Speed
There are different estimates of the present speed of sea level rise. The main reason is estimates are made over different time intervals, and in some cases using different mathematical models to try and fit curves. Here are a few examples showing different results:
| Start (year CE) | End (year CE) | Rise (mm) | Speed (mm/year) |
|---|---|---|---|
| 0000 | 2016 | 416 | 0.2 |
| 1800 | 2016 | 296 | 1.4 |
| 1900 | 2016 | 236 | 2.0 |
| 1993 | 2016 | 76 | 3.3 |
| 2000 | 2016 | 56 | 3.5 |
| 2011 | 2016 | 29 | 5.8 |
The odd year 1993 was chosen because it is from when NASA (National Aeronautics and Space Administration in USA) provides satellite measurements, which are both more frequent and exact than previous measurements and estimates. According to the NASA data, there could have been a tipping point for the speed of sea level rise after 2011:
| Start (year CE) | End (year CE) | Rise (mm) | Speed (mm/year) |
|---|---|---|---|
| 1993 | 2011 | 47 | 2.6 |
| 2011 | 2016 | 29 | 5.8 |
This change has been observed over such short interval that it may be a random or short period fluctuation though. NOAA (National Oceanic and Atmospheric Administration in USA) uses 19 year averages for their own estimates of trends, which has the advantage of smoothing out most random and short period fluctuations, but the disadvantage of obscuring and delaying the discovery of any real abrupt changes in trends.
Regression
The sea level rise estimate is based on polynomial regression of satellite measurements from 1993 and onwards. Regression was made using first (linear), second (quadratic) and third (cubic) degree polynomials. Yearly averages of measurements for the years when data is available are also shown.
Linear regression usually gives the best estimate over long periods, assuming the changes are constant. Quadratic regression usually gives the best estimates over intermediate periods, assuming the changes shift somewhat linear over time. Cubic regression usually gives best estimates over rather short periods, assuming the changes aren't too drastical.
Linear regression gives a sea level rise 1993-2016 of 73 mm and 2011-2016 of 16 mm ≈ 3.2 mm/year, while quadratic regression gives 73 mm and 17 mm ≈ 3.5 mm/year, respectively, and cubic regression gives 80 mm and 23 mm ≈ 4.6 mm/year, respectively, compared to the observed values of 76 mm and 29 mm ≈ 5.8 mm/year, respectively. Assuming the acceleration of sea level rise 2011-2016 is temporary, the quadratic regression fits good with individual measurement cycles (several per year) and best with the yearly averages, but if the acceleration is a real tipping point, the cubic regression fits better with both individual cycles and yearly averages. Further into the future, the cubic regression gives improbable values, like a sea level rise of 60 mm/year 2060, which would be one of the fastest sea level rises ever, possibly even faster than the fastest periods of glacial melting ("Meltwater pulses") after (the latest) Weichselian ice age.
None of the three regression methods gives a good fit with reality for the last few years, but the cubic regression fits best and probably will for the next few years, especially with the increase of average sea level rise from 2.6 mm/year 1993-2011 to 5.8 mm/year 2011-2016, while an updated quadratic regression probably fits best for a more distant future.
Sea level rise
Estimates from linear (k=1), quadratic (k=2) and cubic (k=3) polynomial model, and actual satellite measurements of sea level rise compared to the 1993 level.
| Year | k=1 (mm cf. 1993) | k=2 (mm cf. 1993) | k=3 (mm cf. 1993) | Actual (mm cf. 1993) |
|---|---|---|---|---|
| 1993 | 0.00 | 0.00 | 0.00 | 0.00 |
| 1994 | 3.17 | 2.77 | 4.68 | 1.17 |
| 1995 | 6.33 | 5.58 | 8.97 | 2.59 |
| 1996 | 9.50 | 8.43 | 12.90 | 6.45 |
| 1997 | 12.66 | 11.31 | 16.51 | 12.26 |
| 1998 | 15.83 | 14.22 | 19.84 | 14.27 |
| 1999 | 19.00 | 17.18 | 22.94 | 17.23 |
| 2000 | 22.16 | 20.16 | 25.85 | 20.23 |
| 2001 | 25.33 | 23.19 | 28.61 | 25.59 |
| 2002 | 28.49 | 26.25 | 31.26 | 28.89 |
| 2003 | 31.66 | 29.34 | 33.85 | 31.96 |
| 2004 | 34.82 | 32.47 | 36.40 | 33.80 |
| 2005 | 37.99 | 35.64 | 38.97 | 38.25 |
| 2006 | 41.16 | 38.84 | 41.60 | 39.25 |
| 2007 | 44.32 | 42.08 | 44.32 | 39.88 |
| 2008 | 47.49 | 45.35 | 47.19 | 42.35 |
| 2009 | 50.65 | 48.66 | 50.24 | 47.13 |
| 2010 | 53.82 | 52.00 | 53.50 | 48.27 |
| 2011 | 56.99 | 55.38 | 57.03 | 47.24 |
| 2012 | 60.15 | 58.80 | 60.87 | 57.88 |
| 2013 | 63.32 | 62.25 | 65.06 | 60.18 |
| 2014 | 66.48 | 65.74 | 69.63 | 63.45 |
| 2015 | 69.65 | 69.26 | 74.63 | 73.75 |
| 2016 | 72.82 | 72.82 | 80.10 | 76.43 |
| 2017 | 75.98 | 76.41 | 86.09 | |
| 2018 | 79.15 | 80.04 | 92.62 | |
| 2019 | 82.31 | 83.71 | 99.76 | |
| 2020 | 85.48 | 87.41 | 107.53 | |
| 2021 | 88.65 | 91.14 | 115.98 | |
| 2022 | 91.81 | 94.92 | 125.14 | |
| 2023 | 94.98 | 98.72 | 135.07 | |
| 2024 | 98.14 | 102.57 | 145.81 | |
| 2025 | 101.31 | 106.45 | 157.38 | |
| 2026 | 104.47 | 110.36 | 169.84 | |
| 2027 | 107.64 | 114.31 | 183.23 | |
| 2028 | 110.81 | 118.30 | 197.59 | |
| 2029 | 113.97 | 122.32 | 212.95 | |
| 2030 | 117.14 | 126.38 | 229.37 | |
| 2031 | 120.30 | 130.47 | 246.88 | |
| 2032 | 123.47 | 134.60 | 265.52 | |
| 2033 | 126.64 | 138.77 | 285.34 | |
| 2034 | 129.80 | 142.97 | 306.38 | |
| 2035 | 132.97 | 147.21 | 328.68 | |
| 2036 | 136.13 | 151.48 | 352.27 | |
| 2037 | 139.30 | 155.79 | 377.21 | |
| 2038 | 142.47 | 160.13 | 403.52 | |
| 2039 | 145.63 | 164.51 | 431.27 | |
| 2040 | 148.80 | 168.92 | 460.48 | |
| 2041 | 151.96 | 173.37 | 491.19 | |
| 2042 | 155.13 | 177.86 | 523.46 | |
| 2043 | 158.29 | 182.38 | 557.31 | |
| 2044 | 161.46 | 186.94 | 592.79 | |
| 2045 | 164.63 | 191.53 | 629.95 | |
| 2046 | 167.79 | 196.16 | 668.82 | |
| 2047 | 170.96 | 200.82 | 709.45 | |
| 2048 | 174.12 | 205.52 | 751.88 | |
| 2049 | 177.29 | 210.26 | 796.14 | |
| 2050 | 180.46 | 215.03 | 842.29 | |
| 2051 | 183.62 | 219.84 | 890.35 | |
| 2052 | 186.79 | 224.68 | 940.38 | |
| 2053 | 189.95 | 229.56 | 992.41 | |
| 2054 | 193.12 | 234.47 | 1046.49 | |
| 2055 | 196.29 | 239.42 | 1102.65 | |
| 2056 | 199.45 | 244.41 | 1160.95 | |
| 2057 | 202.62 | 249.43 | 1221.41 | |
| 2058 | 205.78 | 254.49 | 1284.09 | |
| 2059 | 208.95 | 259.58 | 1349.02 | |
| 2060 | 212.12 | 264.71 | 1416.24 | |
| 2061 | 215.28 | 269.87 | 1485.80 | |
| 2062 | 218.45 | 275.07 | 1557.74 | |
| 2063 | 221.61 | 280.31 | 1632.09 | |
| 2064 | 224.78 | 285.58 | 1708.91 | |
| 2065 | 227.94 | 290.89 | 1788.23 | |
| 2066 | 231.11 | 296.23 | 1870.09 | |
| 2067 | 234.28 | 301.61 | 1954.53 | |
| 2068 | 237.44 | 307.02 | 2041.60 | |
| 2069 | 240.61 | 312.47 | 2131.34 | |
| 2070 | 243.77 | 317.96 | 2223.79 | |
| 2071 | 246.94 | 323.48 | 2318.99 | |
| 2072 | 250.11 | 329.03 | 2416.98 | |
| 2073 | 253.27 | 334.62 | 2517.80 | |
| 2074 | 256.44 | 340.25 | 2621.50 | |
| 2075 | 259.60 | 345.92 | 2728.11 | |
| 2076 | 262.77 | 351.62 | 2837.68 | |
| 2077 | 265.94 | 357.35 | 2950.25 | |
| 2078 | 269.10 | 363.12 | 3065.86 | |
| 2079 | 272.27 | 368.93 | 3184.56 | |
| 2080 | 275.43 | 374.77 | 3306.37 | |
| 2081 | 278.60 | 380.65 | 3431.35 | |
| 2082 | 281.76 | 386.56 | 3559.54 | |
| 2083 | 284.93 | 392.51 | 3690.97 | |
| 2084 | 288.10 | 398.49 | 3825.70 | |
| 2085 | 291.26 | 404.51 | 3963.75 | |
| 2086 | 294.43 | 410.57 | 4105.18 | |
| 2087 | 297.59 | 416.66 | 4250.02 | |
| 2088 | 300.76 | 422.79 | 4398.31 | |
| 2089 | 303.93 | 428.95 | 4550.10 | |
| 2090 | 307.09 | 435.15 | 4705.43 | |
| 2091 | 310.26 | 441.38 | 4864.34 | |
| 2092 | 313.42 | 447.65 | 5026.87 | |
| 2093 | 316.59 | 453.96 | 5193.06 | |
| 2094 | 319.76 | 460.30 | 5362.95 | |
| 2095 | 322.92 | 466.68 | 5536.59 | |
| 2096 | 326.09 | 473.09 | 5714.01 | |
| 2097 | 329.25 | 479.54 | 5895.27 | |
| 2098 | 332.42 | 486.02 | 6080.39 | |
| 2099 | 335.59 | 492.54 | 6269.42 | |
| 2100 | 338.75 | 499.10 | 6462.41 | |
| 2101 | 341.92 | 505.69 | 6659.39 | |
| 2102 | 345.08 | 512.32 | 6860.40 | |
| 2103 | 348.25 | 518.98 | 7065.49 | |
| 2104 | 351.41 | 525.68 | 7274.70 | |
| 2105 | 354.58 | 532.41 | 7488.07 | |
| 2106 | 357.75 | 539.18 | 7705.64 | |
| 2107 | 360.91 | 545.99 | 7927.45 | |
| 2108 | 364.08 | 552.83 | 8153.54 | |
| 2109 | 367.24 | 559.71 | 8383.96 | |
| 2110 | 370.41 | 566.62 | 8618.75 | |
| 2111 | 373.58 | 573.57 | 8857.94 | |
| 2112 | 376.74 | 580.55 | 9101.59 | |
| 2113 | 379.91 | 587.57 | 9349.72 | |
| 2114 | 383.07 | 594.62 | 9602.39 | |
| 2115 | 386.24 | 601.71 | 9859.63 | |
| 2116 | 389.41 | 608.84 | 10121.49 | |
| 2117 | 392.57 | 616.00 | 10388.00 | |
| 2118 | 395.74 | 623.20 | 10659.21 | |
| 2119 | 398.90 | 630.43 | 10935.17 | |
| 2120 | 402.07 | 637.70 | 11215.90 | |
| 2121 | 405.24 | 645.01 | 11501.45 | |
| 2122 | 408.40 | 652.35 | 11791.87 | |
| 2123 | 411.57 | 659.72 | 12087.19 | |
| 2124 | 414.73 | 667.14 | 12387.47 | |
| 2125 | 417.90 | 674.58 | 12692.72 | |
| 2126 | 421.06 | 682.07 | 13003.01 | |
| 2127 | 424.23 | 689.59 | 13318.37 | |
| 2128 | 427.40 | 697.14 | 13638.85 | |
| 2129 | 430.56 | 704.73 | 13964.47 | |
| 2130 | 433.73 | 712.36 | 14295.29 | |
| 2131 | 436.89 | 720.02 | 14631.35 | |
| 2132 | 440.06 | 727.72 | 14972.69 | |
| 2133 | 443.23 | 735.45 | 15319.35 | |
| 2134 | 446.39 | 743.22 | 15671.37 | |
| 2135 | 449.56 | 751.02 | 16028.79 | |
| 2136 | 452.72 | 758.86 | 16391.65 | |
| 2137 | 455.89 | 766.74 | 16760.00 | |
| 2138 | 459.06 | 774.65 | 17133.88 | |
| 2139 | 462.22 | 782.60 | 17513.33 | |
| 2140 | 465.39 | 790.58 | 17898.38 | |
| 2141 | 468.55 | 798.60 | 18289.09 | |
| 2142 | 471.72 | 806.65 | 18685.49 | |
| 2143 | 474.88 | 814.74 | 19087.63 | |
| 2144 | 478.05 | 822.87 | 19495.54 | |
| 2145 | 481.22 | 831.03 | 19909.26 | |
| 2146 | 484.38 | 839.22 | 20328.85 | |
| 2147 | 487.55 | 847.46 | 20754.33 | |
| 2148 | 490.71 | 855.72 | 21185.76 | |
| 2149 | 493.88 | 864.03 | 21623.17 | |
| 2150 | 497.05 | 872.37 | 22066.61 | |
| 2151 | 500.21 | 880.74 | 22516.11 | |
| 2152 | 503.38 | 889.15 | 22971.72 | |
| 2153 | 506.54 | 897.60 | 23433.47 | |
| 2154 | 509.71 | 906.08 | 23901.42 | |
| 2155 | 512.88 | 914.60 | 24375.60 | |
| 2156 | 516.04 | 923.15 | 24856.05 | |
| 2157 | 519.21 | 931.74 | 25342.81 | |
| 2158 | 522.37 | 940.37 | 25835.93 | |
| 2159 | 525.54 | 949.03 | 26335.45 | |
| 2160 | 528.71 | 957.73 | 26841.41 | |
| 2161 | 531.87 | 966.46 | 27353.85 | |
| 2162 | 535.04 | 975.23 | 27872.81 | |
| 2163 | 538.20 | 984.03 | 28398.33 | |
| 2164 | 541.37 | 992.87 | 28930.46 | |
| 2165 | 544.53 | 1001.74 | 29469.23 | |
| 2166 | 547.70 | 1010.65 | 30014.69 | |
| 2167 | 550.87 | 1019.60 | 30566.88 | |
| 2168 | 554.03 | 1028.58 | 31125.84 | |
| 2169 | 557.20 | 1037.60 | 31691.61 | |
| 2170 | 560.36 | 1046.65 | 32264.23 | |
| 2171 | 563.53 | 1055.74 | 32843.75 | |
| 2172 | 566.70 | 1064.86 | 33430.21 | |
| 2173 | 569.86 | 1074.03 | 34023.64 | |
| 2174 | 573.03 | 1083.22 | 34624.09 | |
| 2175 | 576.19 | 1092.45 | 35231.60 | |
| 2176 | 579.36 | 1101.72 | 35846.22 | |
| 2177 | 582.53 | 1111.02 | 36467.98 | |
| 2178 | 585.69 | 1120.36 | 37096.92 | |
| 2179 | 588.86 | 1129.74 | 37733.09 | |
| 2180 | 592.02 | 1139.15 | 38376.52 | |
| 2181 | 595.19 | 1148.59 | 39027.27 | |
| 2182 | 598.35 | 1158.07 | 39685.36 | |
| 2183 | 601.52 | 1167.59 | 40350.85 | |
| 2184 | 604.69 | 1177.14 | 41023.77 | |
| 2185 | 607.85 | 1186.73 | 41704.17 | |
| 2186 | 611.02 | 1196.35 | 42392.08 | |
| 2187 | 614.18 | 1206.01 | 43087.55 | |
| 2188 | 617.35 | 1215.71 | 43790.62 | |
| 2189 | 620.52 | 1225.44 | 44501.33 | |
| 2190 | 623.68 | 1235.21 | 45219.72 | |
| 2191 | 626.85 | 1245.01 | 45945.83 | |
| 2192 | 630.01 | 1254.85 | 46679.71 | |
| 2193 | 633.18 | 1264.72 | 47421.40 | |
| 2194 | 636.35 | 1274.63 | 48170.93 | |
| 2195 | 639.51 | 1284.58 | 48928.36 | |
| 2196 | 642.68 | 1294.56 | 49693.71 | |
| 2197 | 645.84 | 1304.57 | 50467.04 | |
| 2198 | 649.01 | 1314.63 | 51248.38 | |
| 2199 | 652.18 | 1324.71 | 52037.77 | |
| 2200 | 655.34 | 1334.84 | 52835.27 |
Sources
Sea level rise data from NASA Goddard Space Flight Center. 2017. Global Mean Sea Level Trend from Integrated Multi-Mission Ocean Altimeters TOPEX/Poseidon. Jason-1. OSTM/Jason-2 Version 4. Ver. 4. PO.DAAC. CA. USA. Dataset accessed 2017-08-28 at 10.5067/GMSLM-TJ124. NASA Sea Level Change. (text file)