The Current Solar Minimum and Its Consequences for Climate

Chapter 11

David Archibald Summa Development Limited

Chapter Outline 1. Introduction 277 2. The Current Minimum 278 3. Summary 287

1. INTRODUCTION A number of cycles in solar activity have been recognized, including the Schwabe (11 years), Hale (22 years), Gleissberg (88 years), de Vries (210 years), and Bond (1,470 years) cycles. There is nothing to suggest that cyclic behavior in solar activity has ceased for any reason. Therefore, predicting when the next minimum should occur should be as simple as counting forward from the last one. The last major minimum, the Dalton Minimum from 1798 to 1822, was two solar cycles long e Solar Cycles 5 and 6. Recent Gleissberg minima appear to be the decade 1690e1700, Solar Cycle 13 from 1889 to 1901, and Solar Cycle 20 from 1964 to 1976. A de Vries cycle event, herein termed the Eddy Minimum, has started exactly 210 years after the start of the Dalton Minimum. Friis-Christensen and Lassen theory, using methodology pioneered by Butler and Johhnson at Armagh, can be used to predict the temperature response to the Eddy Minimum for individual climate stations with a high degree of conﬁdence. The latitude of the US-Canadian border is expected to lose a month from its growing season with the potential for un-seasonal frosts to further reduce agricultural productivity.

2. THE CURRENT MINIMUM As recently as 2008, there was a wide range in estimated amplitudes for Solar Cycle 24, from Dikpati at 190 and Hathaway at 170 respectively to Clilverd (2005) at 42 and Badalyan et al. (2001) at 50. This enormous divergence in projections of solar activity generated very little interest from the climate science community, despite the large impact it would have on climate (Archibald, 2006, 2007). The basis of Clilverd’s prediction was a model for sunspot number using low-frequency solar oscillations, with periods of 22, 53, 88, 106, 213, and 420 years modulating the 11-year Schwabe cycle. The model predicts a period of quiet solar activity lasting until approximately 2030 fol- lowed by a recovery during the middle of the century to more typical solar activity cycles with peak sunspot numbers around 120. The graphs in Figs. 1e15 show data related to solar activity. Additional data may be found in Archibald (2010). The Eddy Minimum (Fig. 1) has started 210 years after the start of the Dalton Minimum, consistent with it being a de Vries Cycle event. The graph in Fig. 2 shows that Solar Cycles 3 and 4, leading up to the Dalton Minimum, are very similar in amplitude and morphology to Solar Cycles 22 and 23, leading up to the current minimum. The two data sets are aligned on the month of transition between Solar Cycles 4 and 5 and between Solar Cycles 23 and 24. In the absence of a signiﬁcant change in Total Solar Irradiance over the solar cycle, modulation of the Earth’s climate by the changing ﬂux in galactic cosmic

200

180 Projected 160 Dalton Eddy Minimum Minimum 140

120

100

60 4 5 24 25 40

0 1701 1731 1761 1791 1821 1851 1881 1911 1941 1971 2001 2031 FIGURE 1 Solar cycle amplitude 1701e2045. Chapter j 11 The Current Solar Minimum 279

180 Solar Cycle 3 Solar Cycle 23 compared to Solar Cycle 4 160 Aligned on month of minimum Solar Cycle 22

140 Solar Cycle 4

120

100 Solar Cycle 23

80 Dalton Minimum

60 Solar Cycle 5 Solar Cycle 6 Solar Cycle Amplitude

40 May 2010 20

0 1777 1781 1785 1789 1793 1797 1801 1805 1809 1813 1817 FIGURE 2 Similarity between precursor cycles.

1.8 Maunder Sporer Minimum Dalton 1.6 Minimum Minimum Decreasing Galactic 1.4 Cosmic Rays

1.2

1.0

0.8

0.6 Modern Little Ice Age 0.4 Warm Period 0.2

0.0 1425 1485 1545 1605 1665 1725 1785 1845 1905 1965 FIGURE 3 Be10 from the Dye 3 ice core, Greenland Plateau. rays was proposed by Svensmark and Friis-Christensen (1997). The Dye 3 Be10 record (Fig.3) shows a correlation between spikes in Be10 and cold periods for the last 600 years. It also shows a steep decline in Be10 in the Modern Warm Period, suggesting a solar origin for this warming. Usokin et al. (2005) found 280 PART j IV Solar Activity

12 Interplanetary Magnetic Field smoothed 27 day average 10 1970s cooling period

6 nanoTeslas

2 Solar Cycle 20 Solar Cycle 21 Solar Cycle 22 Solar Cycle 23

0 1966 1970 1973 1977 1980 1984 1987 1991 1994 1998 2001 2005 2009 FIGURE 4 Interplanetary Magnetic Field 1966e2010.

300

250 Solar Cycle 23

1970s Cooling Period 200 Projection

150

Solar Flux Units Flux Solar 100

F10.7 Flux 1948 - 2020 0 1948 1953 1958 1963 1968 1973 1978 1983 1988 1993 1998 2003 2008 2013 2018 FIGURE 5 F10.7 ﬂux 1948e2020.

that the level of solar activity during the past 70 years is exceptional, and the previous period of equally high activity occurred more than 8,000 years ago. The strength of the Interplanetary Magnetic Field (Fig. 4) has fallen to levels below that of previous solar cycle transitions. What is also interesting in Chapter j 11 The Current Solar Minimum 281

aa Index 35 1970s 1868 - 2010 Cooling Period 30

10 Increasing Solar Activity

5 Little Ice Age Modern Warm Period

0 1868 1888 1908 1928 1948 1968 1988 2008 FIGURE 6 The aa Index 1868e2010.

7500 Oulu Neutron Count 23/24 Solar 1964 - 2009 Minimum 21/22 Solar 22/23 Solar 7000 1970s Cooling Minimum Minimum Period 6500

6000

5500

5000 Monthly Average Counts per Minute Data: Sodankyla Geophysical Observatory 4500 1964 1968 1972 1976 1980 1984 1988 1992 1996 2000 2004 2008 FIGURE 7 Oulu, Finland neutron monitor count 1960e2010. this data is the ﬂatness of this solar magnetic indicator during the 1970s cooling period. The F10.7 index (Fig. 5) is a measure of the solar radio ﬂux near the peak of the observed solar radio emission. Emission from the Sun at radio wavelengths 282 PART j IV Solar Activity

FIGURE 8 The correlation between solar cycle length and mean annual temperature at Armagh, Northern Ireland.

1.6

1.4 Archangel, Russia rsq = 0.38 1.2

1.0 Correlation = 0.6 degrees/annum 0.8

0.6

0.4 Degrees Celsius 0.2

0.0

-0.2

-0.4 9 9.5 10 10.5 11 11.5 12 12.5 13

Solar Cycle Length Years FIGURE 9 Archangel, Russia e solar cycle length relative to average annual temperature. Chapter j 11 The Current Solar Minimum 283

10.5 Providence, Rhode Island 10.0 rsq = 0.38

9.5

9.0

8.5 Correlation = 0.62 degrees/annum Degrees Celsius 8.0

7.5

7.0 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Solar Cycle Length Years FIGURE 10 Providence, Rhode Island e solar cycle length relative to average annual temperature.

8.5 Hanover, New Hampshire 8.0 rsq = 0.53

7.5

7.0

6.5 Correlation = 0.73 degrees/annum Degrees Celsius

6.0

5.5

5.0 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Solar Cycle Length Years FIGURE 11 Hanover, New Hampshire e solar cycle length relative to average annual temperature. 284 PART j IV Solar Activity

12.0

11.5 West Chester, Pennsylvania rsq = 0.29 11.0

10.5

10.0

Degree Celsius 9.5 Correlation = 0.5 degrees/annum

9.0

8.5

8.0 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Solar Cycle Length Years FIGURE 12 West Chester, Pennsylvania e solar cycle length relative to average annual temperature.

8.5

Portland, Maine 8.0 rsq = 0.49

7.5

7.0

6.5 Degree Celsius

6.0 Correlation = 0.70 degrees/annum

5.5

5.0 9.0 9.5 10.0 10.5 11.0 11.5 12.0 12.5 13.0 Solar Cycle Length Years FIGURE 13 Portland, Maine e solar cycle length relative to average annual temperature.

is due primarily to diffuse, non-radiative heating of coronal plasma trapped in the magnetic ﬁelds overlying active regions. It is the best indicator of overall solar activity levels and is not subject to observer bias in the way that the counting of sunspots is. The graph above shows the F10.7 ﬂux from 1948 with Chapter j 11 The Current Solar Minimum 285

300

200 17 23 15 21 19

100

-100 Solar Cycle Amplitude 20 S.C. 24 S.C. 25 16 22 -200 18 Eddy Minimum

-300 1914 1924 1934 1944 1954 1964 1974 1984 1994 2004 2014 2024 2034 2044 FIGURE 14 The ability to look forward using a model of solar activity.

4 Parana River Streamflow 3

1 Sunspot Number

-1

-2

-3

-4 1909 1919 1929 1939 1949 1959 1969 1979 1989 FIGURE 15 The correlation between the de-trended time series for the Parana River stream flow and sunspot number. a projection to 2020. Note the lower activity of the 1970s cooling period. Activity over the next 10 years is projected to be much lower again. The aa Index (Fig. 6) is a geomagnetic activity index which is driven by the solar coronal magnetic field strength. The strength of the solar coronal magnetic field doubled over the 20th century. At the same time, the Earth came 286 PART j IV Solar Activity

out of the Little Ice Age. There was a dip in the aa Index associated with the 1970s cooling period. The aa Index has now fallen back to levels last seen in the Little Ice Age in the late 19th century. Aweaker Interplanetary Magnetic Field results in more galactic cosmic rays reaching the inner planets of the solar system, seen in Fig. 7 of the neutron count of the Oulu station in Finland. The peak neutron count can be more than a year later than the month of solar minimum. This is due to the time the solar wind takes to reach the heliopause, which is the boundary of the solar atmo- sphere with interstellar space. Note the much higher average neutron count during the 1970s cooling period associated with Solar Cycle 20. The increased galactic cosmic ray flux expected over Solar Cycle 24 will cause increased cloudiness, which will in turn increase the Earth’s albedo, and the world will then cool in search of a new equilibrium temperature. Friis-Christensen and Lassen (1991) demonstrated that global temperature over a solar cycle is better correlated with the length of the previous solar cycle than with solar cycle amplitude. In 1996, Butler and Johnson at the Armagh Observatory applied that theory to the temperature record of the observatory and produced the graph shown in Fig. 8. This graph can be considered as the Rosetta Stone of solareclimate studies; in that it has significant predictive power. Simply, Solar Cycle 22 was 9.6 years long, equating to a temperature of about 9.6 C at Armagh. Solar Cycle 23 was 12.5 years long, equating to a temperature of 8.2 C at Armagh. The difference is 1.4 C which is the temperature fall, on average, predicted over Solar Cycle 24. There is not much scatter on this graph and therefore this result is almost certain. A number of European temperature records show a correlation between solar cycle length and temperature, including the Central England Temperature record and de Bilt in the Netherlands. Generally, the more northerly the loca- tion, the better the correlation. The graph in Fig. 9 shows the correlation for Archangel in Russia. Providence, Rhode Island will be 1.8 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 10). Hanover, New Hampshire will be 2.2 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 11). West Chester, Pennsylvania will be 1.5 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 12). Portland, Maine will be 2.1 C colder over Solar Cycle 24 relative to its average temperature over Solar Cycle 23 (Fig. 13). The graph in Fig. 14 is from a model provided by Ed Fix (this volume). The notion that the orbits of the planets, particularly Jupiter, are responsible for generating the sunspot cycle has been with us since the discovery of the sunspot cycle by Samuel Schwabe in 1843. The model is based on changes in the Sun’s orbit about the barycenter of the solar system as the driver of the sunspot cycle. It is a simple oscillatory model driven by the acceleration of the radial component of the barycenter’s position relative to the Sun. The model has Chapter j 11 The Current Solar Minimum 287 a very good hindcast match. At face value, it is predicting two very short and weak cycles. What is more likely is that there will be phase destruction over Solar Cycle 24, including the possibility that the solar magnetic poles will not reverse at solar maximum, predicted by other methods to be in 2015. The Parana River, in central South America, runs through Brazil, Paraguay, and Argentina for nearly 4,000 km and is the second largest river in South America after the Amazon. Its outlet is the River Plata a few kilometers north of Buenos Aires. In 2010, three Argentinean researchers, Pablo Mauas, Andrea Buccino, and Eduardo Flamenco, published a paper showing the very strong correlation between sunspot activity and stream flow of the Parana River (Fig. 15). The relationship demonstrated has predictive power, and points to future drought conditions in the Amazon region as a consequence of the weak activity of Solar Cycle 24.

3. SUMMARY The world has entered a de Vries cycle event in solar activity which will produce a decline in temperature in the range of 1.2e2.2 C in the mid-latitude regions, with a consequent impact on agricultural productivity.

REFERENCES Archibald, D., 2006. Solar cycles 24 and 25 and predicted climate response: Energy and Envi- ronment 17, 29e38. Archibald, D., 2007. Climate outlook to 2030: Energy and Environment 18, 615e619. Archibald, D., 2010. The Past and Future of Climate. Rhaetian Management Pty Ltd, p. 142. Badalyan, O.G., Obridko, V.N., Sykora, J., 2001. Brightness of the coronal green line and prediction for activity cycles 23 and 24: Solar Physics 199, 421e435. Butler, C.J., Johnston, D.J., 1996. A provisional long mean air temperature series for Armagh Observatory. Journal of Atmospheric and Terrestrial Physics 58, 1657e1672. Clilverd, M., 2005. Prediction of solar activity the next 100 years. Solar Activity: Exploration, Understanding and Prediction, Workshop in Lund, Sweden. Friis-Christensen, E., Lassen, K., 1991. Length of the solar cycle: an indicator of solar activity closely associated with climate: Science 254, 698e700. Solheim, E., 2010. Solen varsler et kaldere tiar: Astronomi 4/10, 4e6. Svensmark, H., Friis-Christensen, E., 1997. Variation in cosmic ray ﬂux and global cloud coverageda missing link in solar-climate relationships: Journal of Atmospheric and Solar Terrestrial Physics 59, 1225. Usokin, I.G., Schuessler, M., Solanki, S.K., Mursula, K., 2005. Solar activity, cosmic rays, and the Earth’s temperature: a millennium-scale comparison. Journal of Geophysical Research 110, A10102.