RealClimate logo


Technical Note: Sorry for the recent unanticipated down-time, we had to perform some necessary updates. Please let us know if you have any problems.

The trouble with sunspots

Filed under: — group @ 13 September 2006

by Gavin Schmidt and Michael Mann

Solar forcing of climate is a subject that gets far more attention than any new observations or improved understanding would warrant. Two new articles appearing today attest to that. One is occasionally tempted to agree with Oscar Wilde when he said:

Why does not science, instead of troubling itself about sunspots, which nobody ever saw, or, if they did, ought not to speak about; why does not science busy itself with drainage and sanitary engineering?

Except in this case it’s Nature rather than Science who are troubling themselves…

A new review paper by Foukal et al does a reasonable job summarising the mainstream opinion on the issue. In particular, they outline quite clearly why some ideas related to long term solar variability (such as solar disk radius changes, or the difference between cycling and non-cycling stars) have recently fallen out of favor. Indeed, they assert that there is little evidence for any solar variability in irradiance that is not related to the shielding/enhancements of sunspots and faculae – which implies only a modest decrease in solar flux at the Maunder Minimum for instance. We could quibble with their use of paleo-reconstructions, their climate modeling approach, and the rather cursory treatment of the substantial body of work relating to amplyfying mechanisms due to UV/ozone links, but we’ve gone over this ground before and we refer readers to those earlier discussions.

Slightly more novel is the description in the News section of a new experiment at CERN that is attempting to test the cosmic-ray/cloud hypothesis by building a large cloud chamber mimicing the atmosphere and firing high energy particles at it. There’s nothing intrinsically wrong with the idea, but given the $11 million to spend on climate change research, we would have tended to favour projects that, unlike this one, have at least some empirical support within the observations….


82 Responses to “The trouble with sunspots”

  1. 1
    Wacki says:

    “There’s nothing intrinsically wrong with the idea, but given the $11 million to spend on climate change research”

    ??????

    Is that how much this single test costs? Or are you talking about something else? How much does climate research get in funding anyway?

    I’ve read this:

    “President Bushâ��s FY 2006 Budget proposes $5.5 billion for climate-change programs and energy tax incentives, which is $250 million (4.8 percent) more than FY 2005, as enacted. This figure includes nearly $3 billion for the Climate Change Technology Program, nearly $2 billion for the Climate Change Science Program, and $200 million for climate-change-related international assistance programs.”

    http://www.whitehouse.gov/news/releases/2005/05/20050518-4.html

    But I’ve also read numerous articles on how they are “cooking the books” by including nuclear fission subsidies that have always existed as part of the “Climate Change Technology Program”. So how much actual funding is climate research getting?

  2. 2

    The sun is overrated for the wrong reasons. The lack of sun spots has been surmised to give a cooling effect, as witnessed during the little ice age. How about however small cooling/warming effects during solar minimas/maximas at every 11 years? Any studies about that? I wonder…. What is most exciting, the sun disk can be used as a fixed sphere of reference, as a way to study atmospheric effects. But largely and surely the paper cited by Foukal et Al. claims no significant warming from the sun since 1978, seems reasonable since the 2 warmest years in history, 2005 and 1998, were off solar activity maxima years. Instead of dreading the solar argument, it may be the best, visible to everyone, proof of AGW effects, since it is the only thing which has a truly regular cycle largely not related with current GT warming trend.. Anyone arguing otherwise must come up with a cosmic revelation.

  3. 3
    Johan says:

    I say better to try and reject than not to try and not have a clue.

  4. 4
    Tim Jones says:

    How is it, with all the science of CO2 and its capture of infrared radiation establishing the fact that it warms the atmosphere, people insist on marginalizing the effect, grasping at straws for any other answer for the cause of climate change?

  5. 5
    Urs Neu says:

    Re #2

    Wayne – there is a number of regression analysis addressing the influence of the 11-year sunspot cycle on global temperature, e.g.

    - Labitzke, K., 2004: On the signal of the 11-year sunspot cycle in the stratosphere and its modulation by the quasi,biennial oscillation. Journal of Atmospheric and Solar-Terrestrial Physics, 66, 1151-1157.
    - Crooks S.A., and L.J. Gray, 2005: Characterization of the 11-year solar signal using a multiple regression analysis of the ERA-40 dataset. J. Climate, 18, 996-1015.

    They find a variation of about 0.1 deg.C. in global Temperature for the rough 1 W/m2 variability in TSI over the 11-year cycle.

    I did a rough analysis myself, eliminating the ENSO signal and volcanic activity from the global temperature series and found a similar result.

    There are claims of stronger influences of the 22-y cycle and even longer term changes, but these studies have problems (see http://www.realclimate.org/index.php/archives/2006/03/solar-variability-statistics-vs-physics-2nd-round/

  6. 6
    Jenny Lindman says:

    Re #4

    There’s no marginalizing the CO2-effect on climte if someone want to try other possible factors no matter how insignificant they may be. The object is to understand climate change and its mechanism, and climate change and mechanisms aren’t all about CO2 (even though much is).

  7. 7
    mark schneeweiss says:

    re #1 In an interview with the BBC, about 2 weeks ago, the new president of the AAAS (American Association for the Advancement of Science) condemned GBJ’s budget proposals.

    He stated that from 2001 to the present day, GBJ had not asked the Congress for any more money to tackle climate change, year on year. He expressed dismay that that GBJ’s suggestion that new technology would address the issue, had not been backed up by any increase in government funding for these technologies.

    Apparently, GBJ is doin sweet FA…

    I hope that answers part of your question.

  8. 8
    PHE says:

    To mimic Oscar Wilde’s question of whether we have the right focus, you could question why the world is so focused on tackling a theoretical problem (AGW) rather than dealing with those with zero doubt that kill millions every year (such as malaria, mal-nutrition and poor drinking water supplies).

    In answer to comment 4 (Tim Jones), far from ‘grasping at straws’, there are many who legitamtely question the conviction with regards to AGW when temperature rises have not been convincingly shown (and I don’t mean proven) to be either at unprecendented rates or levels.

  9. 9

    Re #7 and “To mimic Oscar Wilde’s question of whether we have the right focus, you could question why the world is so focused on tackling a theoretical problem (AGW)”

    Because it’s not a theoretical problem. There’s no doubt about it among climate scientists these days. Try following this blog for a while and reading the articles.

    -BPL

  10. 10

    Even a small change in minimum solar irradiation (measured – but still discussed) can give a rather important change in surface temperature. See the work of Scafetta and West.

    The problem is that there is only one 22-year (or two magnetically opposite 11-year) solar cycles measured by satellites. All estimates of solar irradiation/strength are based on proxies, which all have much in common, but differ in amplitude and even timing (for where the peak influence on climate should be in the cycle).

    Further, longer-term cycles (like MWP-LIA-current) have more impact than shorter cycles (as good as the 22 yr Hale cycle has 1.5 times more impact than the 11-year cycle) for the same difference in irradiation. And there is some delay (order of magnitude 30 years and longer) for relative steady changes in energy flux (like the 1950-2000 period vs. the 1900-1950 period), due to the inertion of the oceans.

    While there is less confidence for the GCR-cloud link in recent years, there is an observed inverse correlation between TOA irradiation and low cloud cover over the 22-year satellite observations. Although the exact mechanism is not known, the effect nevertheless is an important positive feedback for the relative small change in TOA irradiation. What that means for historical long-term changes in solar radiation, that still is an open question…

    Anyway, the experiment at CERN may give a lot of answers about the GCR-cloud link and, as far as I did understand, also on other particle ionisation / cloud questions (thus not only about GCR).

    [Response:The work by Scafetta & West is discussed here If new and updated TSI data are used, then the trends they calculate vanish. -rasmus]

  11. 11

    #5 Thanks for the reference Urs, Makes a lot of sense that there is a temperature effect with sun cycles. It is a matter of compelling proof, or of great interest during solar minimas as to see if AGW nullifies or reduces the cooling. I looked at quite prominent but not numerous sun spots of 2005 and found them virtually non existent in 2006, although 2006 has been slighty cooler than 2005 so far (for the NH), temperatures during 2005 exceeded those of tthe last solar maxima 2001-2002, suggesting the AGW signal itself.

  12. 12
    Nereo Preto says:

    I find this topic of extreme interest, mostly because I am doing research on pre-industrial times. Thus, I took the time to quickly read Nature’s review article and the News Feature by Jeff Kanipe. I also read some of the earlier debates in your (great!) blog. I must admit I am with Jeff Kanipe when he writes that “those within the climate community are mindful of lobbies that seek to discredit their work, and believe enough doubt has been cast on the cosmic-ray theory to discredit it, if not ignore it completely”. At least, this was my impression.

    I’d like to give Cosmic Rays (or Total Solar Irradiance) a chance. Let me be clear on this point: I do not believe that the global warming of the last century has much to do with Solar Activity or Cosmic Ray Flux. However, this does not mean that a link does not exist at all. I believe, then, it is worth studying it. Firstly, because it might be of help for the understanding of ancient natural climate change; secondly, because these studies might highlight unexpected non-linear features of the climate system, that might not be evident to climate scientists working on more classical theories.

    An interesting point here is that “there is little evidence for any solar variability in irradiance that is not related to the shielding/enhancements of sunspots and faculae”. If this is true, than the right feature to look for in climate and climate proxies is the 11-years sunspot cycle. I know there’s no trace of it in instrumental temperature time series. However, in my only excursion out of the Triassic (250-200 Ma, not exactly yesterday, I must admit…), we found 11-year-cycles in a stalagmite growth rate. Was that an isolated case, or the 11-years cycle makes an appearance in proxy series once in a while? And, if so, what that it means?

  13. 13
    Bob KC says:

    we would have tended to favour projects that … have at least some empirical support within the observations….

    Here is some recent (and interesting) empirical support for the cosmic ray/cloud connection…

    [Response:Saw that. Not convinced. Why didn't they use data from the Atlantic region as well? and their definition of regions also seems a little odd. There may be something here, but the odder the data manipulation, the less convincing the study. - gavin]

  14. 14
    Vivian Francis says:

    Nice opening paragraph. It made me laugh. Thanks for all the time and effort everyone here has put into this website, I’ve learned a lot.

  15. 15
    Nick says:

    Empirical evidence that Galactic Cosmic Ray fluxes impact cloudiness includes the recent paper by Harrison and Stephenson, rather unambiguously entitled “Empirical evidence for a nonlinear effect of galactic cosmic rays on clouds”, Proceedings of the Royal Society A-Mathematical Physical And Engineering Sciences 462 (2068): 1221-1233 Apr 8 2006.

    Abstract: Galactic cosmic ray (GCR) changes have been suggested to affect weather and climate, and new evidence is presented here directly linking GCRs with clouds. Clouds increase the diffuse solar radiation, measured continuously at UK surface meteorological sites since 1947. The ratio of diffuse to total solar radiation-the diffuse fraction, (DF)-is used to infer cloud, and is compared with the daily mean neutron count rate measured at Climax; Colorado from 1951-2000, which provides a globally representative indicator of cosmic rays. Across the UK, oil days of high cosmic ray flux (above 3600 X 10(2) neutron counts h(-1), which occur 87% of the time on average) compared with low cosmic ray flux, (i) the chance of an overcast day increases by (19 +/- 4)%; and (ii) the diffuse fraction increases by (2 +/- 0.3)%. During sudden transient reductions in cosmic rays (e.g. Forbush events), simultaneous decreases occur in the diffuse fraction. The diffuse radiation changes are; therefore; unambiguously due to cosmic rays. Although the statistically significant nonlinear cosmic ray effect is small, it will have a considerably larger aggregate effect on longer timescale (e.g. centennial) climate variations when day-to-day variability averages out.

    Haven’t read it yet, but looks interesting.

    Cheers,

    Nick.

  16. 16
    Mark J. Fiore says:

    We can do very little about the natural variations in the sunspot cycle. We need to focus on the solutions available to us here on Earth. The new study about the methane released fron the melting Siberian permafrost, as well as the new study about the methane hydrates released from the seabed floor, confirm the stories in the news about these two issues.Those stories have appeared for at least a few years now. I have copies of news releases from ENN and ENS about both these issues, published a few years ago. The release of methane drastically increases the negative feedback cycle.The heat storage capacity of the oceans have masked the effect of global warming,and as the heat storage capacity of the oceans max out we will also see a drastic negative feedback cycle on the melting of methane hydrates and permafrost melt, FURTHER increasing the negative feedback cycle. This feedback loop is the true weapon of mass destruction for the planet. As I have said before, Love Lock feels the tipping point has already passed. If so, as I have said in the past, we need reductions NOW of 80% below 1990 levels of co2 output. If the earth approaches 550 ppm as scheduled I see little hope for any type of normal future for our children. Can the Republicans in the house and Senate please stop messing around and support strong climate change mitigation legislation? Please?

  17. 17
    Pascal says:

    there is a correlation between solar activity and GCR : maybe we can admit it.
    there is a correlation between GCR and cloudiness : it’s less easy to admit, but we can try.
    So there is a correlation between solar activity and cloudiness.

    So why can’t we see only a very weak correlation between mean global temperature and solar activity in the 11 years cycle?
    So why this weak correlation is completely explained by variation of radiative flux entering atmosphere and not at all by hypothetic cloudiness variations?

  18. 18
    Tim Jones says:

    “PHE” wrote:
    “To mimic Oscar Wilde’s question of whether we have the right focus, you could question why the world is so focused on tackling a theoretical problem (AGW) ….”

    Do you really think the world wide effort to address anthropogenic climate change is to play with a “theoretical” problem? The only thing theoretical is your assertion that it’s a theoretical problem.

    “In answer to comment 4 (Tim Jones), far from ‘grasping at straws’, there are many who legitimately question the conviction with regards to AGW when temperature rises have not been convincingly shown (and I don’t mean proven) to be either at unprecendented rates or levels.”

    In the first place the “many” has been reduced to a handful of diehard “outliers.” Most of these are shills for extractive energy interests on the payroll to keep injecting doubt into the body politic so business as usual practitioners can proceed unhindered by serious attempts to stop the pollution.

    As to “temperature rises have not been convincingly shown (and I don’t mean proven) to be either at unprecendented rates or levels,” I ask “with respect to when?” This is a strawman argument. Nobody is claiming that AGHG warming will exceed the warming of the PETM, for instance, though it could provoke climate feedbacks which make it do that. With respect to the last million years the levels of CO2 and the levels of warming are equal to and exceeding the highest iduring the MWP. Global mean temperatures over land and ocean are the highest surface temperatures measured since before 1880. The observed rate of warming is also unprecedented, with both the level and rate since 1979 being compelling evidence of rapid climate change.
    see:
    http://www.ncdc.noaa.gov/img/climate/research/2005/ann/global-blended-temp-pg.gif

    No natural forcing can be shown to cause the level or rate of global warming we have now. A combination of human impacts can, from carbon soot to CO2 to deforestation – with anthropogenic CO2 the leading culprit.

    From http://www.gaiehouston.co.uk/climate.htm
    The impact of the changing climate in the 20th Century

    IPCC:

    Arctic air temperatures increased by about 5C in the 20th century-ten times faster than the global-mean surface temperature-while Arctic sea-surface temperatures rose by 1C over the past 20 years.

    In the Northern Hemisphere, spring and summer sea-ice cover decreased by about 10-15% from the 1950s to the year 2000: sea-ice extent in the Nordic seas has shrunk by over 30% over the last 130 years.

    Arctic sea-ice thickness declined by about 40% during late summer and early autumn in the last three decades of the 20th century.

    Alaska’s boreal forests have been expanding northward by some 100 kilometres for every one degree Celsius of temperature rise.

    The major seal breeding grounds in the Bering Sea have seen fur-seal pup numbers fall by half between the 1950s and the 1980s.

    Precipitation over many mid- to high latitude land areas in the Northern Hemisphere has become more and more intense.

    Rainfall has generally declined in the topics and subtropics of both hemispheres; when rain does fall, it is frequently so heavy that it causes erosion and flooding.

    In large parts of Eastern Europe, European Russia, Central Canada and California, peak stream flows have advanced from spring to winter, since more precipitation falls as rain rather than snow, thus reaching rivers more rapidly than before.

    In Africa’s large catchment basins of Niger, lake Chad and Senegal, total available water has decreased by 40%.

    Desertification has been exacerbated by lower average annual rainfall, runoff and soil moisture, especially in southern, northern and western Africa.

    Increased summer drying and the associated risk of drought have been observed in a few continental areas, including Central Asia and the Sahel.

    In the Alps, some plant species have been migrating upwards by one to four meters per decade; some plants previously found only on mountain tops have now disappeared.

    Cold- and cool-water fish are losing suitable habitat; warm-water fish are expanding their ranges in both northern and southern hemispheres.

    Changes in climatic variables have increased the frequency and intensity of pest and disease outbreaks as the related organisms shift their ranges poleward or to higher elevations.

    Almost two thirds of the glaciers in the Himalayan and Tienshan mountains have retreated in the past decade; Andean glaciers have also receded dramatically in the past several decades.

    Vast expanses of the oceans have warmed over the past 50 years; globally, sea-surface temperatures have risen in line with land temperatures.

    The global mean sea-level has risen by 10-20cm during the 20th century-ten times faster than the rate for the previous three thousand years.

    Seventy per cent of sandy shorelines have retreated over the past 100 years; 2-30 per cent are stable, while less than 10 per cent are advancing.

    Seawater is seeping into freshwater aquifers and intruding into estuaries in low-lying coastal areas around the world, particularly on low-lying islands.

    end quote

    There’s nothing “theoretical” about the observed effects and there’s nothing theoretical about what most of it’s caused by. AGHG warming is certain enough to demand action. And it’s happening, but all too slowly, predominantly because of misleading skeptics such as PHE, whoever that is.

  19. 19
    A.Syme says:

    In the 1980′s there was a book published called The Jupiter Effect. The authers were trying to link earth changes to the position of the planets. The one thing I remember from this book was their idea that during solor maxima, the influx of charged particles from the sun was routed to the polar regions by the earths magnetic field. This would actually raise the barometric pressure in the polar regions and push the jet stream farther south. because of this winter would be colder in the mid-latitudes.

  20. 20
    llewelly says:

    Re: A.Syme

    In the 1980′s there was a book published called The Jupiter Effect.

    I read it as a child. I recall thinking it was akin to Worlds In Collision, but marginally less kooky. Unfortunately – my memories of it are vague. A quick google found this negative review

  21. 21

    Re: Tim #18

    Your list from the IPCC, for the most part, is evidence of global warming, and not specific to an anthropogenic cause.

    Re: Wayne #2

    A strong 11 year cyclic solar signal in the climate is not needed for the solar theory, since there is evidence that for more than 60 years, solar activity has been at one of its highest levels in the past 8000 years. See the Solanki references already discussed at:

    http://www.realclimate.org/index.php?p=180

    We don’t have accurate enough data on the increase in solar forcing since 1850 to determine how much of the recent warming was previously unrealized climate commitment from the continuing high levels of solar forcing vs how much was from increases in GHG forcing. Unless we get models of solar behavior so accurate that when run them in reverse we can recover earlier levels of solar forcing with a high level of confidence, we will never be able to confidently attribute the 20th century warming.

    In addition, attributing the recent warming would require model accuracies on the order 0.1W/m^2 to apportion the on the order of 1W/m^2 imbalance in the earth’s energy budget between the various forcings (globally and annually averaged). We may not yet have enough accurate data to validate models to that level accuracy for another couple of decades, some question whether even recent satellite data is accurate enough to validate models to that level of accuracy.

    Current AR4 models were “validated” against the 20th century climate data, despite having systematic positive biases in surface albedo that averaged nearly 2% (a bias against solar forcing), and while having climate sensitivities that varied by over a factor of two among the models. This shows that current efforts at model validation are poorly constrained by the available data, and have errors large than the phenomena we are trying to simulate. Whether the current climate is warming, and has unrealized climate commitment to further warming or even to cooling is all determined by net forcing imbalances smaller than 1% of the solar flux at the surface.

    We have evidence that the climate is warmer, and that there is commitment to further warming independent of the models, but attributing past warming and projecting future warming is largely dependent on the models, and they are not yet up to the task.

  22. 22

    Re #19 (and maybe of interest for Nereo in #12, because of the rain patterns…),

    With or without the Jupiter Effect, there is observed evidence that the solar cycle(s) influence the jet stream position and rain patterns.
    See Shindell for the NH.
    See NASA for the USA
    And see what happens even on local scale here for Boston
    Or for the Mississippi delta
    And for Portugal
    There are many more examples…

    Also longer term solar cycles are detected in nature.

  23. 23
    Jeffrey Davis says:

    We have evidence that the climate is warmer, and that there is commitment to further warming independent of the models, but attributing past warming and projecting future warming is largely dependent on the models, and they are not yet up to the task.

    We have evidence that the train has lost its brakes and that the conductor is dead. We can’t be sure until the train either jumps the track or the engine runs out of steam. So, starting up our car and moving it from the crossing is a hasty thing to do.

  24. 24
    Phillip Shaw says:

    Re #16: Mark, I believe that you used the term “negative feedback” where you meant to use “positive feedback”. These terms are borrowed from engineering and their connotations don’t refer to whether they are beneficial or harmful, but rather to whether they decrease the amplitude (negative feedback) or increase the amplitude (positive feedback). In talking about AGW, negative feedback is positive (beneficial) and positive feedback is negative (harmful).

  25. 25
    SecularAnimist says:

    gavin wrote: “A new review paper by Foukal et al does a reasonable job summarising the mainstream opinion on the issue.”

    The main CNN web page today has a link to this Reuters article about that paper:

    Study acquits sun of climate change
    September 15, 2006
    Reuters

    The sun’s energy output has barely varied over the past 1,000 years, raising chances that global warming has human rather than celestial causes, a study showed on Wednesday.

    Researchers from Germany, Switzerland and the United States found that the sun’s brightness varied by only 0.07 percent over 11-year sunspot cycles, far too little to account for the rise in temperatures since the Industrial Revolution.

    “Our results imply that over the past century climate change due to human influences must far outweigh the effects of changes in the sun’s brightness,” said Tom Wigley of the U.S. National Center for Atmospheric Research.

    Most experts say emissions of greenhouse gases, mainly from burning fossil fuels in power plants, factories and cars, are the main cause of a 0.6 Celsius (1.1 Fahrenheit) rise in temperatures over the past century.

    A dwindling group of scientists says that the dominant cause of warming is a natural variation in the climate system, or a gradual rise in the sun’s energy output.

    “The solar contribution to warming over the past 30 years is negligible,” the researchers wrote in the journal Nature of evidence about the sun from satellite observations since 1978.

    They also found little sign of solar warming or cooling when they checked telescope observations of sunspots against temperature records going back to the 17th century.

    They then checked more ancient evidence of rare isotopes and temperatures trapped in sea sediments and Greenland and Antarctic ice and also found no dramatic shifts in solar energy output for at least the past millennium.

    “This basically rules out the sun as the cause of global warming,” Henk Spruit, a co-author of the report from the Max Planck Institute in Germany, told Reuters.

    Many scientists say greenhouse gases might push up world temperatures by perhaps another 3 Celsius by 2100, causing more droughts, floods, disease and rising global sea levels.

    Spruit said a “Little Ice Age” around the 17th century, when London’s Thames River froze, seemed limited mainly to western Europe and so was not a planet-wide cooling that might have implied a dimmer sun.

    And global Ice Ages, like the last one which ended about 10,000 years ago, seem linked to cyclical shifts in the earth’s orbit around the sun rather than to changes in solar output.

    “Overall, we can find no evidence for solar luminosity variations of sufficient amplitude to drive significant climate variations on centennial, millennial or even million-year timescales,” the report said.

    Solar activity is now around a low on the 11-year cycle after a 2000 peak, when bright spots called faculae emit more heat and outweigh the heat-plugging effect of dark sunspots. Both faculae and dark sunspots are most common at the peaks.

    Still, the report also said there could be other, more subtle solar effects on the climate, such as from cosmic rays or ultraviolet radiation. It said they would be hard to detect.

  26. 26
    Willis Eschenbach says:

    Re 18, there is a big problem with depending on the IPCC for your data. For example, you quote the IPCC as saying:

    Arctic air temperatures increased by about 5C in the 20th century-ten times faster than the global-mean surface temperature-while Arctic sea-surface temperatures rose by 1C over the past 20 years.

    However, this is not the case at all.

    The Jones dataset shows the Arctic air temperatures (north of 65°N) as warming by ~ 1°C from 1900 to 2000.

    The GHCN dataset shows ~ 1.1°C Arctic warming (north of 65°N) during the same period.

    The Arctic Climate Impact Assessment (ACIA) report states:

    Based on the analysis of the climate of the 20th century,it is very probable that the Arctic has warmed over the past century,although the warming has not been uniform. Land stations north of 60° N indicate that the average surface temperature increased by approximately 0.09 °C/decade during the past century, which is greater than the 0.06 °C/decade increase averaged over the Northern Hemisphere.

    In other words, the IPCC “fact” is wrong by a factor of five. This is not surprising, because the IPCC is a political body rather than a scientific body, but it highlights the problem with depending on the IPCC for your facts …

    w.

    [Response: When is an 'IPCC fact' not actually an 'IPCC fact'? When it doesn't appear in the IPCC report. There are no such statements in TAR WG1, though there is a similar, though ambiguous, statement in WGII. The actual wording appears to come from Mark Lynas's book High Tide (quotation?) (who sometimes reads this, so maybe he can provide a clarification). Rather than jumping to wild conclusions about the 'obvious' political bias of the IPCC, maybe five minutes with google would haved helped find the source of the quote and the possible cause of the mis-interpretation. Of course, maybe it's more fun to jump to conclusions.... - gavin]

  27. 27
    C. W. Magee says:

    With regards to the cosmic ray experiment, you have to remember that for particle physicists used to spending gigadollars on equipment, $11 mil probably seems like a lot less money than it does for Earth scientists used to grants in the tens of kilodollar range.

  28. 28
    Mark Bahner says:

    Submitted without comment. ;-)

    SCIENTISTS PREDICT SOLAR DOWNTURN, GLOBAL COOLING
    New Scientist magazine, 16 September 2006

    RUSSIAN ACADEMY OF SCIENCE REPORT WARNS OF GLOBAL COOLING IN 6-9 YEARS
    MosNews, 25 August 2006

  29. 29
    Jeff Weffer says:

    The Sun clearly has cycles.

    There is VERY clearly an 11 year cycle and there is VERY clearly a longer-term cycle greater than 325 years (we don’t know how long it is because we are still in it.)

    http://solarscience.msfc.nasa.gov/images/ssn_yearly.jpg

    So the Sun, a powerful complex body, has at least two clear cycles. We don’t know how many cycles the Sun really has or how much variance there may be in those cycles.

    And Sunspots are just an indication of what is happening in the Sun. The Sunspots, themselves, are not the culprit, they are just an indicator.

    We also know there is a clear 115,000 year cycle of ice ages followed by inter-glacials.

    Why the rush to judgement to discount solar cycles when they are clearly there?

  30. 30
    A.Syme says:

    Another item that needs to be looked at in the earth-sun connection is the influence of the earths magnetic field. Far from being static ( always in a state of flux!) the changes are well documented in rock formations. Has anyone looked at the history of the magnetic field in relation to past climate changes?

    [Response: yes. There isn't any. - gavin]

  31. 31
    Grant says:

    Re: #29

    The 11-year solar cycle is indeed quite clear. But I don’t know of any evidence for other cycles in solar output. As has been discussed here often, it’s not possible to conclude cyclic behavior from a time series which is shorter than the supposed cycle.

    The cycle of ice ages is believed not to be due to changes in solar output, but in the amount of solar energy intercepted by earth, and its geographic distribution, due to cyclic changes in the earth’s orbit. The fact that ice ages correlate with earth’s orbital variations argues very strongly that it’s the orbit and not the sun, that has been causing climate variations driving the ice ages for the last million years or so.

    What’s your evidence for solar cycles besides the 11-year cycle?

  32. 32
    Hank Roberts says:

    We don’t know how variable the Sun is over the longer term. One of the first impressions from melted rocks photographed on an Apollo visit suggest a huge flare event that’s used as the premise for this story:
    http://homepage.ntlworld.com/adam.milner/books/inconstant_moon.htm

    Brief flare events in fact have been remarkable:
    http://www.otago.ac.nz/news/news/2004/16-03-04_press_release.html

    Study of the melted Moon rock samples that made the premise for Niven’s science fiction story seems to have kept that size flare in the realm of fantasy, though.
    http://www.sciencemag.org/cgi/content/abstract/172/3983/556

  33. 33
    Willis Eschenbach says:

    Re #18, Gavin, thank you for your response. I’m not sure what you mean when you say that the 5°C/century is not from the IPCC. The TAR says:

    The land stations show that warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world. Although not geographically uniform, the magnitude of the warming is about 5°C per century, with areas of cooling in eastern Canada, the north Atlantic, and Greenland (Koerner and Lundgaard, 1996; Borzenkova, 1999a,b; Jones et al., 1999; Serreze et al., 2000).

    Now, a statement like “the magnitude of the warming is about 5°C per century” seems pretty clear to me … but in case it was ambiguous, or meant only warming in a certain area of the Arctic, I took a look at the Arctic temperature records (from 65°N to 90°N) by 30° segments. I calculated the trends from either 1900-2000, or as much of that period as there were records.

    The greatest warming was in the area above Alaska and western Canada, from 180°W to 120°W. This area was affected by about a 1° temperature rise from the PDO in 1976-78. This warming, far from being 5°/century, was a maximum of 1.3°/century and an average of 1.2°/century, including the PDO shift.

    Outside of this 180°W-150°W area, the greatest warming was 0.5°, and the average warming was 0° (because of the above noted cooling in Canada etc. mentioned above) … that is to say, no warming at all.

    To summarize: 1/4 of the Arctic was affected by the PDO shift, and warmed by ~1.2°. The other 3/4 of the Arctic did not warm at all. Indeed, the references quoted by the IPCC, such as Figure 3 of Serreze et al., 2000, show that the Arctic as a whole is no warmer now than it was in 1930.

    To paraphrase your rather abrupt response to me, rather than jumping to wild conclusions about the lack of political bias of the IPCC, maybe five minutes with the actual data would haved helped you to verify that the IPCC claim of 5°/century warming anywhere in the Arctic was simply not possible. Of course, maybe it’s more fun to jump to conclusions …

    w.

    [Response: Try figure 1 in the Serreze et al paper. There are large areas of the Arctic with trends > 0.5°/decade (i.e. 5°/century). These are recent trends, not the change over the century though - which is why the WGII statement was ambiguous. The paraphrasing that you objected to originally was incorrect, but that paraphrasing did not come from IPCC. Had I reviewed the text (which I didn't) I would have suggested making their statement more explicit. I'll leave it to the readers to decide who's the long jumper here... - gavin]

  34. 34
    William Astley says:

    Re: 31 “The fact that ice ages correlate with the earth’s orbital variations argues very strongly that it’s orbit and not the sun, that has been causing climate variations driving the ice ages for the last million years or so.”

    The above statement is incorrect for the following reasons:

    If the 10kyr so called warm period (Holocene, current) followed by the 90kyr glacial period (Wisconsin, last), has only due to orbital changes, the earth would now be starting the next glacial period, as the planet is currently farthest from the sun during the summer solstice (June 21) and closest to the sun during the winter solstice (December 21) which is exactly opposite to the orbital position 11kyrs ago at the beginning of the warm period. (Cold summers are a necessary condition to begin the glacial period and warm summers are required to end the glacial cycle.)

    The Greenland ice sheet record shows sharp periodic drops in temperature, which cannot be explained by slow orbital changes. For example the Greenland Ice Cores, show 10C to 30C, periodic drops in temperature on the ice sheet. The Rapid Climatic Change Events, RCCEs (called Rickys), occur in less than a decade, last roughly 100yrs, at which time the temperature on the ice sheet recovers to a level lower than the temperature at the beginning of the RCCE cycle.

    During the RCCEs there is an 800 times increase in dust in the ice sheet record, as compared to current conditions. Some believe, the massive increase in atmospheric dust and the very, very, windy conditions during the periodic RCCEs bring iron to the vast areas of the ocean that are currently almost lifeless due to low iron. Iron is an essential metal in chlorophyll. The extra iron some believe cause a significant increase in phytoplankton production. The increased phytoplankton production during the RCCEs reduces the CO2 level in the atmosphere, which along with the increase in the ice sheet further cools the planet. Atmospheric CO2 is around 300 ppm in the warm period. It drops in stages to 180 ppm at the end of the glacial period, at which time 1/3 of the earth’s land mass and vast areas of the high latitude oceans are covered with ice.

    The question as to what causes the RCCEs has not been answered. Solar variance is most certainly on the short list of suspects. The following is an excerpt from M.Christl et al’s (2004) paper in the Journal of Atmospheric and Solar-Terrestrial Physics, which explains how the sun could affect the earth’s temperature:

    “A leading candidate to explain the link between relatively feeble solar fluctuation and climate is the effect of solar (magnetic) modulated glactic cosmic rays (GCR) on cloud formation (Editors of science, 2002). … their contribution to the global radiation climate forcing is estimated to be about -28 W/m^2 (Hartman, 1993). This is one order of magnitude larger than the radiative forcing caused by the anthropogenic greenhouse gases (IPCC, 2001).

    The infrequent and periodic solar event that would cause a RCCE is something that increases cloud formation, in my opinion, both directly (Extended period of massive solar flares. Solar flare composition may differ from the current flares.)and indirectly (Change in the number of sunspots per cycle, such as the Maunder minimum.)Astronomers have observed both events in other stars that are a similar age, size, and composition as our sun. The physics as to why these solar events are occurring and what controls their periodicity, is not known at this time.

    [Response: 'ice ages' generally refers to the long term cycles (20,000 to 100,000 years) which are highly correlated to orbital variations. The shorter term 'millenial' variations (sometimes called Dansgaard-Oeschger events, or interstadials) are a very separate phenomenon for which the triggers are not yet fully understood, although the ocean overturning circulation is strongly implicated. There is no clear evidence that solar forcings are responsible. The quoted statement above was correct, and your characterisation of the Holocene is not. High northern latitudes have indeed cooled from their peak around 10kyr ago and there are hints that the tropics have warmed exactly in line with what is expected from orbital forcing (Kim et al, 2004). -gavin]

  35. 35
    Harry N says:

    Speaking of media coverage of the Nature study, we have this piece over at National Geographic News. The link is to page two, where the reporter quotes Solanki as saying “These authors have looked at the simplest mechanism, and they find that this mechanism does not produce the same level of change that has been observed,”, and that “this could be suggesting that there are other mechanisms acting for the way that the sun influences climate.”

    Seems to be a fair amount of speculation there, in the section entitled “Sun Not Off the Hook for Warming”, including about galactic rays (I thought there was no trend in them in recent decades?). I understand the need to consider possibilities, but evidence is what counts in the end, and perhaps it should be made more clear how much scientific support there is for any speculation put forth.

  36. 36
    Charlie T says:

    Re #10
    …If new and updated TSI data are used, then the trends they calculate vanish. -rasmus]

    -I am a bit confused; which dataset has been updated?
    If it is the ACRIM dataset then surely the climate sensitivity that they calculated from Lean et al 1995(irradiance since 1610) still stands [at 1.5x to 3x larger than the model pedictions]?
    Or has the Lean et al (1995) reconstruction been revised?

  37. 37

    Re #31,

    Have a look at more cycles here for biological activity and ice cover measured in sediments.

    And in tree rings in Asia (there are similar findings in Northern Europe).

    And from ice cores (page 13):

    Particularly exciting results from high-resolution ice cores include the observation that many geochemical parameters show strong spectral power at frequencies close to or identical to those observed in the sun. Worldwide coolings during the Holocene have a quasi-periodicity of 2600 years in phase with previously defined ~2500 year variations in d14C (e.g., Denton and Karlen, 1973; Stuiver and Braziunas, 1989, 1993;
    O’Brien et al., 1995). Also, d18O in the GISP2 core is coherent with both the ice-core 10Be time-series and with the tree-ring record of atmospheric 14C (Stuiver et al, 1995; Figure 11). Remarkably, the series are coherent not only in phase but also in amplitude, providing what is probably the best evidence to date for the elusive sunclimate relationship, a subject of debate for more than a century.

    For solar influences on the monsoon, measured in a stalagmite:

    The stalagmite revealed that cycles of 558, 206, and 159 years, on average, are superimposed on a jumble of variations in monsoonal rains since the last ice age. These climate periodicities resemble those in the record of varying carbon-14 in tree rings, the authors note, cycles widely attributed to variations in solar activity.

    With a little Googling, one can find many more…

    [Response: With a little googling one can find many purported attributions of cycles to solar forcing - but if one looks into most of them they are not coherent to each other nor to the 14C production funciton that is most reasonably tied to solar activity. It's precisely because 99% of the these attributions don't actually cohere that the sub-genre of solar forcing of climate has the reputation it has among many climate scientists. Thus when working on this topic (as I and others here have), one has to be absolutely scrupilous not to uncritically accept claims that others have made. The statement above for instance on the coherence of d18O and 10Be in ice cores is 99% a statement about snow accumulation changes, not 10Be production (which is modulated by solar). Every time this kind of erroneous stuff gets quoted, you make it harder for serious science to be done. If, as I presume, you'd like this to be looked at seriously, take responsibility for your own descriptions of it and don't simply parrot stuff you find through google. - gavin]

  38. 38
    GH says:

    Can anyone comment on Bard and Frank’s Earth Planet. Sci. Lett. 248, 1 (2006)? From Science’s “Highlights of the recent literature” service :

    “Bard and Frank provide a thorough critical review of both the problematic evidence for longer changes in solar irradiance and the possible climatic effects these changes could have induced. The authors point out that many proposed connections, for example between the records of cosmogenic nuclides such as 14C and 10Be and records of climate change, are based on correlations–some of which have large and perhaps unappreciated uncertainties–and on imperfect and indirect records. They conclude that there might still be a connection between solar changes and the Medieval Warm Period and Little Ice Age, but that overall solar changes, most of which remain unproven, probably represent a second-order influence on the behavior of Earth’s recent climate.

  39. 39
    Willis Eschenbach says:

    Gavin, thank you kindly for your response in 33. You advise me to look at Figure 1 in Serreze, which shows that there are a few small places (a total of about 17% of the area) in the Arctic that have warmed rapidly during the thirty year period from 1966 to 1995. However, it is well known (and supported by Serreze) that the 1960′s were anomalously cold in the Arctic, so that rise is neither surprising nor unnatural.

    Now, since only 17% of the area is warming at that rate, it is highly misleading to state, as the IPCC does, that “Although not geographically uniform, the magnitude of the warming is about 5°C per century …” This is deception that reveals the IPCC bias, only 17% of the area has been warming at that rate, and not for the century, but for only 30 years.

    Because they were not discussing the warming since 1966, but the warming per century. To describe this short term warming as “5°/century” is very misleading, and reveals the political agenda of the IPCC. It’s like looking a 20° warming from 9AM to noon, and describing it as “120°/day”.

    It is mathematically correct, since 20° in three hours works out to 120° in a day … but a 120° rise in a day is as unlikely as a 5° Arctic rise in the last century.

    w.

  40. 40

    Re #37 (comment),

    Gavin, I am aware of the accumulation problem in ice cores vs. 10Be production. As mostly, I try to look at the evidence as described in the article itself. In the case of the article I quoted, the correlation of ice core 10Be is influenced both by solar activity and snow accumulation while d18O is directly connected to climate (temperature/ice sheet volume), but that also correlates with 14C in tree rings over the same periods, which is mainly connected to solar activity cycles…

    I know of the controversy between solar scientists and climate model scientists… IMHO, climate scientists should listen a bit more carefully to what solar scientists say, and include in the models a few items which are quite certain since the start of the satellite era. A good example is the solar-cloud connection over the last two cycles. I mean the inverse correlation between (TOA) irradiation (not GCR) and cloud cover. As far as I know, no model does that predict (or use that as parametrisation).

  41. 41
    Grant says:

    Re: solar cycles

    I worked for 10 years doing time series analysis for astrophysicists studying variable stars. So I decided to look into the variability of the sun more closely. A literature search identifies three classes of papers:

    1. Papers that conlude there is no confirmable influence of solar activity on climate,

    2. Papers that point out confirmable correlations of solar cycle activity with changes in the *stratosphere*, but only *hypothesize* about *possible* effects on the troposphere or relating to SAT,

    3. Papers which Gavin quite correctly characterizes by “but if one looks into most of them they are not coherent to each other nor to the 14C production funciton that is most reasonably tied to solar activity. It’s precisely because 99% of the these attributions don’t actually cohere that the sub-genre of solar forcing of climate has the reputation it has among many climate scientists.”

    Frankly, I think he was a little kind. I saw papers that tout complex mathematical models but give no clue as to what the model *is*, papers that claim “strong correlation” when no numerical estimate of significance is given nor are the statistical tests described, graphs illustrating strong correlation which *look* rather obviously like the “correlation” is false (and I don’t say such things lightly — I do this professionally), papers with *no references* (always a warning sign). Overall, the quality of the research published that falls into class 3 is — there’s no polite way to say this — abysmal.

    The best research I’ve found so far was already noted in #38: “They conclude that there might still be a connection between solar changes and the Medieval Warm Period and Little Ice Age, but that overall solar changes, most of which remain unproven, probably represent a second-order influence on the behavior of Earth’s recent climate.”

    I remain highly skeptical of attribution of global warming to solar variability.

  42. 42
    Tim Jones says:

    Willis Eschenbach wrote:

    Re 18, there is a big problem with depending on the IPCC for your data. For example, you quote the IPCC as saying:
    Arctic air temperatures increased by about 5C in the 20th century-ten times faster than the global-mean surface temperature-while Arctic sea-surface temperatures rose by 1C over the past 20 years.

    However, this is not the case at all.
    [...]

    My reply:
    From:
    Climate Change 2001: IPCC Third Assessment Review
    Working Group II: Impacts, Adaptation and Vulnerability
    http://www.grida.no/climate/ipcc_tar/wg2/597.htm
    (excerpt)
    “The land stations show that warming in the Arctic, as indicated by daily maximum and minimum temperatures, has been as great as in any other part of the world. Although not geographically uniform, the magnitude of the warming is about 5°C per century….

    See also:

    Polar Regions (Arctic and Antarctic)
    http://www.grida.no/climate/ipcc_tar/wg2/pdf/wg2TARchap16.pdf
    “In the Arctic, extensive land areas show a 20th-century. warming trend in air temperature of as much as 5°C. Over sea ice, there has been slight warming….”

    From the Arctic Climate Impact Assessment (ACIA) Overview report,

    http://amap.no/workdocs/index.cfm?action=getfile&dirsub=%2FACIA%2Foverview&filename=ArcticImpacts%2Epdf&CFID=3127464&CFTOKEN=91984283&sort=default

    Page 18,
    “Temperatures have increased sharply in recent decades over most of the region, especially in winter.
    Winter increases in Alaska and western Canada have been around 3-4º C over the past half century.”

    Page 28,
    “In Alaska and western Canada, winter temperatures have increased as much as 3-4º C in the last 50 years.”

    Can someone clarify the discrepancy between the above and what Willis quoted:

    “Based on the analysis of the climate of the 20th century, it is very probable that the Arctic has warmed
    over the past century, although the warming has not been uniform. Land stations north of 60º N indicate that the
    average surface temperature increased by approximately 0.09ºC/decade during the past century, which is greater
    than the 0.06 ºC/decade increase averaged over the Northern Hemisphere.”

    And please, what is the average increase in Arctic temperatures since 1900?

  43. 43
    Willis Eschenbach says:

    In 42, Grant, you say:

    I remain highly skeptical of attribution of global warming to solar variability.

    If that is the case, how do you explain the cooling of the Earth as it entered the Little Ice, and the warming since the Little Ice Age? If it’s not the sun, what is the cause of that cooling and warming?

    w.

  44. 44

    What is Nature doing publishing as a “review” article, an article with apparently new research using an obsolete climate model (“the upwelling-diffusion energy balance climate model used by IPCC”)? Even the current models, which have been subjected to the latest diagnostic research, have been shown to be problematic and biased against solar forcing (see references at my URL). If I recall correctly, the TAR relegated the simpler model used by this paper to interpolation between the leading edge results and validated the model only by the rough equivilence of its results to the leading models of its time.

    Foukal, et al, drive this model with reconstructions of solar irradiance from paleo proxies. Their model of solar irradiance accounts for 80% of the variance over the last couple solar cycles, which they extend via sunspot and Be isotope records back 1000 years. Foukal, in his Oct. 2004 Science publication, states “It should then be possible to move beyond modeling based on speculative irradiance changes toward a more physically based understanding of Sun-climate relations.” It is unclear whether it is from his new modeling in this Nature paper, or the modeling with the MAGICC model in his 2004 paper that he bases this papers’s statement “Further simulations with solar forcing alone show that the solar contribution to warming over the past 30 years is negligible” He references the 2004 paper for the statement, but that paper does not explicitly support this result.

    He notes that a factor of 3 increase in the amplitude of solar irradiances were enough to account for “a climate variation of the amplitude suggested by the seventeenth-century cooling.” The error range statistically inherent in an irradiance model based on two solar cycles, plus the errors in the paleo reconstructions and the simplified or obsolete models should make a significant dent in that factor of 3 range. Even without the error range, if his modeling shows negligible solar contribution to the last 30 years, his models must have been unable to represent the climate commitment due to ocean thermal inertia from the increases in solar forcing prior to 30 years ago.

    If the authors think the works supporting, e.g., the Gleisberg and Suess cycles, are unconvincing, a paper purporting to be a “review” paper should explicitly discuss and present its arguments for dismissing them. After all, it is less than a year since Nature published:

    Holger Braun, et al, “Possible solar origin of the 1,470-year glacial climate cycle demonstrated in a coupled model” Nature 438, 208-211 (10 November 2005)

    which argues for the superposition of these two cycles. If those cycles persist across both glacial and interglacial climates, it is hard to argue that they are the result of multidecadal or multi-centenial internal climate modes rather than some external forcing. While not supported by a “physically based understanding”, they should at least be a reminder that a physically based understanding of 80% of the variation over two solar cycles might be insufficient to support this paper’s conclusions.

    While I share Foukal’s preference for more physicallly based understanding, I hesitate to accept as complete or conclusive, “understanding” which leaves so much of the past and current climate variation unexplained.

  45. 45
    grant says:

    Re: #42, #43

    Forgive me for being unclear. I should have said, “I remain highly skeptical of attribution of *modern* global warming to solar variability.”

  46. 46
    Charlie T says:

    Re #44 Grant, are you highly skeptical of the idea that ALL of the modern warming can be attributed to solar variation ( I think that you would be in the vast majority there) or do you think that solar variation has no impact on warming or cooling?
    ie do you think that Scafetta and West(#10 above), for example, are wrong in thinking that the higher solar radiation during cycle 22-23 (1991-2002) compared to cycle 21-22 (1980-1991) would lead to higher temperatures?
    (and which could lead to lower temperatures than expected during the current period (2002-2013) as the 22 year Hale Cycle solar-radiation component goes low )

  47. 47
    William Astley says:

    Re: #38 “Can anyone comment on Bard and Frank’s Earth Planet” “Bard and Frank provide a thorough critical review… cosmogenic nuclides such as 14C and 10Be and records of climatic change… but that overall solar change changes, most of which remain unproven, probably represent a second-order influence in the behavior of the Earth’s recent climate.”

    The cosmogenic nuclides, 14C and 10Be are created by charged particles that move at close to the speed light, accelerated to the speed of light by some unknown galactic process. The hypothesis is that solar variance, changes the earth’s magnetic field, which in turn changes the amount of Galactic Cosmic Particles that penetrate the earth’s atmosphere. An increase or decrease in the GCPs it is hypothesized would cause an increase or decrease in cloud formation which would in turn cool or warm the earth.

    The search is for a periodic solar event that would cause a major change in temperature, such as that associated with the Younger Dryas. The solar affect on the Earth’s magnetic field and the subsequent changes in GCPs that penetrate the atomsphere, may not be the solution.

    A second climate change/solar hypothesis concerns Coronal Mass Ejections (CME) which are massive injections of charged particles, from the sun as opposed to galactic sources. As the velocity of CMEs is 200 to 1000 km/s rather than close to the speed of light, CMEs do not create isotopes of C or Be. If the solar climate change is due to CMEs there would not be a change in 14C or 10Be.

    Recently it has been found that CMEs can occur independent of solar flares. Specifically what causes CMEs and how they vary over time is not known. A NASA mission “Stereo Launch” is scheduled Oct 18, 2006, to study CMEs.

    CMEs have an associated magnetic field which enables them to penetrate the earth’s magnetic field. The impact distorts the magnetosphere creating an electric field that accelerates electrons trapped in the magnetosphere.

    It appears at present there is no explanation as to what caused the Younger Dryas, return from warm temperatures to near glacial temperatures, in less than a decade and then a return a thousand years later, also in less than a decade back to warmer interglacial temperatures. Seager et al’s 2002 paper directly challenged the thermohaline conveyor hypothesis: “For many years, the leading theory for what caused the Younger Dryas… has a release of water from glacial Lake Agassiz,… Recently, however evidence emerged that the Younger Dryas began before the breach… What is more, the temperature changes induced by a shutdown in the conveyor are too small to explain what went on during the Younger Dryas. Some climatologists appeal to a large expansion in sea ice to explain the sever winter cooling. I agree that something of this sort probably happened, but it’s not at all clear to me how stopping the Atlantic conveyor could cause a sufficient redistribution of heat to bring on this vast change.” Seager ran similuations and referenced simulations done by others, that showed a stoppage of the thermohaline conveyor would only reduce European coastal temperatures 1 to 2C in the winter, not the 10 to 15C required to explain the Younger Dryas. In addion, his July-August American Scientist article (based on the 2002 paper) provides a simple to understand explain of why the west coast of Europe is warmer than the east coast of the US.

    Solving the Younger Dryas problem (the climate record shows other Younger Dryas events, which appear to be periodic), would be a break through. The fact that others have failed to solve the problem, would imply other hypothesizes should be investigated, as opposed to summarily excluding solar variance.

  48. 48
    Grant says:

    Re: #46

    I subscribe to the first (majoriy) opinion, that solar variations have a 2nd-order effect on surface temperature.

    I’ve seen what appears to be quality research claiming that the solar cycle has a noticeable effect on the *stratosphere*. This can affect the troposphere not only through direct heating, but also by changing the pattern of stratospheric winds. There are hints of observed effects on tropospheric temperatures, but the response seems to be strongly latitude-dependent — “zonal” warming/cooling rather than “global.” Also, it seems to me that some of the warming in the 1st half of the 20th century may be, in part, due to increased solar output. Furthermore, there is satellite evidence of a (slight!) cyclic variation of the solar constant with the sunspot cycle.

    I have looked in great detail at SAT, in an attempt to find any discernable hint of the solar cycle in the surface temperature record. There is none. Of course, that doesn’t mean that variations with the solar cycle have no influence on surface temperature, it just means that whatever cyclic response does exist is below the detection level. If one assumes that solar variation has a 2nd-order effect, this is not really surprising; there are lots of 1st-order effects to “drown it out,” such as natural variations, aerosol loading (both natural and man-made), and of course greenhouse gases.

    Frankly, I’d be quite surprised if solar variation has *no* effect, but what I’ve seen indicates that it’s not a viable explanation for modern global warming.

  49. 49
    muller.charles says:

    Gray, Haigh and Harrison (Hadley Center) published a technical note about ‘Influence of solar changes on the Earth’s climate (2005). Reading what they say about high energy particles and clouds (pp. 48-68), I suppose there are some “empirical support” linking cosmic rays to clouds. So, the 11 million $ experiment you mention could be useful to clarify the subject. I also suppose there are some other scientific interests in that experiment.

  50. 50
    Jon Sumby says:

    This is slightly off-topic. The rather pathetic sceptic site ‘Friends of Science’ has a diagram (which appears to be connected to the Hadley Centre), which shows that there would only be a net 0.6 degC reducton in predicted warming if the Kyoto Protocol was followed. Tracking back from the graph, I found it seems to relate to a statement made by a Dr Baliunas to a Senate committee on March 13th, 2002.

    However, I am seeking more information or informed comment about this question:

    Given the increasing knowledge-base and refinement of climate change data and models has there been any sound, peer-reviewed, estimates of the effect of a full acceptance, and adherance to, the Kyoto Protocol would have on the currently accepted climate change models? In other words, in the face of unstoppable changes (ocean acidification, phytoplankton decline, arctic methane pumping, albedo changes, ice-sheet loss in Greenland, El Nino reinforcement, etc.), if Kyoto was followed to the letter; would we still be spitting into the wind?

    If anybody can answer this, or have solid data on Kyoto effects on climate change, I would be grateful. For instance, has anybody run the business-as-usual models with Kyoto reductions? (e.g. the IS92A? scenario)
    Jon


Switch to our mobile site