The magnetic field of the Earth is our invisible friend. Imperceptible in our day to day but fundamental for the microbial life has managed to evolve to the point where we are today. Without that invisible magnetic field our planet wouldn’t be able to keep the gases in the atmosphere safe from solar winds. Extrasolar radiation would destroy the DNA of living organisms and most likely our planet would resemble Mars.
1 - Structure of the Magnetosphere seen from space. Credits: ESA
Taking into account the latest published studies, the hypothesis that the Earth's magnetic field was preparing for an imminent reversal had grown. However a new scientific study that has been published, describes this worrying situation as unlikely.
This paper published a couple of months ago, collects both direct observation (observatory / satellite) and indirect (archaeomagnetic) data.
But what is archaeomagnetism?
Archaeomagnetism studies the magnetic field of the Earth in terms of the variation in direction as well as the intensity recorded in the past. Using archaeological materials that have undergone heating processes at high temperature (> 570 ° C).
”.. ancient civilizations, when baking pottery, were also inadvertently recording the Earth’s magnetic field. This archaeomagnetic record can be retrieved from ancient baked clay (and from historical lavas) using laboratory techniques developed more than one hundred years ago..”
Q1 - doi.org/10.1016/j.pepi.2017.11.005
From this study it is clear that the Earth's magnetic field could be going through a "valley" before intensifying again. Apparently the last peak of intensity occurred 570-750 after Christ, and from that moment began a long and gradual decline in its intensity.
2 - Virtual Axial Dipole Moment (VADM) obtained from archaeointensity data for the entirety of the last two millennia. - doi.org/10.1016/j.pepi.2017.11.005
3 - Continuous decrease of the geomagnetic axial dipole for the last four centuries. - doi.org/10.1016/j.pepi.2017.11.005
(a) Seven linear solutions sets for the last four centuries are represented in light green shaded area; continuous green lines represent the extremes of each linear solution set. Yellow and red lines represent the ADM of CHAOS-5 and gufm1, respectively. Blue line represents the common linear solution for the sets of linear regressions, obtained exclusively from archaeointensity data.
Q2 - doi.org/10.1016/j.pepi.2017.11.005
(v) “Comparable duration of the dipole decay and the ADM SV timescale suggests that this event may be reaching its end soon, and therefore tend to disfavor the hypothesis of an imminent geomagnetic reversal.”
Q3 - doi.org/10.1016/j.pepi.2017.11.005
This is one of the five most important conclusions that this paper offers us. And it couldn't be better news considering the enormous importance that the magnetosphere has for life on Earth.
References
1 - Magnetosphere
http://m.esa.int/Our_Activities/Space_Science/Cluster/Earth_s_magnetosphere_behaves_like_a_sieve
Q1, Q2, Q3, 2, 3 - “Continuous millennial decrease of the Earth’s magnetic axial dipole”. Wilbor Poletti et al. - doi.org/10.1016/j.pepi.2017.11.005
https://www.sciencedirect.com/science/article/pii/S0031920117302054
”I have to highlight, that despite being a recently published article, it's open access. Normally to be able to read a recent paper you have to pay considerable amounts of dollars. However, this extensive paper is free. The large number of papers used by this group of scientists, makes this paper a good index, both archaeomagnetism and direct observation of the earth's magnetic field.”
