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The earth's magnetic field is constantly changing. In the past, variation from year to year has been not so great so as to make estimates of location unreliable from place to place worldwide, and such practices as land surveying and navigation at sea have been able to use updated maps for currently reliable data. In recent years, however, the magnetic poles (called dip poles) of the earth have been moving more quickly such that services and trades that rely on currently updated locations of the dip poles have had to obtain more frequent assessment and updates.
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Observed north dip poles during 1831 - 2007 are yellow squares.
Modeled pole locations from 1590 to 2020 are circles progressing from blue to yellow.
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[Obviously, the locations for 2020, 2019, 2018 and 2017 are estimates. This present data is current as of 2015.]
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Magnetic poles are defined in different ways. They are commonly understood as positions on the Earth's surface where the geomagnetic field is vertical (i.e., perpendicular) to the ellipsoid. These north and south positions, called dip poles, do not need to be (and are not currently) antipodal. In principle the dip poles can be found by conducting a magnetic survey to determine where the field is vertical. Other definitions of geomagnetic poles depend on the way the poles are computed from a geomagnetic model. In practice the geomagnetic field is vertical on oval-shaped loci traced on a daily basis, with considerable variation from one day to the next.
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It has been long understood that dip poles migrate over time. In 1831, James Clark Ross located the north dip pole position in northern Canada. Natural Resources Canada (NRCan) tracked the North Magnetic Pole, which is slowly drifting across the Canadian Arctic, by periodically carrying out magnetic surveys to reestablish the Pole's location from 1948 to 1994. An international collaboration, led by a French fundraising association, Poly-Arctique, and involving NRCan, Institut de Physique du Globe de Paris and Bureau de Recherche Geologique et Miniere, added two locations of the North Magnetic Pole in 2001 and 2007. The most recent survey determined that the Pole is moving approximately north-northwest at 55 km per year.
Modeled pole locations for magnetic north from 1831 to 2020 [1831.000 - 2020.000 -- these are not observed north pole locations]:
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261.931 70.411 1831.000 262.011 70.346 1832.000 262.108 70.271 1833.000 262.221 70.189 1834.000 262.350 70.105 1835.000
262.496 70.021 1836.000 262.657 69.936 1837.000 262.829 69.848 1838.000 262.998 69.761 1839.000 263.140 69.681 1840.000
263.235 69.615 1841.000 263.289 69.560 1842.000 263.311 69.510 1843.000 263.312 69.463 1844.000 263.301 69.420 1845.000
263.287 69.379 1846.000 263.270 69.341 1847.000 263.251 69.311 1848.000 263.231 69.288 1849.000 263.215 69.271 1850.000
263.206 69.259 1851.000 263.203 69.249 1852.000 263.204 69.240 1853.000 263.208 69.230 1854.000 263.214 69.219 1855.000
263.221 69.205 1856.000 263.229 69.192 1857.000 263.238 69.180 1858.000 263.243 69.174 1859.000 263.237 69.178 1860.000
263.211 69.196 1861.000 263.174 69.225 1862.000 263.135 69.259 1863.000 263.101 69.296 1864.000 263.076 69.336 1865.000
263.066 69.375 1866.000 263.063 69.414 1867.000 263.062 69.455 1868.000 263.056 69.496 1869.000 263.044 69.536 1870.000
263.025 69.575 1871.000 263.004 69.615 1872.000 262.986 69.659 1873.000 262.968 69.708 1874.000 262.942 69.760 1875.000
262.900 69.812 1876.000 262.847 69.863 1877.000 262.789 69.914 1878.000 262.733 69.964 1879.000 262.686 70.013 1880.000
262.652 70.061 1881.000 262.628 70.111 1882.000 262.611 70.163 1883.000 262.598 70.218 1884.000 262.591 70.276 1885.000
262.589 70.335 1886.000 262.590 70.394 1887.000 262.590 70.448 1888.000 262.585 70.497 1889.000 262.574 70.546 1890.000
262.606 70.584 1891.000 262.718 70.600 1892.000 262.894 70.592 1893.000 263.110 70.564 1894.000 263.338 70.525 1895.000
263.547 70.483 1896.000 263.712 70.449 1897.000 263.813 70.430 1898.000 263.845 70.433 1899.000 263.814 70.460 1900.000
263.756 70.499 1901.000 263.697 70.539 1902.000 263.638 70.578 1903.000 263.579 70.618 1904.000 263.520 70.657 1905.000
263.472 70.683 1906.000 263.424 70.708 1907.000 263.376 70.734 1908.000 263.328 70.760 1909.000 263.280 70.785 1910.000
263.218 70.834 1911.000 263.156 70.883 1912.000 263.094 70.931 1913.000 263.031 70.981 1914.000 262.968 71.030 1915.000
262.898 71.091 1916.000 262.827 71.152 1917.000 262.756 71.214 1918.000 262.686 71.275 1919.000 262.615 71.337 1920.000
262.494 71.426 1921.000 262.374 71.516 1922.000 262.252 71.606 1923.000 262.130 71.696 1924.000 262.007 71.786 1925.000
261.872 71.881 1926.000 261.735 71.977 1927.000 261.597 72.073 1928.000 261.457 72.170 1929.000 261.317 72.268 1930.000
261.191 72.371 1931.000 261.064 72.475 1932.000 260.934 72.580 1933.000 260.802 72.687 1934.000 260.667 72.796 1935.000
260.564 72.894 1936.000 260.458 72.993 1937.000 260.351 73.093 1938.000 260.241 73.195 1939.000 260.129 73.299 1940.000
260.062 73.421 1941.000 259.992 73.544 1942.000 259.918 73.670 1943.000 259.842 73.797 1944.000 259.762 73.926 1945.000
259.643 74.066 1946.000 259.521 74.208 1947.000 259.397 74.350 1948.000 259.270 74.494 1949.000 259.141 74.638 1950.000
259.039 74.741 1951.000 258.932 74.848 1952.000 258.821 74.957 1953.000 258.704 75.069 1954.000 258.582 75.184 1955.000
258.658 75.208 1956.000 258.734 75.232 1957.000 258.812 75.255 1958.000 258.889 75.278 1959.000 258.967 75.301 1960.000
258.908 75.364 1961.000 258.848 75.429 1962.000 258.787 75.494 1963.000 258.725 75.560 1964.000 258.663 75.626 1965.000
258.735 75.677 1966.000 258.807 75.728 1967.000 258.880 75.778 1968.000 258.953 75.829 1969.000 259.026 75.878 1970.000
259.092 75.934 1971.000 259.158 75.989 1972.000 259.225 76.044 1973.000 259.293 76.098 1974.000 259.362 76.153 1975.000
259.158 76.303 1976.000 258.952 76.454 1977.000 258.745 76.604 1978.000 258.535 76.755 1979.000 258.323 76.906 1980.000
258.140 77.005 1981.000 257.956 77.104 1982.000 257.769 77.202 1983.000 257.581 77.300 1984.000 257.391 77.398 1985.000
257.184 77.537 1986.000 256.973 77.677 1987.000 256.757 77.816 1988.000 256.537 77.956 1989.000 256.311 78.095 1990.000
256.010 78.286 1991.000 255.699 78.476 1992.000 255.380 78.665 1993.000 255.050 78.854 1994.000 254.710 79.043 1995.000
253.995 79.417 1996.000 253.211 79.798 1997.000 252.350 80.185 1998.000 251.403 80.576 1999.000 250.360 80.972 2000.000
248.992 81.427 2001.000 247.468 81.879 2002.000 245.769 82.325 2003.000 243.881 82.762 2004.000 241.782 83.186 2005.000
239.408 83.602 2006.000 236.784 83.995 2007.000 233.900 84.363 2008.000 230.751 84.702 2009.000 227.166 85.020 2010.000
222.596 85.370 2011.000 217.521 85.676 2012.000 211.982 85.933 2013.000 206.059 86.138 2014.000
199.975 86.289 2015.000 193.710 86.395 2016.000
187.413 86.455 2017.000 181.245 86.471 2018.000 175.346 86.448 2019.000 169.818 86.391 2020.000
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[The years' data for 2015 and 2017 are in bold - degrees longitude west, degrees latitude north, year.]
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The cause of the earth's magnetic field is not actually known, but there are theories proposed that would explain it. It is thought that some large quantity of ferrous material in the earth's core is moving to produce this field, but how much iron, where exactly it's located and how fast it's moving are all unknowns and up for speculation. One thing scientists can agree on is that wherever this iron is precisely, it exists at a temperature of over 1,000 degrees Fahrenheit, or perhaps even 2,000, which would mean it would be molten at atmospheric pressure, however, since it is expected to have an ambient pressure of hundreds of atmospheres, the liquidity/solidity or whatever state it is in cannot be certain. In any event, since the magnetic poles of the earth are observed to in fact be moving, we can reasonably presume that the ferrous or iron mass deep within the earth must not only be moving so as to generate this field but must be moving in a variable manner, that is, moving differently today than it has moved in previous centuries.
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Since it is essentially unknown what forces are acting on the iron inside the earth, we cannot know for sure what kinds of changes the magnetic field will undergo in the future. We can presume to expect it to move in a somewhat predictable manner, but as you can see from the image above, in the years 1732 (George Washington's birthday and the square root of 3), 1859, 1890 and 1900 the north dip pole changed direction of drift quite abruptly and without apparent or observable cause as far as we know (the birth of Washington or the square root of 3 can't explain a pole shift), therefore a similar change could likewise occur in our present age and we have no way of predicting it or even of anticipating when or whether it will occur.
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