North American Fruit Explorers mailing list at ibiblio

[Bob Randall <YearRoundGardening@comcast.net>]

As best I can determine, the USDA has not updated its zone chart since 1990, though they are said to be working on it. However, others have. See the National Arbor Day site http://www.arborday.org/media/map_change.cfm

They conclude that things nationwide have been getting warmer as far as zones (see their maps).  It would be interesting if the USDA has opposite results since presumably they are using the same temperature data.

I have been looking at the situation in the Houston area for many years since it became obvious that the zone info and chill info was off base in helping people select fruit trees over diverse climate ranges.  Based on a large number of online area airport weather readings, it is very clear that the Houston area has gotten warmer since the last really cold weather in 1989. 

For whatever the weather data are worth, the last 20 years have been the warmest winters and summers in the last 140 here.  However, the period from 1969-1989 was the coldest, but closely tied with a period in the 19th century. So obviously, other factors (volcanic activity?) than greenhouse induced global climate change affects how cold or hot it gets in a decade.

For whatever it is worth, parts of Houston area are in zone 10 (using averages), and coastal areas like Matagorda and Galveston are even in zone 11 some years while averaging 10b.  See my data summaries (which are easy to check through NOAA and other sites) at http://www.urbanharvest.org/advice/basics/weather_data.html .

"Share What You Grow and What You Know!"

Bob Randall, Ph.D.

YearRoundGardening@comcast.net

713-661-9737

On Jul 24, 2009, at 12:29 PM, Richard Harrison wrote:

Ginda,

      I don't want to "fight" about GW, either, but wanted to point out that the USDA zone chart(which indicates the minimum temperature of Winters) shown by the speaker at the fruit meeting in LA recently indicated the zones had actually expanded Southward, rather than Northward. So this is cooling, not warming. However, no one predict the future with any degree of accuracy.

      Yes, I agree, some areas may be on a warming trend and others in a cooling trend, temporarily. Personally, I didn't care for the negative sound of the topic title--and after looking at the link discovered flaws which affected the controversial conclusion(title of post).

I consider it very questionable if not misinformation---even if it was written by Ph D's.

                                                              Richard

--- On Fri, 7/24/09, Ginda Fisher <list@ginda.us> wrote:

From: Ginda Fisher <list@ginda.us>
Subject: Re: [NAFEX] California's screwed tree crops
To: "North American Fruit Explorers" <nafex@lists.ibiblio.org>, "nafex@lists.ibiblio.org" <nafex@lists.ibiblio.org>
Date: Friday, July 24, 2009, 8:49 AM

Sure, I don't want to fight about global warming today.  I do want to elaborate a little on the prior post, from Richard Harrison, asserting an increase in chill hours in some warmer states.

That's not inconsistent with global warming.  My understanding is that chill hours are not hours when it's really cold, but are only hours when it's sorta chilly (near or above freezing, up to 40 or 50F), when the trees are metabolically active but 'feel cold'.   I gather that in very cold places the native  trees don't need a lot of chill hours, since they have to come out of dormancy quickly and do their thing.  It's places with long bumpy springs and late frosts where the local trees have adapted by needing a lot of chill hours.

So if global warming is linked in some areas with a longer spring, you could easily get both higher average temps and more or similar chill hours.

Also, the US is a large country with lots of climate zones, some quite chilly.  Surely agricultural plantings can move north if we get even quite a lot of global warming.  Concurrant disruption of rainfall patterns is a more serious agricultural threat, but I'm sure the US will continue to be able to grow food _somewhere_, however cliate change plays out.

-- Ginda

---

Alan Haigh wrote:

Please members, can we refrain from another fruitless debate on global warming?
_______________________________________________ 

-----Inline Attachment Follows-----

_______________________________________________
nafex mailing list
nafex@lists.ibiblio.org

Reproduction of list messages or archives is not allowed.
This includes distribution on other email lists or reproduction on web sites.
Permission to reproduce is NEVER granted, so don't claim you have permission!

**YOU MUST BE SUBSCRIBED TO POST!**
Posts from email addresses that are not subscribed are discarded.
No exceptions. 
----
To subscribe or unsubscribe, go to the bottom of this page (also can be used to change other email options):
http://lists.ibiblio.org/mailman/listinfo/nafex

File attachments are NOT stripped by this list.
TAKE STEPS TO PROTECT YOURSELF FROM COMPUTER VIRUSES!
Please do not send binary files.
Use plain text ONLY in emails!

NAFEX web site:   http://www.nafex.org/

_______________________________________________
nafex mailing list
nafex@lists.ibiblio.org

Reproduction of list messages or archives is not allowed.
This includes distribution on other email lists or reproduction on web sites.
Permission to reproduce is NEVER granted, so don't claim you have permission!

**YOU MUST BE SUBSCRIBED TO POST!**
Posts from email addresses that are not subscribed are discarded.
No exceptions.  
----
To subscribe or unsubscribe, go to the bottom of this page (also can be used to change other email options):
http://lists.ibiblio.org/mailman/listinfo/nafex

File attachments are NOT stripped by this list.
TAKE STEPS TO PROTECT YOURSELF FROM COMPUTER VIRUSES!
Please do not send binary files.
Use plain text ONLY in emails!

NAFEX web site:   http://www.nafex.org/