On 29/11/2019 09:54, Martin Brown wrote:
Lindzen's Iris hypothesis made a serious attempt to use clouds to limit
the effect of CO2 rise in the tropics but it was not borne out when it
was tested experimentally. Some debate still exists as to whether or not
it could still play a part in limiting AGW.
I view him as a true scientist despite his denialist tendencies he was
genuinely making a serious effort to refine the climate models.
https://en.wikipedia.org/wiki/Iris_hypothesis
References at the bottom to primary literature.
You have to look very carefully at the affiliations and credentials of
anyone claiming to have strong evidence for the Iris hypothesis - they
are usually in hock to Australian, US or USSR fossil fuel interests.
You might be interested in this (highly abbreviated and slightly edited)
exchange of emails between Wibjörn Karlén (professor emeritus of
physical geography and quaternary geology at Stockholm University,
Sweden) and KevinTrenberth (of the Climate Analysis Section at the US
National Center for Atmospheric Research).
Karlen was interested in the land-based temperature rise in Nordic
countries as reported by the IPCC and CRU, and had run the published
data himself in order to reproduce the results, but failed to find any
increase in temperatures. He emailed Professor Jones of the CRU, who
passed the query on to Trenberth.
Karlen wrote that "In attempts to reconstruct the temperature I find an
increase from the early 1900s to ca 1935, a trend down until the mid
1970s and so another increase to about the same temperature level as in
the late 1930s. A distinct warming to a temperature about 0.5 deg C
above the level 1940 is reported in the IPCC diagrams. I have been
searching for this recent increase, which is very important for the
discussion about a possible human influence on climate, but I have
basically failed to find an increase above the late 1930s".
Trenberth replied mentioning dramatic decreases in Arctic sea ice in
recent years and that these and other indicators show that there is no
doubt about recent warming, although it should be noted that Karlen is
specifically interested in land temperatures rather than sea ice. The
latter then goes on to say that "Except for Denmark, the data sets show
an increase after the 1970s to the same level as in the late 1930s or
lower. None demonstrates the distinct increase IPCC indicates".
Karlen then quotes from a paper: "One example of published data not
supporting a major temperature increase during recent time is: Polyakov,
I.V., Bekryaev, R.V., Alekseev, G.H., Bhatt,U.S., Colony, R.L., Johnson,
M.A., Maskshtas, A.P. and Walsh, D., 2003: Variability and Trends of Air
Temperature and Pressure in the Maritime Arctic, 1875-2000. Journal of
Climate: Vol. 16 (12): 2067-2077.
He included many more stations than I did in my calculation of
temperatures N 65 N, but the result is similar. It is hard to find
evidence of a drastic warming of the Arctic."
Karlen then says "So, I find it necessary to object to the talk about a
scaring temperature increase because of increased human release of CO2.
In fact, the warming seems to be limited to densely populated areas. The
often mentioned correlation between temperature and CO2 is not
convincing. If there is a factor explaining a major part of changes in
the temperature, it is solar irradiation. There are numerous studies
demonstrating this correlation but papers are not accepted by IPCC. Most
likely, any reduction of CO2 release will have no effect whatsoever on
the temperature (independent of how expensive)".
Keeping in mind the above, Trenberth replies "You can object all you
like but you are not looking at the evidence and you need to have a
basis, which you have not established. You seem to doubt that CO2 has
increased and that it is a greenhouse gas and you are very wrong.". This
is to say the least a surprising statement, since Karlen is trying and
failing to reproduce the results published by the IPCC and the CRU, his
own researches suggesting he is correct in not finding any evidence of
warming.
Finally, Karlen says that in his mind, it has to be accepted that it is
great if the release of CO2 can be reduced because the earth's resources
are being used up and will will be more scarce in the future, but 'we
are in error' if we claim a global warming caused by CO2.
Trenberth disagrees.
Whether Karlen is 'in hock to Australian, US or USSR fossil fuel
interests' or not, one has to admire his scientific integrity in
pursuing the anomaly between his analysis of the published data sets and
his own researches that show no warming. and his fortitude at the nature
of the reception his enquiries received.
The much more extensive original source can be found at
https://tinyurl.com/y3ubvbwf
--
Spike