Just one more thing to worry about

So, it would appear from this research, that the environmental effect of Earth's magnetic field flipping (which last happened 42,000 years ago) on the planet is not particularly well understood:

One temporary flip of the poles, known as the Laschamps excursion, happened 42,000 years ago and lasted for about 1,000 years. Previous work found little evidence that the event had a profound impact on the planet, possibly because the focus had not been on the period during which the poles were actually shifting, researchers say.

Now scientists say the flip, together with a period of low solar activity, could have been behind a vast array of climatic and environmental phenomena with dramatic ramifications. “It probably would have seemed like the end of days,” said Prof Chris Turney of the University of New South Wales and co-author of the study....

Writing in the journal Science, Turney and his colleagues describe how they carried out radiocarbon analyses of the rings of ancient kauri trees preserved in northern New Zealand wetlands, some of which were more than 42,000 years old.

This allowed them to track over time the rise in carbon-14 levels in the atmosphere produced by increasing levels of high energy cosmic radiation reaching the Earth during the Laschamps excursion. As a result they were able to date the atmospheric changes in more detail than offered by previous records, such as mineral deposits.

They then examined numerous records and materials from all over the world, including from lake and ice cores, and found that a host of major environmental changes occurred at the same time as the carbon-14 levels peaked.

So, what did happen in this period?: 

“We see this massive growth of the ice sheet over North America … we see tropical rain belts in the west Pacific shifting dramatically at that point, and then also wind belts in the southern ocean and a drying out in Australia,” said Turney.

The researchers also used a model to examine how the chemistry of the atmosphere might change if the Earth’s magnetic field was lost and there was a prolonged period of low solar activity, which would have further reduced Earth’s protection against cosmic radiation. Ice core records suggest such dips in solar activity, known as the “grand solar minima”, coincided with the Laschamps excursion.

The results reveal that the atmospheric changes could have resulted in huge shifts in the climate, electrical storms and widespread colourful aurora.

Some stuff in the report is pretty speculative:

...the team suggest they could also be linked to the emergence of red ochre handprints, the suggestion being that humans may have used the pigment as a sunscreen against the increased levels of ultraviolet radiation hitting the Earth as a result of the depletion of ozone.

They also suggest the rise in the use of caves by our ancestors around this time, as well as the rise in cave art, might be down to the fact that underground spaces offered shelter from the harsh conditions. The situation may also have boosted competition, potentially contributing to the end of the Neanderthals, Turney said.

Of course, the worry is how well our civilisation could cope:

The Earth’s magnetic field has weakened by about 9% over the past 170 years, and the researchers say another flip could be on the cards. Such a situation could have a dramatic effect, not least by devastating electricity grids and satellite networks.

All a worry...