Below is a collection of graphs showing visualisations of the HadCRUT global temperature estimations.
HadCRUT is a global temperature dataset, providing gridded temperature anomalies across the world as well as averages for the hemispheres and the globe as a whole.
According to climate researcher Ole Humlum, the global temperature records can be devided into three quality classes. The records with highest quality is the global satellitte datasets (UAH and RSS). The second highest quality records is the HadCRUT records.
As the satellite records only go back to late 1970s, and media and government actors usually refers to records going back to 1800s, the HadCRUT dataset is presented here.
There are three records presented here, HadCRUT3, HadCRUT4, HadCRUT5 Non-Infilled and HadCRUT5 Analysis. By filtering the different records, you can investigate the evoluation in the temperature estimations.
HadCRUT3 records has been updated to May 2014, HadCRUT4 will be updated until December 2021. After that only the HadCRUT5 records will be updated.
What is the estimated trend in global temperatures, what is it’s uncertainty, and has the historical estimation changed over time?
Why two HadCRUT5 versions?
The following explanation is given by Climatic Research Unit (University of East Anglia) for the rationale behind duplicate temperature records with the HadCRUT5 version:
For the global land and ocean dataset, there are also now two versions.
HadCRUT5 Non-Infilled uses similar gridding methods as HadCRUT4, i.e. temperature anomaly values are estimated only in grid cells close to where we have measurements.
HadCRUT5 Analysis estimates temperature anomalies using the spatial connectedness of temperature anomaly patterns. This extends the the geographical coverage by estimating temperature anomalies further from the available measurements. This improves the representation of less well observed regions in our estimates of global and hemispheric temperature change.
For our best estimate of how global temperature has changed since 1850, we recommend you use the HadCRUT5 Analysis.
Thus, HadCRUT5 Analysis extends estimation of temperatures to regions where we have with low observation coverage, most notably the polar regions.
Uncertainty
Extracts from Met Office UK FAQ site related to HadCRUT4 (updated 29 March 2012):
Q: What are the uncertainties and what implications do they have for the records?
A: The accuracy with which we can calculate a global average varies from year to year depending on many factors. The new version of HadCRUT provides much more detailed information enabling anyone to see what the uncertainties are and whether they affect their analysis.
Q: Was 2010 (or 1998 or 2005) the warmest year on record?
A: The short answer is, maybe. It is not possible to calculate the global average temperature anomaly with perfect accuracy because the underlying data contain measurement errors and because the measurements do not cover the whole globe.
However, it is possible to quantify the accuracy with which we can measure the global temperature and that forms an important part of the creation of the HadCRUT4 data set. The accuracy with which we can measure the global average temperature of 2010 is around one tenth of a degree Celsius. The difference between the median estimates for 1998 and 2010 is around one hundredth of a degree, which is much less than the accuracy with which either value can be calculated.
This means that we can’t know for certain – based on this information alone – which was warmer. However, the difference between 2010 and 1989 is around four tenths of a degree, so we can say with a good deal of confidence that 2010 was warmer than 1989, or indeed any year prior to 1996.
Imporant information
- The graphs are interactive, use filters to change between HadCRUT versions, attributes, and months.
- Below the graph you can change between pages. By default the annual estimates are shown, monthly estimates are shown in page 2.
- The graphs are filtered to HadCRUT4 by default as this was the version used between 2014 and 2020, and thus the recently most circulated global HadCRUT estimates.
Chart 1 – HadCRUT Global Temperature Estimates with Uncertainty Range
Chart 2 – Comparison of HadCRUT versions
Chart 3 – Evolutions of HadCRUT estimates
This graph shows the change in estimated temperatures against the previous version starting with HadCRUT3 to 2013, and against HadCRUT4 from 2014 as default.
For example – the blue bars shows the changed estimate of HadCRUT4 versus HadCRUT3.
The total change to the current recommended version (HadCRUT5 Analysis) is represented as the total bar (irrepective of colour).
Table 1 – HadCRUT versions with uncertainty limits
Evolution of Observation Coverage
The estimated grid coverage maps give a good overview of the observation coverage between the various versions.
HadCRUT3:
HadCRUT4:
HadCRUT5:
Showing the evolution of observation coverage in addition to the current coverage including filled in estimated observations.
HadCRUT – informasjon og forskning:
HadCRUT3:
Link til Met Office UK information page: Met Office Hadley Centre observations datasets (HadCRUT3)
HadCRUT4:
Link til Met Office UK information page: Met Office Hadley Centre observations datasets (HadCRUT4)
HadCRUT5:
Link til Met Office UK information page: Met Office Hadley Centre observations datasets (HadCRUT5)
Morice, C.P., J.J. Kennedy, N.A. Rayner, J.P. Winn, E. Hogan, R.E. Killick, R.J.H. Dunn, T.J. Osborn, P.D. Jones and I.R. Simpson (in press) An updated assessment of near-surface temperature change from 1850: the HadCRUT5 dataset. Journal of Geophysical Research (Atmospheres) doi:10.1029/2019JD032361 (supporting information).’
The illustration photo shows the September 2021 anomaly vs. 1961-1990 mean as estimated with HadCRUT4. From the UK Met Office web site, accessed 26.10.2021.