U.S. gov­ern­ment fi­nally catches up on north mag­netic pole’s puz­zling drift

The Washington Post Sunday - - POLITICS & THE NATION - BY SARAH KA­PLAN sarah.ka­[email protected]­post.com

Mag­netic north is not where it used to be.

Since 2015, the place to which a com­pass points has been sprint­ing to­ward Siberia at a pace of more than 30 miles a year. And, af­ter a de­lay caused by the month­long par­tial gov­ern­ment shut­down in the United States, hu­mans fi­nally have caught up.

Sci­en­tists on Mon­day re­leased an emer­gency up­date to the World Mag­netic Model, which cell­phone GPS sys­tems and mil­i­tary nav­i­ga­tors use to ori­ent them­selves. It’s a mi­nor change for most of us — no­tice­able only to peo­ple at­tempt­ing to nav­i­gate very pre­cisely very close to the Arc­tic.

The north mag­netic pole’s in­ex­orable drift sug­gests some­thing strange — and po­ten­tially pow­er­ful — is tak­ing place deep within Earth. Only by track­ing it, said Univer­sity of Leeds geo­physi­cist Phil Liver­more, can sci­en­tists hope to un­der­stand what is go­ing on.

The planet’s mag­netic field is gen­er­ated nearly 2,000 miles be­neath our feet, in the swirling, spin­ning ball of molten metal that forms Earth’s core.

Changes in that un­der­ground flow can al­ter Earth’s mag­netic field lines — and the poles where they con­verge. Con­se­quently, mag­netic north does not align with geo­graphic north (the end point of Earth’s ro­ta­tional axis), and it is con­stantly on the move.

The first ex­pe­di­tion to find mag­netic north, in 1831, pin­pointed it in the Cana­dian Arc­tic. By the time the U.S. Army went look­ing for it in the late 1940s, it had shifted 250 miles to the north­west. Since 1990, it has moved a whop­ping 600 miles and can be found in the mid­dle of the Arc­tic Ocean, 4 de­grees south of geo­graphic north — for the mo­ment.

Cu­ri­ously, the south mag­netic pole, off the coast of eastern Antarc­tica, has re­mained rel­a­tively sta­ble since 1990.

Liver­more’s re­search sug­gests the north pole’s lo­ca­tion is con­trolled by two patches of mag­netic field be­neath Canada and Siberia.

In 2017, he re­ported that the Cana­dian patch seems to be weak­en­ing, the re­sult of a liq­uid iron slosh­ing through Earth’s core. Speak­ing at a meet­ing of the Amer­i­can Geo­phys­i­cal Union in De­cem­ber, Liver­more sug­gested that the tu­mult far be­low the Arc­tic may ex­plain the move­ment of the mag­netic field lines above it.

Sci­en­tists with the Na­tional Oceanic and At­mo­spheric Ad­min­is­tra­tion and the British Ge­o­log­i­cal Sur­vey col­lab­o­rate to pro­duce a new World Mag­netic Model — a math­e­mat­i­cal rep­re­sen­ta­tion of the field — ev­ery five years.

The next up­date was not sched­uled un­til 2020. But Earth had other plans.

Fluc­tu­a­tions in the Arc­tic were oc­cur­ring faster than pre­dicted. By the sum­mer, the dis­crep­ancy between the World Mag­netic Model and the real-time lo­ca­tion of the north mag­netic pole had nearly ex­ceeded the thresh­old needed for ac­cu­rate nav­i­ga­tion, said Wil­liam Brown, a ge­o­mag­netic field mod­eler for the British Ge­o­log­i­cal Sur­vey. He and his U.S. coun­ter­parts worked on a new model, which was al­most ready to be re­leased when much of the U.S. fed­eral gov­ern­ment ran out of fund­ing.

Though the British agency was able to pub­lish el­e­ments of the new model on its site, NOAA was re­spon­si­ble for host­ing the model and mak­ing it avail­able for pub­lic use. This por­tion of the model did not be­come avail­able un­til Mon­day, a week af­ter most NOAA em­ploy­ees re­turned to work.

The mag­netic poles some­times flip, with north be­com­ing south. Such an event has oc­curred an av­er­age of three times ev­ery mil­lion years — and the last one was 780,000 years ago.

“There’s no ev­i­dence” that the changes in the Arc­tic are a sign of a re­ver­sal, Liver­more said. Any­way, mag­netic field re­ver­sals have typ­i­cally un­folded over the course of 1,000 years or so — giv­ing plenty of time for even the U.S. fed­eral gov­ern­ment to ad­just.

DAVID GOLD­MAN/AS­SO­CI­ATED PRESS

Chief Of­fi­cer Harri Ve­nalainen nav­i­gates the ice­breaker MSV Nordica through the Beau­fort Sea while travers­ing the North­west Pas­sage. Arc­tic nav­i­ga­tors rely on the Word Mag­netic Model for ori­en­ta­tion.

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