Earth's magnetic flip could increase cancer rates

A team of scientists has demonstrated that the last magnetic reversal of the Earth 786,000 years ago actually happened very quickly, in less than 100 years - roughly a human lifetime.

Today, such a reversal can increase cancer rates and potentially wreak havoc with our electrical grid, generating currents that might take it down.

"Since Earth's magnetic field protects life from energetic particles from the Sun and cosmic rays - both of which can cause genetic mutations - a weakening or temporary loss of the field before a permanent reversal could increase cancer rates," cautioned researchers from the University of California, Berkeley in the US.

The danger to life would be even greater if flips were preceded by long periods of unstable magnetic behaviour, they added.

The discovery comes at a time when a new evidence indicates that the intensity of the Earth's magnetic field is decreasing 10 times faster than normal, leading some geophysicists to predict a reversal within a few thousand years.

The Earth's magnetic field has flipped - though not overnight - many times throughout the planet's history.

Its dipole magnetic field, like that of a bar magnet, remains about the same intensity for thousands to millions of years.

But for completely unknown reasons, it occasionally weakens and, presumably over a few thousand years, reverses direction.

A magnetic reversal is a major planet-wide event driven by convection in Earth's iron core.

The new finding is based on measurements of the magnetic field alignment in layers of ancient lake sediments now exposed in the Sulmona basin of the Apennine Mountains, east of Rome, Italy.

"We should be thinking more about what the biologic effects would be," added Paul Renne, director of the Berkeley Geochronology Center and a professor of earth and planetary science.

The team of scientists from Italy, France, the Columbia University and the University of California, Berkeley contributed towards the study.

The study is set to appear in the Geophysical Journal International.