valdis.kletni...@vt.edu wrote:
On Sat, 28 Nov 2009 10:49:32 +0100, Martin Tomasek said:
So you can measure global area represented by different climates, but
averaging temperature over the areas (or globally) is quackery. Average
global temperature has no meaning.
So during the last ice age, what did the global average temperature do?
This is difficult question. We know of ice ages by proxies, such as
traces of big moving blocks on rock surfaces, ice cores etc. These
proxies are mostly placed in arctic area or high in the mountains (so
you have no reliable data from Africa). BTW, this is one sources of
difficulties in dating of egyptian Sphinx, which appears to be about
8000 years older than the age shown by radionuclid dating and noone
knows what to do with that. <http://www.nap.edu/catalog.php?record_id=11676>
We know that weather is chaotic system, which we are unable to predict
for a long time and which has unevenly (and one should say chaotically)
distributed temperature over space. So, average temperature depends on
methodology of measurement. It depends on which places you choose to
include in global average and on weights of the places (you are
calculating weighted average).
I believe that in most cases of ice age global temperature calculation
you will get temperature lower than today.
I tried to find more information on proxies in and near Africa, I'll
read this book, seems promising:
http://www.nap.edu/catalog.php?record_id=11676 but also a little
disappointing - they use graphs produced by Michael Mann, infamous by
his invention of 'hockey stick chart'. And they also use tree ring data
(which is not reliable temperature proxy).
Speaking of Michael Mann, here is funny video reacting to leaked emails:
http://www.youtube.com/watch?v=nEiLgbBGKVk (They discarded temperature
data, obtained by tree ring proxies, from IPCC report. It showed
temperature decline).
--
Martin Tomasek
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