Global mean temperature
Steve Milloy , Bio and Archives--April 20, 2011
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Fortunately, the AMSU's "Channel 5" data, which is nominally focused on the 600 millibar (about 14,000 feet or 4 kilometers in altitude) region of the atmosphere, "sees" the entire region of interest from surface to 5 millibar (up to about 70,000 feet or 20 kilometers).
Why do we want to look at such a large chunk of the atmosphere, even including a bit of the stratosphere?
Mainly because a global mean temperature is a largely meaningless and entirely synthetic metric. There is no "global mean" location where people actually live and experience this fantasy metric. Other than telling us whether we are in an ice age or interglacial period, the global mean temperature isn't really very informative.
On the other hand, a little basic knowledge of the world, namely that the tropics receive the largest amount of solar radiation and do not vary in temperature very much, allows us to infer quite a bit from small changes in bulk atmospheric temperature. How? Because the tropics are so stable temperature-wise, small changes in net atmospheric temperature suggest either larger low-to-high latitude temperature gradients (when the atmosphere is generally cooler) or lower such gradients (when the atmosphere is warmer).
OK. So what?
These temperature gradients are basically the Earth's weather engine — both vertically, as the temperature varies with altitude, and horizontally, as the temperature varies with latitude. "Mother Nature" is a born meddler and hates gradients. She is constantly trying to transfer abundant warmth and moisture from where there is plenty to where there is little.
The greater the disparity, the stronger and faster the winds and the higher the flow of tropical moisture to higher latitudes as "Ma" (Gaia, Pachamama, [insert favored Earth deity here]...) tries to "balance" the planet (or at least rearrange its thermal furniture).
JunkScience.com's Global Thermometer could very well be looking at the birth of a brand new "global storminess and extreme weather event potential" indicator! Perhaps we'll develop an odometer-style readout ranging from green, when the planet is comparatively warmer to red when the net disparity is greatest and extreme weather more likely. Stay tuned for that!
Meanwhile, bear in mind that Earth's surface temperature cycles a couple of degrees Centigrade warmer than the yearly average in the northern summer and a couple below that average in the northern winter, so absolute temperature is not really that important — except for debates about whether the planet has a fever and whether Dr. Obama should bleed it of CO2!
Remember too, that the tropics are relatively stable as far as temperatures go so if the world's atmosphere cools, the potential energy transfer from tropics to poles increases. On the other hand, if the atmosphere is warmer than has historically been the case, then you can expect reduced wind speeds and less extreme precipitation events. If nothing else, JunkScience.com's Global Thermometer might turn out to be useful as a sell signal for wind energy stocks.View Comments
Steve Milloy publishes JunkScience.com and GreenHellBlog.com and is the author of Green Hell: How Environmentalists Plan to Control Your Life and What You Can Do to Stop Them