Patterns of climate change across Scotland: technical report - Sniffer

SNIFFER Project CC03: Patterns of Climate Change across Scotland April 2006
has increased significantly. At a regional level there have been significant temperature rises
since 1914, particularly in East and West Scotland where temperatures have risen from an
annual average of approximately 6.7°C (East Scotland) and 7.8°C (West Scotland) to 7.5°C
and 8.3°C respectively. The apparent inconsistency between these two sets of figures, with
the fact that more of the regions and seasons show significant trends during the later
(shorter) period, suggests a more rapid rise in temperatures over this later part of the
twentieth century. This can also be seen in Figure 3, which presents the ninety-year timeseries
of annual mean temperatures for the regions (1914 to 2004).
Table 2 - Mean Temperature changes (°C), 1961 to 2004 and 1914 to 2004. Statistically
significant trends are shown in bold (significant at the 1% level) or italic (significant at the 5%
level) type.
1961-2004 1914-2004
North East West
North East West
Scotland Scotland Scotland Scotland Scotland Scotland Scotland Scotland
Spring 1.03 1.23 1.20 1.14 0.59 0.83 0.66 0.69
Summer 1.06 1.12 1.08 1.08 0.50 0.59 0.43 0.51
Autumn 0.64 0.68 0.66 0.66 0.46 0.85 0.68 0.64
Winter 1.03 1.39 1.31 1.22 0.02 0.45 0.33 0.24
Annual 0.92 1.08 1.04 1.00 0.37 0.66 0.51 0.50
Figure 3 - Annual mean temperature (°C) for Scottish regions, 1914 to 2004, with
smoothed curve. The vertical dashed line marks the position of 1961.
Annual Mean temperature for the three Scottish districts, with 30-year smooth filter, 1914-2004
9.0
8.5
Mean temperature (deg C)
8.0
7.5
7.0
6.5
6.0
5.5
1914
1917
1920
1923
1926
1929
1932
1935
1938
1941
1944
1947
1950
1953
1956
1959
1962
1965
1968
1971
1974
1977
1980
1983
1986
1989
1992
1995
1998
2001
2004
N Scotland
E Scotland
W Scotland
The pattern of Scottish regional temperature change (Figure 3), where the weighted running
mean is shown by the smoothed curve, is very similar to that seen in the global mean
temperature time-series (not shown). Here there is an increase throughout the first half of the
twentieth century, then a decrease throughout the fifties and sixties before rising once again
toward the end of the century. It is also clear that average annual temperature in each region
is now higher than at any other time in this record, i.e. since 1914. The inter-annual, or yearby-year,
variation in temperatures is also apparent in Figure 3. It is interesting to note that
whilst the West Scotland region is slightly milder than the other two, that all three regions see
very similar inter-annual variation across the period, i.e. when one region experiences a
warm or cold year so do the other two. The mapped trends in seasonal mean temperature for
the period 1961 to 2004 are presented in Figure 4. It can be seen that average seasonal
temperatures have increased everywhere in Scotland during this period, although the
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