When Was The Last Time It Was Colder Than Average Where You Live?

I was curious about how evenly distributed the observed warming is, so I put together a few visualizations of it.

To determine when it was last colder than average, I used a really simple algorithm:

• Find the average temperature for each lat/lon location over each decade
• Find the average temperature for each lat/lon location from 1850-1900
• Note the last decade average that was lower than the 1850-1900 average for each lat/lon

That's it. What these plots represent are the last decade that each location was colder than the period from 1850-1900. I've included the code used (I used MATLAB for this) and the data set at the end of the post.

For the results, here is the US:

Here is a hoverable version of the same data:

Here is the same thing for Europe:

Again, hoverable version:

It struck me as interesting that in both locations, the 1970's were the last decade in which any of the locations were colder than average. If you look at plots of temperature anomaly though, they all ramp up a bit before then and we've seen really dramatic warming since then, so it makes sense.

Sample code is here

Data are 1/4 deg monthly sets here