While all the usual suspects (and some new ones like ‘Occasional Cortex’) are focused on CO2 in the atmosphere rising to 1/10th of its level back in Earth’s warm humid past, Sun watchers have noticed a disturbing trend which is likely to have a real effect on our climate, and not necessarily for the better.
Activity levels and energy output of the Sun change over a series of long term cycles, of which the underlying frequency is the 11 year (average) sunspot cycle, but with slower variations spanning many cycles. Observers have noted a slowing down of the Sun’s internal “dynamo” which drives the sunspot cycle, and in particular, the last two cycles have peaked lower, and feature an elongated tapering off to almost no sunspots before rising to a smaller peak in the next cycle, indeed, Cycle 24 is already on the downswing, and projections for Cycle 25 are not optimistic.
Glad you asked. When the Sun is in an active phase, not only is its energy output a little higher, but more to the point, the Solar Wind (a constant stream of charged particles from the Sun) is more powerful, the interplanetary magnetic field is stronger, and cosmic rays (very energetic charged particles from deep space) are slowed and deflected before they can impact the Earth’s atmosphere. Image courtesy Jo Nova
When the sunspot counts are lower, the Solar Wind is less energetic, the interplanetary magnetic field is weaker, and more high energy cosmic rays reach the upper atmosphere, where those very fast protons and electrons cause a cascade of secondary particles and gamma radiation. Those cascades of ionizing particles and radiation can trigger condensation nuclei (the basis of cloud formation) and even provide the ionized path which begins a lightning strike.
Several analyses have shown that an increase in the number and energy of cosmic rays reaching our atmosphere causes an increase in cloud formation, and one study which initially set out to debunk that theory actually found that indeed, cosmic rays did not correlate perfectly with cloud formation at all altitudes, but did correlate very closely with low level (Tropospheric) cloud formation – the very clouds which do the most to reflect heat away from Earth, thus cooling the planet.
But wait, there’s more: I said there were multiple layers of Solar cycles, with some lasting decades or longer, well, during the latter part of the 20th century we enjoyed a Solar Grand Maximum – a series of sunspot cycles with higher peaks and shorter lows than the long term average. Remember all that fuss about man made cooling/nuclear winter? Well, as a result, in the 1960s and 1970s we made huge efforts to clean up sulfur and nitrogen oxides and particulates from the atmosphere, allowing the warming promoted by less cosmic rays and less clouds to take full effect. (Steve covered that here)
In other words, it should not have been a surprise to good climatologists and atmospheric scientists that “warming” occurred during the 1980s and 1990s, and if you knew about the Grand Maximum and subsequent decline in Solar activity, it would also not have been surprising that global temperatures have plateaued for some 20 years now. However, not only have we fallen off the Grand Maximum, but recent Solar cycles have shown noticeably lower highs and longer lows (see header picture), leading to predictions of a pattern like the Maunder Minimum of the late 17th and early 18th centuries, or the milder Dalton Minimum of the early 19th century, occurring by the mid 21st century – IE more tropospheric cloud cover and a distinct cooling trend, even a mini Ice Age. How unusual is the recent Grand Maximum which the Global Warming believers have hung their hats on? Here’s three millennia of history, and wouldn’t ya know – the really high peaks are roughly every 1500 years:
Isn’t it wonderful how the hand of GOD on the Sun’s thermostat can make such fools out of the high priests of Climate Change?