Australia's weather bureau rejects newspaper claims of flawed temperature records
Australia's Bureau of Meteorology has rejected a newspaper "audit" alleging widespread errors in its climate data. It acknowledges a small number of duplicated entries but says their effect on the long-term temperature record is statistically irrelevant.
Australia's Bureau of Meteorology (BoM), the national weather and climate agency, has come under fire after the newspaper The Australian ran a series of stories based on a so-called "forensic audit" of the bureau's temperature data. The paper claims the audit found "widespread errors" that raise questions about the integrity of records used for climate analysis. On Thursday night the bureau issued a statement saying the claims rested on several misunderstandings and that accusations of human intervention in the data were false and unsubstantiated.
What ACORN-SAT is
The bureau publishes raw data from its weather stations. Its main dataset for tracking climate change, ACORN-SAT, uses observations from 112 stations and applies quality control to remove the effects of local changes, such as a station being moved. According to this dataset, Australia has warmed by more than 1.5C since 1910.
The claims
The audit report was written by a retired scientist, Geoff Sherrington, and a former computer engineer, Tom Berger. It does not describe its methodology, saying only that statistical software and coding were used. The most prominent example cited by the newspaper is minimum temperatures for August 1907 at Sydney's Observatory Hill, which appear duplicated from August 1867. Data from before 1910 is not used in ACORN-SAT.
The bureau said fewer than 200 observations out of 7 million in ACORN-SAT were affected by duplication. At Observatory Hill, 10 months showed duplicated minimum temperatures, only three of them after 1910, and one more month was found at Charleville, Queensland. Its working hypothesis is that the errors arose in the 1950s or 1960s, when handwritten field books were transferred to punch cards.
On a run of 17 consecutive days at 31C at Palmerville in 2004, the bureau said the audit appeared to overlook that observations were then recorded to the nearest degree, and that lower variability in the tropics makes repeated values more likely.
Reactions
Former prime minister Tony Abbott called for an independent review. Independent Tasmanian MP Andrew Wilkie, who forwarded the report to the bureau, said he had no reason to reconsider his trust in it. ACORN-SAT has already been examined in two independent reviews.
