Saturday, August 2, 2014
Exerpted from http://hockeyschtick.blogspot.com/2014/08/why-does-co2-cool-stratosphere-warm.html
I have been searching for an explanation of a predicted mid-tropospheric "hot spot" which Anthropogenic Warming Theory has long touted as one result of theory. Below is an excerpt from "The Hockey Schtick" blog which discusses this issue. First however, note from the graphic above that this alleged hot spot still awaits detection, for whatever implications that may have for AGW theory.
A paper published today in the Journal of Climate uses "a chemistry-climate
model coupled to an ocean model" to arrive at a number of seeming
contradictory conclusions about the opposing radiative effects of the
greenhouse gases CO2, water vapor, ozone, and halocarbons (CFCs)
depending upon the levels in the atmosphere where each of these are
present.
Conventional AGW theory proposes the existence of a mid-troposphere "hot spot" and an overlying cooling of the stratosphere because heat is "trapped" in the "hot spot" and therefore can't make it to the stratosphere. However, despite millions of weather balloon and satellite observations over the past 60 years, the "hot spot" has still not been found and thus questions the fundamental theory of anthropogenic
According to the abstract below, the net radiative effect of these greenhouse gases in the troposphere vs. tropopause vs. stratosphere are:
GHG troposphere tropopause stratosphere
CO2 warming warming cooling
water vapor ? cooling cooling
ozone ? warming warming
CFCs warming ? cooling?
I've been asking CAGW believers for years why CO2 and other greenhouse gases have opposite radiative effects upon global temperatures depending upon where they happen to be located in the atmosphere, and have yet to receive a satisfactory answer. Even the warmists themselves can't seem to agree on this fundamental question underlying CAGW theory. Wikipedia propagandist William Connolley disagrees with Gavin Schmidt and RealClimate on why increased greenhouse gases would cause the stratosphere to cool.
RealClimate links to this site (update: link broken, but this is a mirror site) for their explanation, which upon examination makes no sense, violates basic physics including the 1st and 2nd laws of thermodynamics and maximum entropy production, contains contradictions, and then concludes "We now know that stratospheric cooling and tropospheric warming are intimately connected and that carbon dioxide plays a part in both processes. At present, however, our understanding of stratospheric cooling is not complete and further research has to be done.":
Excerpt in blue text from the site Gavin & RealClimate claim has the definitive answer to the question "why does the stratosphere cool?" [emphasis added]:
Why does the stratosphere cool?
There are several reasons why the stratosphere is cooling. The two best understood are:
1) depletion of stratospheric ozone
2) increase in atmospheric carbon dioxide
Cooling due to ozone depletion
The first
effect is easy to understand. Less ozone leads to less absorption
of ultra-violet radiation from the Sun. As a result, solar radiation is
not converted into heat radiation in the stratosphere. So cooling due
to ozone depletion is simply reduced heating as a consequence of reduced
absorption of ultra-violet radiation. Ozone also acts as a greenhouse
gas in the lower stratosphere. Less ozone means less absorption of
infra-red heat radiation and therefore less heat trapping.
At an altitude of about 20 km, the effects of ultra-violet and infra-red radiation are about the same. Ozone levels decrease the higher we go in the atmosphere but there are other greenhouse gases present in the air which we have to consider. |
Cooling due to the greenhouse effect
The second effect is more complicated. Greenhouse gases (CO2, O3,
CFC) absorb infra-red radiation from the surface of the Earth and trap
the heat in the troposphere. If this absorption is really strong, the
greenhouse gas blocks most of the outgoing infra-red radiation close to
the Earth's surface. This means that only a small amount of outgoing
infra-red radiation reaches carbon dioxide in the upper troposphere and
the lower stratosphere. On the other hand, carbon dioxide emits heat
radiation, which is lost from the stratosphere into space. In the
stratosphere, this emission of heat becomes larger than the
energy received from below by absorption and, as a result, there is a
net energy loss from the stratosphere and a resulting cooling. Other
greenhouse gases, such as ozone and chlorofluorocarbons (CFC's), have a
weaker impact because their concentrations in the troposphere are
smaller. They do not entirely block the whole radiation in their
wavelength regime so some reaches the stratosphere where it can
be absorbed and, as a consequence, heat this region of the atmosphere.
|
Where does cooling take place?
The impact
of decreasing ozone concentrations is largest in the lower stratosphere,
at an altitude of around 20 km, whereas increases in carbon dioxide
lead to highest cooling at altitudes between 40 and 50 km (Figure 3).
All these different effects mean that some parts of the stratosphere are
cooling more than others.
|
Other influences
It is
possible that greenhouse warming could disturb the heating of the
Arctic stratosphere by changing planetary waves. These waves are
triggered by the surface structure in the Northern Hemisphere (mountain
ranges like the Himalayas, or the alternation of land and sea). Recent
studies show that increases in the stratospheric water vapour
concentration could also have a strong cooling effect, comparable to the
effect of ozone loss.
Conclusions
We now
know that stratospheric cooling and tropospheric warming are intimately
connected and that carbon dioxide plays a part in both processes. At
present, however, our understanding of stratospheric cooling is not
complete and further research has to be done. We do, however,
already know that observed and predicted cooling in the stratosphere
makes the formation of an Arctic ozone hole more likely.
[end excerpt]
Note the quote above "In the stratosphere, this emission of heat [proper term is radiation] becomes larger than the energy received from below by absorption and, as a result, there is a net energy loss from the stratosphere and a resulting cooling." Basic physics question: How can CO2 increase emission of radiation to space if it is absorbing less radiation from below? This would violate the 1st law of thermodynamics which requires conservation of energy. Secondly, the graph above [from an AGW model] shows that CO2 greatly increases cooling of the stratosphere but has essentially zero effect warming or cooling on the troposphere [below the dotted line]. Therefore, this graph indicates a net cooling effect of CO2 upon the atmosphere. Therefore, can anyone please provide a plausible explanation that does not violate the laws of thermodynamics as to why increased CO2 allegedly warms the troposphere and cools the stratosphere? And why the model output above shows CO2 has a strong cooling effect in the stratosphere, but essentially zero warming or cooling effect in the troposphere? And if the stratosphere cools thus increasing the temperature gradient between troposphere and stratosphere, why that would not increase heat transfer from the troposphere to stratosphere (thus cooling the troposphere)? |
Journal of Climate 2014 ; e-View
