Decay of Earth's Magnetic Field

On the dashboard of my car I have a magnetic compass.  I know that GPS navigators (Satnavs) are all the rage now, but my little compass usually works well, isn’t intrusive and doesn’t tell me to go to places that don’t exist or are impossible to back out of, and doesn't cost me anything to update.  Compasses depend on the magnetic field of the Earth, of course, and there are two qualities that matter here.  The first is its direction, and the second is how strong the magnetic field is.

Although for many years it was assumed that both of these were unchanging it is now accepted that the direction of the field has switched many times in the past, and that the strength of Earth's magnetism is steadily decreasing.  While the last is unlikely ever to affect my ability to drive in the right direction it does ask some questions about how long life has existed on the Earth.

The magnetic field of the Earth is important to us because it protects us.  The magnetosphere, generated by the planet's magnetic field, is a protective magnetic screen which surrounds the Earth.  Without that protective screen we would quickly be in dire trouble because it guides dangerous radiation coming from the sun around and away from our planet.  There is, as usual, considerable argument about this, but it is interesting just how much reaction occurs to things like the thinning of the ozone layer which also protect us from certain types of radiation that the magnetosphere doesn't block.

Modern measurements seem to imply that the magnetic field strength is halving every 1,400 years or so.  This means that 1,400 years ago it was twice as strong as it is now, and 2,800 years ago it was four times stronger.  7,000 years ago it would have been about 32 times as strong, and 10,000 years ago more that 100 times as strong.  It is certainly reckoned to have diminished by about 10% in the last 150 years.

If this extrapolation is correct then it really puts an upper limit on how long ago this process started, because beyond 10,000 years the strength of the magnetism would have been impossibly high.  So somewhere between that point and now the magnetic field was probably regenerated, perhaps when a switch in direction occurred, and, when that happened, any life on this planet would quite likely have been annihilated, due to the temporary failure of the protective field.

The main objection to this claim is that there are striated magnetic patterns across the ocean floor.  The contemporary deduction from this is that magnetic reversal has happened on many occasions but it cannot have been a problem because we still find life on the Earth!  This, as an one who is at all logical will see, is a circular argument.  The assumption is that life has continued without breaks on Earth.  There is actually no proof of this, and we are turning up evidence of mass extinctions.  Whether we like it or not, this is a problem to evolutionists, for with the field reversal comes a period in which the Earth is quite clearly unprotected, and this would have been seriously inimical to life, by and large.

Quote from the British Geological Survey site

“Is there any danger to life (in magnetic reversals)?  Almost certainly not.  The Earth's magnetic field is contained within a region of space, known as the magnetosphere, by the action of the solar wind.  The magnetosphere deflects many, but not all, of the high-energy particles that flow from the Sun in the solar wind and from other sources in the galaxy.  Sometimes the Sun is particularly active, for example when there are many sunspots, and it may send clouds of high-energy particles in the direction of the Earth.  During such solar 'flares' and 'coronal mass ejections', astronauts in Earth orbit may need extra shelter to avoid higher doses of radiation.  Therefore we know that the Earth's magnetic field offers only some, rather than complete, resistance to particle radiation from space.  Indeed high-energy particles can actually be accelerated within the magnetosphere.  (This last is simply disingenuous.  The whole point here is that they change their direction so that they miss the Earth.)

At the Earth's surface, the atmosphere acts as an extra blanket to stop all but the most energetic of the solar and galactic radiation.  In the absence of a magnetic field, the atmosphere would still stop most of the radiation.  Indeed the atmosphere shields us from high-energy radiation as effectively as a concrete layer some 13 feet thick.  (But this depends entirely on the type of radiation.  Cosmic rays wouldn't even notice this.)

Human beings have been on the Earth for a number of million years, during which there have been many reversals, and there is no obvious correlation between human development and reversals.  Similarly, reversal patterns do not match patterns in species extinction during geological history.  (This, it has to said, is pure assumption and not supported by many other considerations, including which are language and social studies, DNA discoveries and new fossil finds.)

Some animals, such as pigeons and whales, may use the Earth's magnetic field for direction finding. Assuming that a reversal takes a number of thousand years, that is, over many generations of each species, each animal may well adapt to the changing magnetic environment, or develop different methods of navigation."

(My comments above are the ones in italics.  All of the above assumes evolution, which is actually the problem, so we have a circular argument here.  As a matter of strict fact radiation is a serious problem to astronauts, far more so than is admitted here, and almost all space 'activity' takes place well within the electromagnetic shield.  Explorations outside that sphere have been strictly limited with respect to length of time and they are scheduled to avoid periods of intense sun activity.

There have been a number of science fiction stories which have drawn on this aspect of danger from unprotected sun radiation in space travel.  It is not chimaerical.  But the bottom line is simply this: we haven't yet experienced a period in which the magnetosphere has significantly reduced, so it might be premature to claim, as the above quote does, that there is no danger.  Remember thalidomide?  The secondary effect of smoking not being a problem?  Lead in petrol not being dangerous?  Etc., etc.)