Solar forcing of North Atlantic surface temperature and salinity over the past millennium

Posted: March 11, 2014 by tallbloke in climate, Natural Variation, Ocean dynamics, paleo, Solar physics

H/T to Dr Michele Casati for alerting us to a new paper in Nature Geoscience which finds that low solar activity is the likely cause of blocking highs bringing polar air into northern Europe during the little ice age.  According to the Sciencedaily post about the paper, it also notes that solar activity is predicted to be low for the coming decades. Looking at the references isn’t obvious where this prediction comes from. I’ll look at the full paper later today and update the post.


Solar forcing of North Atlantic surface temperature and salinity over the past millennium
Paola Moffa-SánchezAndreas BornIan R. HallDavid J. R. Thornalley & Stephen Barker

There were several centennial-scale fluctuations in the climate and oceanography of the North Atlantic region over the past 1,000 years, including a period of relative cooling from about AD 1450 to 1850 known as the Little Ice Age1. These variations may be linked to changes in solar irradiance, amplified through feedbacks including the Atlantic meridional overturning circulation2. Changes in the return limb of the Atlantic meridional overturning circulation are reflected in water properties at the base of the mixed layer south of Iceland.

Here we reconstruct thermocline temperature and salinity in this region from AD 818 to 1780 using paired δ18O and Mg/Ca ratio measurements of foraminifer shells from a subdecadally resolved marine sediment core. The reconstructed centennial-scale variations in hydrography correlate with variability in total solar irradiance. We find a similar correlation in a simulation of climate over the past 1,000 years. We infer that the hydrographic changes probably reflect variability in the strength of the subpolar gyre associated with changes in atmospheric circulation. Specifically, in the simulation, low solar irradiance promotes the development of frequent and persistent atmospheric blocking events, in which a quasi-stationary high-pressure system in the eastern North Atlantic modifies the flow of the westerly winds. We conclude that this process could have contributed to the consecutive cold winters documented in Europe during the Little Ice Age.

From the Sciencedaily article:

The study, led by Cardiff University scientists, in collaboration with colleagues at the University of Bern, is published today in the journal Nature Geoscience.

Dr Paola Moffa-Sanchez, lead author from Cardiff University School of Earth and Ocean Sciences, explained: “We used seafloor sediments taken from south of Iceland to study changes in the warm surface ocean current. This was done by analysing the chemical composition of fossilised microorganisms that had once lived in the surface of the ocean. These measurements were then used to reconstruct the seawater temperature and the salinity of this key ocean current over the past 1000 years.”

The results of these analyses revealed large and abrupt temperature and salinity changes in the north-flowing warm current on time-scales of several decades to centuries. Cold ocean conditions were found to match periods of low solar energy output, corresponding to intervals of low sunspot activity observed on the surface of the sun. Using a physics-based climate model, the authors were able to test the response of the ocean to changes in the solar output and found similar results to the data.

“By using the climate model it was also possible to explore how the changes in solar output affected the surface circulation of the Atlantic Ocean,” said Prof Ian Hall, a co-author of the study. “The circulation of the surface of the Atlantic Ocean is typically tightly linked to changes in the wind patterns. Analysis of the atmosphere component in the climate model revealed that during periods of solar minima there was a high-pressure system located west of the British Isles. This feature is often referred to as atmospheric blocking, and it is called this because it blocks the warm westerly winds diverting them and allowing cold Arctic air to flow south bringing harsh winters to Europe, such as those recently experienced in 2010 and 2013.”

Meteorological studies have previously found similar effects of solar variability on the strength and duration of atmospheric winter blockings over the last 50 years, and although the exact nature of this relationship is not yet clear, it is thought to be due to complex processes happening in the upper layers of the atmosphere known as the stratosphere.

Dr Paola Moffa-Sanchez added: “In this study we show that this relationship is also at play on longer time-scales and the large ocean changes, recorded in the microfossils, may have helped sustain this atmospheric pattern. Indeed we propose that this combined ocean-atmospheric response to solar output minima may help explain the notoriously severe winters experienced across Europe between the 16th and 18th centuries, so vividly depicted in many paintings, including those of the famous London Frost Fairs on the River Thames, but also leading to extensive crop failures and famine as corroborated in the record of wheat prices during these periods.”

Read the rest here.

  1. ren says:

    Tallbloke you have pdf here.

    [Mod note: Different study covering a similar topic for the C20th]

  2. tallbloke says:

    Solar effects on climate are clearly greater than the small (0.1%) decadal variation in total solar irradiance the IPCC uses to dismiss solar influence. Bad science IPCC, no cookies.

  3. ren says:

    New Zealand climate variability
    New Zealand climate, particularly rainfall and wind patterns, shows systematic variations at different time periods. Due to the short instrumental record, most of the identified variation is strictly weather and not climate, and includes: a quasi-biennial oscillation (QBO) associated with sea-level pressure and meridional (north-south) flow around New Zealand; the ENSO pattern with periods of 3-8 years; a decadal pattern strongly correlated with the 11 year Schwabe sunspot cycle; and cycles with periods of 18-22 years that also correlate well with the Hale magnetic solar cycle. A 70-80 year pattern linked to the PDO is also evident, which some have correlated to the 60-120 yea Gleissberg cycle that is associated with modulation of the Schwabe cycle amplitude. Proxy data also suggest
    the presence of a 200-220 year de Vries solar cycle (also known as Seuss Cycle).

  4. tallbloke says:

    Thanks ren. We know that the medieval warm period was global in extent from the many studies done all around the world. The climate science establishment is keen to compartmentalise natural variability effects into ‘regional climate’ in order to keep their ‘global climate change caused by co2’ narrative on track. Unfortunately for them, the Antarctic as a whole has refused to warm, the high latitude southern ocean has been cooling since the mid 1980’s. And the ‘adjustments’ to the temperature data of Australia and New Zealand have been exposed.

    ‘Global warming (and sudden cooling) is largely a northern hemisphere phenomenon. This fact doesn’t sit well with co2 being ‘a well mixed gas’, with similar levels worldwide on the annual average. The take home conclusion is that natural variability is playing a bigger role in ‘climate change’ than the UN/government funded IPCC and government funded national science institutions are willing to admit.

  5. Euan Mearns says:

    Predictions suggest a prolonged period of low sun activity over the next few decades, but any associated natural temperature changes will be much smaller than those created by human carbon dioxide emissions, say researchers.

    this is standard narrative, and

    Thanks ren. We know that the medieval warm period was global in extent from the many studies done all around the world.</blockquote.

    Ah – it may be present everywhere but was its impact always warming? On the telly here the other night a small bloke talking about Scottish forests. 4000 years ago the country was covered in Caledonian pine wood from head to toe and then the climate suddenly became much wetter and vast areas of trees died as soils became acid. The lesson learned was that climate can change quickly, not that it may change of its own accord.

  6. ren says:

    It can be seen that temperatures the Atlantic is associated with the position of the polar vortex.

    It is worth also be noted that changes the position of the magnetic pole.

  7. tallbloke says:

    Euan: Areas denuded of trees usually get hotter (and so drier) at the surface. So tree dieoff may be a negative feedback to a wetter regional climate. The many paleo studies done around the world seem to indicate a generally warm MWP:

    If predictions of lower solar activity over the next few decades have become ‘standard narrative’, we shoud be able to find the source of these predictions and see what forecasting technique they are based on. I’ll have a look at the full paper later and see who they reference.

  8. cornwallwindwatch says:

    Can you possibly email us so we can send you something to check out for us. It has to do with climate comments made locally here which look and smell a lot like BS. Many thanks

  9. tallbloke says:

    I see wuwt already has a post up on this:

    With an interesting position statement from Leif Svalgaard – my bold:

    lsvalgaard says:
    March 10, 2014 at 3:37 pm
    Janice Moore says:
    March 10, 2014 at 2:43 pm
    Would you please do many of us who highly value your thinking a favor? We need to hear from you that you agree that the null hypothesis re: human CO2 as a climate driver is NOT DISPROVEN
    I don’t like double negatives. For me the issue is this:
    x% is due to solar activity and related
    y% is due to man [CO2, land use, manipulation of data]
    z% is due to random fluctuations of a complex non-linear system [e.g. ocean related]
    w% is due to long-period cycles [e.g. due to orbit changes or solar energy production]

    We do not know what x, y, z, and w are. To assume that any one of them is 100% is silly, so they are likely all rather small. If we assume they are equal, that gives us 25% for each which to within a factor of 2 sounds reasonable.

    Long period cycles in solar energy production. Well I never. 🙂
    He’s ignoring the medium term cycles in oceans which correlate with LOD (and planetary motion) but we’ll get to those.

  10. Euan Mearns says:

    It’s the acknowledgement of solar impact on climate actually existing, but that its impact is much less than anthropogenic forcing that is the standard narrative. Have you seen this one:

    Solar forcing of winter climate variability in the Northern Hemisphere
    Sarah Ineson1*, Adam A. Scaife1, Jeff R. Knight1, James C. Manners1, Nick J. Dunstone1, Lesley J. Gray2 and Joanna D. Haigh3


    If the updated measurements of solar ultraviolet irradiance are correct, low solar activity, as observed during recent years, drives cold win- ters in northern Europe and the United States, and mild winters over southern Europe and Canada, with little direct change in globally averaged temperature.

    Its possible they are partly correct.

  11. tallbloke says:

    Euan: Look at the paper ren linked. the blocking patterns bringing cold into northern Europe also push the wet and windy stuff down over Iberia and the mediterranean. That’ll make it colder there too. However, the question is, what was the LIA like in Siberia and N. America?

    By the way, this useful comment on the wuwt discussion tells us how to get at the full size figures in paywalled papers:

    Bill Illis:
    In this case, the main large size graph is particularly impressive. Based on the chart, it doesn’t look like they screwed around with the basic data. Be10 and volcanic influences on TSI, very closely correlated to the temp from do18. I don’t think anyone has done this at high resolution before.

    Just for reader’s info, in the journal “Nature”, the link to the large scale charts will have “fig_tab” in the link line or “images_article” rather than “carousel”. Just change it in the link line. small image with carousel below.

  12. ren says:

    Tallbloke look at solar activity. Vortex pattern formed in October, when solar activity was a significant decrease. Then the activity increased. It was protected Europe against the blockade.

  13. tallbloke says:

    Does anyone read Russian?

    E. Borisenkov, and V. Pasetski. The thousand-year annals of the extreme meteorological phenomena. (Moscow: “Mysl,” 1988. ISBN 5244002120), 190. (in Russian)

  14. dscott says:

    Consider that solar variability may not be the “direct” cause of the wind shift due to watts per square meter but of the amount of insolation affecting phytoplankton growth. The color of water affects its albedo. Higher insolation encourages greater biological growth which in turn affects the ability of the water to “store” heat at the surface via lowering albedo to allow “more” light to penetrate the surface instead of being reflected and the specific heat of the water since it is a “solution” of H2O and biological matter.

    The IPCC people don’t really factor in the biological response of the earth’s climate system because they assume the biosphere doesn’t change all that much just as they mistakenly (or deceptively) claim the Specific Humidity of the atmosphere doesn’t change. They ignore the greening of the Sahara in response to higher CO2 (reducing the need for water by plants). See “Orbital Monsoon Hypothesis:‎

  15. Paul Vaughan says:

    The link tip should say “images” (not “images_article”):

    – –

    As a matter of principle I don’t venture into certain types of commentary, but this exception is due:

    Regarding w, x, y, & z = 25% to within a factor of 2: If this is “science”, then I say ___ science (starts with a capital “F”). If I were to follow through with writing what needs to be said about this dark veil, it would pass moderation nowhere. What we sacrifice to afford civility includes the truth. The sacrifice is unsustainable.

  16. Rog, Leif commet is funny.

    I think….
    Nature Geoscience, open or close on the solar-climate connection ?

    Quote :
    “…The study concludes that although the temperature changes expected from future solar activity are much smaller than the warming from human carbon dioxide emissions…”

    Last words, phrases ….important in communication !


    “…Our results show that the current hiatus is part of natural climate variability, tied specifically to a La-Niña-like decadal cooling. Although similar decadal hiatus events may occur in the future, the multi-decadal warming trend is very likely to continue with greenhouse gas increase…”

    Dare un colpo al cerchio e uno alla botte




  17. ren says:

    It is worth comparing Ap in winter in December, January and February 2013 with Ap in October 2013 and January and February 2014.

  18. ren says:

    Due to the weakening of the Sun’s magnetic field over a long period of time, which is perfectly visible, solar activity will have a huge impact on the climate in the high and mid-latitudes.

  19. p.g.sharrow says:

    @ren You are correct. A weak solar magnetic field is caused by chaos in its’ organization. A more chaotic Earth magnetic field is the result. I am not sure of the cause but I would guess the Solar system barycenter mixing of the Solar furnace is the culprit.
    Long ago while I was learning about electrical control systems on earlier Naval ships, Magnetic Amplifiers were covered. Manipulation of electrical energy by use of magnetic field, small currents to manage large ones in early DC powered machines. pg

  20. oldbrew says:

    ‘the multi-decadal warming trend is very likely to continue with greenhouse gas increase’

    Continue? Should say ‘resume’ as there’s nothing happening this century so far.

    And if water vapour – i.e. by far the largest GHG – declines there won’t even be a net GHG increase. They have no idea what water vapour is going to do, so of course this is just the usual cliche to satisfy the reviewers.

  21. tallbloke says:

    Global warming is just *so* last millenium. 😉

  22. oldbrew says:

    Even last millennium they couldn’t make the Antarctic toe the line.

    The polar seesaw is unlikely to go away any time soon.

  23. R J Salvador says:


    I agree with you that electromagnetic forces could have a significant effect on the movement of material both here on earth and on the sun. It may be that the earth is acting like a homopolar motor and the injection of the solar wind and the alteration to the CGR flux alters the magnetic field and then the flow patterns of air and water on earth through the Lorenz force as these materials move through the field. There is reason to believe that the sun also interacts with the magnetic field of the Jovian planets in some as yet undetermined way modulating the solar cycle.

    Good Luck with your experiment!


  24. ren says:

    Forecast polar vortex at an altitude of about 17 km on March 16. Winter returns to Europe.,70.78,419

  25. ren says:

    Pressure distribution at a height of 15 km.

  26. w.w.wygart says:

    Maybe a meteorologist can help me out here. Aren’t ALL Highs technically a “blocking high”? nothing gets by them more or less by definition. Lows may worm and squirm, the jet streams may flow down hill towards them, but Highs stay resolutely uphill deflecting all around them. The term gets bandied about these days as if it were a new or rare phenom. Is it? Of course there is also the pernicious ‘stationary high’, possibly the worst of the new breed. Can anyone tell me what has really changed? other than terminology?


  27. tallbloke says:

    W^3, the idea of persistent highs (especially over Greenland) has been around a century and more. as has ‘the Aleutian low’.

  28. […] Solar forcing of North Atlantic surface temperature and salinity over the past millennium […]

  29. w.w.wygart says:

    TB, thanks, what I’m really interested in is if there is something new and different going on – or claims to that effect – that we didn’t all learn in ‘Weather for Mariners’ years ago.

    Regards, W^3

  30. oldbrew says:

    @ W^3 : see link e.g. pages 18-19:

    ‘Blocking episodes comprise extensive and quasi-stationary anticyclones which can persist for several weeks, leading to extended cold periods in winter as the mild maritime westerly winds are replaced by continental north-easterlies and the land surface cools under cloudless skies. These changes are associated with a meander in the jet stream in the upper troposphere and lower stratosphere.’

  31. tallbloke says:

    W^3: Same sh1t, different decade. Or century. Steve Goddard recently posted a newspaper clipping from the 1920’s discussing nlocking.

  32. w.w.wygart says:

    Ok, that’s about what I figured.