZ 23 916 23 654 31 059 26 657 Asymptotic significance(two-sided) 0 Minimum (m Maximum (m Comparison of morphometric characteristics of thermokarst lakes Results of the rank-based Mann-Whitney-U test for morphometric di Interquartile range 0.17 0.21 0.05 Interquartile range 0.60 0.82 0.24 N Area Interquartile range (m Circularity index Elongation index Main orientationDepth WNW 10 m and more NNE up to 4 m up to 35 m NNE Outlines Smooth shorelines More complicated Smooth, circular Table 5. single basins. Area values for all lakes including lakes subgroups were found for area, circularity index, and orientation of major axis. Table 4. lakes on Yedoma uplands and lakes in basins. Significant di Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | c − − − − − − − 30 Aryta Dzhangy- c 21 erences between c ff 10 10 4.2 3.8 42 27.210.7 26.2 27.0 323 300248 300 278 900 247 000 71 386 400 8 425 000 004 852 . . c − − − − − − − 2 − erences between the two subgroups ff 180 000 0 . . 9 index of major axis − 1532 1531 254 000 0 . . Area Elongation Orientation 13 − 15 30 15 35 25 46 5 44 0 42 7 0 205 375 227 549 14 841 92 11 Ebe-Basyn Khardang Dzhangylakh Kurungnakh Botulu Sobo Buor-Ylar Bel’kej- a ) (57) (93) (23) (116) (5) (185) (27) (4) ) 33 725 400 134 137 200 5 246 700 102 766 700 674 900 84 509 600 12 266 200 126 000 2 b 2 ) 553 100 1 451 100 351 600 329 900 ) 4500 2700 1800 2700 8600 2400 4500 8100 ) 2 2 ) 160.7 826.7 93.9 259.5 14.5 262.1 32.2 5.6 2 2 ) 13 003 200 22 835 900 3 566 900 19 425 600 674 900 20 781 600 6 111 900 126 000 ) 28 098 200 128 906 600 1 811 200 99 235 100 a 2 2 (two-sided) Mann-Whitney-UZ 4724Asymptotic significance 9823 0 17 742 14 400 m ≥ N Median (m Median of singlebasins (m Percentage of 380 000island area Total lake area 1 as 211 300a percentage of total basin area 17.5Median lake 224 area 700 26.3percentage Max. depth (m) 228 700 15.6 13.4 13.7 1.9 1.7 7.3 38.2 3.7 16.0 2.3 Max. relief height(m a.s.l.) Max. ice complex 51N ( 33Area Total (m 66Median (m 48Percentage ofisland area N 43 16 8.1 55 38 2.8 36 36 42 3.8 21 7.5 4.7 30 7.9 19.0 2.3 Area Total (m thickness (m) Comparison of thermokarst features and permafrost characteristics between major Results of the rank-based Mann-Whitney-U test for morphometric di Yedoma uplandsand Percentage basins of island area 21.0 16.2 5.6 39.6 4.7 32.2 38.1 2.3 Lakes on Total area (m Island Area (km Lakes Basins Inferred from 1:200 000 topographical maps. Estimated from outcrop studies (Grigoriev, 1993) and maximum relief height. Values indicate the “visible” thickness above the river water level because the Ice Complex base is situated below the sea level here. a b c islands of the study area. Table 7. were found for all three morphometric variables. Table 6. lakes on Yedoma uplands and single basins. Significant di Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1534 1533 Typical stratigraphical composition of the study area with lower fluvial sand unit, upper Location of the study area in the Lena River Delta, North Siberia. Fig. 2. Ice Complex unit, andcolors. Holocene Person for cover. scale (photo Ice by M. wedges Ulrich, in 26 the August 2008). Ice Complex appear in light grey Fig. 1. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | western part, (a) NASA. © 1536 1535 mosaic, band 4, GeoCover 2000 + Overview of study area with all thermokarst features investigated: Types of thermokarst features distinguished in this study. eastern part. Landsat-7 ETM Fig. 4. (b) Fig. 3. Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | on Yedoma 2 ). 2 single basins. Inter- 14 400 m (d) ≥ 10 000 m = , and 2 lakes (a) 14 400 m ≥ all lakes 1538 1537 (c) west. = ◦ in basins, 2 of all water bodies in the study area (1 ha north, 180 = ◦ area 14 400 m ≥ east, 90 lakes = ◦ (b) , 0 Frequency distribution of major axis orientation for ◦ Histogram of 1 = Fig. 6. uplands, Fig. 5. vals Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | , from 2 , from N to SE; 2 421 200 m = ) between basin and ◦ , from N to S. Bathymetric 2 1 841 400 m = south. 2 460 134 m = ◦ , from N to S; lake 4 = 2 frequency distribution of normalized distances (a) 1540 1539 west, 270 221 400 m = ◦ = frequency distribution of angles (in (b) north, 180 , from NW to SE; lake 6 = 2 ◦ east, 90 , from N to S; lake 3 2 = ◦ 1 636 790 m = Bathymetric profiles of lakes in relation to relief position. For lake locations see 104 400 m Position of lakes within single basins: = N to S; lake 5 data from lakes 5 and 6 from Pavlova and Dorozhkina (2000). lake 2 Fig. 8. Fig. 4. Lake areas and profile directions are as follows: lake 1 lake centroids. 0 Fig. 7. between lake and basin centroids, Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | south. = ◦ ) were cal- ◦ west, 270 = ◦ north, 180 = ◦ east, 90 = ◦ 1542 1541 indicates a profile section across a Yedoma and thermokarst 0 DEM of Kurungnakh Island indicating the position of thermokarst features above and Position of pingos within single basins. Normalized distances and angles (in basin assemblage (see Fig. 11). below the Ice Complex boundarycovered by at features 17 under m which a.s.l.graded. the Ice Of The Complex line the deposits between total should a Kurungnakh and have a already Island completely area, de- 28.1 % is Fig. 10. Fig. 9. culated between basin centroids and pingos. 0 Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | ected by thermokarst or thermal erosion ff 1544 1543 . This area (33.7 % of Kurungnakh Island) is vulnerable to future thermokarst. ◦ 2 < Yedoma uplands of Kurungnakh Island una Profile section across a Yedoma and thermokarst basin assemblage on Kurungnakh Is- with slopes Fig. 12. Fig. 11. land (for position see Fig.potential 10) of showing thermokarst topographic is positions much of greaterderived investigated on from features. Yedoma uplands the The than ALOS thaw in PRISM basins.the DEM, The the approximate profile depths position line of was of lakes2003; from the Wetterich bathymetric et Ice measurements, al., and Complex 2008).similar base Positions environments of from in taliks outcrop other are regions studies hypothetical, (West based (Schirrmeister and on et Plug, modeling 2008). studies al., of Discussion Paper | Discussion Paper | Discussion Paper | Discussion Paper | 1545 Scheme of thermokarst development in Yedoma landscapes of the Lena River Delta in plane view (left) Fig. 13. and cross section (right).uplands 1: – flat, initial undisturbed stage Yedoma uplands with3: with lateral polygonal and thermokarst tundra. vertical lakes 2: thermokarstdeveloped. on thermokarst development, 4: lake Yedoma lakes partially uplands sedimentation, on talik drained, Yedoma –partial in coalesced mature refreezing non-steady thermokarst of stage state. basin former with with talik,drained remaining taberites, lateral coalesced or and thermokarst expansion lake second-generation basin sediments only, thermokarst with with lake lake pingo. ice – sedimentation, aggradation and talik peat fully accumulation. 5: partially