Scientific benefits from undertaking data rescue activities: some examples of what can be achieved with long records Phil Jones Climatic Research Unit University of East Anglia Norwich, UK

Summary of scientific benefits Longer records for analysis and assessment of trends Longer records for analysis and assessment of trends Able to place recent records in a much longer context Able to place recent records in a much longer context Provide longer records for assessing impacts of climate change Provide longer records for assessing impacts of climate change Provide longer records for the calibration of natural and documentary proxies Provide longer records for the calibration of natural and documentary proxies Provide longer records for Reanalysis * extensions further back in time Provide longer records for Reanalysis * extensions further back in time Ensures NMSs are aware of early data in their country and their possible shortcomings Ensures NMSs are aware of early data in their country and their possible shortcomings * model-based assimilation of the past – so internally consistent

Placing in a longer context Some long European records Some long European records European summer of 2003 European summer of 2003 Central England temperature extremes since 1772 Central England temperature extremes since 1772

Long European regional temperatures

Extreme Heat Wave Summer 2003 Europe: Heat waves in Central Europe (35-50ºN, 0-20ºE) in JJA Trend plus variability? Max temps in Basle ( and 2003)

Counts of daily temperature extremes in the CET Series Defined as > 90%ile (warm) and < 10%ile (cold) – relative to the period and to the time of year Annual number of warm days/cold days Could have used as the base period. Changing the base period just changes the level

Longer records for assessment of proxy evidence Documentary Records (N. Sweden – where the instrumental record has been extended back from the 1860s to 1800, Klingbjer and Moberg, 2003 ) Documentary Records (N. Sweden – where the instrumental record has been extended back from the 1860s to 1800, Klingbjer and Moberg, 2003 ) Natural Proxy Records (N. Fennoscandian trees and Greenland examples – the latter extending the instrumental record from the 1870s to the 1780s) Natural Proxy Records (N. Fennoscandian trees and Greenland examples – the latter extending the instrumental record from the 1870s to the 1780s) Both extend the instrumental record beyond that readily available from the local NMS Both extend the instrumental record beyond that readily available from the local NMS Klingbjer and Moberg (2003) Int. J. Climatol. 23,

N. Fennoscandia (Haparanda, Klingbjer and Moberg, 2003) Comparison of instrumental, documentary and natural proxy data

SW Greenland temperatures

Seasonal temperatures for SW Greenland From Vinther et al (2006) JGR

Running correlations (30-year window) between Greenland ice cores (winter oxygen isotope values) and SW Greenland winter temperatures

Assessment of changes in extremes Require long series of daily data (earlier CET example) Require long series of daily data (earlier CET example) Consistent measures of extremes Consistent measures of extremes Extremes are how the public and governments perceive climate change Extremes are how the public and governments perceive climate change

10 th (left) and 90 th (right) percentiles Frequency of occurrence of cold or warm temperatures for 202 global stations with at least 80% complete data between 1901 and 2003 for 3 time periods: 1901 to 1950 (black), 1951 to 1978 (green) and 1979 to 2003 (orange) Warm nights are increasing; cold nights decreasing  fewer more 

Longer records to look at the influence of the circulation on surface temperature and precipitation series Paris – daily pressure (MSLP) data can be digitized back to 1670s with only a few missing years Paris – daily pressure (MSLP) data can be digitized back to 1670s with only a few missing years London – back to the 1690s London – back to the 1690s Together these two sites produce a useful winter measure of westerly flow (Paris minus London ≈ NAO) Together these two sites produce a useful winter measure of westerly flow (Paris minus London ≈ NAO)

The Royal Society's Meteorological Record ( ) - London The Royal Society's Meteorological Record ( ) - London Appendix to Phil.Trans publication Appendix to Phil.Trans publication Twice daily observations Twice daily observations Very nearly complete, but gap from Very nearly complete, but gap from Extracted Internal/External Temperature & Pressure Extracted Internal/External Temperature & Pressure [SOURCE: Philosophical Transactions of the Royal Society of London, 1775]

James Jurin's Weather Diary ( ) - London Once daily observation of temperature, pressure & wind direction Once daily observation of temperature, pressure & wind direction Observation time included Observation time included

Joseph de L'Isle's Weather Diary ( ) - Paris Three or four observations per day Three or four observations per day Temperature, pressure, state of the sky Temperature, pressure, state of the sky Mostly readings from 2+ barometers Mostly readings from 2+ barometers Temperature scale problematic Temperature scale problematic

Running 30-year correlation between winter Paris minus London Pressure Index and several temperature series and one precipitation series From Jones et al. (2003) in AGU book on the NAO by Hurrell et al. Correlations generally consistent except for England and Wales precipitation and NH temperatures north of 20ºN

Conclusions Longer records than currently available to each NMS are generally available across Europe and the Mediterranean Longer records than currently available to each NMS are generally available across Europe and the Mediterranean Records need finding, digitizing and then assessing for homogeneity Records need finding, digitizing and then assessing for homogeneity Records often located in libraries/archives, sometimes in other countries. They may take some finding, but they generally exist Records often located in libraries/archives, sometimes in other countries. They may take some finding, but they generally exist