Agree to Disagree
Debate in a non-hostile environment
The Legend for Global Warming Contour Maps can be found at the bottom of this page.
The Global Warming Contour Maps, and Line Graphs, in this article, are based on NOAA’s new ClimDiv temperature series. ClimDiv’s temperatures start in 1895, and it replaces the older USHCN temperature series (US Historical Climate Network). You can read about it here:
When you first look at the following 3 Global Warming Contour Maps, your first reaction may be, “they all look the same”. But look more closely, there are subtle differences. The 3 contour maps are based on the same ClimDiv temperature series, but they are actually displaying 3 different temperatures!
The first contour map is showing AVERAGE temperatures. This is the average of the daily average temperatures (also called Tavg).
The second contour map is showing MINIMUM temperatures. This is the average of the daily minimum temperatures (also called Tmin).
The third contour map is showing MAXIMUM temperatures. This is the average of the daily maximum temperatures (also called Tmax).
You may ask, “why do we care about the difference between Tavg, Tmin, and Tmax?”
There is a good reason to care. If Tmax gets too high, then humans will start dying in the afternoons, when the hottest time of the day occurs.
If that isn’t enough to make you reduce your carbon footprint, then consider an even more horrifying scenario. If Tmin gets too high, then humans will stop getting cold at night. It is enough to give you goose-bumps (actually you won’t get goose-bumps any more, because it won’t be cold enough).
All joking aside, what do the Global Warming Contour Maps tell us about global warming. On the top-right of each contour map, there is a box which tells you the warming rate for the whole interval (1900 to 2018 for these contour maps).
The warming rate for Tavg is +0.85 degrees Celsius per century.
The warming rate for Tmin is +0.94 degrees Celsius per century.
The warming rate for Tmax is +0.75 degrees Celsius per century.
Note that the warming rate for Tavg, is approximately the average of the warming rates for Tmin and Tmax (which is what we would expect).
So now we know, Tmin is warming faster than Tmax (in the USA, at least). At the warming rates calculated here, over a 100 year period, Tmin will increase by +0.19 degrees Celsius, more than Tmax. Note that these numbers were calculated for the period 1900 to 2018. During a lot of that period, global warming was NOT happening. Maybe I should calculate the difference between Tavg, Tmin, and Tmax, over the period 1970 to 2018, when global warming was happening. [***remember not to mention the slowdown/pause here, we don’t want to lose half the audience]
When I get time, I will calculate the difference between Tavg, Tmin, and Tmax, over the period 1970 to 2018, when global warming was happening.
Remember to look at the Legend for Global Warming Contour Maps, to find out what warming rates the different colours represent.
Enjoy looking for differences between the 3 contour maps. It is like those puzzles, where you have to find 10 differences between 2 similar looking pictures. A clue, look at the size of the green areas, and the red areas.