Environmental changes of the last 1000 years on Prince of Wales Island, Nunavut, Canada

Figures & data

Figure 1. Sites with paleoclimate reconstructions of the past 1,000–2,000 years used in this study. Lake sediment records are denoted by a circle and color-coded by proxy type. The new record from this study is indicated in red (SW08).

Table 1. Pollen and spore taxa identified in core SW08. The local and regional taxa were used in numerical analyses. Taxa denoted with an asterisk (*) were part of the modern training set but were not found in the core.

Local and Regional
Betula	Saxifraga oppositifolia
Alnus	Saxifragaceae undiff
Salix	Polygonaceae undiff
Ericaceae	Ranunculaceae undiff
Artemisia	Thalictrum*
Caryophyllaceae	Rosaceae undiff
Chenopodiaceae	Potentilla*
Brassicaceae	Rubus chamaemorus
Asteraceae	Lycopodium annotinum*
Cyperaceae	L. clavatum*
Dryas	Huperzia selago*
Poaceae	Lycopodium undiff
Fabaceae*	Selaginella
Oxyria	Polypodiaceae*
Papaver	Equisetum
Pedicularis*	Sphagnum
Long Distance Picea undiff Abies Pinus Populus Carpinus/Ostrya Juglans Acer Juniperus Fraxinus Morus Celtis Corylus Ulmus Urtica

Table 2. ²¹⁰Pb results and ages based on constant-rate-of-supply (CRS) (Appleby and Oldfield 1978) model. The supported activity for all samples was 64.0 Bq/kg.

Top Depth (cm)	Bottom Depth (cm)	Midpoint Depth (cm)	Subsample weight (mg)	Unsupported Activity (Bq/kg)	Year CE	CRS Error (years)
		0.0		134.78	2017	0.00
0.0	0.5	0.25	763.80	78.22	2015	0.23
0.5	1.0	0.75	786.60	132.24	2011	0.72
1.0	1.5	1.25	750.70	137.30	2004	1.25
1.5	2.0	1.75	719.10	152.96	1993	2.12
3.0	3.5	3.25	386.40	18.89	1962	7.23
6.0	6.5	6.25	537.50	12.73	1920	17.90
8.0	8.5	8.25	841.90	0.00	1880	19.11
8.5	9.0	8.75	837.20	22.39	N/A

Table 3. Radiocarbon ages and hardwater-corrected dates. *: Indicates dates rejected and not used in developing the chronology. All dates are based on aquatic mosses extracted from the sediment. Samples were calibrated using OxCal v4.2.4 (Bronk Ramsey 2009) and the IntCal13 calibration curve (Reimer et al. 2013).

Lab ID	Depth (cm)	^14C yr BP	Error (±)	2σ cal BP range	Median cal BP	Hard watercorrected median cal BP
*UOC‐5309	12–13	1961	29	1,830–1,989	1,909.5	N/A
UOC‐5310	15–16	1449	26	1,300–1,385	1,342.5	486.5
UOC‐5311	19–20	1647	24	1,441–1,613	1,527	671
UOC‐5312	25–26	1812	34	1,623–1,825	1,724	868
*UOC‐5313	37–38	1756	24	1,600–1,727	1,663.5	N/A
*UOC‐5314	45–46	1710	24	1,556–1,696	1,626	N/A

Figure 2. Age-depth curve for core SW08. Triangles are ²¹⁰Pb ages; Circles are the ¹⁴C median calibrated dates with 2σ age range; red circles are ¹⁴C dates rejected from age-depth model; Squares are hardwater-corrected ¹⁴C dates (see text for details). Solid line represents the corrected age-depth model; dashed line is the age-depth model without hardwater correction.

Figure 3. Local and regional pollen in core SW08. The second line in the curves of the rarer taxa is a 5x exaggeration. Sums were calculated based on entire pollen assemblage (local, regional, and long-distance), although the numbers in the final column include all pollen and spores counted.

Figure 4. Long-distance, local, and regional pollen percentages, pollen concentrations, accumulation rates, and mean July temperature (°C) reconstruction for core SW08. Sums were calculated based on entire pollen assemblage (local, regional and long-distance). On the temperature reconstruction, grey lines are the standard deviation of the three best analogs and the red line is a loess curve (span = 0.25) fitted to the reconstruction.

Figure 5. Principal Component Analysis (PCA) for SW08 pollen percentages. Only taxa used in the July temperature reconstruction were included in the PCA (Table 1). Panel (a) shows the loadings and (b) shows the scores coloured by year CE and grouped by climatic periods identified in the literature.

Figure 6. Pollen-based temperature reconstructions in the Central and Western Arctic. The horizontal line is the mean for each record based on a reference period from 1000–2000 CE. Note: the reconstructions for SL06, JR01, and MB01 differ from the original publications because they were redone using the new modern database from Gajewski (2015).

Figure 7. (A) Comparison of the average of all the records (n = 40) relative to their common period (1090–1960 CE; orange line) computed for this study and the average for all the records (standard deviation with respect to 980–1800 CE; blue line) from Kaufman et al. (2009). The solid gray line shows the number of records used to compute the average for this study over time (orange line). (B) Average for this study with (orange line) and without (blue line) additional records from the Canadian Arctic Archipelago. (C) Average for this study (orange line) and the PaiCo reconstruction (blue) from McKay and Kaufman (2014). Note: McKay and Kaufman (2014) is a reconstruction of annual temperature anomalies, whereas the averages from this study and Kaufman et al. (2009) are standardized values (z-scores).

Figure 8. Principal Component Analysis (PCA) of proxy climate records from the Arctic. (A) Records from 1090–1960 CE (PCA₁) showing the loadings colored by proxy type. (B) Scores grouped by clusters established using Ward’s method. (C) Records from 10–1960 CE (PCA₂) showing loadings colored by proxy type (same legend as in panel A). (D) Scores grouped by clusters established using Ward’s method. Note the different axis scales.

Figure 9. (A) Maps of the loadings from PCA₁ and associated scores over time for component 1 and (B) component 2. (C) Maps of loadings from PCA₂ and associated scores over time for component 1 and (D) component 2.

Table A1. List of reconstructions included in the synthesis study. Sites in bold are included in both PCA₁ (1090–1960 CE) and PCA₂ (10–1960 CE).

Site	Region	Lat	Long	Archive	Proxy	Reference
Arc_1_Bluelake	Alaska	68.1	−150.5	Lake sediment	Varve thickness	Bird et al. (2009)
Arc_7_GulfAlaska	Alaska	61.0	−146.6	Tree Ring	Ring width	Wiles et al. (2014)
Arc_41_Hudson	Alaska	61.9	−145.7	Lake sediment	Chironomids	Clegg et al. (2011)
Arc_42_lynx	Alaska	66.1	−145.4	Lake sediment	Chironomids	Clegg et al. (2011)
Arc_40_Moose	Alaska	61.3	−143.6	Lake sediment	Chironomids	Clegg et al. (2010)
Arc_23_Iceberg	Alaska	60.8	−143.0	Lake sediment	Varve thickness	Loso et al. (2006)
MB01	Victoria Island, NWT	69.8	−112.1	Lake sediment	Pollen	Peros and Gajewski (2009)
SW08	Prince of Wales Isl, NU	72.3	−97.27	Lake sediment	Pollen	Tamo and Gajewski, this volume
SL06	Boothia Peninsula, NU	68.6	−91.9	Lake sediment	Pollen	Peros and Gajewski (2009)
DV09	Devon Island, NU	75.6	−89.3	Lake sediment	Varve thickness	Courtney Mustaphi and Gajewski (2013)
Arc_54_Lake4	Southampton Isl, NU	65.1	−83.8	Lake sediment	Chironomids	Rolland et al. (2009)
Arc_44_Devon	Devon Island, NU	75.3	−82.5	Ice core	δ^18O	Fisher et al. (1983)
Arc_20_LakeC2	Ellesmere Island, NU	82.1	−77.2	Lake sediment	Varve thickness	Lamoureux and Bradley (1996)
Agassiz Ice Cap	Ellesmere Island, NU	81.0	−75	Ice core	δ^18O	Lecavalier et al. (2017)
Arc_4_Lower Lake	Ellesmere Island, NU	81.4	−69.5	Lake sediment	Mass accumulation rate	Cook et al. (2009)
Arc_30_BigRoundLake	Baffin island, NU	69.9	−68.8	Lake sediment	Varve thickness	Thomas and Briner (2009)
Arc_53_Penny	Baffin Island, NU	67.3	−66.8	Ice core	δ^18O	Fisher et al. (1998)
Arc_25_Donard	Baffin Island, NU	66.7	−61.4	Lake sediment	Varve thickness	Moore et al. (2001)
Arc_43_Braya	Greenland	67.0	−50.7	Lake sediment	U^K’37	D’Andrea et al. (2011)
Arc_52_Igaliku	Greenland	61.0	−45.4	Lake sediment	Pollen accumulation	Massa et al. (2012)
Arc_35_DYE3	Greenland	65.2	−43.8	Ice core	δ^18O	Vinther et al. (2010)
Arc_32_NGRIP1	Greenland	75.1	−42.3	Ice core	δ^18O	Vinther et al. (2006)
Arc_11_GISP2	Greenland	72.1	−38.1	Ice core	δ^18O	Grootes and Stuiver (1997)
Arc_36_GRIP	Greenland	72.6	−37.6	Ice core	δ^18O	Vinther et al. (2010)
Arc_34_Crete	Greenland	71.1	−37.3	Ice core	δ^18O	Vinther et al. (2010)
Arc_28_B18	Greenland	76.6	−36.4	Ice core	δ^18O	Schwager (2000)
Arc_59_Renland	Greenland	71.3	−26.7	Ice core	δ^18O	Vinther et al. (2008)
Arc_22_Hvitarvatn	Iceland	64.6	−19.8	Lake sediment	Varve thickness	Larsen et al. (2011)
Arc_57_MD99-2275	North Atlantic	66.6	−17.4	Marine sediment	U^K’37	Sicre et al. (2011)
Arc_55_P1003	North Atlantic	63.8	5.3	Marine sediment	δ^18O	Sejrup, Haflidason, and Andrews (2011)
Arc_58_MSm5/5–712	North Atlantic	78.9	6.8	Marine sediment	Planktic forams	Spielhagen et al. (2011)
Arc_38_MD95-2011	North Atlantic	67.0	7.6	Marine sediment	Diatoms	Berner et al. (2011)
Arc_49_Okshola Cave	Scandinavia	67	15	Speleothem	δ^18O	Linge et al. (2009)
Arc_17_Lomonosovfonna	North Atlantic	78.9	17.4	Ice core	δ^18O	Divine et al. (2011)
Arc_12_Tornetrask	Scandinavia	68.3	19.6	Tree Ring	Ring Width	Grudd (2008)
Arc_15_Lapland	Scandinavia	69.0	25.0	Tree Ring	Ring width	Helama et al. (2009)
Arc_51_Pieni	Scandinavia	64.3	30.1	Lake sediment	Chironomids	Luoto and Helama (2010)
Arc_10_PolarUrals	Central Russia	66.8	65.8	Tree Ring	Max. density	Esper, Cook, and Schweingruber (2002)
Arc_3_Yamal	Central Russia	67.5	70.0	Tree Ring	Ring width	Briffa et al. (2008)
Arc_2_AvamTaimyr	Central Russia	72.0	101.0	Tree Ring	Ring width	Briffa et al. (2008)

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