Today it snowed in Princeton. This alone strikes me as odd, because I can remember very few Octobers in which it has snowed in New Jersey. What strikes me as far more bizarre is that it snowed today and yet it was nearly 70 degrees Fahrenheit only two days ago.
In general, I often wonder whether the weather in the New York City area is not becoming increasingly erratic from day to day. In fact, I often wonder whether sudden shifts in temperature are not likely to prove more dangerous for planet Earth than any gradual change in the mean temperature.
Tonight I decided to do some simple data analysis to determine whether or not there really is greater changes in the day-to-day temperature than there were when I was younger. My analysis of average temperature data for New York City for the past fourteen years left me with some surprising results, which are graphically depicted below.
What do these graphs show?
First, they show that the mean change in temperature from day to day has not consistently grown over the last fourteen years. My perceptions of increasingly unpredictable weather do not seem to have been very accurate.
Second, they show that the mean temperature is, indeed, increasing each year. Global warming seems to be meaningfully affecting the average temperature in New York City.
Third, they show that the weather’s variance has been relatively constant for the last fourteen years. The weather, relative to its mean, is not getting more extreme.
In short, I seem to have totally wrong. The weather may be hotter than before, but it is not some much more erratic than it was ten years ago.