It may sound awkward at first glance, but serious research are being carried out around the changes of the magnetic fields of the Earth and findings lead to a potential link with climate change. If so, no need to say that it would affect agriculture too.
The origin of these investigations are on the interest to predict the changes on the North-South magnetic axis with the time. We know since long ago that the North magnetic pole doesn´t coincide with the geographic North pole, because the magnetic one changes continuously. This variation (magnetic declination) is very small, but it´s still sufficient to have to be considered in maps, charts, navigational methods and instruments. Even in the GPS era, the magnetic compass is still an essential tool in ships, planes and for many travelers.
We also know, that the mentioned variation isn´t stable. The changes can be predicted for short periods of time (well, some years, actually), but the change is capricious: it doesn´t match with a fix pattern. So it cannot be predicted for longer term periods. The reasons? The number one leads to the Earth nucleus, an apparently unstable “ambient” that determines heavily the magnetic fields of our planet.
Now, some researches carried out by analyzing the orientation of magnetic particles contained in samples of soil extracted from certain locations, revealed that the magnetic poles of the planet have changed their position so much in the past, that they even were on opposite positions to where them are now.
Yet it´s true that it took many thousand years “the travel”, it is also true that scientists are finding some acceleration in the changes in the last years.
The correlation between the trace of temperature evolution, obtained from glacier age samples, and that of the magnetic fields variation, is well studied and unveils that big changes in climate -like desertifications and glaciations- are always linked. It´s a proven fact.
And what is the connection of Earth magnetic field with climate?
It´s not yet clear which one causes changes in the other.
Well, on one side, the magnetic fields act as a shield protecting the Earth surface from the “impact” of high energy particles which may cause some disruption in elements such as the electric power grid, problems in air communications, and reduction of the life of geostationary satellites -like those governing the GPS system-, among others. But another effect of these particles reaching the surface of the planet, either ground or oceans, is heat transfer and, thus, temperature change, so its variations activate a chain reaction in the complex climate mechanism.
On a different line, some scientist refer to the solar particles affecting what they call “cloud seeds” -other particles which act as aggregators of vapor molecules and start up cloud formation-; so, the variation in the magnetic shield would influence the amount of clouds in the atmosphere.
Other theory is that changes in the heating of the core of the planet and the transmission of heat through the mantle and its layers, cause climate change and, obviously, in the magnetic fields too.
Maybe at the end of the day, men and modernity may not be the real reason -or at least not completely- of the alleged global warming that we are experiencing.
PD: Shall we have to use a compass to predict the weather tomorrow?