I got to wondering.
Is there a way to compare two different “Greenhouse Gas” levels in the air and see what the actual impact might be? We can’t fiddle with CO2, but nature regularly changes the H2O content of the air.
Has nature “run the experiment” for us? What do you find when you look at two places, at about the same latitude (so with about the same solar heat exposure) but with very different humidities?
As water is widely stated to be a “much more potent green house gas”, ought there not to be some visible impact from this stuff? I mean, if it can be “wobbled” back and forth from “near none” to “near 100%” humidity, that ought to show some effect if the GHG thesis “has legs”, no? If it is “trapping heat”, then there ought to be some heat trapped. And if it is not, then that argues for “other effects” being larger.
So I started looking at some places.
First up is Barstow California. It is at about the dead center of the Mohave Desert. It is a nice “test case” as it is not too far from the Pacific Ocean, yet is kept near bone dry by the mountain range between it, and the ocean. Barstow itself, however, is not all that high in elevation. The Wiki puts it at 2,178 ft (664 m) so not too much elevation impact. Here is the chart from Wunderground:
If we look off to the east, we can find a nice humid city in a similar latitude. Houston Texas.
And, if you look north, but still behind a mountain range from the ocean, you will find Bakersfield. It is more humid than Barstow, but still shielded from the ocean by a mountain range.
Now, looking at these, the GHG thesis says that the ones with the most Green House Gases ought to be racking up more heat. That’s how this whole GHG Global Warming thing is supposed to work. More GHG, more heat. More heat, higher temperatures. Higher temperatures, the sky is falling…
But when I look at that graphs, I see lower temperatures where it is more humid. It is hotter where there is LESS water. Now add to that the fact that Barstow is a couple of thousand feet HIGHER than Bakersfield and Houston, and we’re supposed to adjust for the “adiabatic lapse rate”. From the wiki:
The environmental lapse rate (ELR), is the rate of decrease of temperature with altitude in the stationary atmosphere at a given time and location. As an average, the International Civil Aviation Organization (ICAO) defines an international standard atmosphere (ISA) with a temperature lapse rate of 6.49 K(°C)/1,000 m (3.56 °F or 1.98 K(°C)/1,000 Ft) from sea level to 11 km (36,090 ft). From 11 km (36,090 ft or 6.8 mi) up to 20 km (65,620 ft or 12.4 mi), the constant temperature is −56.5 °C (−69.7 °F), which is the lowest assumed temperature in the ISA. The standard atmosphere contains no moisture. Unlike the idealized ISA, the temperature of the actual atmosphere does not always fall at a uniform rate with height. For example, there can be an inversion layer in which the temperature increases with height.
So, absent inversion layers, and for purposes of aviation safety (so it ought to be usable) the “lapse rate” is about 7 F over 2000 feet (or about 4 C). To make the temperatures “comparable” we ought to ADD that much to Barstow to make up for the cooling from the air rising as it is raised to 2000 feet.
Now, you can make the case that Houston is just too far away. It is influenced too much by the entirely different body of water that is the Gulf of Mexico. But… It is the closer match to Barstow in terms of temperatures. The “very close” city of Bakersfield is much much cooler.
Yahoo Maps makes it all of 130 miles, down slope, from Barstow to Bakersfield. In substantially a straight line West North West.
Oh, and that is the direction “the weather comes from” in that most of the time weather arrives from that 270 degree direction, as you can see in the wind section above.
So if the weather is coming in the same way, off the same ocean, and the adiabatic effects are cooling Barstow, and the GHG level is lower in Barstow, and GHG level is much higher in Bakersfield, why is Barstow hotter?
A Simpler Case
Ah, but there are complications, I hear someone thinking. Different elevations. Different distances from the ocean. Different number of mountains between city and sea. Bakersfield in The Great Valley, Barstow in a desert behind the mountains (though, to me, that’s the thing we are trying to measure, that ‘desert vs not’…)
Is there s simpler case? Can we find somewhere with high humidity in one place, yet low in another, at about the same level (sea level would be nice) and surrounded by the same water? THAT would be an almost pure GHG test. One with high GHG levels, the other low.
The Big Island of Hawaii provides just such a place. The “Kona Coast” has very little rain. About 95% of the time, the air is dry. It is in the “rain shadow” of the mountains, so air rising up them has had the water squeezed out. Hilo is is on the tropical side. Both are at sea level, and about the same latitude. The same Pacific Ocean surrounds them both.
If there is anything to this GHG thesis, then we ought to see much more “heat” trapped at Hilo and higher temperatures from all that “Green House Effect”.
It is a bit more subtile, but still pretty clear. Kona is warmer than Hilo. Oh Dear, those GHG effects are just not cutting it… Notice in particular that the scales chosen by Wunderground are even shifted. The scale is chosen based on the particular temperature ranges in the graphs. Also note that in winter, Kona is about 75 F while Hilo is running about 72 F. Much of the time Hilo is sitting with low excursions on the 70 F line in winter, while Kona barely touchs it with the major excursion dips. In summer, Hilo is about dead on the 75 F line, very rarely getting close to 80 F. Kona is running about 77 F (easier to see if you click on the graph for a bigger version) with peaks regularly hitting the 80 F (27C) line and occasionally passing above it.
Whatever effect water as a “Green House Gas” might be having on the ground temperatures at these places is very clearly and very completely swamped by other atmospheric processes.
As there is much more water in the air than CO2, any effect from CO2 will be even more minor ( I’m tempted to say “completely irrelevant”…)
In the end, it is not “green house gasses” that matter to any recorded changes in the ground temperatures, as we have a couple of existence proofs here that other processes are driving those ground temps, and not GHG levels. For my money, this is a big “dig here”, and one where folks could find a lot of “matched cities” around the world for such comparisons. Cities by the Nile matched to those a bit away in the desert. Perhaps Sydney and Back-o-Burke?
At any rate, as a “first look”, there is little to zero evidence for GHG warming (one is tempted to say “negative”, as in “inverse correlation”).
This is, however, very much in keeping with the “Clouds” thesis. The notion that what is controlling surface temperatures is the hydrological cycle and cloud formation. Another “dig here”, IMHO.
Even if we can not run a CO2 GHG real world experiment, nature has run a real world GHG water vapor experiment for us, and does it every day all around the world. It says “Hydrological Cycle rules, GHG drools”…