Robert, it was you who made reference to the data
"...And if you have a look at both the ISCCP-FD and ERBE SW(up)
datasets - there is clearly a decrease in reflected SW (less cloud)
from the 1980's to the 1990's..."
I just pointed out that there are problems with both sets, the ERBE
instrument being one which I studied. The IPCC AR4 reference to which
you pointed comments on the later ERBS data, concluding:
"In summary, while there is some consistency between ISCCP, ERBS,
SAGE II and surface observations of a reduction in high cloud cover
during the 1990s relative to the 1980s, there are substantial
uncertainties in decadal trends in all data sets and at present there
is no clear consensus on changes in total cloudiness over decadal time
scales...."
Yes, yet again, let me remind you that there is lots of evidence of
variation in climate. That knowledge is one of the reasons we address
"climate change" these days, not simply "global warming". However, I
do think it's important for mankind that our civilization has evolved
during the Holocene, which appears to be a warm period relative to the
norm over the past 3 million years or so. During the past 8000 years,
the variation in climate appears to have been rather minor, compared
to the climate of the Ice Ages. I do not assume that the future will
be a repeat of the warm conditions of the past 8 thousand years. If
climate were not influenced by mankind's activities, I think it's
clear that at some time in the future, Ice Age conditions would
return, continuing the long term pattern. I don't see how you can
conclude that I expect climate to be stable, as mankind is changing
the basic physics of the situation. After all, climate can be thought
of as the statistics of weather and that includes the statistics of
the longer variations as well.
E. S.
------------------------------------------------
On Nov 7, 7:30 pm, Robert I Ellison <[email protected]>
wrote:
> Eric,
>
> I am not sure whose ERBE data reference you are talking about. The
> ERBE data is graphed and discussed in AR4 - section 3.4.3 from
> memory. The ISCCP data and a reasonably detailed dicussion of errrors
> and problems is found at -http://isccp.giss.nasa.gov/projects/browse_fc.html
>
> Wild simply discusses decadal changes in surface insolation -
> brightening and dimming. The ISCCP record is discussed along with DTR
> and surface SSR records predominantly.
>
> I was simply talking about climate variability - which is evident in
> any of the records and at any timescale. I can't help it of you have
> foolishly been hoisted on your own petard with a false assumption of
> climate stability.
>
> Cheers
> Robert
>
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