The weather maps have some disturbing information today that prompts us to take a look at the “big picture” to see what may be going on. What’s most disturbing is the way the Northern Hemisphere as a whole keeps pushing higher and higher with reports of daily air temperature anomalies. All of a sudden the number has popped up to +1.6C, and that’s not from a long pre-industrial baseline. This base is on average only three decades old, 1979-2000. The familiar line graphs of running temperatures for the entire globe all show a steadily rising trend of about 0.18C per decade over this period, giving a 30-year total of just over 0.5C. The global number you see below the map is all the way up to 0.8C for this one day, and it would be even higher were not the Southern Hemisphere doing the world a big favor with minus-0.1, just as they have been reporting for the past several months. The north has really gone crazy, and we need to investigate.
Warm and cold anomalies often have a way of balancing out, but not yesterday. Almost all of the land area in the eastern half of the NH was warm, and there was not a bit of cool in the US lower 48. As we’ll see on the next map, this was actually a pretty big day for all the streams of water vapor that keep flying over our heads. They are easy to spot from color shading alone, most decisively covering a broad area that stretches from equator to pole in the east. Anything having a brown tone will now hold enough vapor to produce a warm anomaly in the NH, and so will the lighter grays in regions where much of the land is elevated, as in large parts of Asia and the western US, or in the far north. Most of Canada is too dark a gray, meaning too dry, and thus too cold.
When studying this map, I can see that a large amount of vapor over the US probably evaporated from ocean waters close to Japan. Likewise, a large share of the vapor over Europe and western Asia originated from waters surrounding the Caribbean Sea and central/north Atlantic. There is almost no limit to how far these streaming batches can travel, up to maybe 10,000 miles, often with the help of fast-moving jetstream winds. Now for a big question: Is there any reason to believe that more vapor than before is now being created and delivered in this way—perhaps even quite a bit more? I think so, at least in the Northern Hemisphere. For one thing, surface water temperatures as a whole are rapidly increasing in this hemisphere, as you can see on this next map, thanks in good part to the steady work being done year after year by CO2, methane and all the other well-mixed greenhouse gases that keep increasing year after year because of human activity. The warmer water created and stored away by their energy is most certainly conducive to higher levels of evaporation. (The SH seas are notably not warming like those in the north, nor is the Equatorial Pacific, for a wholly different set of reasons.)
There is one more piece to this story that I think is critically important. High-altitude vapor streams are only created from surfaces that have reached a certain temperature, which is around 25C. Without an assist from this much energy the new vapors would not be able to ascend the full three to four miles required for reaching the level of the atmosphere where jetstream winds are blowing. The water temperature anomalies revealed on the map above, ranging up to three degrees and possibly more in spots, have served to expand the size of the “warm pool” of surface waters having temperatures at and above the 25C minimum. The areas of expansion are all located beneath the hemispheric “umbrella” of jetstream occupation, and they are also a little closer to the landmasses that surviving vapors are destined to fly over. It is not difficult to pinpoint where warm pool advances have been made in the past thirty years, and we can also see the way naturally effective vapor streams are now forming with regularity along these newly extended outer borders of the warm pool.
Carl