Little Ice Age (Solar Influence)

CO2 Science Magazine ^ | December 18, 2002 | Staff Summary

[PeaceBeWithYou]

How much of an influence the sun has exerted on earth's climate during the 20th Century is a topic of heated discussion in the area of global climate change.  The primary reason for differing opinions on the subject derives from the fact that although numerous studies have demonstrated significant correlations between certain measures of solar activity and various climatic phenomena (Reid, 1991, 1997, 1999, 2000), the magnitude of the variable solar radiative forcing reported in these studies is generally so small it is difficult to see how it could possibly produce climatic effects of the magnitude observed (Broecker, 1999).  Supporters of solar effects theories counter by contending that various positive feedback mechanisms may amplify the initial solar perturbation to the extent that significant changes in climate do indeed result.  In this summary, we highlight some of the recent scientific literature that demonstrates the viability of such solar linkages and the emerging belief that small changes in the sun's energy output produced the coldest period of the past millennium, i.e., the Little Ice Age.

Many solar-climate studies utilize tree-ring records of ¹⁴C as a measure of solar activity, because solar activity (including variations in the number of sunspots and the brightness of the sun) influences the production of atmospheric ¹⁴C, such that periods of higher solar activity yield a lower production and atmospheric burden of ¹⁴C (Perry and Hsu, 2000).  This being the case, it can be appreciated that as trees remove carbon from the air and sequester it in their tissues, they are recording a history of solar activity that could be influencing earth's atmosphere-ocean system.  Thus, the history of ¹⁴C contained in tree rings has been examined by a number of authors as a proxy indicator of solar activity and compared with various indices of climate.

A good example of this type of work is the study of Hong et al. (2000), who developed a high-resolution ð¹⁸O record from plant cellulose deposited in a peat bog in the Jilin Province of China (42° 20' N, 126° 22' E), from which they inferred that the most dramatic cold events of the Little Ice Age were centered at about AD 1550, 1650 and 1750.  In comparing their ð¹⁸O temperature record with changes in atmospheric ¹⁴C derived from tree rings, the authors report a "remarkable, nearly one to one, correspondence," which led them to conclude that the temperature history of this region was "forced mainly by solar variability."

Verschuren et al. (2000) also utilized a ¹⁴C record as a proxy for solar activity, comparing it with a decadal-scale history of precipitation in equatorial east Africa over the past 1000 years.  The results of their analysis revealed that this region experienced relatively wet conditions during the Little Ice Age from AD 1270 to 1850.  However, this latter period was interrupted by three periods of prolonged dryness: 1390-1420, 1560-1625 and 1760-1840.  These "episodes of persistent aridity," in the words of the authors, were "more severe than any recorded drought of the twentieth century."  In addition, they discovered that "all three severe drought events of the past 700 years were broadly coeval with phases of high solar radiation, and the intervening periods of increased moisture were coeval with phases of low solar radiation."  Dean and Schwalb (2000) report similar solar-related drought conditions with periodicities of 200 and 400 years for the Great Plains during the main cold phase of the Little Ice Age, as do Haug et al. (2001) for tropical Venezuela.

Other authors have also made the case for a solar-forced Little Ice Age.  Vaganov et al. (2000) found a significant correlation between solar activity and temperature during the Little Ice Age in the Asian subarctic.  Nearby in Europe, a review of the relationship of extreme weather events to climate during the Holocene implicates solar forcing as the factor responsible for above-average rainfall during the Little Ice Age.  According to Starkel (2002), continuous rains and high-intensity downpours coincided with periods of reduced solar activity and were major problems that often led to severe flooding there.

In North America, an analysis of more than 700 pollen diagrams by Viau et al. (2002) indicates a vegetation transition that "culminat[ed] in the Little Ice Age, with maximum cooling 300 years ago."  In contemplating the reason for the transition the authors state that "although several mechanisms for such natural forcing have been advanced, recent evidence points to a potential solar forcing (Bond et al., 2001) associated with ocean-atmosphere feedbacks acting as global teleconnections agents."

Bond et al. (2001) examined deep-sea sediment cores in the North Atlantic and cosmogenic nuclides sequestered in the Greenland ice cap (¹⁰Be) and Northern Hemispheric tree rings (¹⁴C) and concluded "it seems almost certain that the well-documented connection between the Maunder solar minimum and the coldest decades of the LIA could not have been a coincidence" and that the Little Ice Age "may have been partly or entirely linked to changes in solar irradiance."

Two additional papers, both model-based studies, also point to a significant role for the sun in producing earth's Little Ice Age climate.  Using a version of the Goddard Institute for Space Studies GCM, Shindell et al. (2001) estimated climatic differences between the period of the Maunder Minimum in solar irradiance (mid-1600s to early 1700s) and a century later, when solar output was relatively high for several decades. The results of their analysis led them to conclude that "colder winter temperatures over the Northern Hemispheric continents during portions of the 15th through the 17th centuries (sometimes called the Little Ice Age) ... may have been influenced by long-term solar variations."  The second of these studies, by Perry and Hsu (2000), developed a simple solar-luminosity model and used it to estimate total solar-output variations in the Holocene.  The model output was well correlated with the amount of carbon 14 in well-dated tree rings throughout the Little Ice Age and prior to it, which finding, in the words of the authors, "supports the hypothesis that the sun is varying its energy production in a manner that is consistent with the superposition of harmonic cycles of solar activity."

So what changes in solar activity are responsible for producing earth's Little Ice Age climate?  Several authors have targeted the approximate 11-year sunspot cycle as a primary suspect, but recent work by Rozelot (2001), who noted that "warm periods on Earth correlate well with smaller apparent diameter of the Sun and colder ones with a bigger Sun," has added variations in the sun's radius to the mix.

With respect to the 11-year sunspot cycle, Dean et al. (2002) examined a 1500-year varve thickness time series taken from a lake sediment core in Minnesota, USA, and report the signal from this oscillation to be strongest between the 14th and 19th centuries, during the Little Ice Age.  Additionally, Parker (1999), Solanki et al. (2000) and Rigozo et al. (2001) all report relative minima in the mean number of annual sunspots during the Little Ice Age.  Relative to the present, sunspot numbers during the Little Ice Age were more than 40 times fewer (Rigozo et al., 2001).  Similarly, analyses of other solar parameters by Rigozo et al. indicate that the strengths of the solar radio flux, the solar wind velocity and the southward component of the interplanetary magnetic field were 1.97, 1.11 and 2.67 times weaker during the Little Ice Age than they are presently.

How do these small changes in solar activity bring about significant and pervasive shifts in earth's global climate, such as the Little Ice Age?  In answer to this question, which has long plagued proponents of a solar-climate link, Bond et al. (2001) describe a scenario whereby solar-induced changes high in the stratosphere are propagated downward through the atmosphere to the earth's surface, where they likely provoke changes in North Atlantic Deep Water formation that alter the global Thermohaline Circulation.  In light of the plausibility of this scenario, they suggest that "the solar signals thus may have been transmitted through the deep ocean as well as through the atmosphere, further contributing to their amplification and global imprint."

Concluding their landmark paper, Bond et al. say the results of their study "demonstrate that the earth's climate system is highly sensitive to extremely weak perturbations in the sun's energy output," noting that their work "supports the presumption that solar variability will continue to influence climate in the future."

Clearly, there is ample ammunition for defending the premise that the global warming of the past century or so may well have been nothing more than the solar-mediated recovery of the earth from the chilly conditions of the Little Ice Age, and that any further warming of the planet that might occur would likely be nothing more than a continuation of the same solar-mediated phenomenon.

References
Bond, G., Kromer, B., Beer, J., Muscheler, R., Evans, M.N., Showers, W., Hoffmann, S., Lotti-Bond, R., Hajdas, I. and Bonani, G.  2001.  Persistent solar influence on North Atlantic climate during the Holocene.  Science 294: 2130-2136.

Broecker, W.  1999.  Climate change prediction.  Science 283: 179.

Dean, W.E. and Schwalb, A.  2000.  Holocene environmental and climatic change in the Northern Great Plains as recorded in the geochemistry of sediments in Pickerel Lake, South Dakota.  Quaternary International 67: 5-20.

Dean, W., Anderson, R., Bradbury, J.P. and Anderson, D.  2002.  A 1500-year record of climatic and environmental change in Elk Lake, Minnesota I: Varve thickness and gray-scale density.  Journal of Paleolimnology 27: 287-299.

Haug, G.H., Hughen, K.A., Sigman, D.M., Peterson, L.C. and Rohl, U.  2001.  Southward migration of the intertropical convergence zone through the Holocene.  Science 293: 1304-1308.

Hong, Y.T., Jiang, H.B., Liu, T.S., Zhou, L.P., Beer, J., Li, H.D., Leng, X.T., Hong, B. and Qin, X.G.  2000.  Response of climate to solar forcing recorded in a 6000-year delta¹⁸O time-series of Chinese peat cellulose.  The Holocene 10: 1-7.

Parker, E.N.  1999.  Sunny side of global warming.  Nature 399: 416-417.

Perry, C.A. and Hsu, K.J.  2000.  Geophysical, archaeological, and historical evidence support a solar-output model for climate change.  Proceedings of the National Academy of Sciences USA 97: 12433-12438.

Reid, G.C.  1991.  Solar total irradiance variations and the global sea surface temperature record.  Journal of Geophysical Research 96: 2835-2844.

Reid, G.C.  1997.  Solar forcing of global climate change since the 17th century.  Climatic Change 37: 391-405.

Reid, G.C.  1999.  Solar variability and its implications for the human environment.  Journal of Atmospheric and Solar-Terrestrial Physics 61(1-2): 3-14.

Reid, G.C.  2000.  Solar variability and the Earth's climate: introduction and overview.  Space Science Reviews 94(1-2): 1-11.

Rigozo, N.R., Echer, E., Vieira, L.E.A. and Nordemann, D.J.R.  2001.  Reconstruction of Wolf sunspot numbers on the basis of spectral characteristics and estimates of associated radio flux and solar wind parameters for the last millennium.  Solar Physics 203: 179-191.

Rozelot, J.P.  2001.  Possible links between the solar radius variations and the Earth's climate evolution over the past four centuries.  Journal of Atmospheric and Solar-Terrestrial Physics 63: 375-386.

Shindell, D.T., Schmidt, G.A., Mann, M.E., Rind, D. and Waple, A.  2001.  Solar forcing of regional climate change during the Maunder Minimum.  Science 294: 2149-2152.

Solanki, S.K., Schussler, M. and Fligge, M.  2000.  Evolution of the sun's large-scale magnetic field since the Maunder minimum.  Nature 408: 445-447.

Starkel, L.  2002.  Change in the frequency of extreme events as the indicator of climatic change in the Holocene (in fluvial systems).  Quaternary International 91: 25-32.

Vaganov, E.A., Briffa, K.R., Naurzbaev, M.M., Schweingruber, F.H., Shiyatov, S.G. and Shishov, V.V.  2000.  Long-term climatic changes in the arctic region of the Northern Hemisphere.  Doklady Earth Sciences 375: 1314-1317.

Viau, A.E., Gajewski, K., Fines, P., Atkinson, D.E. and Sawada, M.C.  2002.  Widespread evidence of 1500 yr climate variability in North America during the past 14,000 yr.  Geology 30: 455-458.

Verschuren, D., Laird, K.R. and Cumming, B.F.  2000.  Rainfall and drought in equatorial east Africa during the past 1,100 years.  Nature 403: 410-414.

[Siobhan]

Your theory is worth being tested, but don't forget that we see the sun through the filter of layers of our atmosphere.

The question I have is what, if anything, has changed in our atmosphere to alter the way light filters to us from the sun.

My own anecdotal experience is that the I perceive the sun as whiter and the sunlight as harsher. I aslo wonder about the Earth's own electro-magnetic fields.......

[Siobhan]

We don't have crows, but it seems like there are more ravens these days.

I have read reports of marked increases in various black colored bird populations:such as crows and grackles in North America.

[Phil V.]

The observation is this: Artificial lighting has gotten warmer, . . . burn dimmer and considerably . . . taking yellow and pink/orange as normal. Then, . . . who stare at computer monitors every waking hour are . . . appreciably whiter, but we are getting unused to natural light.

Does that have anything to do with this observation . . .? . . . I remember that Tonto (Kemosabi's pal) could tell time by the sun. I tried to do that, but I could not see the numbers. Is that because the sun is now whiter and the extra light is blocking the numbers? Can Tonto still tell time by looking at the sun? . . . probably not . . . pity.

SUVs must GO!

[ancient_geezer]

This article at SEPP implies that the IPCC generated assumptions to get the results they wanted:

It appears the IPCC apparently is not above a few ad-hoc changes to their reports as well:

http://www.sepp.org/keyissue.html

The IPCC Controversy: In May 1996, unannounced and possibly unauthorized changes to the latest United Nations report on climate change touched off a firestorm of controversy within the scientific community. The Intergovernmental Panel on Climate Change (IPCC), the science group that advises the United Nations on the global warming issue, presented the draft of its most recent report in December 1995, and it was approved by the delegations. When the printed report appeared in May 1996, however, it was discovered that substantial changes and deletions had been made to the body of the report to make it "conform to the Policymakers Summary." The clandestine changes put a spin on the report's conclusions that "the balance of evidence suggests a discernible human influence on global climate." Lead authors of the crucial--and doctored--Chapter 8, dealing with the detection and attribution of climate change, have since backed off from this conclusion and now admit that it may take 10 years or more before any human influence on climate can be detected. For commentary and letters on this issue, see IPCC.

[Valin]

Some say the world will end in ice,
and others say by fire.
But what I've tasted of desire,
I think I'd rather fire.

[SevenDaysInMay]

I think it may be that we're getting accustomed to yellow journalism.

[geopyg]

Gee- Who'd a thunk the SUN would have an effect on our climate?! I was doing some work for an environmental geologist and mentioned that I had read an article that said Mar's polar ice caps were shrinking.

I said something like "it's terrible that we drive our SUV's and run our factories and cause all these greenhouse gases. It's getting so bad that now they are even causing Mar's ice caps to melt". He said "Yeah, you wonder where it's going to end" in all seriousness. I looked at him kind of funny and said, no - it probably has something to do with that big heater in the sky. He said "oh".

Perhaps he was just trying to be polite to me and making small-talk, but I don't think so.

[justa-hairyape]

How could something that is so obvious have gone so virtually ignored for almost the entire previous millenia ? Yes virginia, the suns output is an important factor affecting the earths climate. In fact its the most important factor. We should have had satellites up in orbit monitoring spectral emmissions from the sun for decades. Of course it varies and of course these variations have a tremendous impact on the earth. Duh ! This is a perfect example of how 'science' has been perverted into 'political science'. The politics of the sun being the problem did not generate enough lobbyist buying influence within washington to get the politicians to fund the research into the sun being the problem (ie- Not enough 'we can fix the sun' lobbyist). So anyone that thinks modern science generates absolute truths, is being naive. If anything, science is being ruined by politically influenced funding. The funding has been generating the science. For science to generate cogent absolutes, the science should be generating the funding.

[aruanan]

I showed another post-doc a graph they produced of the solar cycles overlaying the land temperature cycles over the past centuries. She then laughed at the notion that global warming cycles are anthropogenic.

[buffyt]

I love to mention that global warming gave us the end to the ice age, and that solar activity affects the earth temperatures. People who believe in manmade global warming just get quiet for a minute or two, before they launch their next attack. I know that our highest recorded temps. here in Lake Jackson Texas were in the 1940s and that doesn't fit into their chart for manmade global warming now.

[RightWhale]

I aslo wonder about the Earth's own electro-magnetic fields.......

The local institute srudies that specifically. The Aurora, plasma fields. They have satellites, sounding rockets, sensors from here to Finland, and more PhDs than would fit in a city bus on the way to a junketconference in Madrid. If there were changes in the mag field, they would be highly incentivized to say something.

[RightWhale]

How could something that is so obvious have gone so virtually ignored for almost the entire previous millenia ?

Scientists are observing the sun as never before. They have sun satellites, sun sensors, solar tomagraphs, and many are making sun science their career. The sun has not been overlooked; the sun is better known than ever before. Meteorologists use sun data in their climate models. Always have, always will.

[Ernest_at_the_Beach]

good reference:

FUEL SCIENCE SEMINAR -- Sallie Baliunas

Title:

SOLAR VARIABILITY AND CLIMATE CHANGE

Speaker:

Ms. Sallie Baliunas
Senior Astrophysicist
Harvard-Smithsonian Center for Astrophysics

Date:

Monday, April 17, 3:30 pm
Ben Bandy Conference Center
Center for Applied Energy Research

Abstract:

Recent evidence for the sun's influence on climate change comes from modern measurement programs and computer simulations of the climate. Not only correlations between solar variability and climate change but also mechanisms underlying them are being studied.

One possible mechanism driving climate change is total irradiance change of the sun. Satellite measurements for nearly two decades show that the sun's total irradiance changes in step with the 11-year sunspot cycle.

Solar variations are generally only crudely predictable, thus leaving us with direct measurements over too short and interval to study properly the solar influence on climate change over time scales of centuries.

But studies of sun-like stars can yield information on solar variability over such time scales. At Mount Wilson Observatory the surface magnetic activity of sun-like stars has been monitored for over 30 years. These records detail the counterpart of the 11-year sunspot cycle in stars close in mass and age to the sun. In parallel, observations of brightness changes in sun-like stars have been made for over a decade. Considered together, these records on surface magnetism and brightness changes in sun-like stars yield estimates of solar variations over centuries.

Those estimated brightness variations have been studied in computer simulations of the climate which suggest that the solar irradiance change explains at least 50% of the variance of the changes in global surface temperature over the last 100 years.

[Ernest_at_the_Beach]

Global Warming Hoax :

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[SunkenCiv]

Note: this topic is from 12/20/2002. Thanks PeaceBeWithYou.

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[SunkenCiv]

GGG managers are SunkenCiv, StayAt HomeMother & Ernest_at_the_Beach	join list or digest view topics view or post blog bookmark post a topic subscribe
Note: this topic is from 12/20/2002. Thanks PeaceBeWithYou. To all -- please ping me to other topics which are appropriate for the GGG list.

[Little Bill]

I was looking at the weather in England over the last several years. It reminded me of the weather fluctuation's leading up to the Great Famine of the early 1300’s, The Black Death, and the Little Ice Age. Looks like research time.

[null and void]

I miss RightWhale...

[SunkenCiv]

Me too.