Estimating Sea-Level Allowances for Atlantic Canada using the Fifth Assessment Report of the IPCC

Figures & data

Fig. 1 (a) Map of eastern Canada. PEI is Prince Edward Island. Abbreviations for tide-gauge names are listed in Table 1. (b) Rates of RSL change and land uplift.

Table 1. Summary of tide-gauge data at 22 stations located along the east coast of Canada.

Station Name	Longitude (°E)	Latitude (°N)	Station ID	Data Period	Years of Data
Argentia	−53.98	47.30	AR	1971–2013	43
Cap-aux-Meules	−61.86	47.38	CAM	1964–2013	18
Charlottetown	−63.12	46.23	CT	1911–2013	92
Halifax	−63.58	44.67	HF	1920–2013	94
Harrington Harbour	−59.48	50.50	HH	1940–1989	47
Lauzon	−71.16	46.83	LZ	1900–2012	100
Lower Escuminac	−64.88	47.08	LE	1973–2013	41
Nain	−61.68	56.55	NN	1964–2013	23
North Sydney	−60.25	46.22	NS	1970–2013	44
Pictou	−62.70	45.68	PT	1957–1995	33
Pointe-au-Père	−68.47	48.52	PAP	1900–1983	72
Port aux Basques	−59.13	47.57	PAB	1936–2013	55
Rimouski-PP^a	−68.51	48.48	RPP	1900–2013	102
Rivière-au-Renard	−64.38	49.00	RAR	1969–2013	44
Saint John	−66.06	45.25	SJ	1905–2013	95
Sainte-Anne-des-Monts	−66.49	49.13	SADM	1969–1997	28
Saint-François IO	−70.81	47.00	SFI	1962–2013	52
Saint-Joseph-de-la-Rive	−70.37	47.45	SJDLR	1969–2013	44
Sept-Îles	−66.38	50.19	SI	1972–2013	42
Shediac Bay	−64.55	46.23	SB	1972–2013	28
St John's	−52.72	47.57	SJS	1936–2013	60
Yarmouth	−66.12	43.83	YM	1900–2013	49

^aRimouski-PP record is a combination of Pointe-au-Père for 1900–1983 and Rimouski for 1984–2013.

Table 2. Rate of RSL rise derived from tide-gauge data based on the complete record at each site, and ASL rise derived from tide-gauge and GPS data. Category A represents high-quality level for which t ≥ 50 years and d ≤ 10 km. Category B represents mid-quality level for which 30 ≤ t < 50 years and d ≤ 20 km, and Category C represents low-quality level for usable sites, with 20 ≤ t < 30 years or 20 < d ≤ 40 km. Category F corresponds to unreliable data points for which t < 20 years or d > 40 km.

Names	Rate of SLR (mm yr^−1)		Absolute Sea Level
	Mean	Standard Error	Mean (mm yr^−1)	Standard Error (mm yr^−1)	Category
Argentia	2.3	0.3	1.9	1.1	C
Cap-aux-Meules	4.2	0.3	3.0	0.9	F
Charlottetown	3.3	0.1	2.1	0.8	A
Halifax	3.2	0.1	2.2	0.6	A
Harrington Harbour	−0.7	0.4	−0.8	0.7	F
Lauzon	−0.6	0.3	2.6	0.8	A
Lower Escuminac	3.2	0.5	2.8	0.7	B
Nain	−1.9	0.4	2.6	0.7	C
North Sydney	3.7	0.4	1.9	0.7	F
Pictou	2.2	1.0	0.8	1.2	C
Pointe-au-Père	−0.6	0.4	—	—	—
Port aux Basques	1.6	0.5	1.6	0.8	F
Rimouski-PP	−0.4	0.2	2.8	0.6	A
Rivière-au-Renard	1.1	0.6	2.2	0.8	C
Saint John	2.2	0.2	1.7	0.6	A
Sainte-Anne-des-Monts	−1.2	0.7	1.4	0.9	C
Saint-François IO	0.4	0.8	3.6	1.1	C
Saint-Joseph-de-la-Rive	−1.1	1.3	1.6	1.4	C
Sept-Îles	1.4	0.6	—	—	—
Shediac Bay	3.1	0.5	2.2	0.8	C
St John's	2.2	0.3	2.1	0.6	A
Yarmouth	3.2	0.3	2.0	0.7	B

Fig. 2 (left) Annual means of hourly water levels for five representative sites. Linear trends were fitted using a least-squares fit. Dashed lines mark the range of two standard deviations. (right) Return level versus return period plots for five representative stations. Solid lines are maximum likelihood curves, and dashed lines show the 95% confidence intervals.

Table 3. Statistics of storm tides derived from tide-gauge data. The third, fifth, and seventh columns are the uncertainty estimates (e.g., the location parameter for Argentia is 1.525 ± 0.057, where the error limits are the 2.5 and 97.5 percentiles).

	Location Parameter (m)		Scale Parameter (m)		50-Year Return Level (m)
Station Name	Mean	2.5–97.5 Percentile Range	Mean	2.5–97.5 Percentile Range	Mean	2.5–97.5 Percentile Range
Argentia	1.525	0.057	0.090	0.042	1.877	0.179
Cap-aux-Meules	0.891	0.111	0.114	0.084	1.334	0.365
Charlottetown	1.513	0.067	0.156	0.050	2.121	0.217
Halifax	1.344	0.043	0.101	0.033	1.740	0.144
Harrington Harbour	1.352	0.068	0.113	0.051	1.791	0.225
Lauzon	3.647	0.079	0.190	0.058	4.388	0.256
Lower Escuminac	1.272	0.097	0.149	0.073	1.855	0.321
Nain	1.584	0.094	0.108	0.069	2.007	0.301
North Sydney	1.013	0.073	0.117	0.054	1.469	0.235
Pictou	1.320	0.134	0.185	0.096	2.043	0.412
Pointe-au-Père	2.666	0.060	0.123	0.040	3.148	0.167
Port aux Basques	1.098	0.045	0.080	0.034	1.412	0.146
Rimouski-PP	2.657	0.049	0.118	0.033	3.118	0.139
Rivière-au-Renard	1.403	0.066	0.106	0.051	1.818	0.220
Saint John	4.284	0.046	0.109	0.033	4.709	0.141
Sainte-Anne-des-Monts	2.081	0.088	0.112	0.069	2.520	0.303
Saint-François IO	4.022	0.106	0.185	0.083	4.744	0.365
Saint-Joseph-de-la-Rive	3.594	0.098	0.159	0.077	4.214	0.334
Sept-Îles	2.035	0.086	0.134	0.062	2.558	0.263
Shediac Bay	1.304	0.176	0.225	0.131	2.180	0.575
St John's	1.091	0.043	0.081	0.032	1.406	0.138
Yarmouth	2.609	0.060	0.101	0.045	3.004	0.197

Fig. 3 (a) Scale parameters and (b) sea-level allowances for RCP8.5_GPS for the 1995–2100 period, estimated from the subsets and full records of detrended annual water level maxima for five tide-gauge stations. The error bars in (a) mark the 2.5–97.5 percentile range.

Table 4. Rates of sea-level change due to the GIA effect estimated from GIA models used for the IPCC's AR5 report.

Names	ICE-5G (mm yr^−1)	ANU (mm yr^−1)	AR5 GIA (mm yr^−1)
			Mean	Standard Error
Argentia	0.21	0.78	0.50	0.28
Cap-aux-Meules	3.05	−2.53	0.26	2.79
Charlottetown	2.35	−1.97	0.19	2.16
Halifax	1.27	−1.04	0.11	1.15
Harrington Harbour	−2.69	−4.15	−3.42	0.73
Lauzon	−1.32	−5.86	−3.59	2.27
Lower Escuminac	2.42	−2.94	−0.26	2.68
Nain	−1.48	−10.84	−6.16	4.68
North Sydney	2.40	−0.96	0.72	1.68
Pictou	2.02	−1.44	0.29	1.73
Pointe-au-Père	−0.01	−5.81	−2.91	2.90
Port aux Basques	1.85	−1.82	0.02	1.83
Rimouski-PP	−0.01	−5.79	−2.90	2.89
Rivière-au-Renard	1.86	−4.12	−1.13	2.99
Saint John	0.74	−2.45	−0.86	1.60
Sainte-Anne-des-Monts	0.65	−5.16	−2.25	2.91
Saint-François IO	−1.16	−5.86	−3.51	2.35
Saint-Joseph-de-la-Rive	−0.97	−6.04	−3.50	2.54
Sept-Îles	−1.58	−6.79	−4.18	2.61
Shediac Bay	1.92	−2.40	−0.24	2.16
St John's	0.27	1.13	0.70	0.43
Yarmouth	0.66	−1.51	−0.42	1.08

Table 5. Vertical motion derived from GPS data. Corrected GPS rates are used to estimate the adjusted GIA using a linear relationship.

Names	Uplift (mm yr^−1)		Correction^c (mm yr^−1)	Adjusted GIA (mm yr^−1)		Tide-gauge-GPS distance (km)
	Mean^a	Error^b		Mean^d	Error^e
Argentia	−0.40	1.01	−0.29	0.44	1.02	35
Cap-aux-Meules	−1.17	0.80	−0.28	1.13	0.82	161
Charlottetown	−1.17	0.80	−0.28	1.13	0.82	1
Halifax	−1.00	0.55	−0.26	0.96	0.57	3
Harrington Harbour	4.56	0.56	−0.36	−4.04	0.58	492
Lauzon	3.21	0.75	−0.31	−2.85	0.77	8
Lower Escuminac	−0.36	0.55	−0.30	0.41	0.57	6
Nain	4.49	0.58	−0.51	−3.84	0.60	2
North Sydney	−1.82	0.57	−0.28	1.73	0.59	42
Pictou	−1.42	0.61	−0.27	1.35	0.63	22
Pointe-au-Père	3.21	0.56	−0.33	−2.83	0.58	9
Port aux Basques	−0.05	0.61	−0.32	0.14	0.63	176
Rimouski-PP	3.21	0.56	−0.33	−2.83	0.58	4
Rivière-au-Renard	1.13	0.59	−0.33	−0.93	0.61	21
Saint John	−0.52	0.56	−0.27	0.53	0.58	1
Sainte-Anne-des-Monts	2.58	0.56	−0.35	−2.24	0.58	0
Saint-François IO	3.21	0.75	−0.31	−2.85	0.77	38
Saint-Joseph-de-la-Rive	2.68	0.55	−0.32	−2.36	0.57	30
Sept-Îles	4.56	0.56	−0.36	−4.04	0.58	2
Shediac Bay	−0.86	0.58	−0.29	0.86	0.60	1
St John's	−0.13	0.54	−0.29	0.19	0.57	4
Yarmouth	−1.19	0.63	−0.25	1.13	0.65	13

^aUplift rates are relative to the centre of the Earth, as expressed in ITRF2005 (International Terrestrial Reference Frame).

^bUplift error is the square root of summed squares of the linear regression error and the uncertainty of the realization of the terrestrial reference.

^cCorrection is for present-day elastic crustal response to ice-mass changes.

^d<Adjusted GIA mean> = −0.9167 × <Uplift mean + Correction > −0.1947.

^e<Adjusted GIA error> = (<Uplift error>² + <Linear regression error of Fig. 4>²)^1/2.

Fig. 4 Relationship between predicted vertical uplift rate and rate of RSL change for the ICE-5G (VM2) model, version 1.3 (Peltier, 2004) and ICE-6G (Peltier et al., 2015) indicated by red dots. The solid blue line is the regression: < Rate of relative sea-level change >  = –0.9167 < vertical uplift > –0.1947. The dashed lines mark the range of two standard deviations of the error.

Fig. 5 (a) The rate of RSL change (mm yr⁻¹) derived from tide-gauge data versus the adjusted GIA rate based on GPS observations. The solid line was constrained to a slope of −1. (b) Modelled GIA rate (based on the average of ICE-5G and ANU models (Church et al., 2013)) versus adjusted GIA rate based on GPS observations. The solid blue line is the regression: <Adjusted GIA rate> = 0.96 < Modelled GIA rate> + 0.57. The error bars in the y-direction mark the two standard deviation range. The error bars in the x-direction mark the absolute difference of the two GIA models.

Fig. 6 Sea-level allowances at tide-gauge stations along the Atlantic coast of Canada (a) for the 1995–2050 period and (b) for the 1995–2100 period. Green vertical bars show the sea-level allowances for RCP8.5, and the red vertical bars show the sea-level allowances for which the modelled GIA projections are replaced by the adjusted GIA projections based on GPS uplift rates. The scale of the red vertical bar in the legend is 0.5 m.

Table 6. Summary of projected sea-level change and sea-level allowances for RCP8.5 and 1995–2050 at tide-gauge stations along the Atlantic coast of Canada. SLR projections are based on IPCC AR5.

Station Name	Scale Parameter (m)	RCP8.5 Projection (m)				Allowance (m)
		Mean	Standard Deviation	5th Percentile	95th Percentile
Argentia	0.090	0.32	0.08	0.19	0.45	0.36
Cap-aux-Meules	0.114	0.31	0.18	0.02	0.60	0.45
Charlottetown	0.156	0.28	0.15	0.03	0.54	0.36
Halifax	0.101	0.32	0.11	0.14	0.50	0.38
Harrington Harbour	0.113	0.08	0.09	−0.07	0.22	0.11
Lauzon	0.190	0.10	0.14	−0.14	0.34	0.15
Lower Escuminac	0.149	0.28	0.18	−0.02	0.58	0.40
Nain	0.108	−0.12	0.26	−0.55	0.31	0.20
North Sydney	0.117	0.34	0.13	0.13	0.55	0.41
Pictou	0.185	0.31	0.14	0.09	0.54	0.36
Pointe-au-Père	0.123	0.12	0.18	−0.18	0.42	0.25
Port aux Basques	0.080	0.30	0.13	0.08	0.51	0.40
Rimouski-PP	0.118	0.12	0.18	−0.18	0.42	0.26
Rivière-au-Renard	0.106	0.23	0.19	−0.08	0.54	0.40
Saint John	0.109	0.24	0.12	0.05	0.44	0.31
Sainte-Anne-des-Monts	0.112	0.15	0.18	−0.15	0.46	0.30
Saint-François IO	0.185	0.10	0.15	−0.14	0.34	0.16
Saint-Joseph-de-la-Rive	0.159	0.10	0.15	−0.15	0.36	0.18
Sept-Îles	0.134	0.05	0.18	−0.24	0.34	0.16
Shediac Bay	0.225	0.26	0.15	0.01	0.51	0.31
St John's	0.081	0.33	0.08	0.19	0.47	0.37
Yarmouth	0.101	0.27	0.11	0.10	0.45	0.33

Table 7. Summary of projected sea-level change and sea-level allowances for RCP8.5 and 1995–2100 at tide-gauge stations along the Atlantic coast of Canada. SLR projections are based on IPCC AR5.

Station Name	Scale Parameter (m)	RCP8.5 Projection (m)				Allowance (m)
		Mean	Standard Deviation	5th Percentile	95th Percentile
Argentia	0.090	0.80	0.22	0.43	1.16	1.07
Cap-aux-Meules	0.114	0.76	0.37	0.16	1.37	1.36
Charlottetown	0.156	0.68	0.30	0.18	1.18	0.98
Halifax	0.101	0.84	0.26	0.41	1.27	1.17
Harrington Harbour	0.113	0.29	0.21	−0.06	0.64	0.49
Lauzon	0.190	0.42	0.32	−0.10	0.95	0.68
Lower Escuminac	0.149	0.73	0.39	0.10	1.37	1.23
Nain	0.108	−0.15	0.51	−0.99	0.69	1.06
North Sydney	0.117	0.83	0.29	0.35	1.30	1.19
Pictou	0.185	0.78	0.31	0.27	1.28	1.03
Pointe-au-Père	0.123	0.43	0.38	−0.19	1.06	1.02
Port aux Basques	0.080	0.74	0.29	0.27	1.21	1.25
Rimouski-PP	0.118	0.44	0.38	−0.19	1.06	1.05
Rivière-au-Renard	0.106	0.62	0.40	−0.03	1.27	1.36
Saint John	0.109	0.66	0.27	0.22	1.10	0.99
Sainte-Anne-des-Monts	0.112	0.50	0.38	−0.12	1.13	1.15
Saint-François IO	0.185	0.43	0.32	−0.10	0.96	0.71
Saint-Joseph-de-la-Rive	0.159	0.43	0.33	−0.11	0.98	0.77
Sept-Îles	0.134	0.30	0.37	−0.30	0.90	0.80
Shediac Bay	0.225	0.64	0.30	0.14	1.14	0.84
St John's	0.081	0.83	0.23	0.45	1.20	1.14
Yarmouth	0.101	0.72	0.25	0.31	1.13	1.03

Table 8. Summary of projected sea-level change and sea-level allowances for RCP8.5_GPS and 1995–2050 at tide-gauge stations along the Atlantic coast of Canada. GIA model projections of IPCC AR5 are replaced with the adjusted GIA data derived from GPS uplift rates.

Station Name	Scale Parameter (m)	RCP8.5_GPS Projection (m)				Allowance (m)
		Mean	Standard Deviation	5th Percentile	95th Percentile
Argentia	0.090	0.32	0.09	0.17	0.47	0.37
Cap-aux-Meules	0.114	0.36	0.13	0.14	0.58	0.44
Charlottetown	0.156	0.34	0.13	0.13	0.54	0.39
Halifax	0.101	0.37	0.10	0.20	0.53	0.42
Harrington Harbour	0.113	0.04	0.09	−0.10	0.19	0.08
Lauzon	0.190	0.14	0.11	−0.04	0.32	0.17
Lower Escuminac	0.149	0.32	0.14	0.08	0.56	0.39
Nain	0.108	0.01	0.17	−0.27	0.28	0.14
North Sydney	0.117	0.39	0.11	0.22	0.57	0.44
Pictou	0.185	0.37	0.12	0.17	0.56	0.41
Pointe-au-Père	0.123	0.12	0.14	−0.10	0.35	0.20
Port aux Basques	0.080	0.30	0.11	0.12	0.48	0.37
Rimouski-PP	0.118	0.12	0.14	−0.10	0.35	0.20
Rivière-au-Renard	0.106	0.24	0.14	0.01	0.47	0.34
Saint John	0.109	0.32	0.10	0.16	0.49	0.37
Sainte-Anne-des-Monts	0.112	0.16	0.14	−0.07	0.38	0.24
Saint-François IO	0.185	0.14	0.11	−0.04	0.32	0.17
Saint-Joseph-de-la-Rive	0.159	0.17	0.11	−0.01	0.35	0.21
Sept-Îles	0.134	0.06	0.14	−0.17	0.28	0.13
Shediac Bay	0.225	0.32	0.12	0.12	0.52	0.36
St John's	0.081	0.30	0.09	0.16	0.44	0.35
Yarmouth	0.101	0.36	0.10	0.20	0.52	0.41

Table 9. Summary of projected sea-level change and sea-level allowances for RCP8.5_GPS and 1995–2100 at tide-gauge stations along the Atlantic coast of Canada. GIA model projections from IPCC AR5 are replaced with the adjusted GIA data derived from GPS uplift rates.

Station Name	Scale Parameter (m)	RCP8.5_GPS Projection (m)				Allowance (m)
		Mean	Standard Deviation	5th Percentile	95th Percentile
Argentia	0.090	0.79	0.24	0.40	1.18	1.10
Cap-aux-Meules	0.114	0.85	0.30	0.37	1.34	1.24
Charlottetown	0.156	0.78	0.26	0.36	1.20	0.99
Halifax	0.101	0.93	0.25	0.52	1.34	1.23
Harrington Harbour	0.113	0.23	0.21	−0.13	0.57	0.42
Lauzon	0.190	0.50	0.27	0.07	0.94	0.68
Lower Escuminac	0.149	0.80	0.32	0.28	1.33	1.15
Nain	0.108	0.09	0.34	−0.47	0.66	0.64
North Sydney	0.117	0.93	0.26	0.51	1.36	1.22
Pictou	0.185	0.89	0.28	0.43	1.35	1.10
Pointe-au-Père	0.123	0.44	0.30	−0.05	0.94	0.81
Port aux Basques	0.080	0.75	0.25	0.34	1.16	1.14
Rimouski-PP	0.118	0.44	0.30	−0.05	0.94	0.83
Rivière-au-Renard	0.106	0.64	0.31	0.12	1.16	1.11
Saint John	0.109	0.80	0.24	0.41	1.20	1.07
Sainte-Anne-des-Monts	0.112	0.51	0.30	0.01	1.00	0.91
Saint-François IO	0.185	0.50	0.27	0.07	0.94	0.69
Saint-Joseph-de-la-Rive	0.159	0.55	0.26	0.12	0.99	0.77
Sept-Îles	0.134	0.32	0.30	−0.18	0.81	0.65
Shediac Bay	0.225	0.75	0.25	0.34	1.17	0.89
St John's	0.081	0.77	0.23	0.40	1.15	1.10
Yarmouth	0.101	0.88	0.24	0.49	1.28	1.16

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