Upper Atmosphere Cooling & Contracting Rapidly - Poss. GHG Response

[hatrack]

"The highest layers of the Earth’s atmosphere are cooling and contracting, most likely in response to increasing levels of greenhouse gases, according to a new study by scientists at the Naval Research Laboratory (NRL). This contraction could result in longer orbital lifetimes for both satellites and hazardous space debris.

In a paper to be published February 5 in the Journal of Geophysical Research - Space Physics, John Emmert, Michael Picone, Judith Lean, and Stephen Knowles report that the average density of the thermosphere has decreased by about 10 percent during the past 35 years. The thermosphere is the highest layer in the atmosphere, and begins at an altitude of about 90 kilometers <60 miles>.

The study utilized orbital tracking data for 27 space objects that have been aloft for over 30 years and whose closest approach to the Earth ranges from 200-800 kilometers <100-500 miles>. The Space Shuttle typically orbits at 300-450 kilometers <200-280 miles>, and the International Space Station is at an altitude of about 400 kilometers <200 miles>. Although the atmosphere is extremely thin in this region (the air at the Earth’s surface is a trillion times thicker), it is enough to exert a drag force on satellites, causing their orbits to decay slowly and ultimately resulting in a fiery disintegration at lower altitudes. By analyzing changes in the orbits of the selected objects, the scientists derived the yearly average density encountered by each object. After adjusting for other factors, the data from every object indicated a long-term decline in the density of the thermosphere.

This decrease in density had been predicted by theoretical simulations of the upper atmosphere’s response to increasing carbon dioxide and other greenhouse gases. In the troposphere (the lowest layer of the atmosphere) greenhouse gases trap infrared radiation, causing the well-known "global warming" effect. Higher in the atmosphere, above about 12 kilometers , however, these gases actually enhance the ability of the atmosphere to radiate heat out to space, thereby causing a cooling effect. As the amount of carbon dioxide increases, the upper atmosphere becomes cooler and contracts, bringing lower-density gas to lower heights. Consequently, at a given height, the average density will decrease. Because each layer of the atmosphere rests on the layers below it, small changes at lower altitudes become amplified at higher altitudes. The NRL study found that the observed decrease in density depends on height in the same way as predicted by the theoretical simulations, indicating that greenhouse gases are a likely source of the change."

EDIT

[SpiralHawk]

1. Relax, Chimpy is all over this issue

as soon as he resolves the "profound moral dilemma" created by the exposure of Janet Jackson's breast during the Super Bowl ("roll the tape replay again, Carl") he plans to order some more "studies" of the "possibilities" that runaway corporo-industrial pollution and auto exhaust have anything at all to do with this.

So, rest easy. kOmMander cHimPee will have an answer to all of this by 2008 or whenever, and if he can't figure it out, Jebbie and Marvin and Neil will form a Task Force with the bin Laden boyz, and suggest some more studies to commence in 2009.

[hatrack]

2. Yes, it's part of his energy plan that includes the Magic Porridge Car

It'll produce unlimited amounts of porridge when we say "Cook, pot, cook!" for the concept Porridge Car that'll be unveiled sometime after he's out of the White House.

(With thanks to Tom Toles, from whom I stole this).

Oh, and did I mention more studies and research?

[Viking12]

3. the Naval Research Laboratory??

More damn whacko-enviro, commie sympathizers perpetrating a scientific hoax :)

[seasat]

4. Y'all wouldn't believe the amount of research done by NRL

A lot of the research has dual use, it applies to the military and to enviromental studies. A lot of oceanographic funding comes from the military too.

I didn't see it in the article but ozone depletion also contributes to stratospheric cooling. The ozone itself absorbs UV radiation and contributes to heating of the stratosphere.

[Dogmudgeon]

5. Not a good thing

Increasing the gradient between the ground and upper atmospheric temperatures has been linked with greater weather instability, more storms, and less predictability. As the upper atmosphere becomes colder, the lower atmosphere becomes warmer -- and vice-versa. This has been proposed as a mechanism in sudden climate change scenarios.

In fact, most of the sudden climate change indicators have begun to move quickly. Scientists at Woods Hole have determined that the North Atlantic thermohaline currents are breaking down ... now. Cloud cover is increasing, and insolation (sunlight reaching the ground) is also down by over 10%. It is starting to look like the early phase of either a mini-ice-age (like the Younger-Dryas period) or the Real Thing.

A large part of this is natural and not caused by humans. But I can't help but wonder how much more quickly it has been brought on human industrial activity.

It is entirely possible that these trends will reverse themselves for a time, but I think the overall pattern is a return to a full ice age within the next thousand years. Preferably not next year!

--bkl
Ice, ice, baby!

[jpak]

6. There was a similar paper in Nature a few years back

If I remember correctly, the authors used radio transmissions to measure the height of the upper atmosphere - they concluded it was contracting in response to greenhouse forcing.

Two independent lines of evidence now point to a significant change in the physical stucture of the atmosphere as the result of human activity.

More evidence that global warming is a myth...

<sarcasm>

[enki23]

7. this is a *good* thing, you know

it'll help keep the new Star Wars satellites in orbit longer. for the safety and security of all americans, then, we should try to increase the amont of greenhouse gasses we produce.