Global warming: Has your plant climate zone changed?

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Is it just here or has your climate zone also shifted in the past decade as a result of global warming?  For the past seven years, mine has.  I am supposed  to be on the border of USDA zone 8b and 9a, but I have just had seven consecutive years of zone 9b winters, including at least one zone 10a winter too.  I don't know whether this will be a permanent change, but I am taking risks by making zone 9b plantings now.  2010 was a zone 8b winter here, so I am definitely taking a risk based on the assumption that zone 8b is gone forever.  

Unfortunately, most of you outside the United States will not be familiar with USDA cold-hardiness zones (zones 1-13), but I have to refer to something as a standard for this discussion.  If you are outside the USA and your climate zone has changed, allowing you to expand your plant collection, please use whatever terminology suits you best.    

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When they updated the zones a few years ago I jumped from high 4 to a low 5.  This doesn't really do much for my container ranch other than allow me some extra weeks out on the balcony, maybe a less severe spring/fall.  

However, the added energy in the system means the extremes can swing hard and fast.  I have to keep a closer eye on the 5 to 10 day outlook.  Sometimes, if only for a day or 3, I have to pull everything in during early Spring or late Fall.  Obviously everything I have is long since pulled indoors by winter months, but I'm sure some gulf-coasters are starting the dread the increased potential for another Polar Vortex to surge south now that the Jet Stream is getting more destabilized...

tl;dr - I think most of us are getting a bump in average temps year-round, but the storm system extremes make that a risky trade-off.

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The last couple of summers have been extremely hot, with inland daytime highs clearing 100F with some regularity.  The last 2 falls were very hot the whole way through December, so the bodies of water were very warm when we did get a cold blast.  As a result, the winters have been in the "10a range", with annual lows in the low or mid-30s.  As @Funkthulhu mentioned, it does make it really hard to compensate for those wild temperature swings, in our case, from 85F down to 33F in little more than 24-48 hours.

2010 was a brutal winter, but the low (26F) was still in our listed 9b range.  It was just cold/chilly for roughly 2 weeks and wore tender plants down.

At this point, I think most of us in the western half of Central Florida are more worried about the lack of rain than anything.

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The climate has definitely shifted in central Florida with much warmer winters.

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When I was a little kid I remember it being much colder, not uncommon to see 28 at least once a year. Now the lowest temp I've seen in 8 years is 31 (09-10). 

 

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I think the recent urbanization in my area has contributed to a warmer microclimate in my immediate surroundings. I would endeavor to say this is a global event.

 

 

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While a topic that can stirr contentious debate, it is none the less an important discussion.  

While a firm believer in what i have personally observed, I will admit that I also share some degree of skepticism regarding the many different scenarios that have been presented regarding the degree that zone shifts may or are shifting towards the warmer. In the overall discussion, there is room for the effects of urbanization, and a general warming trend, accelerated by various influences.  

Here in Phoenix, there is no doubt that the area's growth is influencing both the effects of heat during the summers, and the lessening degree that we may experience sub 32f cold during the winter. Still, as most people know, such changes have been slower/ perhaps less noticeable in the outlying parts of town. Even so, these areas have also experienced the effects of an overall warming trend.. and may continue to do so, especially since a sizable swath of the area between Phoenix and Tucson is poised for substantial nearer term growth/ development, which most certainly will influence the local climate.

When I ponder how the areas  overall climate might change under warming scenerios, I always take the past into account. At one time, the region here likely expressed a climate similar to what currently exists around the border of Sonora and Sinaloa.. still dry, yet warmer, with summer precipitation having more influence,  thus being more tropical. 

During the last glacial period, the region was cooler with the effects of winter precipitation being more dominant. It is the coming out of that "cooler" period that allowed Saguaro, Ironwood, Creasote Bush, and Ocotillo to expand their range north. Under some suggested data, these indicators of the Sonoran Desert, and the eco-  region itself may continue to expand up into southern Nevada, and push further north into territory  currently occupied by the Mojave Desert in California.  It is well known that cold susceptability determined how far north succulent- type plants could establish themselves. This same influence also determined how far south temperate plants would be able to survive since many like it cooler/ colder. 

How fast such changes might happen depend upon what actually happens, no matter what 1000 graphs might depict. Anyone can easily realize that as the Northern boundaries of a climate shift "up", so will the core or southern boundries.. which would tend to be the warmer end of the spectrum. Here, it is plausible that most of the valley/ lower elevations areas between Phoenix and Yuma shift to a solid zone 10.. with favored core urban areas in the low deserts expressing 5-8 winters out of 10 that would qualify as borderline zone 11. As it stands, zone 10 is only depicted in the warmer parts of town, with outlying spots ranging between 9a and borderline 10a' ish. 

Still, even if such happens, there would likely still be intense, albeit brief cold spells. Like mentioned, there exist the likelihood that the jet stream exhibits wild fluctuations at times, bringing wild weather with it under a warmer overall climate.  I highly doubt a time would come that one could say " Phoenix hasn't been below 40 degrees in 25 years.." 

Interestingly, I came across a hypothetical study from the Institute of Physics science department that showed, in their analysis, a similar warming in the coming decades. This same study also looked at the extant that such crops and Oranges, Kiwi, and Almonds could be cultivated in the future, if such changes occur. Again, this is hypothetical, though plausible. This same study also seems to push zones 5 or lower out of the U.S. entirely. 

As ive likely stated a few times before, another thing worth noting when considering a warming climate is the wildlife aspect. What and who is expanding their range, ..wintering in areas where they might  have vacated in the past to escape cold exposure.. What insects are not dying off from cold exposure, etc.. this aspect  can show obvious trends over time. Ongoing data from such places as Ebird and other sites that collect daily/monthly/yearly data through field observations yields some interesting results. 

In any event, I think we'll see trees like Royal Poinciana, African Tulip Tree, and other cold sensitive stuff considered quite marginal here become more commonly encountered locally. Heck, i'd even go out on a limb and say one might even come across some decent Coconuts.. maybe even a few nicely grown Veitchia, or Adonida specimens in a super ideal shady spot in someone's yard here.  How likely? Hard to say.. we all know our flavor of summer heat is likely a bigger limiting factor as far as success of these palms, or any other tropical that dislike aridity.

I also think the ideal of encountering some nice looking Coconuts somewhere along the far southern California coast, or being able to cultivate Oranges in New Mexico or parts of the Pac. Northwest isn't as far fetched as might be assumed. 

Really, I think more people would benefit from a milder climate than not, even if there are drawbacks to be taken seriously as well. Only time, not hypothesis, will tell.

For now, enjoy what "else" you might be able to cultivate, or how far you might be able to push the envelope.  Perhaps the time is right to see who can grow the first Florida grown and fruited Mangosteen?.. or Cloves. 

 

 

 

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There hasn't been a real killing freeze (<27/28F) in Brownsville, Texas since 1989. The extreme southern coast is even milder and zone 11 winters are not uncommon. Going to be a sad day when a real freeze kills all the tropicals. But if the mild string continues, maybe we'll see some more coconuts pop up in S. Texas. 

As for Houston, the heat island really helps in a radiational freeze...but the one freak advective freeze every now and then really ruins everything. Zone 10 plants sometimes survive for years and get quite big until a freeze strong enough to damage queen palms completely torches them. Still, Bismarckia and Ravenea rivularis (bud hardy) are good choices for the warmer parts of town. Galveston comfortably averages zone 10 for the last 20 years.

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Posted (edited)

We've had a particularly nasty winter, no so much in extreme cold, but long and lingering wet and periodic cold. So in this case the numbers still state zone 8b, but it's taken a greater toll than cooler years with shorter duration. USDA numbers mean very little on overall plant health, only a basic guideline. 

Edited by Las Palmas Norte
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Posted (edited)

Mangosteen was fruited outdoors in Bal Harbor Florida for the first time in the 1960s and then a bunch of times after that, at the same location. (Bill Whitman)

If you can find one, Five Decades with Tropical Fruit is packed with fruitawsome takes of tropical fruits!

 

I say that because of the mangosteen comment, and I can't figure how to qoute on my phone, so it seems wonky. 

Edited by Alan_Tampa
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Sorry, it was 1976

1494029462767-2141300935.jpg

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Past seven years have been solid 10b borderline 11a in a normal 10a zone here in Cape Coral... Southwest Florida.  Also much more humid than normal.  All good.  Now if we could get some substantial rains.  Come on rainy season!!  

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Much of NYC and the eastern tip of Long Island now sit on the borderline of zone 7b and 8a. Only the hardiest palms will survive that, of course, but it's better than nothing. I'm actually more concerned about rain and melting snow causing rot than the actual cold itself.

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Zone 10a.  No changes in the last 10 years.

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Zone 10A........but my plants think it's zone 11!

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Posted (edited)

10 years ago the airport was label as 7b it now 8a on zonal maps. 

Edited by Palm crazy
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I don't pay much attention to temperature records but my plant behavior has changed in the last few years.  I have one Rhododendron 'Noyo Chief', (said to be a cultivar of R. arborescens).  The flower trusses would be open between April 15th and May 30th, exactly 6 weeks, for 15 years.  For the last 3 years the trusses begin in February and the last ones are still out in August.

Archontophoenix cunninghamiana, Chamaedorea carchensis (benzei), and Rhopalostylis baueri have all recently made seeds for the first time, even though they previously had flowered for many years.   

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