How do AGW skeptics explain the cooling stratosphere?

Question

The stratosphere has been on a long-term cooling trend since global balloon coverage became available in the 1950's.
http://cdiac.ornl.gov/trends/temp/sterin/sterin.html
http://hadobs.metoffice.com/hadat/images/update_images/global_upper_air.png

Climatologists explain this by the increased greenhouse effect, which traps more heat at the surface, allowing less heat to escape to the stratosphere.

Since AGW skeptics don't believe increased CO2 is responsible for the warming surface, what mechanism do they propose that can warm the surface AND cool the stratosphere at the same time?

jbtascam: You're missing the point. If CO2 is responsible for only a fraction of the surface warming, the sun must be responsible for the rest. But increasing solar output would heat the stratosphere too -- which isn't happening.

Ben O: So you can't explain it.

Tomcat: Ozone depletion didn't begin until about 1980, but stratospheric cooling began long before that. Also, ozone depletion cools the stratosphere only at mid and high latitudes, but the tropical stratosphere is cooling too.
http://cdiac.ornl.gov/trends/temp/sterin/graphics/tropics.gif

Dr. Jello: So you can't explain it.

Ron C: Your source doesn't mention the stratosphere at all, nor provide any evidence that land use changes have anything to do with it.

Answer 1

They can't.

Answer 2

I fail to see where this directly attributable to CO2. Perhaps you could enlighten me with some empirical evidence that links CO2? The Laštovička 2004 paper (and the 2006 paper, which I believe used the upper atmosphere trends ending in 1997) mentions that geomagnetic and solar activity have played some role in the cooling upper atmosphere, but there hasn't been any particularly good assessment of the extent of their roles. And increased water vapor likely makes up a majority of the rest. Maybe CO2 is playing a role, and it is likely, but we just don't know. Beyond that, the SSU data shows a lack of cooling for at least 12 years at altitudes of 50km--well into the upper stratosphere and generally high enough to remove the influences of the H2O/ozone interaction. Above that, we have no temperature record, and I have yet to see a more up to date assessment of the trends. "The higher up one goes, the more important the CO2 related cooling is. It's interesting to note that significant solar forcing would have exactly the opposite effect (it would cause a warming) - yet another reason to doubt that solar forcing is a significant factor in recent decades." Read the climate commitment studies of Wigley, et al, and Meehl, et al, to understand how the argument that recent solar activity has not increased is simplistic and wrong. If the level of solar forcing reached prior to 1940 continues (which is unlikely per Solanki), then there will be a solar contribution to the energy imblance resulting in sea level rise for several more centuries. Presumably most of the temperature response occurs in the first few decades, although arguably, that response was delayed by the causes of the midcentury cooling (aerosols, among other things).

Answer 3

Yeah, I hear this argument a lot; “the stratosphere is cooling, just look at this graph.”

But, (and I’m prepared to accept that I’m hallucinating, or something, here) I just don’t see it.

Let’s analyse the graph in your second link…

The graph starts in 1958 and shows cooling until about 1971.

From 1971 until 1982 the cooling stops completely or even reverses slightly.

Then in 1982 we get the El Chichon volcanic eruption which causes a sudden rise and fall that completely obscures the natural trend. Clearly there has been a sudden and dramatic drop between the before and after temperatures.

When the effects of the El Chichon eruption end in about 1985 we then see very slight warming for about 6 years until about 1991 when we get the Pinatubo eruption.

Again, the Pinatubo eruption results in a sudden rise and fall that completely obscures the natural trend and, once again, there is a sudden and dramatic drop between the before and after temperatures.

After Pinatubo we see cooling from 1994 until about 1998.

Finally, from 1998 to the present we see no cooling at all, if anything there is a very slight warming trend.

So, we are lead to believe that the steadily increasing levels of CO2 in the atmosphere should cause a steady cooling of the stratosphere as more and more outgoing radiation is prevented from reaching it.

However, you are showing a graph covering 50 years that, outside of the effects of volcanic activity, only shows cooling for 17 years, while showing no trend or warming for 26 years. Thus, it is not immediately obvious from your graph that continuous, steady stratospheric cooling is actually happening.

It seems to me that since 1971, outside of the effects of volcanic activity there has been very little stratospheric cooling and none at all over the last 10 years when CO2 levels have been rising faster than ever.

Keith, could you educate me as to exactly where this supposed CO2-induced cooling is on your graph?

Answer 4

It's nice to see so much science flown around.

I'm a skeptic because the global warming debate is buried in political and economic agenda.

Skepticism is required.

The decisions made by our politicians impacts their reelection chances and the economy in serious ways.

http://www.epa.gov/ocfo/budget/2008/2008bib.pdf
"EPA estimates that the $35 million for National Clean Diesel Campaign grants will leverage at least an additional $72 million in funding assistance and reduce PM by approximately 5,040 tons, achieving up to an estimated $1.4 billion dollars in health benefits."

This is just a portion of the EPA's budget. Look at the rest of it. There are big dollars here. See the Appendix D Budget tables.

Also see Goal 1 (Clean Air and Global Climate Change)page 1-1
"...protect the stratospheric ozone layer, minimize the risks from radiation releases, reduce greenhouse gas intensity, and enhance science and research."

Note that Reduce Green House Gas Intensity and Enhance Science and Research had an increase in dollars while the other parts of Goal 1 were decreased. The other major goals also include sections for enhancing science and research. The scientific community has a vested interest in the amount of spending in these areas.

I use this source to illustrate the big money associated with the global warming debate. This just shows one gov't agency.

Should we really think that our politicians and those in other nations are trying to save the planet? I think it's just a way for scientist and government to fatten their pockets.

Answer 5

The dominant factor in stratospheric cooling is ozone depletion. Ozone scattering UV energy is the main source of heat in the stratosphere.


"Ozone depletion also explains much of the observed reduction in stratospheric and upper tropospheric temperatures.[6][7] The source of the warmth of the stratosphere is the absorption of UV radiation by ozone, hence reduced ozone leads to cooling. Some stratospheric cooling is also predicted from increases in greenhouse gases such as CO2; however the ozone-induced cooling appears to be dominant.
"

http://en.wikipedia.org/wiki/Ozone_depletion

EDIT:

Keith

If we are going to cherry pick then lets cherry pick, According to your graph neither the surface nor the troposphere showed any warming until 1975 but the stratosphere shows cooling, doesn't exactly explain AGW, does it? And Ozone levels were sparsely monitored before satellite data, so there is no way of knowing what ozone levels were before 1978 with any granularity.

I repeat, Ozone scattering of UV energy in the stratosphere is the primary source of heat in the stratosphere, regardless of latitude.

.

.

Answer 6

Land use/ land cover changes would have the same affect. Only more of the heat is trapped at the surface. Roger Pielke believes land use/ land cover changes are responsible for a greater amount of climate change than rising CO2. Read his conclusions here:

http://climatesci.colorado.edu/2007/09/02/summary-conclusions-of-climate-science/

Edit-
Keith, I used the source only to show that Pielke believes land use/ land cover change is more responsible for global warming than CO2. The fact these changes trap heat at the surface is self-evident. You do not have to believe CO2 is trapping heat at the surface, it could be land use/ land cover changes.

Answer 7

I don't know - could be a lot of things.

I would suggest that the stratosphere gets most of its heat from convection from the lower atmosphere and heating of the stratosphere would be more consistant with global warming.

For believers, AGW can explain anything. Increase in stratospheric temperature, reduction in stratospheric temperature, droughts, floods, decrease in hurricanes, and increase in hurricanes anything can be explained after the event.

What AGW theory can't do very well is predict things before they happen.

Answer 8

AGW skeptics do not claim, as you say, that CO2 is not responsible for any surface warming.

AGW skeptics point out that the most warming you will see as a result of doubling CO2 from 280 ppm to 560 ppm is ~1 degree C.

We are skeptical of flawed computer models and blow-hard, has-been politicians telling us that "catastrophic" warming is upon us, and we must sacrifice our lifestyles and children to the gods of green, lest the entire human race perish in CO2s wrath!

A slightly warmer world will be better for everyone, just as it was in the Medieval warm period!

Much better than a COOLER world (the coming Ice-Age can be alleviated by pumping CO2 into the air - remember THAT scam?)

Answer 9

Climatologist can take any event from the past and blame it on "man made global warming". Droughts, floods, warmer temps, colder temps, rising sea levels, lower sea levels, more hurricanes, fewer hurricanes have all been blamed on warming.

Climatologist can take any event that occurred in the past and find a cause "linked" to global warming. What they cannot do is tell you what events will happen in the future because of "global warming".

The Earths climate changes all the time. There is no static climate. Man is not the reason why the climate changes. These are just natural occurrences.