Historical Temperature Patterns for California

Temperature anomalies are calculated by comparing measured values to a baseline to detect changes relative to that baseline. Using data from the Western Regional Climate Center www.wrcc.dri.edu, I explored the temperature anomaly for both the maximum yearly temperature and the minimum yearly temperature in California, USA. The anomaly for both is calculated as the difference between the yearly maximum (or minimum) and a baseline (in this case set as the average maximum (or minimum) for the period between 1949 and 2005). Thus generally, positive anomalies represent years that are warmer than the baseline period and negative anomalies represent years that are cooler.

Minimum temperatures increasing more than Maximum temperatures?

Here I have gone a step further and calculated the difference between the maximum anomaly and the minimum anomaly (the difference between the red and blue lines in the figure above). This value tells us something about what might be accounting for shifts in temperature. In this case, negative values represent periods where the difference between maximum yearly temperature its baseline was less than the difference between the minimum yearly value and its baseline. This means that during periods when this value is negative, even though we may be seeing increases in maximum temperatures, we are seeing even greater increases in minimum temperatures.

(Take home: While it may be getting hotter, its also getting less cold)