Re: OT: interesting global warming quote found elsewhwere

On Jul 27, 2:14 pm, d...@xxxxxxxxxxxxxx (Don Klipstein) wrote:
In <246d2b98-79c2-4b77-814a-63d950028...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,





bill.slo...@xxxxxxxx wrote:
On Jul 25, 4:22 pm, d...@xxxxxxxxxxxxxx (Don Klipstein) wrote:
In <c0c8b408-ea13-4cbd-82f1-80c4700c8...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,

bill.slo...@xxxxxxxx wrote:
On Jul 25, 1:11 am, d...@xxxxxxxxxxxxxx (Don Klipstein) wrote:
In <a6347502-bc82-4a2c-b474-787e17d3b...@xxxxxxxxxxxxxxxxxxxxxxxxxxxx>,
bill.slo...@xxxxxxxx wrote in part:

Mankind hasn't been around long enough to have run into a seriously
warm climate. For about 40 million years - between 60 and 100 milion
years ago - the climate was lot warmer and there were crocodiles
living inside the arctic and antarctic circle. In order to get the
heat balance to work, it seems to be necessary to postulate lots of
intense hurricanes and typhoons extending much further north and south
from the equator to more enough heat to of the tropics to the poles.
The coast of California wouldn't have be a good place to live in that
era.

  So how warm was the world when we had much higher CO2 and no icecaps or
ice sheets?  7, maybe 10 degrees C warmer than it is now?

http://environment.newscientist.com/channel/earth/mg19826611.200-
when-crocodiles-roamed-the-arctic.html

The article is back in Nijmegen, but IIRR the world was about 20C
warmer.

  That article does indeed claim that Antarctica was once warm and
forested.

  However, 10's of millions of years ago to one or two hundred million
years ago, Antarctica was far from its present location.  I find it easy
for Antarctica to have had crocodiles 70 or 100 or 125 million years ago
in the Cretaceous Age when the global average temperatue was maybe 22
degrees C and Antarctica was at least majority north of the Antarctic
Circle.

That wasn't the message of the article - IIRR Antartica was close
enogh to the south pole back then to be within the Antarctic Circle
and to have a sunless winter.

  Now, what is the ratio of warming of the Califormia cost to warming of
the whole globe according to climate models that are coming up more true
so far, and according to whatever historical data says anything about
California?
  It appears to me that California will warm up a little less than the
world as a whole during the summer and about keep pace in the winter - and
lag many decades also, since coastal CA's air is usually from the Pacific
Ocean.

Calfornia's problem with that sort of warming would be intense
hurricanes - one of the points made in the New Scientist article was
that to get the temperature distribution to match the evidence from
the geological record a lot more heat had to be travelling from the
equatorial regions to to poles then than now.

  I expect that the LA-SD region of California with such extreme warming
would run into a hurricane problem a little worse than Acapulco has to
deal with now.  And that the SF area and West Coast North America will
only worsen to about what LA and SD deal with now.

As far as the frequency of hurricanes go you may be right. The
intensity of the hurricanes - with much larger areas of hot ocean to
track over before they hit land - is a different question.

  The ocean off CA is still not going to be nearly as hot as the tropical
oceans.  The hurricanes will weaken when approaching CA, the way they now
do once past about 35 or so degrees N going up the East Coast.





The mechanism proposed was lots of intense hurricans over a much wider
belt arond the equator - as you'd expect, since hurricans grow where
the sea surface temperature is over about 26.5C

  That is not a critical temperature carved in stone.  Should the middle
and upper troposphere in hurricane formation areas also warm, then the
critical sea surface temperature for hurricane formation will aslo rise -
probably by a small amount.  Also keep in mind that the tropics will warm
less than the globe as a whole.

But give the hurricanes a bigger playground to grow in, and they can
get bigger and stronger before they hit the coast.

  Furthermore, keep in mind that the hurricane uptick of the last decade
or so is in significant part not from global warming but from the Atlantic
multidecadal oscillation.

Agreed. But that's about the frequency, not the intensity.

  Intensity also.  The multidecadal oscillation affects temperatures of
the Carribean and the Gulf Stream and the Gulf Loop Current.





- that mixed the
surface layers of the tropical oceans much more thoroughly - and
deeply than they are mixed at the moment, putting a lot wmore warm
water into the cean currents flowing towards the poles.

  That one is a more serious concern, to the extent there is an increase
of hurricane activity that is independent of the multidecadal oscillations
of the Atlantic and Pacific oceans.  That can melt away sea ice in polar
and near-polar regions - for now in/near the Arctic, since most tropical
cyclones are in the northern hemisphere.

With enough intense hurricans around, the coast of California would
not be a good place to build a conventional house.

  I would advise coastal Southern CA to be advised that in a few centuries
they may get what Acapulco gets now.

But with stronger winds and heavier rainfall.

  I doubt it - the ocean for hundreds of miles offshore CA would be a lot
cooler than the tropical oceans, so hurricanes would weaken when
approaching CA.  As for frequency - I was even counting on westerly winds
turning them towards the shore.





  How bad would it be if LA and San Diego become more like Acapulco and SF
becomes like San Diego or a degree or two warmer than San Diego is now?

Better analogies would be Galverston and New Orleans.

  How do you see coastal California getting that bad?  The climate
forecast models that made more sense to me have LA and SD hardly worse
than Acapulco (besides sea level higher) even if we warm up our planet to
what it was like in the Cretaceous Age.

  The worst I see for coastal CA if the world gets that warm is having to
move a couple hundred meters uphill - which is not far.  

Probably not far enough to cope with storm surges

  A Cat-5 hurricane storm surge is generally 6-9 meters.

Cat-6?

  If Cat-6 is invented, such storms would only exist where there is
extremely warm water to sustain them.

or a long enough track over water at or above 26.5C - you can trade
distance against surface water temperature, so long as the surface
water temperature stays abobe 26.5C

  Ever hear of a Cat-4 or 5 hitting New England or Nova Scotia?  The
strongest hurricanes do weaken when they get away from the warmest water.

Hurricanes weaken when the sea surface temperature falls below 26.5C
- warmer water drives them harder, but the cut-off point is an
absolute temperature, set by the vapour pressure of water over the sea
surface. Move the isotherms further from the equator, and the tracks
become longer, and more northerly coastlines will be exposed to
maximally intense hurricanes.

--
Bill Sloman, Nijmegen
.

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