Wednesday, January 28, 2009

Global Magnetic Field

I am hesitant to say much on this until I am in possession of a lot more information. It is easy to imagine a cause and effect relationship between the waxing and waning of the magnetic field and a cosmic ray – precipitation connection. Except our real data is a mere thirty years old. During this time there was a real uptrend in apparent global heat, now recently reversed.

Magnetic fields will change at the same pace. Thus a correlation is unavoidable. And it is a compelling hypothesis.

I just think that the time spans are far too short or subject to eyeball selection that makes results suspect. We will be seeing more of this.

The earth's magnetic field impacts climate: Danish study COPENHAGEN, Jan 12 (AFP) Jan 12, 2009

The earth's climate has been significantly affected by the planet's
magnetic field , according to a Danish study published Monday that could challenge the notion that human emissions are responsible for global warming.

"Our results show a strong correlation between the strength of the earth's magnetic field and the amount of precipitation in the tropics," one of the two Danish geophysicists behind the study, Mads Faurschou Knudsen of the geology department at Aarhus University in western Denmark, told the Videnskab journal.

He and his colleague Peter Riisager, of the Geological Survey of Denmark and Greenland (GEUS), compared a reconstruction of the prehistoric magnetic field 5,000 years ago based on data drawn from stalagmites and stalactites found in China and Oman.

The results of the study, which has also been published in US scientific journal Geology, lend support to a controversial theory published a decade ago by Danish astrophysicist Henrik Svensmark, who claimed the climate was highly influenced by galactic cosmic ray (GCR) particles penetrating the earth's atmosphere.

Svensmark's theory, which pitted him against today's mainstream theorists who claim
carbon dioxide (CO2) is responsible for global warming, involved a link between the earth's magnetic field and climate, since that field helps regulate the number of GCR particles that reach the earth's atmosphere.

"The only way we can explain the (geomagnetic-climate) connection is through the exact same physical mechanisms that were present in Henrik Svensmark's theory," Knudsen said.

"If changes in the magnetic field, which occur independently of the earth's climate, can be linked to changes in precipitation, then it can only be explained through the magnetic field's blocking of the cosmetic rays," he said.

The two scientists acknowledged that CO2 plays an important role in the changing climate, "but the climate is an incredibly complex system, and it is unlikely we have a full overview over which factors play a part and how important each is in a given circumstance," Riisager told Videnskab.


Radical said...

You might be interested in this paper.

Climate Change and the Earth's Magnetic Poles, A Possible Connection

Author: Kerton, Adrian K.

Source: Energy & Environment, Volume 20, Numbers 1-2, January 2009 , pp. 75-83(9)

Publisher: Multi-Science Publishing Co Ltd

Many natural mechanisms have been proposed for climate change during the past millennia, however, none of these appears to have accounted for the change in global temperature seen over the second half of the last century. As such the rise in temperature has been attributed to man made mechanisms. Analysis of the movement of the Earth's magnetic poles over the last 105 years demonstrates strong correlations between the position of the north magnetic, and geomagnetic poles, and both northern hemisphere and global temperatures. Although these correlations are surprising, a statistical analysis shows there is a less than one percent chance they are random, but it is not clear how movements of the poles affect climate. Links between changes in the Earth's magnetic field and climate change, have been proposed previously although the exact mechanism is disputed. These include: The Earth's magnetic field affects the energy transfer rates from the solar wind to the Earth's atmosphere which in turn affects the North Atlantic Oscillation. Movement of the poles changes the geographic distribution of galactic and solar cosmic rays, moving them to particularly climate sensitive areas. Changes in distribution of ultraviolet rays resulting from the movement of the magnetic field, may result in increases in the death rates of carbon sinking oceanic plant life such as phytoplankton.


Document Type: Research article

DOI: 10.1260/095830509787689286

arclein said...

The linkages are clearly suggestive, except the magnitudes are such that they are likely buried in the noise.

Including CO2, we have several proposed climate drivers, any one of which is small compared to the known two degree oscillation that has been sustained throughout the Holocene.

That the magnetic field is likely linked to solar magnetic field variation and thus to sunspot activity and that the correlation stands up is good news.

The question then becomes how mush of the temperature signal belongs to this causation? Again we need a lot more data.

Radical said...

I did try to chase back in time, however as soon as you go back before 1900 you have a choice of a multitude of temperature reconstructions and a number of differing estimates of the pole positions. Going back a long way you find the geological record shows anomalies like the North pole was apparently near the equator but this is because the continent has drifted away from the Northern position it previously held. For now the correlations are just that, however they do reinforce the paleomagnetic studies that temperature and the magnetic field are linked, so hopefully my contribution has added to the great debate.