The Effect of Solar Variability on Climate

Calculations and conclusions by

Timo Niroma, Helsinki, Finland


Januaries in 1843-1895

degrees   amount of
Celsius   winters
-16...-14  3 xxx
-14...-12  3 xxx
-12...-10  4 xxxx
-10... -8 10 xxxxxxxxxx
 -8... -6  8 xxxxxxxx
 -6... -4  9 xxxxxxxxx
 -4... -2  7 xxxxxxx
 -2...  0  8 xxxxxxxx
  0...  2  1 x

Januaries in 1896-1948

degrees   amount of
Celsius   winters
-16...-14  1 x
-14...-12  2 xx
-12...-10  - 
-10... -8  7 xxxxxxx
 -8... -6 13 xxxxxxxxxxxxx
 -6... -4 13 xxxxxxxxxxxxx
 -4... -2 10 xxxxxxxxxx
 -2...  0  5 xxxxx
  0...  2  2 xx

Januaries in 1949-2001

degrees   amount of
Celsius   winters
-18...-16  1 x
-16...-14  -    
-14...-12  2 xx
-12...-10  2 xx
-10... -8  7 xxxxxxx
 -8... -6  6 xxxxxx
 -6... -4  6 xxxxxx
 -4... -2 14 xxxxxxxxxxxxxx
 -2...  0 14 xxxxxxxxxxxxxx
  0...  2  1 x

The first interval differs from the second and third (or approx. the 19th century) in one essential respect. When the temperature in the second interval reaches both the temperature ranges of -8...-6 and -6...-4 degrees C 13 times and in the third interval the temperature ranges of -4...-2 and -2...0 degrees C 14 times, there is no such 4-degree accumulation in the first interval.

We must be satisfied with 10 times when the greatest amount of months is reached between temperatures of -10...-8 degrees C in the first interval. If go down to 7 occurrences all the five 2-degree intervals from -10 to 0 degrees C are reached. Same downing brings to the second interval a continuous temperature range from -10 to -2 degrees C, but to bring as broad a temperature range for the third interval we must include 6 occurrences, which gives a continuous temperature range from -10 to 0 degrees C.

A second essential difference between the three intervals is that all 2-degree temperature ranges between -16 and -10 degrees in the first interval get at least 3 hits, making together 10 hits, compared to 3 hits in the second and 5 hits in the third interval. One of the hits in the third interval goes into the range of 16-18 degrees C (year 1987), the all-time cold during the last 170 years.

As the histogram 1843-1895 shows there is one very lonely bystander on the lower side of the temperatures. That is the year 1861 with a temperature of -15.3 degrees C. What makes this interesting is that the second coldest winter occurred in 1862 with a temperature of -14.4 degrees. And the fourth place is taken by the winter 1867 with -13.6 degrees. What makes this still more interesting is that two of the four warmest winters occurred in 1863 (-1.1 degrees) and 1866 (-0.1 degrees). So something very strange was happening in the climate in 1861-1867. In 1867 the extreme cold continued to June, when all months had temperatures about 5 degrees below the normal.

The histogram 1896-1948 shows three lonely bystanders at the lower side of the temperatures. The loneliest is 1942 with a temperature of -15.9 degrees C, 81 years later than the previous record. Oddly enough, the two lonely ones, only a little milder occurred in 1941 and 1940 with temperatures of -12.7 and -12.4, respectively. So what happened in 1861-1862 occurs again in 1940-1942. And the lonely ones on the warm side occur in 1930 (+1.4 degrees), 1925 (+1.1 degrees), and 1932 (-0.6 degrees). In interesting corollary with the previous interval are the years 1925 and 1926. While the latter was the fourth coldest during this interval, the former was the second warmest. So the years of 1925-1934 had same kind of turbulence as the years 1861-1867.

The histogram 1949-2001 shows clearly a tendency of winters to tighten towards some temperature. When the first histograms shows very dispersed temperatures: six winters there are in 3 different ranges: -8.0...-8.9, -6.0...-6.9, and -1.0...-1.9 degrees C added the 5 winters range of -5.0...-5.9 degrees C, all varying throughout 5 decades, as wide a dispersal is not seen in the 20th century. So when we can say that when during the latter part of the 19th century there was no typical winter temperatures (-1 was as normal or typical as -9 or anything between), the first part of the 20th century shows already a strong concentration in the temperature range of -6.0... -6.9 degrees C with 12 winters or 23% falling in this category. A secondary concentration exists between the temperatures of -4.0... -4.9 degrees C with 8 winters. Altogether 25 winters or nearly half during this period fall in the range of -4.0...-6.9 degrees C, which thus is the typical range for the second interval.

During the third interval there is clear concentration of temperatures between -1.0...-3.9 degrees C with 23 winters or 43% of winters falling in this category. So this shows a grest tendency in winter temperatures during the 20th century to move further from the Little Ice Age temperatures towards a new Medieval Optimum.

If we look at the extremes, we see that the all-time coldest January since 1829 was in 1987 with a temperature of -16.5 degrees C. The second coldest during this interval was two years earlier, in 1985, with a temperature of 13.9 degrees C. The third and fourth coldest winters are also pairwise 19 years earlier, or in 1968 and 1966, with a temperature around -12 degrees C. Only one January had a plus-temperature, 1989 with its 0.5 degrees C. Between 0.0 and -0.9 there is a reord amount of 5 winters: 1949, 1975, 1983, 1992 and 1993. We can now again see oddity from the series 1983, 1985, 1987 and 1989 are found the two coldest winters surrounded by two very warm winters. The 1980's has thus a rival in its variability only in the 1870's, 110 years earlier. Something comparable is also in the middle of these periods, from 1925 to 1942.


Julies in 1843-1895

degrees amount of
Celsius summers
13...14  1 x
14...15  7 xxxxxxx
15...16 13 xxxxxxxxxxxxx
16...17 13 xxxxxxxxxxxxx
17...18 12 xxxxxxxxxxxx
18...19  4 xxxx
19...20  3 xxx

Julies in 1896-1948

degrees amount of
Celsius summers
13...14  2 xx
14...15  2 xx
15...16  6 xxxxxx
16...17 10 xxxxxxxxxx
17...18 10 xxxxxxxxxx
18...19 14 xxxxxxxxxxxxxx
19...20  5 xxxxx
20...21  2 xx
21...22  2 xx

Julies in 1949-2001

degrees amount of
Celsius summers
14...15  3 xxx
15...16 11 xxxxxxxxxxx
16...17 14 xxxxxxxxxxxxxx
17...18 12 xxxxxxxxxxxx
18...19  7 xxxxxxx
19...20  2 xx
20...21  4 xxxx

The first interval has a wide range of favorite temperatures. Three temperatures, 15-16, 16-17, and 17-18 degrees C all have 12-13 hits. The second interval, approx. the first part of the 20nd century, is the warmest of the three intervals, and in the histograms it becomes evident, when the first place in the amount of hits is taken by the range of 18-19 degrees C with 14 hits.

We can say that the normal temperature during the first interval was from 15 to 18 degrees C and during the second interval from 18 to 19 degrees C. The third interval should be shown with half a degree histogram, because the dividing line between high and medium rate of hits goes around 17.5 degrees (8 and 4 from 17.1...17.5 and 17.6...18.0, respectively). However, if we take the whole degree histogram, and take as the limit at least 10 hits, the first and third interval are equal: the typical temperature range was from 15 to 18 degrees C, when the second interval has a typical range of 16 to 19 degrees C.

The lowest temperatures in the first and second intervals are 13-14 degrees C, but when the first interval has no month over 20 degrees C, the second interval has 4 times a July in the temperature range of 20-22 degrees C, with all time high (during the 170 years) in 1914 and 1927. In the extreme values the third interval differs from both the others. it has four summers just above 20 degrees C (20-20.5), but none below 14.5 degrees C.

The histogram 1843-1895 shows one really cold summer, that of 1862, with a temperature of 13.1 degrees C. The second coldest is the next summer or 1863 with a temperature of 14.3 degrees C. The fourth to sixth coldest are the summers 1844, 1848 and 1849 in that order with temperatures 14.3...14.6 degrees C. First we can notice that the famous 1860's are here again, the cold weather during the beginning of the 1860's concerns also summers. If we take the two coldest winters and the two coldest summers during this intervals, we get a the winter 1861, the whole year 1862 and the summer 1863, with two very warm interruptions, namely the summer 1861 and the winter 1863.

Anyway most of the summers, 39 exactly or 74% are rather smoothly between 15.0 and 17.9 degrees C.

The histogram 1896-1948 differs in many respects from that of the previous period. The range 14...15 degrees C has dropped from 7 to only 2 summers and the range 15...16 degrees C from 13 to only 6 summers. The ranges 16...17 and 17...18 degrees C has dropped from 12-13 to 10 summers in both groups. The reversed trend comes only in the range 18...19 degrees C now having 14 summers instead of only 4 summers in the previous period. So there really is a complete turnover. And when we add that the highest range in the previous period was 19...20 degrees C with only 3 summers, this period has 5 summers in this periods, and still in the ranges 20...21 and 21...22 degrees 2 summers in both, sowe have in the above 19 degrees C category now 9 summers or the previous 6% is now 17%.

As the histogram shows there are four summers that are clearly cold compared with other summers in this period: 1902, 1904, 1921 and 1928 with all in the range of 13.7...14.5 degrees C, when all the others have a temperature at least 15.5 degrees C. In the warm end, the two distinguishing summers are 1914 and 1927, with temperatures of 21.3...21.4 degrees, almost one degree above all the others. Here is again one interesting contrast: when the summer 1928 was coldest in this period, the summer 1927 was the second warmest. The only year when both winter and summer were warm is 1925. When we add cold winter of 1926, we have here again in 1925-1928 an interesting turbulence.

Now most of the summer, 34 or 64% are smoothly between 16.0 and 18.9 degrees C.

Winters during the first part of the 20th century were warmer than those in 19th century and the winters during the latter part of the 20th century were warmer than in beginning of the last century. Similarly the summers during the first part of the 20th century were warmer than during the 19th century, but now there occurs a deviation from the general warming pattern: the histogram 1949-2001 shows that during the latter part of the 20th century summers were COLDER than during the first part.

As the histogram 1949-2001 shows there really are no lonely outsiders on the cold side: there is instead a growing series of temperatures from 14.8 to 17.5 degrees C, after which the amount of temperatures per unit drops abruptly to half of the previous density. There are 22 summers with temperatures from 16.1 to 17.5 degrees C, but only 12 summers with temperatures from 17.6 to 19.5 degrees C. In the denser part there are two really dense peaks, the first at 16.2-16.3 degrees C with 7 summers and the second at 17.1-17.5 degrees C with 8 summers.

At the warm end there are 5 lonely outsiders between 19.8 and 20.4 degrees C. They occurred in years 1972, 1973, 1988, 1994 and 2001, all except 1994, having a temperature in range 20.2...20.4 degrees C. There are no extremities on the cold and warm side near each other, except the years 1996 (third coldest with 15.0 degrees C) and 1997 (sixth warmest, 19.2 degrees C).

A 2000 year perspective for the climate and sunspots:
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