There may be enough basis for a solar/climate thread so I’ll begin and see where it leads. This new publication Cosmic rays, solar activity, and changes in the Earth’s climate | SpringerLink is nicely paywalled so I emailed first author. I understand it includes 21st century predictions that would soon become testable. If not already. My overall idea is to here explore evidence that next one (or two or three) solar cycles will be weak, how weak, and to what extent that could influence surface T. I stated recently nearby that solar cycle predictions are based on carrying forward multi-cycle patterns. This appears to be the case in Stozhkov et al. 2017 as well.
Current sunspot cycle 24 is drawing to a close. One can read websites asserting weakest in 200 years. Thought you might want to compare it to cycle 14, about 110 years ago. I'd not wish to assert they are much different.
I kinda take a long view and consider solar flares to be 'noise' in the system. So I see our Sun as: Over time, a layered Sun occurs: Source: Evolution of Stars I appreciate folks trying to find some way out of the greenhouse gas accumulation and man-made, global warming. Just my understanding is in the far and distant past, the Sun, solar output was 30% less than what we have today. So higher CO{2} levels were needed to warm the poles for flora and fauna. But over time, even our Sun has moved to more helium burning making it larger and hotter. Source: We are heading for the warmest climate in half a billion years, says new study NOTE: I'm still more interested in current, satellite data. This paleo report is interesting only to the extent it supports or validates climate models. Bob Wilson
I have always understood helium ignition to be a far future thing, not a current thing. The hydrogen burning stage takes the great majority of the star's life. Each subsequent stage, burning helium, then carbon, and so on, is progressively much shorter.
It is much more complex than that. And the last time I looked at this was just after SN1987A, before the WWW expansion, so details are vastly more available now. Thanks for bringing this up, this pass has been much more than a simple refresher. Hydrogen to helium decreases the atom count by four, not just two. And that reaction is also the most energetic per nucleon, the later ones produce less. For the Sun's mass, apparently only a small portion of the helium will ever burn into carbon, but that takes place as a runaway helium 'flash', lasting just a few minutes. That isn't yet the end of stellar life, as hydrogen continues to burn, some carbon slowly burns into oxygen, and several other things happen. But the fusion will stop, outer gas layers are shed non-catastrophically, and the core ends up as a tiny but very dense white dwarf. For 25X the Sun's mass, the hydrogen burns in 7 million years, then the helium in 700k, the carbon in 600, the neon in 1 year, the oxygen in 6 months, then the silicon lasts just a single day. Then it goes BANG! Links will have to wait until I'm done traveling and can write on something better than a mobile device.
Only posting link to illustrate that solar cycle research is a lively thing, and that sun may be undergoing changes: https://www.sciencedaily.com/releases/2017/07/170704093626.htm
There is no doubt that sunspots were few or absent during much of the time commonly called "Little Ice Age". Nor that Europe was markedly colder and 'worse fed'. Evidence is less clear for rest of world, especially in terms of simultaneity. To make sure our focus is not inappropriately narrow, some links: Abrupt onset of the Little Ice Age triggered by volcanism and sustained by sea-ice/ocean feedbacks - Miller - 2012 - Geophysical Research Letters - Wiley Online Library http://www.nature.com/ngeo/journal/v7/n2/full/ngeo2040.html The Day the Sun Turned Blue: A Volcanic Eruption in the Early 1460s and Its Possible Climatic Impact—A Natural Disaster Perceived Globally in the Late Middle Ages? | SpringerLink So, we would appreciate volcanism during 'the Age'. According to some predictions, next solar cyle (or few) will be weak. I am not immediately swayed that such, absent some volcanic action, could little ice age us again. Especially as CO2 as a log10 concentration ratio is 6.5% higher than in that big chill. Largest 20th century eruptions were not particularly large. They led to -T but small and not for long. One might suspect that volcanoes (and -sunspots) have stronger battles to fight against +CO2. I suppose it is all about 'net watts' - if there were just some objective way to sort that out...
On this topic see https://www.sciencedaily.com/releases/2017/07/170703121011.htm With caution that this sentence "The new estimate is with 1361 watts per square meter lower than before." is garbled to the extent of lacking any meaning. From cited paper's abstract one instead supposes the new estimate is 0.04 watts lower than before. Something like that.
Was that Little Ice age accompanied by more volcanic action? Seems a fair question. Let us enquire Smithsonian Institution - Global Volcanism Program: Worldwide Holocene Volcano and Eruption Information To see number of 'puffs', but not size of each because they do not offer data. Graph binned by 300 years seems to show LIA volcanic uppiness Since 1800, there have been even more puffs/300 yr In Smithsonian database, but this might mean that lately, none are being missed. Yet the question at hand is whether Little Ice Age was only solar driven, without any volcanic contribution. Readers here ought to draw their own conclusions. Could be hard work to pin Little Ice Age on only solar, with no volcanic contributions. So happy that this is not my job
Volcanoes and earthquakes are affected by the Suns magnetic activity.During solar minimum of sunspots there are still coronal "holes" which bombard the Earths magnetic field .Its not just a coincidence there is an increase of volcanism during Solar minimum. But to think the volcanism is the main causation of climate is simplistic.As is the CO2 theory.
Solar minima occur about every 11 years - is there a similar pattern in volcanic activity? That would be strong empirical evidence. Still looking for eruption sizes during LIA. Smithsonian list is only events and locations. It seems likely that someone has sorted that out. Alternatively, sulfuric acid in ice cores. Only larger eruptions provide that, and stratospheric sulfate is a clear mechanistic cause for 'year or few' cooling.
Here's one comparison. TOMS is satellite that can measure atmos. SO2. Largest eruptions here were not during solar minima
Volcanic explosivity index is a measure of total material ejected, not just SO2. All VEI I could find, 3 or greater since 1900. A fella who 'wanted it to be true' would look at red numbers during solar minima and ignore all others. To neutral eyes, the pattern might be less convincing. Red numbers are rather wide. Dots would be better. Not my best graph ever I might not take this further but there are statistical tests for whether timing is related to solar cycle. VEI 3 seems to be minimum size to get stuff into stratosphere, and the don't all do so. Mt. St. Helens shot sorta sideways. Long 'dry spells' are not supportive of solar control. Somehow, mountains must be 'ready'. Still think ice core sulfate is a better way to examine this. Hope something turns up there.
