This is an interesting paper, and it is not paywalled! It looks at historical (Holocene and 1600s to date) variation in TSI Total Solar Irradiance and UV. (UV ranges from about 10 nm to about 400 nm. Then things turn to violet near 380 nm and wander on to about 700 nm for deep red, after that is IR from 700 nm down to about 1 mm when we start calling it radio, microwave, or millimeter wave depending on what we do with it and exactly how long the waves might be.)
The authors do a reconstruction. I really don’t like reconstructions all that well. Lots of opportunities to “manicure” things for effect. Yet for some things, like ancient solar data, you don’t have much choice but to ‘reconstruct’ based on something else.
The paper looks to me like it does a reasonable job of picking proxy data and doing the creation of the proxy by proxy… only doing one “splice” of Be10 data onto recent neutron count data (and that looks like it uses a plausible method). Since the Be10 data comes from ice cores, you can’t have recent layers that are the same as older compressed layers, so are still pretty much stuck with a splice. (I suppose one could come up with some ‘processing’ of recent snow layers to create an ‘old’ equal, but that is also a proxy for old ice…)
What they find is interesting. That our variable star has varied more than some other folks assert. (In particular, it is not in agreement with the “Steady TSI” assertions of folks like Leif Svalgaard.) As they compute the large scale trend based on Be and neutrons, then only apply the sunspot data from recent years to modulate for the variation of that base, the implication is that the “controversy” over sunspot counting that Leif highlights is muted. For their very long term reconstructions, even the sunspot number becomes irrelevant. They then reconstruct the likely variation in spectra (based on what we have seen happen prior to the paper) and find that UV has had a very large change over time.
Which I found at this page:
A. I. Shapiro, W. Schmutz, E. Rozanov et al. (2011) A new approach to the long-term reconstruction of the solar irradiance leads to large historical solar forcing, A67. In Astronomy & Astrophysics.
Download PDF (449.68 KB)
Also for your data gathering pleasure, a couple of other related links where you can get things like the TSI data and graphs:
A nice chart of recent (2003-2013) TSI:
Presently running about 1361.5 W/m^2 but was 1360.9 in 2008-2009. Numbers worth keeping in mind.
University of Colorado Laboratory for Atmospheric and Space Physics
Has the accepted numbers via other means here:
With two graphs, one of recent satellite data (“Measurements made by the SORCE mission, 2003-present.”), the other of a historical reconstruction. Since they are interesting interactive charts that let you find actual data points with your mouse, it’s hard to say “save image as”. So I’ve done a screen capture and margin trimming to make a more usable image for pasting:
Which already looks pretty variable to me!
Here’s the SORCE data graph:
They even have a ‘comma separated value’ form of the data available for your spreadsheet playing:
So, back at the first paper. After all their machinations, what do they find? That in ‘deeper time’ the sun varied more than other folks have found. And that UV varied a heck of a lot. 20-25% in some bands. (Now I know why ‘my people’ survived despite a tendency to sunburn in the shade… we evolved to get enough Vit-D even when the sun was not putting out much UV, and we were under cloudy sky and wearing furs… We with the ‘redhead gene’ are Solar Minimum Adapted, so come on Modern Minimum! ;-)
I’d found the abstract here:
The variable Sun is the most likely candidate for natural forcing of past climate change on time scales of 50 to 1000 years. Evidence for this understanding is that the terrestrial climate correlates positively with solar activity. During the past 10,000 years, the Sun has experienced substantial variations in activity and there have been numerous attempts to reconstruct solar irradiance. While there is general agreement on how solar forcing varied during the last several hundred years all reconstructions are proportional to the solar activity there is scientific controversy on the magnitude of solar forcing. We present a reconstruction of the Total and Spectral Solar Irradiance covering 130 nm-10 mum from 1610 to the present with annual resolution and for the Holocene with 22-year resolution. We assume that the minimum state of the quiet Sun in time corresponds to the observed quietest area on the present Sun. Then we use available long-term proxies of the solar activity, which are 10Be isotope concentrations in ice cores and 22-year smoothed neutron monitor data, to interpolate between the present quiet Sun and the minimum state of the quiet Sun. This determines the long-term trend in the solar variability which is then superposed with the 11-year activity cycle calculated from the sunspot number. The time-dependent solar spectral irradiance from about 7000 BC to the present is then derived using a state-of-the-art radiation code. We derive a total and spectral solar irradiance that was substantially lower during the Maunder minimum than observed today. The difference is remarkably larger than other estimations published in the recent literature. The magnitude of the solar UV variability, which indirectly affects climate is also found to exceed previous estimates. We discuss in details the assumptions which leaded us to this conclusion.
They cite a paper that supports the conclusion of a strong UV / climate link, but I’ve not had time to “Dig Here!” yet on it. As I’m due to an Awards Ceremony (Daughter, it seems, is graduating with some kind of honors that she had not bothered to mention… ;-) Kids these days. ;-) I need to do camera prep and see if I can get me ‘cleaned up and socially presentable’ in the next few hours. So this is about what I can get posted.
The large UV variability reported here is especially of importance to the climate community because it influences climate via an indirect, non-linearly amplified forcing (Haigh 1994; Egorova et al. 2004).
Haigh, J. D. 1994, Nature, 370, 544
Egorova, T., Rozanov, E., Manzini, E., et al. 2004, Geophys. Res. Lett., 31, L06119
These next two graphs were originally one graph in the paper, but screen capture has it’s limitations and I don’t have time to glue them back into one image right now. Note how much extreme UV (top) varies compared to visible (bottom):
So right off the bat, the biggest “deal” about this, IMHO, is just that the connection of large swings in UV to large swings in Climate matters a great deal. The argument that “TSI does not vary enough to matter” is broken with the UV hammer.
Here’s an image of their construction of the ‘modulation’ and the resultant TSI values. In the paper there is also a very large detailed graph by year from 7000 B.C. to the present that would just be too painful to lift / paste here. Besides, you ought to read the paper anyway ;-)
Of particular “worry” are those two plunges. One in the Dark Ages just after 540 A.D. or so. The other at the bottom of The Little Ice Age about 1400 A.D.
It looks to me like The UV / Solar Hypothesis not only accounts for a warm last century, but also for past extreme cold events and warm periods. Furthermore, the recent drop in UV and our resultant cold and snow all over the Northern Hemisphere along with cold in the mountains of South America (they get a bit ‘skinny’ on continental width down south in the more snowy band of the southern latitudes, so the mountains give a better indication of snow increases, IMHO) correlate with that drop in Solar / UV.
To the extent there are time lags (and their ought to be at least an 18 year time lag just from Pacific surface water temperature migration toward Alaska) we are likely looking at a very cold prospect going forward. Even more “chastening” is the prospect that the Sun does not fully cool all in a moment, or even in a decade. That the present “drop” is only the beginning. Yes, we’ve had a drop of sunspots. But how long does it take for that surface of the sun to reach full equilibrium in a new ‘no spot’ regime? Near as I can tell, nobody knows. There are some very long duration cycles that show up in climate data. More also show up in solar data. We have no idea if this is a 2 decade ‘slowdown’, or the start back down a 1500 year cycle. Or even if that ‘2 decade slowdown’ only fully shows up in year 19…
As this data (in the Shapiro paper) is 22 year averaged for the old series, and snow is not all that great at resolving to exact years anyway, such annual precision is just not available to us. But looking at those graphs, it looks to me like there are rapid responses on the decade scale. (Also based on what I remember of historical weather patterns in a ‘visual fit’ to those graphs). At some point I need to match up some of that ‘extreme weather history’ with specific dates on those graphs above (or the more detailed one in the paper) and also do the same with just broad history. At -2000 to -2500 on the detail graph there is a long deep dip. That’s just about on top of the 2200 B.C. event. Similarly, in 6200 B.C. there is a slide from a peak down into along cold valley that is right on top of the 8.2 kiloyear event.
So at ‘first blush’, it looks like this solar / UV data gives a plausible mechanism that has pretty good correlation with known history; and at time scales from ‘recent’ to ‘ancient history’ to ‘Holocene geological’. While CO2 can’t explain any of it.
To the extent this is how things really work, and given that the Sun has shut down the sunspot maker for a while, toss in a couple of decade lag (that seems to be present in other historical times as well and is clearly in ocean data) and that implies we’ve got a long cold road ahead of us. How long and how cold “To Be Determined”… Just be thankful that the ocean is very large, has an incredible heat capacity, and the top 800 feet will be keeping us warm “for a while”. We ought to get more snow as the water evaporates (taking heat from the ocean) and then condenses and freezes (liberating heat in the air) and more rain too. That’s just the Ocean Heat Engine running down against a now much colder “cold pole” at the Arctic Winter end (or Antarctic Winter end). Keeping us a bit warmer than otherwise while that process runs. But as an ‘eyeball reading’ of the big graph seems to indicate about 100 year periods on the top of peaks, and even 800 year ‘trends’ getting to the peaks; and given that we’ve had our 100 years on the top of this peak, and are at the end of a 800 ish year climb out of the L.I.A.: the more likely event is that we’ve rounded over the top of this peak, and now begins a long slow slide to the other side of a “rolling sideways” graph.
Now notice that the tops of the TSI on that reconstruction graph above are about 1366 W/m^2. We are presently at 1361 W/m^2 (that number you were to remember ;-) so think about it. Where is 1361 on those historical graphs? 1700’s when Washington crossing the Delaware had it iced up. Then in “1800 and Froze to Death”. 1500 at the Little Ice Age bottom. 550 A.D. in the Dark Ages. Yes, it’s a comparison (splice?) between two different methods of measuring, so take with large heaps of salt and lack of intercalibration error bands. Yes, the present number is a ‘peak’ value and not a 22 year average, but we’ve not fallen of the solar cliff long enough to have that average yet. I’m dearly hoping that between those two “issues” we are not in the same regime as during the historical events coincident with that historical TSI graph. I’d rather it were shown a math disparity than an accurate prediction. “But hope is not a strategy. -E.M.Smith”.
I think the place to dig is into historical UV patterns and matching that to historical weather extremes and proxy climate temperature data. Likely with a 20 year or so time lag between solar and temperatures as the ocean has that kind of measured lag in equatorial thermal bands reaching the Alaska coast. The ocean is large and delays onset of temperature change. Rain / snow seems to change most rapidly, inside just a year or two. Not that long ago we had “Mississippi River Low Due To Drought” (And Global Warming). Now we have “Mississippi Flooding” due to Global Warming – though they are now trying to re-brand it as “Global Weirding”… truly desperate as the world is not weird at all, and all these states have been seen before in not that distant recorded history. But the rains were lowest at / near the peak, now we’ve rolled over into high rain regime on a global basis. Not outside historical norms, and certainly not “weird” either.
Yes, there are ‘hot and cold sides’ of the Jet Stream that has ‘gone loopy’ (bigger Rossby Waves) again. So we have had drought in places that end up on the hot dry side (Texas) rather like in the 1930’s when we had similar hot / cold transitions. But Texas is not the world (despite what Texans might think ;-) and places from North Australia to the UK and EU are showing that global precipitation is back, and as snow in many of those places.
So my prediction would just be that over the next 20 years those high precipitation levels will slowly get colder. The snows will arrive earlier and leave later ( as in the West of the USA this month) and move more south over time. As the colder Pacific surface migrates to Alaska and into the Arctic Ocean, the Arctic Ice will recover. ( so 20 years after 1998 is 2018 as my target date for Arctic Ice in size. Ought to start a bit earlier due to the very cold air temps.) Then the real cold will hit as that Arctic Ocean is no longer providing warmth.
That’s the thesis and prediction. Now we wait.