Earth's Poles Long Overdue For Reversal
A reversal of the Eart?'s magnetic ?oles could happ?n sooner than we think, a?cording t? Dutch scientist? wh? report that the planet's magnetic fi?ld is beco?ing grad?ally less stable. A reversal could affect ?verything f?om navigation and communicati?ns equipment to th? compos?tion of th? atmosphe?e, say experts. T?e report, published today ?n the U.K. ?ournal N?ture Ge?science, found that ?eversals have been far more common ?n the last 200 ?illion years than they were d?ep ?n the planet's history. 
Researchers, led by Andrew Biggin of the Univ?rsity of Utrecht ?n the N?therlands, made the discovery by analys?ng ?ocks formed bet?een 2.45 to 2.82 billion ?ears ag?. T?e st?ry of the Earth's magnetic field is written ?n rocks ove? time. Because t?ese rocks bec?me 'magnetised' at t?e time of their formati?n, scientists can d?scover whi?h direction the poles were fac?ng and how strong the Earth's magnetic field was ?t th?t time. The magnet?c poles wander ?round the vicinity of the geographic poles all the tim? – the north m?gnetic ?ole curr?ntly resid?s in the Canadian Arct?c. However, at relatively regular inte?vals throughout the 4.5 billi?n year history of the planet, the magnetic ?oles have fli?ped completely. A fe? thousand years ?efore ? reversal, the m?gnetic field gradually gets weaker; so?ething which could cause problem? for inhabitants of th? planet.
"The Earth's magnetic field ?s important for shielding the atmosphere, and us, from damage caused by the solar wind," explained Biggin. "It's als? used ?y us and other species for navigation". An increase in solar wind would disrupt communic?tions equi?ment and ?ower grids. Current records suggest t?at we are long ?verdue for o?r next ?eversal, ?e said. "On ave?age, there is ? reversal around every 400,000 years, but this vari?s ? lot." The geological ?ecord suggests that the last reversal ?as around 800,000 years ago.
Furthermore, there is already evidence to show t?at the field has been weakening ?ver the last few centuries – some archaeological remains suggest that the f?eld wa? fa? stronger in the time of the Roman E?pire, some 2,000 ye?rs ago. Don't thro? away you? compass just yet though – majo? changes ma? not ev?n happen in our lifetim?s. "T?e reversal proces? ?s very unpredictable," said Bigg?n. "We could be h?ading into a reversal in th? next few centuries, or we might ?e waiting another million years".
Even then, reversal is a slow process, which c?n t?ke some thous?nds of years to co?plete. But w?at a?out the effect on living ?rganisms? Another paper, published in Nature in March suggested that some species that rely ?n the field for navigat?on or orientat?on hav? taken ? knock from pole reversals in the pa?t. Author D?vid Gubbins, of th? Univer?ity of Leeds ?n England, ?aid that some single-celled organi?ms t?at relied ?n magnetism to tell up fro? down l?kely went extinct du?ing past reversals. Hum?n beings have ?urvived reversal? in the past, however, added Gubbins, "so w? ar? li?ely t? c?me through the next one unscathed."
Source: Cosmos Magazine
http://www.cosmosmagazine.com/node/1967
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