Yet another paper showing the spooky non-relationship with the local thermonuclear reactor. Thanks to climate models we all know that jiggles in solar radiation mean nothing much to Earth, otherwise we might wonder if the pattern of lows in sunlight and highs in floods meant something…
The River Ammer is in Southern Germany, and Markus Czymzik and others dug through the sediments nearby and graphed the flood layers alongside the small changes in solar radiation (TSI). They noticed that a less active sun correlates with more floods. At the low point of every solar cycle there appears to be more rain. (Don’t buy a house on a floodplain in southern Germany in the next few years.)
There is a pretty neat correlation there in the last 90 years, and then in the second graph they take that correlation back to 3,500BC, back when the Funnelbeaker culture was making nice pots in the same area. This same odd coincidence of the sun and rainfall patterns was also found by researchers in Chile, China and Australian and Indonesia. Low solar activity tends to occur at the same time as the winter jet stream in the North Atlantic gets blocked. And solar activity seems to affect Earth’s atmospheric pressure. None of these things occurs in climate models.
Repeat after me, the sun has no effect on our climate. …
Naturally, TSI itself is probably not the driver, it is just a marker for some other effect operating within and from the sun itself. (Read more on the possible mechanisms below). It’s another reminder of what the global climate models don’t know, and explains why they are so terrible at predicting rain.
Oh for a mechanism?
As David Evans outlined there are as many as seven different ways the sun could affect our cloud cover (and thus in turn the rainfall). It could also be the solar magnetic effect on cosmic rays, or through plantkon that generate aerosols that seed clouds, etc etc. There are interplanetary electric fields, there is the dynamic ever shifting solar wind, and who knows, meteoric dust which also changes with solar cycles.
The researchers talk about the solar top down mechanism, which involves the cyclic UV shifts that appear to occur in every solar cycle, and also about cosmic rays. But Stephen Wilde has long ago developed a theory about UV acting on the stratosphere and mesosphere that changes the jet stream patterns, which lays out a mechanism in more detail.
One amplifying feedback proposed by model studies is the so-called solar top-down mechanism (Gray et al., 2010; Haigh, 1996; Ineson et al., 2011; Lockwood, 2012). Larger changes in solar UV emissions influence stratospheric ozone concentration, heating and circulation and, consequently, strength and stability of the polar vortex. These disturbances are expected to communicate downwards to the troposphere via a chain of processes that is still under investigation to modify position and strength of the midlatitude storm tracks mainly over the North Atlantic and Europe (Gray et al., 2010; Haigh, 1996; Ineson et al., 2011; Lockwood, 2012). Under further consideration are the effects of energetic particles from the Sun and galactic cosmic rays on cloud cover and precipitation.
The only lag or delay mentioned in this paper is a 3 year gap after TSI peaks, not the key pattern of a delay of a solar cycle which would fit in with the work David Evans has done.
For more info : CO2science
Czymzik, M., Muscheler, R. and Brauer, A. 2016. Solar modulation of flood frequency in central Europe during spring and summer on inter-annual to multi-centennial timescales. Climate of the Past 12: 799-805.