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11 January 2009

Solar Activity and Climate


Space weather may also in the long term affect the Earth's climate. Solar ultra-violet, visible and heat radiation are the primary factors for the Earth's climate, including global average temperatures, and these energy sources appear to be quite constant. However, many scientists have observed corrrelations between the solar magnetic activity, which is reflected in the sunspot frequency, and climate parameters at the Earth. Sunspots has been recorded through several hundreds of years which makes it possible to compare their variable frequency to climate variations to the extent that reliable climatological records exists. One of the most striking comparisons was published by E. Friis-Christensen og K. Lassen, DMI, in "Science" in 1991. In their work they compared the average temperatureat the northern hemisphere with the average solar activity defined through the interval between successive sunspot maxima. The more active the sun - the shorter the interval: the solar cycle runs more intense. Their results are displayed in the figure above:

The red curve illustrates the solar activity, which is generally
increasing through an interval of 100 years, since the cycle length
has decreased from around 11.5 years to less than 10 years. Within
the same interval the Earth's average temperature as indicated by
the blue curve has increased by approximately 0.7 degree C. Even
the finer structures in the two curves have similar appearances.

(Reference: Friis-Christensen, E., and K. Lassen, Length of the solar
cycle: An indicator of solar activity closely associated with climate,
Science, 254, 698-700, 1991).

2 comments:

Anonymous said...

Keeping in mind that windmills are hazardous to birds, be wary of the unintended consequences of believing and contributing to the all-knowing environmental lobby groups.
Water vapour is the most important green house gas followed by methane. The third important greenhouse gas is CO2, and it does not correlate well with global warming or cooling either; in fact, CO2 in the atmosphere trails warming which is clear natural evidence for its well-studied inverse solubility in water: CO2 dissolves in cold water and bubbles out of warm water. The equilibrium in seawater is very high, making seawater a great 'sink'; CO2 is 34 times more soluble in water than air is soluble in water.
Correlation is not causation to be sure. The causation has been studied, however, and while the radiation from the sun varies only in the fourth decimal place, the magnetism is awesome.
“Using a box of air in a Copenhagen lab, physicists traced the growth of clusters of molecules of the kind that build cloud condensation nuclei. These are specks of sulphuric acid on which cloud droplets form. High-energy particles driven through the laboratory ceiling by exploded stars far away in the Galaxy - the cosmic rays - liberate electrons in the air, which help the molecular clusters to form much faster than climate scientists have modeled in the atmosphere. That may explain the link between cosmic rays, cloudiness and climate change.”
As I understand it, the hypothesis of the Danish National Space Center goes as follows:
Quiet sun → reduced magnetic and thermal flux = reduced solar wind → geomagnetic shield drops → galactic cosmic ray flux → more low-level clouds and more snow → more albedo effect (more heat reflected) → colder climate
Active sun → enhanced magnetic and thermal flux = solar wind → geomagnetic shield response → less low-level clouds → less albedo (less heat reflected) → warmer climate
That is how the bulk of climate change might work, coupled with (modulated by) sunspot peak frequency there are cycles of global warming and cooling like waves in the ocean. When the waves are closely spaced, the planets warm; when the waves are spaced farther apart, the planets cool.
The ultimate cause of the solar magnetic cycle may be cyclicity in the Sun-Jupiter centre of gravity. We await more on that. In addition, although the post 60s warming period is over, it has allowed the principal green house gas, water vapour, to kick in with humidity, clouds, rain and snow depending on where you live to provide the negative feedback that scientists use to explain the existence of complex life on Earth for 550 million years. The planet heats and cools naturally and our gasses are the thermostat.
Check the web site of the Danish National Space Center.
http://www.space.dtu.dk/English/Research/Research_divisions/Sun_Climate/Experiments_SC/SKY.aspx

Sains & Teknologi said...

a reasonable comment