Earth's dynamo limit of predictability
and J. Aubert2
Received 20 November 2009; revised 22 January 2010; accepted 19 February 2010; published 25 March 2010.
 Earth's magnetic field is currently decreasing, reducing
the protection it offers against charged particles coming
from space and increasing space weather hazards within the
nearEarth environment. Modeling the future evolution of
the field is thus of considerable interest. But how far in the
future this can conceivably be done is still an open question.
Here we report on the first systematic investigation of the
limit of predictability of fully consistent 3D numerical
dynamo simulations, and suggest that the Earth's dynamo is
likely unpredictable beyond a century, making decade