Over the past few years a theory linking cosmic ray flux on earth with cold and cool temperatures on earth has been advanced by Svenmark. To explain this one needs to know that when the earth is warm, biological activity becomes maximum. Biological activity discriminates agains carbon 13 because it is heavier. Life likes carbon 12. so when the oceans have high concentrations of C13 biological activity is high. Knowing this, Svenmark reasoned that long periods of warmth would have little seasonality and that means that the standard deviation of C13 measurements should be low. So, using this, he created a curve of C13 content of the oceans over the past four billion years. He then compared it with the cosmic ray flux as seen in geologic record of the atomic products cosmic rays produce as they collide with nucleii high in the atmosphere. Svenmark found that these two curves correlate with a .92 correlation coefficient--a really good correlation. Svenmark's chart can be seen below.
This theory has been given some support by the work of Shaviv and Veizer. They say
“Growing evidence, such as the correlations between paleoclimate records and solar and cosmic ray activity indicators (e.g., 10Be, 14C), suggests that extraterrestrial
phenomena are responsible for at least some climatic variability on time scales ranging from days to millennia (Friis-Christensen and Lassen, 1991; Tinsley and Deen, 1991; Soon et al., 1996; Svensmark, 1998; Beer et al., 2000; Egorova et al., 2000; Soon et al., 2000; Björck et al., 2001; Bond et al., 2001; Hodell et al., 2001; Kromer et al., 2001; Labitzke and Weber, 2001; Neff et al., 2001; Todd and Kniveton, 2001; Pang and Yau, 2002; Solanki, 2002). These correlations mostly surpass those, if any, for the coeval climate and CO2. Empirical observations indicate that the climate link could be via solar wind modulation of the galactic cosmic ray flux (CRF) (Tinsley and Deen, 1991; Svensmark, 1998; Marsh and Svensmark, 2000; Todd and Kniveton, 2001; Shaviv, 2002a, 2002b) because an increase in solar activity results not only in enhanced thermal energy flux, but also in more intense solar wind that attenuates the CRF reaching Earth. The CRF, in turn, correlates convincingly with the low-altitude cloud cover on time scales from days (Forbush phenomenon) to decades (sun spot cycle). The postulated causation sequence is therefore: brighter sun => enhanced thermal flux +solar wind => muted CRF => less lowlevel clouds => less albedo => warmer climate. Diminished solar activity results in an opposite effect. The apparent departure from this pattern in the 1990s (Solanki, 2002) may prove to be a satellite calibration problem (Marsh and Svensmark, 2003).” Nir J. Shaviv and Jan Veizer, “Celectial Driver of Phanerozoic Climate?” GSA Today, July 2003, p. 5
If this theory is correct, then as the sun's protective magnetic field around the earth goes down, we should see more clouds, a rise in the earth's albedo (reflected light) and cooler temperatures. So, what is the sun's magnetic field doing? It is declining to unprecedented low levels.
This site contains the records of the Suns magnetic field. The AP index, is the planetary average of the changs in the earth's geomagnetic field caused by the sun. When the index is low, the sun's magnetic field is weak and cosmic rays can bombard the earth with ease causing clouds. Here is a plot of the AP Index since 1991
The sun is very very quiet magnetially, even with the recent splurge of sunspots. If the cosmic ray/cloud connection is true, we should get even colder if the solar magnetism stays at these levels.
I posted earlier in this blog the work of Livingston and Penn who predicted that sunspots would disappear by 2015 because the sun's magnetic field is dropping and by then, it will be so weak that it will be unable to hold up the walls of a sunspot. Here is the solar magnetism measured by Livington and Penn. Note that if the solar magnetism/cosmic ray flux/cloud connection is real it would explain the cooling over the past 10 years.
One can find that at least up until 2007 the earth's albedo was increasing, according to Palle et al, meaning it is refecting more light and thus should be experiencing cooler temperatures.
And now we see the decline in the Ap index. If it increases the cloud cover, then better stoke up the furnace.
What are the implications of this? Well one thing that comes to mind right now is that since the sun is behaving weirdly right now, we must question whether or not our usual rules apply. On Dec. 21, 2006, Nasa put up a web site predicting:
Evidence is mounting: the next solar cycle is going to be a big one.
Solar cycle 24, due to peak in 2010 or 2011 "looks like its going to be one of the most intense cycles since record-keeping began almost 400 years ago," says solar physicist David Hathaway of the Marshall Space Flight Center. He and colleague Robert Wilson presented this conclusion last week at the American Geophysical Union meeting in San Francisco.
. . .
"It all hangs together," says Hathaway. Stay tuned for solar activity
Apart from being utterly wrong about the future of the solar cycle which turned out to be unusually small, an interesting thought comes up when perusing this prediction of 4 years ago in light of the recent flurry of sunspots on the sun over the past month--not a lot, but a flurry compared to most of 2009. What if we are NOW in solar maximum, and we are still having spotless days--something that doesn't happen in normal solar maximums? If that is the case, then we can expect even fewer sunspots as we go into the normal decline, taking us up to 2015 when the magnetic fields might be too small to support sunspots.
If this happens, you better buy a good winter coat.