What’s 300 km Among Friends?

North American Plant Hardiness Zones

North American Plant Hardiness Zones

An interesting paper on crop zone movement


It is a very short paper ( 3 pages, with graphs…) that purports to show the degree of movement to be expected in crop zones from the coming cold cycle. Interesting to note is that it is date stamped with December 2008. Some people are just a little quicker than others…

Ok, so David Archibald takes the crop hardiness zone map and shows where some folks have said it moved warm zones north based on degrees of heating, then compares it with expanded crop production during those years, allows some for better growing methods, and turns it around the other way. How much will be lost and how far will zones move if we head back to cold?

The answer is basically we in the USA lose about 19% of production (about what we export today) and the degree of zone movement depends on the latitude. Things move further Up North and shift less the closer you get to the Equator. (At the equator, you are basically: warm warm warm hot hot v.hot v.hot hot hot warm warm warm, so any change is just going to be knocking off a bit of the Very Hot or moving a bit of ‘warm’ into the ‘hot’… ) For the USA, he comes up with these numbers:

30° N 160 km southward shift
35° N 300 km southward shift
40° N 420 km southward shift

So if you are in Oregon, you are going to have ‘an issue’ (Sorry Pamela… embrace barley! ;-) but if you are in, oh, the Central Valley of California, you will cool off to about the temperatures of Eugene Oregon. One of my favorite places.

Generally pretty manageable.

One just hopes we don’t get a larger event… the paper is based on the notion of a normal solar cycle and is projecting just the next decade. If we’ve got a Grand Minimum and / or some more volcanoes toss their cookies, well, it’s going to be worse.

“Consequently, using the 0.7° C per year of solar cycle length relationship, there will be a 2.1o C decline in temperature of the mid-latitudes next decade during Solar Cycle 24.”

So what happens if the ‘solar cycle’ runs out to 40 years?

And that, I think, somewhat highlights the problem of a Grand Minimum. We just don’t know what happens. There are some indications that the solar cycle does continue (isotopes from solar cycling in ocean deposits and ice) but we don’t get any sunspots nor any visible increase in output. So which one do you believe? The Be isotopes or the lack of sunshine?

Do you call it a cycle due to one part of the sun cycling, or do you not?

If we have Sacramento like Eugene, it’s a feature. If we have Sacramento like Whitehorse Canada? Not so much…


So I’m left with the wonderful feeling of hopefulness that the next decade promises to be a fairly nice time. A bit cooler, but unless you are pushing the edge on crops, not a big deal. Yet after that… There is this bit of disquiet over just what happens in 2020 if things keep on not happening sun-wize. We could adjust to a 20% loss of grain production just by having “Meatless Mondays” (or what we had when I was a kid: On Monday we had “resurrection” whatever was leftover from the Sunday meal was reprised…) and similar minor changes. But after that? Then it gets hard. Very hard.

Though mostly for folks dependent on others and already eating the grains directly. It takes 10 pounds of grain to make one pound of beef, so a Meatless Monday that displaces one pound of Beef gives you 10 lbs of grain. Enough for a whole week… You don’t want to go completely vegetarian, as the cows also eat things like corn leaves and stems (“silage”) that we otherwise can’t eat. Maximum productivity comes with some ruminant animals on the farm. But for folks already just barely making it, they do not have that choice.

So will Americans give up the Big Mac Attack every couple of days so folks in Somalia and Ethiopia can have corn? I don’t know. I hope so, but I just don’t know.

Winners and Losers

OK, we could make a nice little map with the Haves and the Have Nots and even the Have Enough In A Crisis. But it’s pretty straight forward. North and South America, Australia, and Ukraine are fine. Oddly, so is France, unless they have a really bad crop failure like they did just before the French Revolution. Everybody else is in trouble. (I would not want to be Ukraine stuck between ‘living room’ and a hungry bear…) Yes, Europe and the Middle East are both largely dependent on others for food. No, that’s not good. Just a quick look at the history of who has had wars and where makes that pretty clear. Southeast Asia probably does OK too. They have a little surplus. Russia, Mongolia, China? Another historically tense place.

World food exports and imports

World food exports and imports

Will Australia and the Americas have the willingness to go for ‘shared suffering’ with Russia, China, Europe and the Middle East? Africa? Will Americans give corn to Mexico, or will the Mexicans just walk in in droves? Could we set up distribution support and payment methods fast enough even if the producers did wish to give away the food?

Lets hope we don’t have to find out. I’d really rather not… With luck the sun will wake up soon and all will be well. If not, we have about 10 years to get ready. I hope that is enough time and that we don’t squander it bickering over CO2.

But hope is not a strategy…


About E.M.Smith

A technical managerial sort interested in things from Stonehenge to computer science. My present "hot buttons' are the mythology of Climate Change and ancient metrology; but things change...
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7 Responses to What’s 300 km Among Friends?

  1. Brego says:

    E.M., the maps that you and Archibald referenced are not crop zone maps, they are hardiness zone maps. They are maps of zones of extreme winter low temperatures. That is only of concern for perennial plants. The overwhelming majority of US agriculture is based on annual plants (grains), or plants we grow as annuals (cotton). The exception is winter wheat, but as long as a good amount of snow cover accompanies that cold it is of no concern.

    Not to dismiss the fruit and nut growers, that’s just the way it is.

    Archibald’s analysis was a little off base.

  2. E.M.Smith says:

    Um, where I grew up in farm country we called them both. Crop hardiness zones. Then again, I’m from “fruit and nut country” and they DID care quite a lot about freezes…

    And extremes of winter do matter for folks growing other crops. Stone fruits, for example, have a MINIMUM REQUIRED days below freezing to set fruit. You must have ‘winter chill’ or no fruit. The dates of first and last frost often determine the entire crop season (all those lettuce growers…) and you will also find that as the hardiness zone gets colder you get later germination of planted seeds. Shorter seasons and less growth. Further, the max north you can grow citrus is zone dependent (Florida, Texas, Arizona, and California care…)

    But yes, the official title is “Hardiness Zone Map”. It still shows you were it gets cold, and where it’s coldest vs warmest. And that also means where it’s cold the longest.

    Also, take a tour through the Sunset Garden Book. You will find that every plant has particular zones where it will grow. Yes, these are not the same as the USDA zones ( I like the Sunset ones better) but are a very similar idea. There are plenty of non-perennial crops that have limits based on the zones they will grow in.

    So maybe part of it is just my California perspective (we do grow a lot of ‘truck crops’ here), but it’s not just all about wheat, corn and soy.

    But even with them, you will find Barley and Canola in the coldest hardiness zones, then wheat and corn, and soy in the warmest. Sorghum and sugarcane down on the Gulf of Mexico coast. Because those hardiness guides tell you when and where you will have enough time non-frozen to grow those crops. And if there is a hope of a two or three crop rotation in a year. So corn in Iowa is easy. In Nunavut, not so much…

    Finally, take a look at all the seed packets at the nursery. Notice they have the same USDA zone maps on them? And they talk about WHEN to plant based on those zones? As those zones shift south, somewhere at the top becomes a non-plantable zone. And everywhere else a shorter growing season. And growing season length determines what you can grow and how much yield. The colder zones have fewer degree-days, so less growth. Even for corn, wheat, and soy.

    Yes, in the warmer zones you have a long enough season that you can lose some days and still crop. Except… then you have longer time in the field, less time to harvest before bad weather, and more losses to ‘unseasonable’ weather.

    I guess the bottom line I’m making here is that the name doesn’t really matter much to me. The effect is still the same. Call it “crop zone” or “hardiness zone” or “crop hardiness zone” it still comes down to “cold up there warm down here” and when the cold moves further south, you get less yield from the warm loving crops. After a few years, folks will plant more cold tolerant crops, but that takes a while.

    Texas and California, for example, both grow rice. Rice needs warmth. Not a lot of rice grown in Washington State. Put the Washington hardiness zones in California, the rice isn’t going to do well. And it’s kind of hard to grow winter wheat in rice paddies in adobe clay and store it in a rice dryer silo.

    Similarly, the Walla Walla onions will likely not do so well at N. Canada conditions and the guys in Colorado are probably not set up to grow Idaho potatoes.

    So I guess my point is that I agree, moving Nebraska corn conditions to Kansas is not a big deal. But move North Dakota conditions to Nebraska and you will not get the same total yield and you will have more cold related crop failures.

    So these folks:


    are celebrating the first time ever that N.D. corn exceeded hard red winter wheat. As it gets colder, those warm driven gains will be undone. Less corn, more wheat (then eventually less wheat, more barley, then…)

    So I guess I’m agreeing that I don’t see much of a problem for the 10 year horizon. It’s the one after that which is the bigger issue. In the 10 year time period, we could have some losses from the marginal production (so N.D. might have lower corn yields for a few years, then those guys would start swapping back to wheat and barley) and I’d expect that kind of 5% to 10% change to be tolerable.

    But if we have a Grand Minimum event, I think the zone changes will be extreme enough and fast enough that agriculture will miss a few years before they get the reactions right. And we don’t have a few years of food storage to buffer that problem…

  3. Doug Proctor says:

    I looked into this subject early in the year. No notes, but this I recall: the current crop hardiness map/guide is based on data from 1980 to 1990. So it is 10 years out of date. There was an attempt an an update that was rejected by the USDA, without a public explanation of why. A farm/horticultural group has a newer one out. The USDA plan on the new hardiness map in 2013, I think, but it will only relate to 1990 – 2000.

    So the map is out-of-date, reflects a period that may not be appropriate, and the new one will be out-of-date, too, but all will relate to climates as understood 10 years or more earlier. Sound useful?

    What I could not determine, though, was whether the plant hardiness map is determined by the official US temperature records which we question for various reasons. The map is used to support the temperature rise position, but may be a product of that position – circular reasoning. If someone can confirm/deny that, I’d be interested.

    There are changes. Wildlife biologists tell me the burrowing owl is nesting and fledgling 1 month earlier than “before”. This may be true or may be because they are studying it better. Summers in the prairies are later now than a few years ago, and winters, earlier. The crop yields show this. But we’ve been through this before, so what does it really mean?

    I don’t know of any practical effects. The winter minimums are less, with less winter-kill than years past, but the winds seem lower in winter than in the 1980s, so there is less drying effects.

    The study claims major movement of plant survival zones. I am unconvinced that a) the data isn’t based on study-bias, b) the map isn’t a product of circular reasoning, and c) is up-to-date enough to be either correct or useful.

    Precise, yes, accurate, maybe not so much.

  4. E.M.Smith says:

    I find the crop / hardiness maps most useful as a way to see the pattern of the gradation from warm to cold, not as an absolute statement. So to me, that is useful.

    If you moved “one zone” warmer or colder, it would have an impact, despite the accuracy of the map.

    In a way, I suppose that’s similar to saying I care about the Delta Map more than the Map per se.

  5. Gary says:

    Oh, “we” will definitely squander what time we have. We’re not like Old Testament Joseph – advisor to the the Pharoah. Let’s hope we have a few Norman Borlaug’s working quietly out of view who will come to the rescue.

  6. Peter says:

    I thought you and your readers might be interested in a fully interactive version of the USDA hardiness zone map as well as individual maps for each state. The map for the entire US is located at:

    An example of a state hardiness zone map can be found at:

    There is also a zipcode to zone search.

  7. E.M.Smith says:

    @Peter: Neat maps! I like the local zoom especially. I’d always wondered how much granularity was in the big coarse maps and if the local microclimate was properly represented. I’m going to have to tour ‘wine country’ with them ;-)

    @Gary: At first I didn’t recognize the name. I knew I’d seen it, but haven’t had “First Coffee” yet…


    reminded me. The guy who made the big bugaboo of my youth go away. When my parents used to try to get me to eat things I didn’t want with “Think of all the starving children in India”, where now we here “Think of all the programmers and production in India”… ( I always asked why we didn’t just send the pickled beets to India… they didn’t like my answer, though ;-) I’ve since come to like pickled beets..)

    FWIW, yeah, there are folks still working on that stuff. Though many efforts are going into GMO, there are also folks working on ‘the regular stuff’. My favorite is the simple method of Rice Intensification.


    They basically recognized that flooding rice fields was not the ideal condition for rice. It was just a cheap and easy way to control weeds. The rice CAN do it, but is not OPTIMAL when doing it. Promises to more or less double rice production world wide if we ever need to do it.

    Once you are not flooding the fields, you can intensify the nutrients in the soil and enhance plant and root growth.

    known as SRI – also as le Systéme de Riziculture Intensive in French and la Sistema Intensivo de Cultivo Arrocero* (SICA) in Spanish — is a methodology for increasing the productivity of irrigated rice cultivation by changing the management of plants, soil, water and nutrients. […] SRI concepts and methods have been successfully adapted to upland unirrigated rice, and they are now being extrapolated to other crops like millet, wheat and sugar cane.

    SRI does not require the purchase of new seeds or the use of new high-yielding varieties. Although the highest yields with SRI have been obtained from improved varieties, most traditional or local varieties of rice respond well to SRI practices and command a higher market price. And while chemical fertilizer and agrochemicals can be applied with SRI, their use is not required as organic materials (compost, manure or any decomposed vegetation) can give good or even better results at low cost. Farmers report that when SRI methods are used correctly, rice plants are better able to resist damage from pests and diseases, reducing or eliminating need for agrochemical protection.

    Because plant populations are greatly reduced with SRI, seed costs are cut by 80-90%, and because paddy fields are not kept continuously flooded, there are water savings of 25 to 50%, a major benefit in many places. […]

    SRI does require skillful management of the factors of production and, at least initially, more labor, particularly for careful transplanting and for weeding. Since yield increases are usually 50 to 100%, and possibly several times present levels,

    So when I’m in a Dismal Science Mood, I remember SRI and get back to a happier normal.

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