The data Franzke used came from the “European Climate Assessment & Dataset Project.” For Fuhlsbüttel, the records reach back for 127 years – much farther than in most other districts; for e.g. Bergedorf, the mean annual temperatures only date back to 1966.
The year with the highest mean temperature to date was 2014 with 10.7 degrees Celsius, nearly two degrees above average; the coolest year was 1940, with only 6.7 degrees. Further, there is an abrupt climb starting in 1990: from this point on, nearly every stripe is red; in other words, the annual mean temperature was nearly always above average. According to Franzke, who is an expert statistician, “That’s definitely no coincidence. The rise in temperatures is statistically significant and can’t be explained by natural fluctuations.”
Ed Hawkins from the University of Reading created the first climate bar codes only a few months ago. The idea has since caught on worldwide, and can even be seen on ties and coffee mugs.