Guest Post by Willis Eschenbach
For several years now, I’ve been saying that the greatest warming is happening in the northern subtropics, at night, in winter… and today I realized that I’ve always believed it because I’ve been reading. it’s somewhere.
Now, those who know me know that I don’t like to trust any claim until I check the numbers myself. So I set out to do it.
I thought I’d look at the fairly recent land data because we have more of it than older data or ocean data. Overall, these are decadent trends in terms of maximum temperature. I’ve used Berkeley Earth Data, although I really doubt it exaggerates warming, for a couple of reasons. First, all the records seem to exaggerate warming, and second, I’m interested in relative trends, not absolute trends.
Figure 1. Trend of maximum monthly mean temperature, 1950-2020
We can see that the greatest variation in maximum temperature is in the Northern Hemisphere (0.23°C/decade), with the Arctic warming the fastest.
Next, here is the trend of the average monthly minimum temperature. Of course, this is the nighttime temperature.
Figure 2. Minimum temperature trend, 1950-2020
Again, minimum temperatures in the Northern Hemisphere are actually warming the fastest. They also heat up faster than maximum temperature (0.25 °C/decade versus 0.23 °C/decade). Also be aware that there are actually a few areas where nighttime temperatures have cooled down…
Finally, I looked at summer and winter trends by latitude. Figure 3 below shows that result.
Figure 3. Trend of minimum and maximum surface temperature by latitude, winter and summer in the northern hemisphere (NH).
Turns out that my statement was correct. The greatest warming is actually in the northern subtropics, in winter, at night (dark blue line). Second largest warming in the same place, same season, during the day. As you can see, winter warming is increasing as you go north of 45°N latitude.
And what are the average daytime and nighttime temperatures of NH winter? Figure 4 shows that result.
Figure 4. Average daytime (red) and winter night temperatures in the Northern Hemisphere, by latitude
Note that at a latitude of about 45°N (thin vertical line in blue), near where the increase in warming begins, mean daytime temperatures are just below freezing, and mean nighttime temperatures are -13°C (9°F)… cold.
This is good news, because I doubt whether the people of Vladivostok will be content with slightly warmer winter nights…or days, for that matter.
And having slept a few times in my youth on a piece of cardboard on the streets of Manhattan in the winter, with newspapers wrapped around my legs and arms inside my clothes to keep out the cold, I can personally guarantee that the homeless housing in New York The city wouldn’t object if winter nights were a little warmer.
Makes me so happy because tonight I’m in my warm fossil fuel house…
The best of late autumn for all,
w.
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