One of the most noticeable changes in North American climate has been the
northward displacement of the Hadley Cell downdraught:
https://en.wikipedia.org/wiki/Hadley_cell
This has resulted in increased occurances of heat waves in the southeast
US, as well as the Mississippi Valley and the Midwest.
A somewhat similar shift took place about 8,300 years ago, when a large
body of fresh water along the eastern edge of the receding Wisconsin Ice Sheet
broke through an ice dam, emptying into the Arctic Ocean. This resulted in a
marked drop in northern hemisphere temperatures for about 300-500 years, which
can be seen in virtually every proxy temperature study north of the equator.
What happened afterwards was a major shift in the climatology of the
northern hemisphere. The Intertropical Convergence Zone (ITCZ) moved about
1000 miles to the south, bringing the seasonal monsoon rains of northern Africa
to an end, which turned a vast grassland into the Sahara Desert. This dramatic
shift in climate appears in all sorts of archaeological records of the area,
mostly in terms of civilisations that collapsed due to widespread crop failures.
During the Medieval Warm Period (MWP, 850-1350 AD), the ITCZ shifted
northward slightly, bringing widespread drought to the Anasazi, Mayan, and
Chinese civilisations, while at the same time allowing Europe to flourish,
including the Norse colonisation of Greenland and Labrador. That all ended
with the Little Ice Age (LIA), which was initialised with a massive volcanic
explosion in either Mexico or Indonesia in 1215.
>
>What has changed at the "......location at the base of the Front Range
>of the Rockies......." to have caused an alteration in the flow of the
>Chinook winds?
>
>Calgary, Alberta is known to experience the effects of Chinook winds in
>winter time. For instance, the temperature can rise from -40C to >15C in
>a matter of half an hour and then plunge back cold again within the same
>length of time minutes or hours later. I know, we lived there for 12 years.
>
>
>>
>> "Global Warming", (renamed to the less polarizing "Climate Change") is
>> not uniform. A one degree global change is not one degree everywhere.
>> It's no change in some places and 10 degrees in others. The greatest
>> change is happening mostly in the arctic regions of the Northern
>> Hemisphere. Changes are not linear, but occur in major steps with
>> catastrophic events.
>>
>
Chris
When the going gets weird, the weird turn pro
- Hunter S. Thompson
--
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