The Role of Space Weather and Cosmic Ray Effects in Climate Change

Lev I. Dorman

Head of Cosmic Ray and Space Weather Center with Emilio Segre Observatory, affiliated to Tel Aviv University, TECHNION and Israel Space Agency, P.O. Box 2217, Qazrin 12900, Israel Chief Scientist of Cosmic Ray Department of IZMIRAN Russian Academy of Science, Troitsk 142090, Moscow Region, Russia

1. Introduction

2. Solar Activity, Cosmic Rays and Climate Change

2.1. Long Term Cosmic Ray Intensity Variations and Climate Change

2.2. The Possible Role of Solar Activity and Solar Irradiance in Climate Change

2.3. Cosmic Rays as an Important Link between Solar Activity and Climate Change

2.4. The Connection between Galactic Cosmic Ray Solar Cycles and the Earth's Cloud Coverage

2.5. The Influence of Cosmic Rays on the Earth's Temperature

2.6. Cosmic Ray Influence on Weather during Maunder Minimum

2.7. The Influence of

Long Term Variations of Cosmic Ray Intensity on Wheat Prices (Related to Climate Change) in Medieval England and Modern USA

2.8. The Connection between Ion Generation in the Atmosphere by Cosmic Rays and Total Surface of Clouds

2.9. The Influence of Big Magnetic Storms (Forbush Decreases) and Solar Cosmic Ray Events on Rainfall

2.10. The Influence of Geomagnetic Disturbances and Solar Activity on the Climate through Energetic Particle Precipitation from Inner Radiation Belt

Climate Change: Observed Impacts on Planet Earth

Copyright © 2009 by Elsevier B.V. All rights of reproduction in any form reserved. 43

2.11. On the Possible Influence of Galactic Cosmic

Rays on Formation of Cirrus Hole and Global Warming

2.12. Description of Long Term Galactic Cosmic Ray Variation by both Convection Diffusion and Drift Mechanisms with Possibility of Forecasting of Some Part of Climate Change in

Near Future Caused by Cosmic Rays

2.13. Influence of Long Term Variation of Main Geomagnetic Field on Global Climate Change through Cosmic Ray Cutoff Rigidity Variation

2.14. Atmospheric lonisation by Cosmic Rays: The Altitude Dependence and Planetary Distribution

2.15. Project 'Cloud' as an Important Step in Understanding the Link between Cosmic Rays and Cloud Formation

3. The Influence on the Earth's Climate of the Solar System Moving Around the Galactic Centre and Crossing Galaxy Arms

4. The Influence of Molecular dust Galactic Clouds on the Earth's Climate

5. The Influence of Interplanetary Dust Sources on the Earth's Climate

6. Space Factors and Global Warming

7. The Influence of Asteroids on the Earth's Climate

8. The Influence of Nearby Supernova on the Earth's Climate

9. Discussion and Conclusions Acknowledgments References

1. INTRODUCTION

There are a number of space phenomena that influence the Earth's climate and determined its long-term and short-term changes. These include:

• the variability of the Sun's irradiation flux energy;

• the variations of the Earth's orbital characteristics;

• the variable solar activity (with periods of 8 15 a (year), average period of about 11 a), general solar magnetic field (average period of 22 a) together with the related phenomena of variable solar wind, coronal mass ejections and shocks in the Heliosphere and modulated galactic cosmic rays (CR) see Section 2;

• the solar CR generated during great solar flares see Section 2.9;

• the precipitation of energetic electrons and protons from the Earth's magnetosphere during magnetic disturbances see Section 2.10;

• the variable Earth's magnetic field's influence on CR cutoff rigidity and changed galactic and solar cosmic ray intensity in the Earth's atmosphere see Section 2.12;

• the moving of the solar system around the galactic centre and crossing the Galaxy arms see Section 3;

• the impacts of the solar system with galactic molecular dust cloud see Section 4;

• the impacts of the solar system with interplanetary zodiac dust cloud see Section 5;

• asteroid impacts see Section 7;

• nearby supernova explosions see Section 8.

The first phenomenon is the subject of Chapter 2 by Shabtai Cohen, and the second is dealt with by Lucas Lourens in Chapter 5. In this Chapter the other phenomena are discussed and compared to anthropogenic induced changes. Details on CR behaviour in the Earth's atmosphere, magnetosphere and in space are the subject of recent publications by the author [1 3]. The role of these factors in our present climate change will be discussed in the final section of this chapter.

2. SOLAR ACTIVITY, COSMIC RAYS AND CLIMATE CHANGE

2.1. Long-Term Cosmic Ray Intensity Variations and Climate Change

About 200 a ago the famous astronomer William Herschel [4] suggested that the price of wheat in England was directly related to the number of sunspots. He noticed that less rain fell when the number of sunspots was small (Joseph in the Bible, recognised a similar periodicity in food production in Egypt, about 4000 a ago). The solar activity level is known from direct observations over the past 450 a, and from data of cosmogenic nuclides (through CR intensity variations) for more than 10 000 a [1,5]. Over this period there is a striking qualitative correlation between cold and warm climate periods and high and low levels of galactic CR intensity (low and high solar activity). As an example, Fig. 1 shows the change in the concentration of radiocarbon during the last millennium (a higher concentration of 14C corresponds to a higher intensity of galactic CR and to lower solar activity). It can be seen from Fig. 1 that during 1000 1300 AD the CR intensity was low and solar activity high, which coincided with the warm medieval period (during this period Vikings settled in Greenland). After 1300 AD solar activity decreased and CR intensity increased, and a long cold period followed (the so-called Little Ice Age, which included the Maunder minimum 1645 1715 AD and lasted until the middle of nineteenth century).

2.2. The Possible Role of Solar Activity and Solar Irradiance in Climate Change

Friis-Christiansen and Lassen [7,8] found, from 400 a of data, that the filtered solar activity cycle length is closely connected to variations of the average surface temperature in the northern hemisphere. Labitzke and Van Loon [9]

A

Medieval W

arm

/

/

\

Age

J

Vik

ings in Gre

v enland

w

\f

Ma

under Minin

1200

1400 Years

1600

1800

1000

1200

1400 Years

1600

1800

FIGURE 1 The change of CR intensity reflected in radiocarbon concentration during the last millennium. The Maunder minimum refers to the period 1645 1715, when sun spots were rare. From Ref. [6].

showed, from solar cycle data, that the air temperature increases with increasing levels of solar activity. Swensmark [6] also discussed the problem of the possible influence of solar activity on the Earth's climate through changes in solar irradiance. But the direct satellite measurements of the solar irradiance during the last two solar cycles showed that the variations during a solar cycle was only about 0.1%, corresponding to about 0.3 Wm 2. This value is too small to explain the present observed climate changes [10]). Much bigger changes during a solar cycle occur in UV radiation (about 10%, which is important in the formation of the ozone layer). High [11] and Shindell et al. [12] suggested that the heating of the stratosphere by UV radiation can be dynamically transported into the troposphere. This effect might be responsible for small contributions towards 11 and 22 a cycle modulation of climate but not to the 100 a of climate change that we are presently experiencing.

2.3. Cosmic Rays as an Important Link between Solar Activity and Climate Change

Many authors have considered the influence of galactic and solar CR on the Earth's climate. Cosmic Radiation is the main source of air ionisation below 40 35 km (only near the ground level, lower than 1 km, are radioactive gases from the soil also important in air ionisation) [1]. The first to suggest a possible influence of air ionisation by CR on the climate was Ney [13]. Swensmark [6] noted that the variation in air ionisation caused by CR could potentially influence the optical transparency of the atmosphere, by either a change in aerosol formation or influence the transition between the different phases of water.

Many other authors considered these possibilities [13 22]. The possible statistical connections between the solar activity cycle and the corresponding long-term CR intensity variations with characteristics of climate change were considered in Dorman et al. [23 25]. Dorman et al. [26] reconstructed CR intensity variations over the last 400 a on the basis of solar activity data and compared the results with radiocarbon and climate change data.

Cosmic radiation plays a key role in the formation of thunderstorms and lightnings [1]. Many authors [27 32] have considered atmospheric electric field phenomena as a possible link between solar activity and the Earth's climate. Also important in the relationship between CR and climate, is the influence of long-term changes in the geomagnetic field on CR intensity through the changes of cutoff rigidity [2]. One can consider the general hierarchical relationship to be: (solar activity cycles + long-term changes in the geomagnetic field) ! (CR long-term modulation in the Heliosphere + long-term variation of cutoff rigidity) ! (long-term variation of clouds covering + atmospheric electric field effects) ! climate change.

2.4. The Connection between Galactic Cosmic Ray Solar Cycles and the Earth's Cloud Coverage

Recent research has shown that the Earth's cloud coverage (observed by satellites) is strongly influenced by CR intensity [6,18,20 22]. Clouds influence the irradiative properties of the atmosphere by both cooling through reflection of incoming short wave solar radiation, and heating through trapping of outgoing long wave radiation (the greenhouse effect). The overall result depends largely on the height of the clouds. According to Hartmann [33], high optically thin clouds tend to heat while low optically thick clouds tend to cool (see Table 1).

From Table 1 it can be seen that low clouds result in a cooling effect of about 17 Wm 2, which means that they play an important role in the Earth's radiation budget [34 36]). The important issue is that even small changes in the lower cloud coverage can result in important changes in the radiation budget and hence has a considerable influence on the Earth's climate (let us remember that the solar irradiance changes during solar cycles is only about 0.3 Wm 2).

Figure 2 shows a comparison of the Earth's total cloud coverage (from satellite observations) with CR intensities (from the Climax neutron monitor (NM)) and solar activity data over 20 a.

From Fig. 2 it can be seen that the correlation of global cloud coverage with CR intensity is much better than with solar activity. Marsh and Swensmark [21] came to conclusion that CR intensity relates well with low global cloud coverage, but not with high and middle clouds (see Fig. 3).

It is important to note that low clouds lead, as rule, to the cooling of the atmosphere. It means that with increasing CR intensity and cloud coverage

TABLE 1 Global annual mean forcing due to various types of clouds, from the Earth Radiation Budget Experiment (ERBE), according to Hartmann [33]

Low

High clouds

Middle clouds

clouds

Parameter

Thin

Thick

Thin

Thick

All

Total

Global fraction /(%)

10.1

8.6

10.7

7.3

26.6

63.3

Forcing (relative to clear sky):

Albedo (SW radiation)/(Wm 2)

4.1

15.6

3.7

9.9

20.2

53.5

Outgoing LW radiation /(Wm 2)

6.5

8.6

4.8

2.4

3.5

25.8

Net forcing/(Wm 2)

2.4

7.0

1.1

7.5

16.7

27.7

The positive forcing increases the net radiation budget of the Earth and leads to a warming; negative forcing decreases the net radiation and causes a cooling. (Note that the global fraction implies that 36.7% of the Earth is cloud free.)

The positive forcing increases the net radiation budget of the Earth and leads to a warming; negative forcing decreases the net radiation and causes a cooling. (Note that the global fraction implies that 36.7% of the Earth is cloud free.)

1980 1985 1990 1995 Years

FIGURE 2 Changes in the Earth's cloud coverage: triangles from satellite Nimbus 7, CMATRIX project [37]; squares from the International Satellite Cloud Climatology Project, ISCCP [38]; diamonds from the Defence Meteorological Satellite Program, DMSP [39,40]. Solid curve CR intensity variation according to Climax NM, normalized to May 1965. Broken curve solar radio flux at 10.7 cm. All data are smoothed using twelve months running mean. From Ref. [6].

1980 1985 1990 1995 Years

FIGURE 2 Changes in the Earth's cloud coverage: triangles from satellite Nimbus 7, CMATRIX project [37]; squares from the International Satellite Cloud Climatology Project, ISCCP [38]; diamonds from the Defence Meteorological Satellite Program, DMSP [39,40]. Solid curve CR intensity variation according to Climax NM, normalized to May 1965. Broken curve solar radio flux at 10.7 cm. All data are smoothed using twelve months running mean. From Ref. [6].

(see Fig. 2), we can expect the surface temperature to decrease. It is in good agreement with the situation shown in Fig. 1 for the last 1000 a, and with direct measurements of the surface temperature over the last four solar cycles (see Section 2.5, below).

"D

10 O

1980

1985 1990 Years

FIGURE 3 CR intensity obtained at the Huancayo/Haleakala NM (normalised to October 1965, curve 2) in comparison with global average monthly cloud coverage anomalies (curves 1) at heights, H, for: a high clouds, H > 6.5 km, b middle clouds, 6.5 km >H > 3.2 km, and c low clouds, H < 3.2 km. From Ref. [21].

10 O

1980

1985 1990 Years

1995

S"

FIGURE 3 CR intensity obtained at the Huancayo/Haleakala NM (normalised to October 1965, curve 2) in comparison with global average monthly cloud coverage anomalies (curves 1) at heights, H, for: a high clouds, H > 6.5 km, b middle clouds, 6.5 km >H > 3.2 km, and c low clouds, H < 3.2 km. From Ref. [21].

2.5. The Influence of Cosmic Rays on the Earth's Temperature

Figure 4 shows a comparison of 11 year moving average Northern Hemisphere marine and land air temperature anomalies for 1935 1995 with CR intensity (constructed for Cheltenham/Fredericksburg for 1937 1975 and Yakutsk for 1953 1994, [41]) and Climax NM data, as well as with other parameters (unfil-tered solar cycle length, sunspot numbers and reconstructed solar irradiance).

From Fig. 4 one can see that the best correlation of global air temperature is with CR intensity, in accordance with the results described in Sections 2.1 2.4 above. According to Swensmark [6], the comparison of Fig. 4 with Fig. 2 shows that the increase of air temperature by 0.3 °C corresponds to a decrease of CR intensity of 3.5% and a decrease of global cloudiness of 3%; this is equivalent to an increase of solar irradiance on the Earth's surface of about 1.5 Wm 2 [42] and is about 5 times bigger than the solar cycle change of solar irradiance, which as we have seen, is only 0.3 Wm 2).

1935 1950 1965 1980 1995 Years

1935 1950 1965 1980 1995 Years

1935 1950 1965 1980 1995 Years a

1935 1950 1965 1980 1995 Years

1935 1950 1965 1980 1995 Years

FIGURE 4 Eleven year average Northern hemisphere marine and land air temperature anomalies, At, (broken curve) compared with: a, unfiltered solar cycle length; b, Eleven year average CR intensity (thick solid curve from ion chambers 1937 1994, normalized to 1965, and thin solid curve from Climax NM, normalized to ion chambers); c, eleven year average of sunspot numbers; and d, decade variation in reconstructed solar irradiance from Ref. [10] (zero level corresponds to 1367 Wm 2). From Ref. [6].

1935 1950 1965 1980 1995 Years d

1935 1950 1965 1980 1995 Years

FIGURE 4 Eleven year average Northern hemisphere marine and land air temperature anomalies, At, (broken curve) compared with: a, unfiltered solar cycle length; b, Eleven year average CR intensity (thick solid curve from ion chambers 1937 1994, normalized to 1965, and thin solid curve from Climax NM, normalized to ion chambers); c, eleven year average of sunspot numbers; and d, decade variation in reconstructed solar irradiance from Ref. [10] (zero level corresponds to 1367 Wm 2). From Ref. [6].

2.6. Cosmic Ray Influence on Weather during Maunder Minimum

Figure 5 shows the situation in the Maunder minimum (a time when sunspots were rare) for: solar irradiance [10,43]); concentration of the cosmogenic isotope 10Be [44] a measure of CR intensity [1]); and reconstructed air surface temperature for the northern hemisphere [45]).

The solar irradiance is almost constant during the Maunder minimum and about 0.24% (or about 0.82 Wm 2) lower than the present value (see Panel a in Fig. 5), but CR intensity and air surface temperature vary in a similar manner see above sections; with increasing CR intensity there is a decrease in air surface temperature (see Panels b and c in Fig. 5). The highest level of CR intensity was between 1690 1700, which corresponds to the minimum of air surface temperature [46] and also to the coldest decade (1690 1700).

1368 1367 1366 1365 1364

1368 1367 1366 1365 1364

1660 1680 1700 1720 Years
1660 1680 1700 1720 Years

1660

1680 1700 Years

1720

FIGURE 5 Situation in the Maunder minimum: a reconstructed solar irradiance [9]; b cosmo genic 10Be concentration [44]; c reconstructed relative change of air surface temperature, At, for the northern hemisphere [45]. From Swensmark [6].

1660

1680 1700 Years

1720

FIGURE 5 Situation in the Maunder minimum: a reconstructed solar irradiance [9]; b cosmo genic 10Be concentration [44]; c reconstructed relative change of air surface temperature, At, for the northern hemisphere [45]. From Swensmark [6].

2.7. The Influence of Long-Term Variations of Cosmic Ray Intensity on Wheat Prices (Related to Climate Change) in Medieval England and Modern USA

Herschel's observations [4] mentioned in Section 2.1, were based on the published wheat prices [47], and showed that five prolonged periods of sunspot numbers correlated with costly wheat. This idea was taken up by the English economist and logician William Stanley Jevons [48]. He directed his attention to the wheat prices from 1259 to 1400 and showed that the time intervals between high prices were close to 10 11 a. This work was later published by Rogers [49]. The coincidence of these intervals with the period of the recently discovered 11 year cycle of solar activity led him to suggest that the solar activity cycle was a 'synchronisation' factor in the fluctuations of wheat prices (Jevons [50]). As a next step, he extrapolated his theory to stock markets of the nineteenth century in England and was impressed by a close coincidence of five stock exchange panics with five minima in solar spot numbers that preceded these panics. He suggested that both solar and economic activities are subjected to a harmonic process with the same constant period of 11 a. However, the subsequent discovery of the non-harmonic behaviour of solar cycles, with periods varying from 8 to 15 a, and the later observation of lack of coincidence between panics predicted by Jevons [48,50] and the actual ones, destroyed his argument.

The Rogers [49] database was used by Pustil'nik et al. [51], Pustil'nik and Yom Din [52] to search for possible influences of solar activity and CR intensity on wheat prices (through climate changes). The graph of wheat prices as a function of time (Fig. 6) contains two specific features:

1. A transition from 'low price' state to 'high price' state during 1530 1630, possibly as a result of access to cheap silver, recently discovered New World.

2. The existence of two populations in the price sample: noise-like variations with low amplitude bursts and several bursts of large amplitude.

Pustil'nik et al. [51], Pustil'nik and Yom Din [52], analysed the data and compared the distribution of intervals of price bursts with the distribution of the intervals between minimums of solar cycles (see Fig. 7).

In their analysis they found that for the sunspot minimum minimum interval distribution the estimated parameters are: median 10.7 a; mean 11.02 a; standard deviation 1.53 a and for the price burst interval distribution, the estimated parameters are: median 11.0 a; mean 11.14 a; and standard deviation 1.44 a.

The main problem with a comparison between the price and solar activity, is the absence of the time interval, common to sunspot observation data

Year's Wheat Prices in the Middle Ages England

Year's Wheat Prices in the Middle Ages England

Years

FIGURE 6 Wheat prices in England during 1259 1702 with a price transition at 1530 1630. From Refs. [51,52].

Years

FIGURE 6 Wheat prices in England during 1259 1702 with a price transition at 1530 1630. From Refs. [51,52].

Hystogram of Price Bursts Intervals

Hystogram of Price Bursts Intervals

CM

CO

LO

V

V

V

V

"O

"O

"O

"O

V

V

V

V

T"

CM

CO

Intervals

Hystogram of the Sunspot Min-Min intervals

Hystogram of the Sunspot Min-Min intervals

Intervals

FIGURE 7 Histograms of the interval distribution for price bursts for the period, 1249 1702, and of minimum minimum intervals of sunspots during 1700 2000. From Refs. [51,52].

Intervals

FIGURE 7 Histograms of the interval distribution for price bursts for the period, 1249 1702, and of minimum minimum intervals of sunspots during 1700 2000. From Refs. [51,52].

(for 1700 2001) and wheat price data (1259 1702). However, the discovery of a strong correlation between the concentration of 10Be isotopes in Greenland ice and CR intensity (according to measurements of CR intensity over the last 60 a [1]) sheds a new light on the problem. In Fig. 8, the wheat prices for 1600 1702 are shown and compared to 10Be data [53]. White marks show prices, averaged for three-year intervals centred on moments of minimum CR intensity. Black marks correspond to average prices in three-year intervals for maximum CR intensities.

As can be seen from Fig. 8, all prices in the neighbourhoods of the seven maxima of CR intensity (correspond approximately to minima of solar activity)

1588 1599 1610 1621 1632 1643 1654 1665 1676 1687 1698 1709

Years

FIGURE 8 Systematic differences in wheat prices at moments of minimum and maximum CR intensity determined according to 10Be data [53]. White diamonds show prices averaged for three year intervals centred on moments of minimum CR intensity (maximum solar activity); black rectangles show prices averaged over three year intervals centred on moments of maximum CR intensity (minimum solar activity). White and black triangles show prices at moments of minimum and maximum CR intensity. From Ref. [52].

Max & Min moments of 10Be and relative prices between 1580 and 1700 (including Maunder Minimum)

t

i

\ \

1

[

A

i 1

I i

Sk

1

u

1

i

ft

à

A

i i

w

i ;

1

f"

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MA

i i

i 1

¡■f'l

FIE3

■il

HH

W\

A'

M

HKI

KU

HI

T*

À

À

M

1588 1599 1610 1621 1632 1643 1654 1665 1676 1687 1698 1709

Years

FIGURE 8 Systematic differences in wheat prices at moments of minimum and maximum CR intensity determined according to 10Be data [53]. White diamonds show prices averaged for three year intervals centred on moments of minimum CR intensity (maximum solar activity); black rectangles show prices averaged over three year intervals centred on moments of maximum CR intensity (minimum solar activity). White and black triangles show prices at moments of minimum and maximum CR intensity. From Ref. [52].

are systematically higher than those in the neighbourhood of the seven minima of CR intensity (maxima of solar activity) in the long-term variation of CR intensity according to 10Be data [53]. A similar result was obtained by Pustil'nik and Yom Din [54] for wheat prices in USA during twentieth century.

2.8. The Connection between Ion Generation in the Atmosphere by Cosmic Rays and Total Surface of Clouds

The time variation of the integral rate of ion generation, q, (approximately proportional to CR intensity) in the middle latitude atmosphere at an altitude between 2 and 5 km was found by Stozhkov et al. [55] for the period January 1984 August 1990 using regular CR balloon measurements. The relative change in q, Aq/q, have been compared with the relative changes of the total surface of clouds over the Atlantic Ocean, AS/S, and are shown in Fig. 9: the correlation coefficient is 0.91 ± 0.04. This result is in good agreement with results described above (see Panel b in Fig. 4 and Panel c in Fig. 5) and shows that there is a direct correlation between cloud cover and CR generated ions.

2.9. The Influence of Big Magnetic Storms (Forbush Decreases) and Solar Cosmic Ray Events on Rainfall

A decrease of atmospheric ionisation leads to a decrease in the concentration of charge condensation centres. In these periods, a decrease of total cloudiness

*

-j*

m i

FIGURE 9 The positive relationship between the relative changes of total clouds covering sur face over Atlantic Ocean, AS/S, in the period January 1984 August 1990 [19] and the relative changes of integral rate of ion generation Aq/q in the middle latitude atmosphere in the altitude interval 2 5 km. From Ref. [55].

and atmosphere turbulence together with an increase in isobaric levels is observed [56]). As a result, a decrease of rainfall is also expected. Stozhkov et al. [57 59] and Stozhkov [60] analysed 70 events of Forbush decreases (defined as a rapid decrease in observed galactic CR intensity, and caused by big geomagnetic storms) observed in 1956 1993 and compared these events with rainfall data over the former USSR. It was found that during the main phase of the Forbush decrease, the daily rainfall levels decreases by about 17%. Similarly, Todd and Kniveton [61,62] investigating 32 Forbush decreases events over the period 1983 2000, found reduced cloud cover of 18% [61] and 12% [62].

During big solar CR events, when CR intensity and ionisation in the atmosphere significantly increases, an inverse situation is expected and the increase in cloudiness leads to an increase in rainfall. A study [57 60] involving 53 events of solar CR enhancements, between 1942 1993, showed a positive increase of about 13% in the total rainfall over the former USSR.

2.10. The Influence of Geomagnetic Disturbances and Solar Activity on the Climate through Energetic Particle Precipitation from Inner Radiation Belt

The relationship between solar and geomagnetic activity and climate parameters (cloudiness, temperature, rainfall, etc.) was considered above and is the subject of much ongoing research. The clearly pronounced relationship observed at high and middle latitudes, is explained by the decrease of galactic CR intensity (energies in the range of MeV and GeV) with increasing solar and geomagnetic activity, and by the appearance of solar CR fluxes ionising the atmosphere [63]). This mechanism works efficiently at high latitudes, because CR particles with energy up to 1 GeV penetrate this region more easily due to its very low cutoff rigidity. Near the equator, in the Brazilian Magnetic

Anomaly (BMA) region, the main part of galactic and solar CR is shielded by a geomagnetic field. This field is at an altitude of 200 300 km and contains large fluxes of energetic protons and electrons trapped in the inner radiation belt. Significant magnetic disturbances can produce precipitation of these particles and subsequent ionisation of the atmosphere. The influence of solar-terrestrial connections on climate in the BMA region was studied by Pugacheva et al. [64]. Two types of correlations were observed: (1) a significant short and long time scale correlation between the index of geomagnetic activity Kp and rainfall in Sao Paulo State; (2) the correlation-anti-correlation of rainfalls with the 11 and 22 a cycles of solar activity for 1860 1990 in Fortaleza. Figure 10 shows the time relationship between Kp-index and rain in Campinas (23°S, 47°W) and in Ubajara (3°S, 41 °W), during 1986. From Fig. 10, it can be seen that, with a delay of 5 11 days, almost every significant (>3.0) increase of the Kp-index is accompanied by an increase in rainfall. The effect is most noticeable at the time of the great geomagnetic storm of 8 February 1986, when the electron fluxes of inner radiation belt reached the atmosphere between 18 and 21 February [65]) and the greatest rainfall of the 1986 was recorded on 19 February. Again, after a series of solar flares, great magnetic disturbances were registered between 19 and 22 March 1991. On 22 March, a Sao Paolo station showed the greatest rainfall of the year.

The relationship between long-term variations of annual rainfall at Campinas, the Kp-index and sunspot numbers are shown in Figs. 11 and 12.

Figures 11 and 12 show the double peak structure of rainfall variation compared to the Kp-index. Only during the 20th solar cycle (1964 1975), weakest of the shown 6 cycles, an anti-correlation between rainfalls and sun-spot numbers is observed in most of Brazil. The Kp rainfall correlation is more pronounced in the regions connected with magnetic lines occupied by trapped particles.

FIGURE 10 The Kp index of geomagnetic activity (top panels) and rainfall level (bottom panels) in Campinas (left panels a) and in Ubajara (right panels b) in 1986. According to Pugacheva et al. [64].
FIGURE 11 Long term variations of rainfalls (Campinas, the bottom panel) in comparison with variations of solar and geomagnetic activity (the top and middle panels, respectively) for 1940 1965. From Ref. [64].

In Fortaleza (4°S, 39°W), located in an empty magnetic tube (L = 1.054), it is the other kind of correlation (see Fig. 13).

From Fig. 13 it can be seen that a correlation exists between sunspot numbers and rainfall between 1860 1900 (11th 13th solar cycles) and 1933 1954 (17th and 18th cycles). The anti-correlation was observed during 1900 1933 (cycles 14th 16th) and during 1954 1990 (cycles 19th 21th). As far as sunspot numbers mainly anti-correlate with the galactic CR flux, an anti-correlation of sunspot numbers with rainfalls could be interpreted as a correlation of rainfalls with the CR. The positive and negative phases of the correlation interchange several times during the long time interval 1860 1990, that was observed earlier in North America (King [66]). Some climate events have a 22 a periodicity similar to the 22 a solar magnetic cycle. Panel b in Fig. 13 demonstrate 22 a periodicity of 11 a running averaged rainfalls in Fortaleza. The phenomenon is observed during 5 periods from 1860 to 1990. During the 11th 16th solar cycles (from 1860 until 1930), the maxima of rainfalls correspond to the maxima of sunspot numbers of odd solar cycles 11th, 13th, 15th and minima of rainfalls correspond to maxima of even solar

to 500

< 1500 1000

b 18B0 1880 1900 1920 1940 19S0 1980

FIGURE 13 The comparison of yearly sunspot numbers long term variation (the top panel) with 3 and 11a running averaged rainfalls (Panels a and b, respectively) in Fortaleza (4°S, 39°W) dur ing 1860 1990. From Ref. [64].

cycles 12th, 14th, 16th. During the 17th solar cycle the phase of the 22 a periodicity is changed to the opposite and the sunspot number maxima of odd cycles 19th and 21st correspond to the minima of rainfall. The effect is not pronounced (excluding years 1957 1977) in Sao Paolo.

The difference in results obtained in Refs. [60 62, 64] can be easily understood if we take into account the large value of the cutoff rigidity in the BMA region. This is the reason why the variations in galactic and solar CR intensity in the BMA region, are not reflected in the ionisation of the air and hence do not influenced the climate. However, in the BMA region other mechanism of solar and magnetic activity can influence climatic parameters such as energetic particle precipitation coming from the inner radiation belt.

2.11. On the Possible Influence of Galactic Cosmic Rays on Formation of Cirrus Hole and Global Warming

According to Ely and Huang [67] and Ely et al. [68], there are expected variations of upper tropospheric ionisation caused by long-term variations of galactic CR intensity. These variations have resulted in the formation of the cirrus hole (a strong latitude dependent modulation of cirrus clouds). The upper tropospheric ionisation is caused, largely, by particles with energy smaller than 1 GeV but bigger than about 500 MeV. In Fig. 14 is shown the long-term modulation of the difference between Mt. Washington and Durham for protons with kinetic energy 650 850 MeV.

1965 1970 1975 1980 1985

FIGURE 14 The observed 22 a modulation of galactic CR between 1.24 GV and 1.41 GV rigidity (i.e. protons with kinetic energy between 650 850 MeV, ionising heavily in the layer 200 300 g/cm2). From Ely et al. [68].

1965 1970 1975 1980 1985

FIGURE 14 The observed 22 a modulation of galactic CR between 1.24 GV and 1.41 GV rigidity (i.e. protons with kinetic energy between 650 850 MeV, ionising heavily in the layer 200 300 g/cm2). From Ely et al. [68].

Figure 14 clearly shows the 22 a modulation of galactic CR intensity in the range 650 850 MeV with an amplitude of more than 3%. Variations of upper tropospheric ionisation do have some influence on the cirrus covering and the 'cirrus hole' is expected to correspond to a decrease in CR intensity.

According to Ely et al. [68], the 'cirrus hole' was observed in different latitude zones over the whole world between 1962 and 1971, centred at 1966 (see Fig. 15).

Figure 15 gives the cirrus cloud cover data over a 25 a period, for the whole world, the equatorial zone (30° S 30°N) and the northern zone (30°N 90°N), showing fractional decreases in cirrus coverage of 7%, 4% and 17%, respectively.

1s55 1960 1965 1970 1975 1980 FIGURE 15 The 'cirrus hole' of the 1960s for: the whole world (the top panel); the equatorial zone (30°S 30°N; middle panel); the northern zone (bottom panel) From Ely et al. [68].

The decrease of cirrus covering leads to an increase in heat loss to outer space (note, that only a 4% change in total cloud cover is equivalent to twice the present greenhouse effect due to anthropogenic carbon dioxide). The influence of cirrus hole in the northern latitude zone (30°N 90°N), where the cirrus covering was reduced by 17%, is expected to be great (this effect of the cirrus hole is reduced in summer by the increase of lower clouds resulting in enhanced insulation) The low temperatures produced from mid to high latitude significantly increase the pressure of the polar air mass and cause frequent 'polar break troughs' at various longitudes in which, for example, cold air from Canada may go all the way to Florida and freeze the grapefruit [68]). However, when the cirrus hole is not present, the heat loss from mid to high latitudes is much less, and the switching of the circulation patterns (Rossby waves) is much less frequent.

2.12. Description of Long-Term Galactic Cosmic Ray Variation by both Convection-Diffusion and Drift Mechanisms with Possibility of Forecasting of Some Part of Climate Change in Near Future Caused by Cosmic Rays

It was shown in previous Sections that CR may be considered as sufficient links determined some part of space weather influence on the climate change. From this point of view it is important to understand mechanisms of galactic CR long-term variations and on this basis to forecast expected CR intensity in near future. In Dorman [69 71] it was made on basis of monthly sunspot numbers with taking into account time-lag between processes on the Sun and situation in the interplanetary space as well as the sign of general magnetic field (see Fig. 16); in Belov et al. [72] mainly on basis of monthly data of solar general magnetic field (see Fig. 17). From Fig. 16 follows that in the frame of used in [69 71] convection-diffusion and drift models can be determined with very good accuracy expected galactic CR intensity in the past (when monthly sunspot numbers are known) as well as behaviour of CR intensity in future if monthly sunspot numbers can be well forecasted. According to Ref. [72], the same can be made with good accuracy on the basis of monthly data on the solar general magnetic field (see Fig. 17). Let us note that described above results obtained in Refs. [69 72] give possibility to forecast some part of climate change connected with CR.

2.13. Influence of Long-Term Variation of Main Geomagnetic Field on Global Climate Change through Cosmic Ray Cutoff Rigidity Variation

The sufficient change of main geomagnetic field leads to change of planetary distribution of cutoff rigidities Rc and to corresponding change of the i-th component of CR intensity N;(Rc, ho) at some level ho in the Earth's

8.35

8.15

8.05

1950 1960 1970 1980 1990 2000 2010

FIGURE 16 Comparison of observed by Climax neutron monitor CR intensity averaging with moving period eleven month LN(CL11M OBS) with predicted on the basis of monthly sunspot numbers from model of convection diffusion modulation, corrected on drift effects LN(CL11M PRED). Correlation coefficient between both curves 0.97. From Dorman [71].

FIGURE 16 Comparison of observed by Climax neutron monitor CR intensity averaging with moving period eleven month LN(CL11M OBS) with predicted on the basis of monthly sunspot numbers from model of convection diffusion modulation, corrected on drift effects LN(CL11M PRED). Correlation coefficient between both curves 0.97. From Dorman [71].

FIGURE 17 The forecast of galactic CR behaviour based on the predicted values of the global characteristics of the solar magnetic field, thick line data of CR intensity observations (Moscow neutron monitor), thin line the predicted CR variation up to 2013 based on data of Kitt Peak Observatory (upper panel) and based on data of Stanford Observatory (bottom panel). From Belov et al. [72].

1979 1983 1987 1991 1995 1999 2003 2007 2011 Years

FIGURE 17 The forecast of galactic CR behaviour based on the predicted values of the global characteristics of the solar magnetic field, thick line data of CR intensity observations (Moscow neutron monitor), thin line the predicted CR variation up to 2013 based on data of Kitt Peak Observatory (upper panel) and based on data of Stanford Observatory (bottom panel). From Belov et al. [72].

a atmosphere ANi(Rc, ho)/Nio = —ARcWi(Rc, ho), where Wi(Rc, ho) is the coupling function (see details in Chapter 3 of Ref. [1]). Variations of CR intensity caused by change of Rc are described in detail in Ref. [2], and here we will demonstrate results of Shea and Smart [73] on Rc changing for the last 300 and 400 a (see Fig. 18 and Table 2, correspondingly).

FIGURE 18 Contours of the change in vertical cutoff rigidity values (in GV) between 1600 and 1900. Full lines reflect positive trend (increasing of cutoff rigidity from 1600 to 1900); dotted lines reflect negative trend. According to Shea and Smart [73].
( \ TABLE 2 Vertical cutoff rigidities (in GV) for various epochs 1600, 1700, 1800, 1900 and 2000, as well as change from 1900 to 2000 owed to changes of geomagnetic field. According to Shea and Smart [73]

(E)

Epoch 2000

Epoch 1900

Epoch 1800

Epoch 1700

Epoch 1600

Change 1900 2000

Region

55

30

2.30

2.84

2.31

1.49

1.31

0.54

Europe

50

0

3.36

2.94

2.01

1.33

1.81

+0.42

Europe

50

15

3.52

3.83

2.85

1.69

1.76

0.31

Europe

40

15

7.22

7.62

5.86

3.98

3.97

0.40

Europe

45

285

1.45

1.20

1.52

2.36

4.1

+0.25

North America

40

255

2.55

3.18

4.08

4.88

5.89

0.63

North America

20

255

8.67

12.02

14.11

15.05

16.85

3.35

North America

20

300

10.01

7.36

9.24

12.31

15.41

+2.65

North America

50

105

4.25

4.65

5.08

5.79

8.60

0.40

Asia

40

120

9.25

9.48

10.24

11.28

13.88

0.23

Asia

35

135

11.79

11.68

12.40

13.13

14.39

+0.11

Japan

25

150

8.56

9.75

10.41

11.54

11.35

1.19

Australia

35

15

4.40

5.93

8.41

11.29

12.19

1.53

South Africa

35

300

8.94

12.07

13.09

10.84

8.10

3.13

South America

Table 2 shows that the change of geomagnetic cutoffs, in the period 1600 1900, is not homogeneous: of the 14 selected regions, 5 showed increasing cutoffs with decreasing CR intensity, and 9 regions showed decreasing cutoffs with increasing CR intensity. From Table 2 it can also be seen that at present time (from 1900 to 2000) there are sufficient change in cutoff rigidities: decreasing (with corresponding increasing of CR intensity) in 10 regions, and increasing (with corresponding decreasing of CR intensity) in 3 regions. These changes give trend in CR intensity change what we need to take into account together with CR 11 and 22 a modulation by solar activity, considered in Section 2.12.

2.14. Atmospheric Ionisation by Cosmic Rays: The Altitude Dependence and Planetary Distribution

The main process in the link between CR and cloudiness is the air ionisation which triggers chemical processes in the atmosphere. Figure 19 shows experimental data [74] of the galactic CR generation of secondary particles and absorption at different cutoff rigidities. Figure 20 illustrates the total ionisation of atmosphere by galactic CR (primary and secondary) as a function of altitude.

The planetary distribution of ionisation at the altitude of 3 km [75], is shown in Fig. 21 for the year 2000, and its time variation during 1950 2000 is presented in Fig. 22.

FIGURE 19 The absorption, I, curves of CR in the atmosphere at different cutoff rigidities (numbers at the top in units of GV) as a function of altitude, H. The horizontal bars indicate the standard deviations. From Ermakov et al. [74].

FIGURE 20 The ion concentration, n, profiles as a function of altitude, H, for different geomag netic cutoff rigidities (numbers at the top are in units of GV). The horizontal bars indicate the standard deviations. From Ermakov et al. [74].

n/103 cm-3

FIGURE 20 The ion concentration, n, profiles as a function of altitude, H, for different geomag netic cutoff rigidities (numbers at the top are in units of GV). The horizontal bars indicate the standard deviations. From Ermakov et al. [74].

-90 - 1 T I r T 1 I T T r 1—I 1 T T 1 r f 1 1 T T I f 1 I T T I f T I I T r

FIGURE 21 Planetary distribution of calculated equilibrium galactic CR induced ionisation at the altitude of 3 km (h = 725 g/cm2) for the year 2000. Contour lines are given as the number of ion pairs per cm in steps of 10 cm . From Usoskin et al. [75].

-90 - 1 T I r T 1 I T T r 1—I 1 T T 1 r f 1 1 T T I f 1 I T T I f T I I T r

FIGURE 21 Planetary distribution of calculated equilibrium galactic CR induced ionisation at the altitude of 3 km (h = 725 g/cm2) for the year 2000. Contour lines are given as the number of ion pairs per cm in steps of 10 cm . From Usoskin et al. [75].

2.15. Project 'Cloud' as an Important Step in Understanding the Link between Cosmic Rays and Cloud Formation

The many unanswered questions in understanding the relationship between CR and cloud formation is being investigated by a special collaboration, within the framework of European Organization for Nuclear Research,

450 I 1 I I ' I 1 T r I T I 1 r I l I I l r l T i l T r I 1 I l I I I » I l T I T r T I l f I

1960 1960 1970 1980 1990 2000 Years

FIGURE 22 Calculated time profiles of the annual ionisation, n, at altitude of 3 km (h 725 g/cm2), induced by galactic CR, for three regions: polar (cutoff rigidity Rc < 1 GV), mid latitudes (Rc « 6 GV) and equatorial (Rc « 15 GV) regions. From Ref. [75].

450 I 1 I I ' I 1 T r I T I 1 r I l I I l r l T i l T r I 1 I l I I I » I l T I T r T I l f I

1960 1960 1970 1980 1990 2000 Years

FIGURE 22 Calculated time profiles of the annual ionisation, n, at altitude of 3 km (h 725 g/cm2), induced by galactic CR, for three regions: polar (cutoff rigidity Rc < 1 GV), mid latitudes (Rc « 6 GV) and equatorial (Rc « 15 GV) regions. From Ref. [75].

involving 17 Institutes and Universities [76]. The experiment, which is named 'CLOUD', is based on a cloud chamber (which is designed to duplicate the conditions prevailing in the atmosphere) and 'CRs' from CERN Proton Synchrotron. The Project will consider possible links between CR, variable Sun intensities and the Earth's climate change (see Fig. 23).

3. THE INFLUENCE ON THE EARTH'S CLIMATE OF THE SOLAR SYSTEM MOVING AROUND THE GALACTIC CENTRE AND CROSSING GALAXY ARMS

The influence of space dust on the Earth's climate has been reviewed [77]. Figure 24 shows the changes of planetary surface temperature for the last 520 Ma according [78]. These data were obtained from the paleoenvironmental records. During this period the solar system crossed Galaxy arms four times. In doing so, there were four alternating warming and cooling periods with temperature changes of more than 5 °C.

The amount of matter inside the galactic arms is more than on the outside. The gravitation influence of this matter attracts the inflow of comets from Oort's cloud to solar system [79,80]. It results in an increase in concentration of interplanetary dust in zodiac cloud and a cooling of the Earth's climate [81].

4. THE INFLUENCE OF MOLECULAR-DUST GALACTIC CLOUDS ON THE EARTH'S CLIMATE

The solar system moves relative to interstellar matter with a velocity about 30 km s 1 and sometimes passes through molecular-dust clouds. During these periods we can expect a decrease in sea level air temperature. According to

FIGURE 23 Possible paths of solar modulated CR influence on different processes in the atmo sphere leading to the formation of clouds and their influence on climate. From Ref. [76].

FIGURE 24 Changes of air temperature, At, near the Earth's surface for the last 520 Ma accord ing to the paleoenvironmental records [78]. From Ref. [77].

0 100 200 300 400 Year (*1000)

FIGURE 25 Changes of temperature, At, relative to modern epoch (bottom thick curve) and dust concentration (upper thin curve) over the last 420 000 a [83]. From Ref. [77].

in 3

0 100 200 300 400 Year (*1000)

FIGURE 25 Changes of temperature, At, relative to modern epoch (bottom thick curve) and dust concentration (upper thin curve) over the last 420 000 a [83]. From Ref. [77].

Dorman [82], the prediction of the interaction of a dust-molecular cloud with the solar system can be performed by measurements of changes in the galactic CR distribution function. From the past we know that the dust between the Sun and the Earth has led to decreases of solar irradiation flux resulting in reduced global planetary temperatures (by 5 7 °C in comparison with the 0.8 °C increase due to the present greenhouse effect). The plasma in a moving molecular dust cloud contains a frozen-in magnetic field; this moving field can modify the stationary galactic CR distribution outside the Heliosphere. The change in the distribution function can be significant, and it should be possible to identify these changes when the distance between the cloud and the Sun becomes comparable with the dimension of the cloud. The continuous observation of the time variation of CR distribution function for many years should make it possible to determining the direction, geometry and the speed of the dust-molecular cloud relative to the Sun. Therefore, it should, in future, be possible to forecast climatic changes caused by this molecular-dust cloud.

Figure 25 shows the temperature changes at the Antarctic station Vostok (bottom curve), which took place over the last 420 000 a according to Petit et al. [83]. These data were obtained from isotopic analysis of O and H extracted from the ice cores at a depth 3300 m. It is seen from Fig. 25 that during this time the warming and cooling periods changed many times and that the temperature changes amounted up to 9 °C. Data obtained from isotope analysis of ice cores in Greenland, which cover the last 100 000 a [79], confirm the existence of large changes in climate.

5. THE INFLUENCE OF INTERPLANETARY DUST SOURCES ON THE EARTH'S CLIMATE

According to Ermakov et al. [77], the dust of zodiac cloud is a major contributory factor to climate changes in the past and at the present time. The proposed mechanism of cosmic dust influence is as follows: dust from

14.6

Pinatubo

14.6

Pinatubo

13.4

1880 1900 1920

FIGURE 26 Yearly average values of the global air temperature, t, near the Earth's surface for the period from 1880 to 2005 [81]. Arrows show the dates of the volcano eruptions with the dust emission to the stratosphere and short times cooling after eruptions. From Ref. [77].

13.4

1880 1900 1920

FIGURE 26 Yearly average values of the global air temperature, t, near the Earth's surface for the period from 1880 to 2005 [81]. Arrows show the dates of the volcano eruptions with the dust emission to the stratosphere and short times cooling after eruptions. From Ref. [77].

interplanetary space enters the Earth's atmosphere during the yearly rotation of the Earth around the Sun. The space dust participates in the processes of cloud formation. The clouds reflect some part of solar irradiance back to space. In this way the dust influences climate. The main sources of interplanetary dust are comets, asteroids and meteor fluxes. The rate of dust production is continually changing. The effect of volcanic dust on the Earth's air temperature is illustrated in Fig. 26 [81]. (Note air temperature can be found at ftp:// ftp.ncdc.noaa.gov/pub/data/anomalies/global meanT C.all)

According to Ermakov et al. [77], the spectral analysis of global surface temperature during 1880 2005 shows the presence of several spectral lines that can be identified with the periods of meteor fluxes, comets and asteroids. The results of analysis have been used [77,84] to predict changes in climate over the next half-century: the interplanetary dust factor of cooling in the next few decades will be more important than the warming from greenhouse effect.

6. SPACE FACTORS AND GLOBAL WARMING

It is now commonly thought of that the current trend of the global warming is causally related to the accelerating consumption of fossil fuels by the industrial nations. However, it has been suggested that this warming is a result of a gradual increase of solar and magnetic activity over the last 100 a. According to Pulkkinen et al. [85], as shown in Figs. 27 and 28, the solar and magn

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