The Effect of Solar Variability on Climate

Calculations and conclusions by

Timo Niroma, Helsinki, Finland

Sunspots
















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Astronomical Aspects of Mankind's Past and Recent Climate

Sunspots and Temperature

Calculations and conclusions by

Timo Niroma, Helsinki, Finland

Helsinki temperatures for 170 years

Helsinki
Illustration from the City of Helsinki Homepage

Temperatures based on data of the Finnish Meteorological Institute, Helsinki The smoothed temperatures in Helsinki, Kaisaniemi, in degrees Celsius, from 1829 to 2002. Smoothed by 27 years (amount suggested by G. Plaut et al.: Interannual and Interdecadal Variability in 335 Years of Central England Temperatures (Science, vol. 268, 1995)). To reduce the overwhelming amount of numbers, every 10th interval has been selected. Be aware of the partial overlapping.

Sunspot numbers based on data of NGDC, Boulder, Colorado The smoothed yearly sunspot numbers, so-called Wolf numbers (Zurich until 1980, International numbers from 1980 (NGDC, Boulder, Colorado)). Smoothed by 78 years (the Gleissberg cycle).

Interval    Jan   July   Sunspot Sunspot  Change in Remarks
Dates      Temp   Temp   Date    Number   Sun's     Jan       July 
(27 years) Winter Summer (running Gleiss) Activity

1830-1856  -7.2   16.1   1840    43                 Coldest   Coldest
1840-1866  -6.6   16.3   1850    45        +2       3.cold    2.cold
1850-1876  -6.7   16.9   1860    48        +3       2.cold
1860-1886  -6.5   16.6   1870    48         -                 cold
1870-1896  -5.8   16.6   1880    44        -4                 cold
1880-1906  -5.4   16.6   1890    42        -2                 cold  
1890-1916  -5.3   17.0   1900    42         -
1900-1926  -5.2   17.2   1910    44        +2       3.warm
1910-1936  -4.8   17.8   1920    50        +6       2.warm    3.warm
1920-1946  -5.4   17.9   1930    54        +4                 Warmest
1930-1956  -5.2   17.9   1940    56        +2                 Warmest
1940-1966  -5.9   17.3   1950    62        +6
1950-1976  -5.4   17.0   1960    66        +4
1960-1986  -5.8   16.9   1964    71       (+5)
1970-1996  -4.6   17.1                              Warmest 
_____________________________________________________________________
1977-2003  -4.4   17.4

The coldest spells during this time period (1830-2003) are before 1870 both in winter and summer. The warmest summers are between 1920 and 1950. Winters are warm in 1920's and again from 1970 onwards. The temperature of summers has slightly rosen since 1970, but not yet achieved the period 1910-1950. Either of these series does not follow the rise of carbon dioxide. The period 1910-1940 is warmer than the period 1940-1980. Taking the summer temperature that period is warmer than any before that during 1830-2003.

Coldest periods 1829-2002 smoothed to 27 year periods 1842-1989: Minor exceptions (1 or 2 years) omitted.

January smoothed -7 or colder:       1842-1859
                 -6 to -7            1860-1881

July smoothed below 17:              1842-1902, 1964-1975

The activity of the sunspot cycle was lowest in 1964-1975 since the beginning of the century.

Warmest periods 1829-2002 smoothed to 27 year periods 1842-1989: Minor exceptions (1 or 2 years) omitted.


January smoothed warmer than -5:    1921-1926, 1982-
              between -6 and -5:    1882-1920, 1927-1981

July smoothed 17 or warmer:         1903-1963, 1976-
              17.5                  1919-1950

The deviating behavior of winters and summers can also be seen here: Although there is a 6-year period in winters already in 1920's, the warming has been much more continuous during the winters than during the summers with the breakup of warming in 1950.

Sunspot number (the so-called Wolf number) 1789-:

- smoothed value below 40:        1789-1836 and 1871-1934
- smoothed value 70 or above:     1936-

Wolf sunspot numbers smoothed by one Gleissberg cycle (77.5 years).




























One Gleissberg cycle consists of seven consecutive sunspot cycles. Its average length is 77.5 years, max length 83.0 years and min length 72.0 years. It measures the intensity of the solar activity (Wolfian sunspot numbers). Its correlation with Helsinki temperatures is higher than the temperature's correlation with the measured CO2. It also has the same kind of fall of its value from about 1860-1870 to 1920-1930 as the temperatures have. CO2 does not have any corresponding fall.

THE LATEST TRENDS:

The latest January values are a new warm record, although during 4 periods in 1908-1939 the temperature was also warm: -4.8 degrees.

July is in its own category, since the value of 16.9 degrees was already achieved during two consecutive periods in 1850-1877 and then again from 1889 to 1915. It has stayed there or higher since then with only one exception. But the all-time high, 18.1 degrees, was reached during the period 1923-1949 and 18.0 degrees was reached first during two periods in 1912-1939 and again in 1922-1951. So today's temperature is almost 1 degree colder than 50-60 years ago.

Helsinki temperatures in cells of 27 years.

27 YEAR NON-OVERLAPPING PERIODS

27 Year Period JANUARY Data

27 Year     avg  change from  cumulative the coldest the warmest
Period     temp  previous     change     month       month   

1842-1868  -6.8                          -15.3       -1.0
1869-1895  -5.9  +0.9                    -13.2        0.3
1896-1922  -5.3  +0.6         +1.5       - 8.8       -1.2
1923-1949  -5.1  +0.2         +1.7       -15.9        1.4
1950-1976  -5.4  -0.3         +1.4       -12.7       -0.3
1977-2003  -4.4  +1.0         +2.4       -16.5        0.5

There are two periods, when there has occurred considerable warming. First one is from the period from 1840-1870 to 1870-1895, the other one from 1950-1980 to 1980-2000. In both cases the warming has been about 1 degree. The periods fits very well with changes in the solar activity. In only one occasion has the temperature dropped, namely from 1920-1950 to 1950-1980. This does not fit with the CO2 increase.

27 Year Period JULY Data

27 Year     avg  change from  cumulative the coldest the warmest
Period     temp  previous     change     month       month   

1842-1868  16.5                          13.1        20.0
1869-1895  16.5   0.0                    14.3        18.6
1896-1922  17.2  +0.7         +0.7       13.9        21.4
1923-1949  18.0  +0.8         +1.5       13.7        21.3
1950-1976  17.0  -1.0         +0.5       14.8        20.4
1977-2003  17.4  +0.4         +0.9       14.9        20.7

Here we can see the contribution of the anomalously high temperatures of the 1930's. Or were they anomalous? If there was even warmer in the middle ages, this is only part of a normal oscillation and a signature of the end of the so called little ice age. The actual warming in summer happened from 1870 onwards, but between the late 1940's and towards the year 1980 there has been almost as cold in summer as in the 1800's, only after the 1980 the temperatures have again risen, but until now not to the 1930's values. The oscillating warming shows us that the temperature does not follow the rise of any greenhouse gases but are very well in accord to the magnetic changes in the sun.


The 22 year smoothed sunspot number beginning from:

1934    64
1935    70
1936    77
1937    81

has at this time an anomalously sudden rise.

The warm Julies occur just around this change:

1930    19
1931    17
1932    20
1933    18
1934    19
1935    17
1936    19
1937    18
1938    19
1939    18
1940    19
1941    21

Graphs

JANUARY temperature from 1829-1999 to 1842-1986, smoothed by 27 years

Compare this to the Gleissberg cycle. The similarity is obvious.

  • Click: GLEISSBERG CYCLES
  • FEBRUARY temperature from 1829-1999 to 1842-1986, smoothed by 27 years

    JUNE temperature from 1829-1999 to 1842-1986, smoothed by 27 years

    JULY temperature from 1829-1999 to 1842-1986, smoothed by 27 years




    53 YEAR PERIODS

    Lastly, to make the arbitrariness of the borders smaller, I have joined the groups, thus reducing the number of them from 6 to 3. In addition to reducing the amount of chance, we get a clearer comparison to the sunspot numbers, because the general tendency during period 1 was low, during period 2 up, and during period 3 high.

    53 Year Period JANUARY Data

    
    53 Year     avg  change from  cumulative lower (25%) upper (75%)
    Period     temp  previous     change     quartile    quartile
    
    1843-1895  -6.4                          -9.0        -3.5
    1896-1948  -5.3  +1.1                    -6.9        -3.0
    1949-2001  -4.8  +0.5         +1.6       -7.4        -2.0
    
    Solar forcing (in sunspot activity expressed in Wolf number):
    
    during     mean of the  mean of the            
    period     maxima       length of cycle
    
    1843-1895  107 (5)      11.6 yrs (5)
    1896-1948  104 (5)      10.5 yrs (5)
    1949-2001  151 (5)      10.6 yrs (4)
                        
    

    The rise from the latter part of the 19th century to the first part of the 20th century is significantly greater than the rise between the parts of the 20th century.

    What does this mean? The temperature is rising from the lows of the "small ice age", which began about 1370-1400 and culminated in 1690-1700 to the coldest decade during the second year-thousand. What one can see is that the warming, though continuing, is clearly slowing down.

    The quartiles give us some additive information. During the latter part there were many really cold winters (25% below -9 degrees C), when in the 20th century the 25% borderline rose to about -7 degrees. The borderline of the warm winters is the only one of these values which has risen during the 20th century more than from the 19th century value.

    JANUARY, interesting behavior

    January in Helsinki has one interesting peculiarity. From 1894 to 1939 (46 years) there is not a single month, whose average temperature would have been below -10 degrees of Celsius. From 1829 to 1893 (65 years) there were 14 such Januaries (22%). From 1940 to 2001 (62 years) there were 8 Januaries that cold (13%).

    This leads to such a peculiarity that the mean temperature from 1894 to 1939 was -4.7 degrees, but these 46 years was followed a period of 48 years or from 1940 to 1987, whose mean temperature was colder, -6.2 degrees. This is against all theories based on the increase of greenhouse gases, but fits very well with the Sun's activity.

    The last 14 Januaries from 1988 to 2001 correspond to both the greenhouse and solar activity theories. Their mean temperature is only -2.3 degrees C. The high and prolonged solar maximum 1989-1992 is rare if not unique in the whole 250-year period of solar observing.

    53 Year Period JULY Data

    
    53 Year     avg  change from  cumulative lower (25%) upper (75%)
    Period     temp  previous     change     quartile    quartile
    
    1843-1895  16.5                          15.4        17.3
    1896-1948  17.6  +1.1                    16.6        18.8
    1949-2001  17.1  -0.5         +0.6       16.0        18.0
    
    

    The July behavior differs dramatically from the winter behavior. This summer warming, 0.6 degrees, agrees with IPCC estimates of the global warming, but differs radically from any trend. From the three periods, the latter part of the 19th century and the both parts of the 20th century, the middle one is the warmest. In fact, year 1934 is the warmest one during the whole period. When the winter warming has slowed down, the summer warming has turned to cooling. The last 14 Julies have however a mean temperature of 17.7 degrees, but that is still far from the years 1930-1941, when the record-high solar activation was accompanied by a mean of 18.5 degrees.

    Conclusions

    Thus we see that the sunspot activity is as good or partly a better explanation for the general warming trend in climate than the amount of greenhouse gases. In particular, the colder climate from 1895 to 1930 gets an explanation through solar activity, and here there is at least a rival explanation for the warming during recent decades. And the warming since 1988 is easily explained by the two high solar cycles in 1976-1996.

    A 60 Year Cycle?

    There may be a 60-year interval when there is some change in both sunspots and climate:

    1630s: Maunder minimum begins
    1690s: Maunder minimum at its deepest, cold, no sunspots
    1750s: warming temperature and rising Sunspot Number
    1810s: very cold and very few sunspots (1810 none at all)
    1870s: slow cooling and medium Sunspot Number
    1930s: sudden warming and sudden increase in Sunspot Number
    1990s: a new warming and high sunspots since 1930s

  • Global warming in Helsinki?


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