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Reconstruction of Solar Irradiance Since 1610: Implications for Climate Change
Abstract
Solar total and ultraviolet (UV) irradiances are reconstructed annually from 1610 to the present. This epoch includes the Maunder Minimum of anomalously low solar activity (circa 1645-1715) and the subsequent increase to the high levels of the present Modern Maximum. In this reconstruction, the Schwabe (11-year) irradiance cycle and a longer term variability component are determined separately, based on contemporary solar and stellar monitoring. The correlation of reconstructed solar irradiance and Northern Hemisphere (NH) surface temperature is 0.86 in the pre-industrial period from 1610 to 1800, implying a predominant solar influence. Extending this correlation to the present suggests that solar forcing may have contributed about half of the observed 0.55°C surface warming since 1860 and one third of the warming since 1970.
... However the satellite data for recent decades suggests, significant uncertainties are present among all the existing satellite measurements (as shown in Fig. 2.4). This is relating to calibration of the instruments and degrading over time. It shows an attempt at compositing the measurements (shown in lower panel of Fig. 2 (2004) and Lean et. al (1995)). The second approach uses aa geomagnetic records (Lockwood and Stamper, 1999), while the third one involves using climate records (Reid, 1997;Beer et al, 2000). The final approach for TSI reconstruction uses numerical models of the Sun to simulate the variations in solar parameters (Sofia and Li, 2001). In most SSN-based methods, solar ...
... In most SSN-based methods, solar radiative output is determined by a balance between decrease due to the presence of sunspots and increase due to the development of faculae, the bright patches on the Sun's surface. The sunspot darkening depends on the area of the Sun covered by the sunspots, whereas, the facular brightening relates to a number of indices, which might include sunspot number (Lean et al. 1995), solar-cycle length, solarcycle decay rate, solar rotation rate and various empirical combinations of all these (Solanki and Fligge, 1998;Hoyt & Schatten, 1993). In determining long-term variability, different techniques were employed in different reconstructions. ...
... In determining long-term variability, different techniques were employed in different reconstructions. For example, Lean et al. (1995) used sunspot cycle amplitude to determine long-term variability, whereas, Hoyt and Schatten (1993) used mainly sunspot length. Solanki & Fligge (1998) made an additional assumption concerning the long-term contribution of the 'quiet sun' based on observations on sun-like stars (Baliunas & Jastrow, 1990) along with the assumption that during the Maunder minimum the Sun was in a non-cycling state. ...
We investigate solar cycle signals in 150 years of Sea Level Pressure (SLP) and Sea Surface Temperature (SST) data, using multiple regression analysis. We detect a solar signal in both SLP and SST in the North Pacific during DJF, similar to that found by Van Loon et al. (2007) but of smaller magnitude. We do not, however, identify the signal they found in the tropics. Our results do not support mechanisms for a solar influence on climate directly involving tropical SSTs. We have used different reconstructions of total solar irradiance to investigate the sensitivity of the results. The series of Krivova & Solanki and Foster give similar results to those acquired using sunspot number but the Hoyt & Schatten solar index sometimes produces different results because of mixing of the solar signal with a long-term trend. Using different approaches Labitzke and van Loon (1992) and Camp and Tung (2007), arrived at different results for a solar influence on winter stratospheric polar temperatures and its relationship to the quasi-biennial oscillation (QBO) in tropical stratospheric zonal winds. We show that these differences appear different largely because of their choices of QBO height. We also show that the effect of the QBO (30, 40 or 50 hPa) combined with solar activity reveals a clear signal in polar annular modes expressed in SLP. We show that the nature of ENSO was different before 1950s (and after1997): this may affect any solar influence. Other authors have suggested that tropical circulations were different during the intervening period. Such observation may have implications relating to the sun, tropical circulation and climate change. During 1958-1997, omission of ENSO from regression gives false warming (cooling) signal of higher (lower) solar on SST in tropics. Such analysis, accompanied by our observation that the years of peak annual sunspot number used by van Loon et al. (2007) generally falls a year or more in advance of the maximum of the smoothed DSO, provides coherence to some apparently conflicting findings. Finally, an atmosphere-ocean coupling process, (mainly involving the Pacific Ocean) is proposed to account for the solar influences. This coupling appears to be disturbed during the later half of the 20th century, probably due to climate change.
... However, Stott et al. (2003b), using the same solar reconstruction but a different model, are not able to completely rule out the possibility that solar forcing might have caused more warming than greenhouse gas forcing over the 20th century due to diffi culties in distinguishing between the patterns of response to solar and greenhouse forcing. This was not the case when using the response to solar forcing based on the alternative reconstruction of Lean et al. (1995), in which case they fi nd a very small likelihood (less than 1%, as opposed to approximately 10%) that solar warming could be greater than greenhouse warming since 1950. Note that recent solar forcing reconstructions show a substantially decreased magnitude of low-frequency variations in solar forcing (Section 2.7.1) compared to Lean et al. (1995) and particularly Hoyt and Schatten (1993). ...
... This was not the case when using the response to solar forcing based on the alternative reconstruction of Lean et al. (1995), in which case they fi nd a very small likelihood (less than 1%, as opposed to approximately 10%) that solar warming could be greater than greenhouse warming since 1950. Note that recent solar forcing reconstructions show a substantially decreased magnitude of low-frequency variations in solar forcing (Section 2.7.1) compared to Lean et al. (1995) and particularly Hoyt and Schatten (1993). ...
... In both these analyses, the response to solar forcing in the model was inferred by fi tting a series of EBMs to the mean coupled model response to the combined effects of anthropogenic and natural forcings. In addition, a combined analysis of the response at the surface and through the depth of the atmosphere using HadCM3 and the solar reconstruction of Lean et al. (1995) concluded that the nearsurface temperature response to solar forcing over 1960 to 1999 is much smaller than the response to greenhouse gases . This conclusion is also supported by the vertical pattern of climate change, which is more consistent with the response to greenhouse gas than to solar forcing (Figure 9.1). ...
... Centennial scale changes in the ISM precipitation occurred during the LIA (Agnihotri et al., 2002;Agnihotri and Dutta, 2003;Kotlia et al., 2015Kotlia et al., , 2017Shah et al., 2020b). As evident from previous studies, the climate changes during the LIA is related to changes in the solar irradiance (Schröder, 1994;Lean et al., 1995;Sinha et al., 2007;Warrier et al., 2017). Total Solar irradiance (TSI) was lower by about 0.25% during the Maunder (1645-1715 AD) and the Spörer (1416-1534 AD) Minima (Lean et al., 1995), with a complete absence of sunspots during the Maunder Minimum (Eddy, 1983). ...
... As evident from previous studies, the climate changes during the LIA is related to changes in the solar irradiance (Schröder, 1994;Lean et al., 1995;Sinha et al., 2007;Warrier et al., 2017). Total Solar irradiance (TSI) was lower by about 0.25% during the Maunder (1645-1715 AD) and the Spörer (1416-1534 AD) Minima (Lean et al., 1995), with a complete absence of sunspots during the Maunder Minimum (Eddy, 1983). The TSI was much lower during the Spörer Minimum as compared to the Maunder Minimum. ...
... The TSI was much lower during the Spörer Minimum as compared to the Maunder Minimum. Similarly, the Dalton minimum was characterized by low TSI values and sunspot numbers (Lean et al., 1995;Steinhilber et al., 2012). ...
Denudation rates are often estimated with high uncertainty using the average mass of material discharged through a drainage basin or considering the rate of surface processes. Estimating long-term denudation rates through these conventional methods requires the assumption that the surficial processes have remained constant throughout time. Since the earth's surface has been obliterated throughout the geological time by climate, tectonics, or the recent anthropogenic activities, the present rate of change may not represent past processes. This study presents changes in denudation rate using the 10Be (meteoric)/9Be ratio for the past 600 years from Anshupa Lake sediment record in the core monsoon zone of India. Paleodenudation rate estimated using 10Be (meteoric)/9Be varies from 392 ± 42 to 95 ± 6 t/km2/yr. Intense Indian Summer Monsoon (ISM) during the periods of solar maxima, which caused decadal-scale floods in the Indian sub-continent, favored a higher rate of denudation than the periods of solar minima, that experienced droughts in the Indian sub-continent due to weakening of ISM.
... The white boxes beneath the SST record include a conclusion of the primary climate modes control, shaping the SST pattern on centennial scales, the suppressed climate modes influence and the secondary control of climate modes affecting the SST pattern on a multi-decadal time scale. b) Solar activity reconstructions including C14 resid/LEAN splice (Stuiver and Braziunas, 1993;Lean et al., 1995), Be10/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000 and C14 Bard/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000. c) Reconstruction of Atlantic Multidecadal Oscillation (AMO) following Mann et al. (2009). ...
... The white boxes beneath the SST record include a conclusion of the primary climate modes control, shaping the SST pattern on centennial scales, the suppressed climate modes influence and the secondary control of climate modes affecting the SST pattern on a multi-decadal time scale. b) Solar activity reconstructions including C14 resid/LEAN splice (Stuiver and Braziunas, 1993;Lean et al., 1995), Be10/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000 and C14 Bard/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000. c) Reconstruction of Atlantic Multidecadal Oscillation (AMO) following Mann et al. (2009). ...
... The white boxes beneath the SST record include a conclusion of the primary climate modes control, shaping the SST pattern on centennial scales, the suppressed climate modes influence and the secondary control of climate modes affecting the SST pattern on a multi-decadal time scale. b) Solar activity reconstructions including C14 resid/LEAN splice (Stuiver and Braziunas, 1993;Lean et al., 1995), Be10/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000 and C14 Bard/LEAN splice (Lean et al., 1995;Bard et al., 1997Bard et al., , 2000. c) Reconstruction of Atlantic Multidecadal Oscillation (AMO) following Mann et al. (2009). ...
The Holocene (<11.7 kyr BP) is characterized by several periods of distinct climate changes. Some of these climate variations had extensive effects on mankind and coincided with demises of extinct high civilizations. Annually-resolved climate reconstructions will certainly play an increasingly important role in public perception, when applying these past patterns to the recent climate debate. The future consequences of the ongoing climate crisis are still challenging to predict, due to the lack of comprehensive, annually-resolved and continuous sea-surface temperature (SST) data. Our 8.55 m long sediment core from the bottom of the Great Blue Hole (Lighthouse Reef, Belize) provides an annually-resolved, continuous and unique southwestern Caribbean climate record for the last 1885 years. The varved, "lake-like" sinkhole successions of marine carbonates encompass approximately the entire Common Era (0 CE-modern), a time window, which is key for studying climatic variations and their effects on human society. Our SST record is based on stable isotopes (d 18 O) and molecular proxy applications (TEX 86). Throughout the Common Era, oxygen isotopes (d 18 O) and TEX 86 data imply a general SST rise of 0.5 C and 1.3 C, respectively, within the southwestern Caribbean. The modulation of SST within the Common Era time series likely operated on two different time levels: (1) Solar (e.g., "Gleissberg Cycles") and volcanic activity triggered climate changes, which in turn induced responses of the Atlantic Multidecadal Oscillation (AMO), the North Atlantic Oscillation (NAO) and the El-Niño-Southern Oscillation (ENSO). Their changing mode of action has been identified as a likely origin of the primary, i.e., centennially scaled SST variability. We suspect long-term positive AMO and NAO modes as the primary key control mechanisms of the Dark Ages Cold and Medieval Warm Period SST patterns. ENSO mode modulation likely exerted primary control on regional SST variability during the Little Ice Age and the Modern Global Warming. (2) Our d 18 O data further indicate a striking secondary control on multi-decadal time scales: d 18 O variations occur with 32e64 years periodicity. This signal is clearly evidence of SST modulation controlled by AMO phase changes (50e70 years) over almost the entire Common Era. Our carbon isotope record (d 13 C) exhibits two remarkable negative anomalies and a long-term up-core decreasing trend. The first excursion (drop of 0.5‰) occurred with the onset of the Medieval Warm Period, which is reconstructed to be a peak time in southwestern Caribbean tropical cyclone (TC) activity. This overlap is stressing a potential context between TC activity, enhanced coastal runoff and increased soil-erosion reflected by 13 C-depleted carbon isotopes. A second anomaly (>1900 CE) is more likely the result of the "Suess Effect" (anthropogenic impact of the Industrial Revolution on carbon isotopes composition) than another reflection of a TC peak activity interval.
... According to the EBAV of the great level shown as the red dashed line in Figure 2(b), the auroras caused by great-storm CMEs could be identified, which were below the red dashed line. Surprisingly, there were many great-storm CMEs between 1500 and 1900, when Spörer minimum (1390-1550), Maunder minimum(1645-1715), and Dalton minimum(1797-1827) were inside (Lean et al. 1995;Solanki & Fligge 2000;Usoskin et al. 2015;Cliver & Herbst 2018;Hayakawa et al. 2020e). There were auroral sighting records in the same year, such as 1620 and 1646, from different places in China. ...
... Stellar spectra. The effects of stellar activity across three spectral types are investigated: G, K and M. For G-star simulations, we use an observed and reconstructed solar irradiance spectrum 42 . The input spectrum version is fixed in the year 1850 and no observed irradiance cycle is included. ...
Low-mass stars show evidence of vigorous magnetic activity in the form of large flares and coronal mass ejections. Such space weather events may have important ramifications for the habitability and observational fingerprints of exoplanetary atmospheres. Here, using a suite of three-dimensional coupled chemistry–climate model simulations, we explore effects of time-dependent stellar activity on rocky planet atmospheres orbiting G, K and M dwarf stars. We employ observed data from the MUSCLES campaign and the Transiting Exoplanet Survey Satellite and test a range of rotation period, magnetic field strength and flare frequency assumptions. We find that recurring flares drive the atmospheres of planets around K and M dwarfs into chemical equilibria that substantially deviate from their pre-flare regimes, whereas the atmospheres of G dwarf planets quickly return to their baseline states. Interestingly, simulated O2-poor and O2-rich atmospheres experiencing flares produce similar mesospheric nitric oxide abundances, suggesting that stellar flares can highlight otherwise undetectable chemical species. Applying a radiative transfer model to our chemistry–climate model results, we find that flare-driven transmission features of bio-indicating chemical species, such as nitrogen dioxide, nitrous oxide and nitric acid, show particular promise for detection by future instruments.
... During Maunder minimum period, very few sunspots appeared on the surface of the Sun, and the overall brightness of the Sun was slightly decreased. Upper panel of the Figure 6 has shown the reconstruction of the cycle-averaged solar total irradiance back to 1610 which also suggests a decrease of the solar irradiance by a value of about 3 W/m 2 [163]. This occurred because the total solar irradiance was reduced by 0.22% that led to a decrease of the average terrestrial temperature measured mainly in the Northern hemisphere in Europe by 1.0-1.5 0 C as shown in lower panel of Figure 6. ...
In the present paper, we have briefly reviewed the impact of solar activities on the terrestrial climate. Increased/decreased solar activity affects the various processes going on into the Sun-Earth system and alters the composition of parameters responsible for the climate change. The amount of high solar activity (sunspots) is directly related with the total solar irradiance (TSI) while the spectral index is associated with the ultraviolet (UV) radiations coming from the Sun. Contrary to the above, decreased solar activity is accountable for increased incidence of the galactic cosmic rays (GCR) which play significant role in cloud formation and ultimately responsible for the changed climate conditions of terrestrial environment. The influence of solar variability on the Earth's climate can be explained by exploring various mechanisms involved. There are no fool proof evidences that the solar variations are a major factor in driving recent global climate change but there are considerable evidences of solar influence on the climate of particular regions as well as throughout the terrestrial environment. During high solar activity, higher temperatures and larger ozone concentrations are observed in the tropical stratosphere. The solar influences on the Earth's climate mainly includes; the changed occurred due to variations in the Sun's radiant output (TSI and UV) and the changes occurred due to the Sun's influence on the energetic particles reaching to the Earth (Solar Energetic Particles, Galactic Cosmic Rays). Following the above regime, we have provided the evidences for the existence of physical links between solar activity and terrestrial climate. Summary of our present understanding of the mechanisms involved in the Sun-climate dynamics are presented.
... Several long-term reconstructions of climate and meteorological data can be found in the literature of the last thirty years [6,[40][41][42][43][44][45][46][47][48][49][50][51]. The analysis of the paper refers to the following sources. ...
Energy efficiency has established as a trending topic in scholarly research in the last four decades. Lately, the purpose of that research strand has broadened so to tackle the increase of greenhouse gas emissions and the issues related to climate change. Human beings and their mass production and consumption activities are thought to be a primary source of climate-altering emissions. However, that assumption has been seldom tested. Here we aim to provide a methodological and empirical framework to check for the causal nexus that allegedly ties together demographic growth, economic development, and climate change. The analysis is based on the historically reconstructed series of several variables that span over the last centuries. Besides, it is based on the class of ARIMAX-ARCH models. The results show evidence for bidirectional causation between human growth and climate change. In particular, we find that solar irradiance and gross domestic product are significant predictors of temperature anomalies. Furthermore, temperature anomalies and solar irradiance are found to exert a positive feedback effect on the growth rate of gross domestic product. As regards the causality measures, despite the strength of the univariate component, the contribution of the exogenous factors is strongly significant in all the estimated models. The analysis we carry out suggests framing climate change within a set of long-run trends.
... 1645-1715 delineates the coldest phase of the LIA (Wanner et al., 2000;Luterbacher et al., 2001), with an increase in climatic variability over wide parts of Europe. This period is characterized by high concentration in atmospheric Δ 14 C (Stuiver and Braziunas, 1993), volcanic eruptions (Briffa et al., 1998) and a reduced solar activity (Spörer, 1887;Maunder, 1922;Eddy, 1976;Lean et al., 1995;Luterbacher et al., 2001). In fact, solar activity during the MM was near its lowest levels of the past 8000 years (Lean and Rind, 1999;Luterbacher et al., 2001). ...
Globorotalia truncatulinoides oscillations have been recorded from different marine sediment cores collected in the central and western Mediterranean Sea. The abundances of this species over the last 500 yrs. demonstrates its potential value as bio-indicator of particular oceanographic condition during the Maunder Minimum (MM) event of the Little Ice Age (LIA). The comparison between the G. truncatulinoides abundance patterns of the Balearic Basin, central and south Tyrrhenian Sea and central and eastern Sicily Channel allows to highlight a similar response of this species during the MM event in the central-western Mediterranean Sea. The ecological meanings of this species and its peculiar high abundance percentages in the total assemblages suggest the development of enhanced vertical mixing conditions during MM winter season with a strong advection of nutrients from the nutrient-rich deeper layers and enhances the productivity levels in the mixed layer. The intensified vertical mixing could be linked to persistence of an atmospheric blocking event recorded by several authors during the MM.
In this chapter, we consider the possible effects of cosmic rays and other space factors on the Earth's climate change. It is well known that many internal and external factors influencing the Earth's climate are variable, unstable, and nonlinear (for example, decreasing the Earth's temperature leads to an increase of snow and the decreasing of the solar energy input into the system, which leads to a further decrease in the Earth's temperature; increasing of cosmic rays intensity leads to increasing of atmosphere ionization and possible increasing cloudiness and precipitation, and so on). From this, it follows that even energetically small factors may have a major influence on climate change. From our point of view, cosmic rays and cosmic dust, through their influence on cloudiness, are important factors in understanding climate change.
We present global fields of decadal annual surface temperature anomalies, referred to the period 1951-1980, for each decade from 1881-1890 to 1981-1990 and for 1984-1993. In addition, we show decadal calendar-seasonal anomaly fields for the warm decades 1936-1945 and 1981-1990. The fields are based on sea surface temperature (SST) and land surface air temperature data. The SSTs are corrected for the pre-World War II use of uninsulated sea temperature buckets and incorporate adjusted satellite-based SSTs from 1982 onward. The generally cold end of the nineteenth century and start to the twentieth century are confirmed, toegether with the substantial warming between about 1920 and 1940. Slight cooling of the northern hemisphere took place between the 1950s and the mid-1970s, although slight warming continued south of the equator. Recent warmth has been most marked over the northern continents in winter and spring, but the 1980s were warm almost everywhere. -from Authors
MANY recent studies have reported an apparent correlation between solar activity and the Earth's climate on the timescale of the 11-year solar cycle1-4 and over longer periods5-10, but to date no physical mechanism has been proposed that can satisfactorily explain the observations. In general, it has been assumed that changes in total solar irradiance outside the atmosphere will be reflected in proportionately equal changes at the tropopause (from where the influence on climate is determined). Here I present results from a two-dimensional radiative-chemical-transport model which show that the spectral composition of the solar variations and the photochemical production of stratospheric ozone together lead to a highly nonlinear relationship between the extraterrestrial and cross-tropopause solar radiative flux. Because of this relationship, at middle to high latitudes in the winter hemisphere less solar radiation reaches the troposphere during periods of higher solar activity. The consequent change in latitudinal temperature gradient also affects infrared radiative forcing and potentially planetary-wave activity. The general mechanism proposed here may explain some features of the observed correlations between solar variability and climate.
Using the Baliunas and Jastrow (1990) study of cyclic variability in solar-type stars, we transform existing solar data to the stellar HK irradiance scale and examine the state of the solar chromosphere when a solar-type star shows little cyclic variability and surface magnetism. To reduce the chromospheric emission to levels for G-type stars showing no chromospheric activity cycles, not only must the sun be free of plages and network; the brightness of the quiet chromosphere in the K line must be reduced to levels seen only in 15 percent of the quiet sun area today. In contrast, the present-day level of K emission from the sun places it in the class of most active solar-type stars, far removed from a noncycling state.
An analysis of the 130-year record of the Earth's global mean temperature reveals a significant warming trend and a residual consistent with an auto-correlated (“red”) noise process whose predictability decays with a timescale of two years. Thus global temperatures, in isolation, do not indicate oscillations at 95% confidence against a red noise null hypothesis. Weak signals identified in the global series can, however, be traced to significant sea surface temperature oscillations in the equatorial Atlantic (period ∼10 years) and the El Niño region of the Pacific (3–5 years). No robust evidence is found in this data for interdecadal oscillations, The 10-year Atlantic oscillation corresponds to a pattern of temperature anomalies which has been associated with interannual variations in West African rainfall and in U.S. hurricane landfall frequency.
The record of globally averaged sea surface temperature (SST) over the past 130 years shows a highly significant correlation with the envelope of the 11-year cycle of solar activity over the same period. This correlation could be explained by a variation in the sun's total irradiance (the solar constant) that is in phase with the solar-cycle envelope, supporting and updating an earlier conclusion by Eddy (1976) that such variations could have played a major role in climate change over the past millennium. Measurements of the total irradiance from spacecraft, rockets, and balloons over the past 25 years have provided evidence of long-term variations and have been used to develop a simple linear relationship between irradiance and the envelope of the sunspot cycle. This relationship has been used to force a one-dimensional model of the thermal structure of the ocean, consisting of a 100-m mixed layer coupled to a deep ocean and including a thermohaline circulation. The model was started in the mid-seventeenth century, at the time of the Maunder Minimum of solar activity, and mixed-layer temperatures were calculated at 6-month intervals up to the present. The total range of irradiance values during the period was about 1%, and the total range of SST was about 1C. Cool periods, when temperatures were about 0.5C below present-day values, were found in the early decades of both the nineteenth and twentieth centuries. The results can be taken as indicating that solar variability has been an important contributor to global climate variations in recent decades. The growing atmospheric burden of greenhouse gases may well have played an important role in the immediate past.
In the historical record of solar activity the period from 1645 to 1715 is a singular epoch during which the number of sunspots decreased markedly for a generation. Known as the Maunder Minimum, this solar epoch coincided with the coldest part of the Little Ice Age (circa 1450 to 1850). We estimate the change at this time in the output of solar ultraviolet (UV) radiation at wavelengths from 120 to 300 nm, relative to contemporary observations. Since this portion of the solar UV spectrum determines ozone composition in the stratosphere, our results bear on the historical variability of ozone and its potential climatic effects. Between the Maunder Minimum and 1986 (the present day solar activity minimum between cycles 21 and 22) we estimate reductions of 64% in the irradiance of the Lyman alpha line of neutral hydrogen (at 121.6 nm), 8% at 200 nm, and 3.5% in the wavelength range from 210 to 250 nm. The reduction in the solar output from the entire spectral band between 120 and 300 nm is estimated to be 0.17 W/m2, which is approximately 6% of the change in the total solar irradiance of 2.7 W/m2 previously estimated by us (Lean et al., 1992a) over the same time span. Because of this diminished UV output due to very low solar activity the Maunder Minimum total ozone concentration may have been 4% below its 1980 level. While the climatic consequences of such a change have yet to be determined, recent work by Haigh (1994) on modulation of radiative climate forcing by stratospheric ozone emphasizes the need to understand the role of UV irradiance variability as one forcing mechanism.
Solar (heliomagnetic), geomagnetic and oceanic forcing all play a role in atmospheric 14CO2 change. Here we assign the variance associated with certain periodicities in a single year (0-450 cal. BP) and a Holocene bidecadal (0-11400 cal. BP) 14CO2 record to specific forcing factors. In the single-year time series the variance in the 2-6-year periodicity range is attributable to El Niño-Southern Oscillation (ENSO) ocean perturbations. A 10-11-year component is partially tied to solar modulation of the cosmic ray flux, and multidecadal variability may relate to either solar modulation or instability of the North Atlantic thermohaline circulation. For the early Holocene bidecadal 14C record we derive a 512-year atmospheric 14C periodicity which relates to instabilities in North Atlantic thermohaline circulation. North Atlantic deep water formation increased near the start, instead of the termination, of the Younger Dryas interval. The ubiquitous 206-year 14C cycle is assigned either to solar modulation, or to solar modulation modified by a climate (ocean) response. The latter modification is discussed as part of a hypothetical mechanism explaining postulated climate-14C relationships in which a minor solar- induced Maunder Minimum climate change is amplified by salinity effects on North Atlantic thermoha line circulation.
Results of experiments with a GCM involving changes in UV input and simulated equatorial QBO are presented, with emphasis on the tropospheric response. The QBO and UV changes alter the temperature in the lower stratosphere/upper troposphere, affecting tropospheric/stratospheric vertical stability. When the extratropical lower stratosphere/upper troposphere warms, tropospheric eddy energy is reduced, leading to extratropical tropospheric cooling of some 0.5°C on the zonal average, and surface temperature changes up to ±5°C locally. Opposite effects occur when the extratropical lower stratosphere/upper troposphere cools. Cooling or warming of the comparable region in the Tropics decreases/increases static stability, accelerating/decelerating the Hadley circulation. -from Authors
The coincidence between the Maunder Minimum of solar magnetic activity from 1645 to 1715 and the coldest temperatures of the Little Ice Age raises the question of possible solar forcing of the Earth's climate. Using a correlation which we find between measured total solar irradiance (corrected for sunspot effects) and a Ca II surrogate for bright magnetic features, we estimate the Sun's radiative output in the absence of such features to be 1365.43 W/m2, or 0.15% below its mean value of 1367.54 W/m2 measured during the period 1980 to 1986 by the ACRIM experiment. Observations of extant solar-type stars suggest that the Ca II surrogate was darker during the Maunder Minimum. Allowing for this, we estimate the total solar irradiance to be 1364.28 W/m2 or 0.24% below its mean value for the 1980 to 1986 period. The decrease in the global equilibrium temperature of the Earth due to a decrease of 0.24% in total solar irradiance lies in the range from 0.2°C to 0.6°C, which can be compared with the approximately 1°C cooling experienced during the Little Ice Age, relative to the present.