Climate change (FOI)Climate change (FOI)
Produced by the Freedom of Information officeAuthored by Government of Jersey and published on
29 March 2019.Prepared internally, no external costs.
Request
With proposition P27/2019 lodged with the States, "Climate Change Emergency", can the Government give details of temperature and rainfall changes in the Island for at least the last 100 years, or further if records exist?
A
I have seen a monthly graph published in the JEP, but this gave no mean figures, can these be given?
B
What site(s) are used to collect these figures?
C
What statistical analysis has been made of the correction figures used to account for geographic changes and urban development across the Island, before publishing these results?
D
How reliable is the historic climate data?
E
Has the local climate data been officially approved and audited, and if so by whom and with what qualification?
Response
A and B
Maison St. Louis Observatory, in St Saviour (‘the Observatory’), is recognised as the official site in Jersey for climatological temperature and rainfall records.
The Observatory commenced the daily recording of air temperature and rainfall on 1 January 1894.
Meteorological period average data is calculated over a 30 year period, with monthly and annual values provided in the following tables. The most recent data is included as a 28 year average.
Monthly mean air temperature (°C) |
|---|
Period | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Average |
|---|
| 1901 to 1930 | 6.1 | 6.0 | 7.3 | 9.2 | 12.6 | 14.8 | 16.8 | 17.2 | 15.6 | 12.5 | 8.9 | 7.1 | 11.19 |
|---|
| 1981 to 2010 | 6.6 | 6.5 | 8.5 | 10.4 | 13.5 | 16.1 | 18.1 | 18.3 | 16.5 | 13.4 | 9.9 | 7.3 | 12.09 |
|---|
| 1991 to 2018 | 6.9 | 6.9 | 8.7 | 10.8 | 13.7 | 16.3 | 18.2 | 18.4 | 16.6 | 13.7 | 10.2 | 7.7 | 12.35 |
|---|
Monthly mean total rainfall (mm) |
Period | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | Average |
|---|
| 1901 to 1930 | 75.4 | 62.1 | 63.1 | 53.0 | 46.6 | 46.5 | 46.6 | 55.6 | 64.4 | 92.1 | 99.5 | 98.3 | 803.1 |
|---|
| 1981 to 2010 | 92.4 | 70.8 | 69.4 | 56.2 | 54.7 | 48.2 | 44.3 | 51.3 | 62.7 | 104.7 | 106.3 | 113.7 | 874.7 |
|---|
| 1991 to 2018 | 96.3 | 76.3 | 66.9 | 57.3 | 55.1 | 47.6 | 47.8 | 62.2 | 59.8 | 95.5 | 114.5 | 121.4 | 903.7 |
|---|
C
No corrections for geographic changes and urban development have been made to these values.
D
The historic records were taken initially by the Jesuits who founded the Observatory. The Jersey Meteorological Section (‘Jersey Met’) took responsibility for the site and the climatological records in the 1980’s. The historical data has been audited against other datasets and we consider the records to be of good quality and of similar quality to that of any other official recording site of its age.
E
In 2004 the site was automated by installing a United Kingdom Met Office approved Automatic Weather Station. The records are monitored, maintained and audited by operational meteorologists within Jersey Met and the United Kingdom Met Office.
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