Weather before we farmed?
October 25, 2010 3:08 PM Subscribe
How was the weather different before we farmed the land?
During the summer, the Midwest is a seemingly endless sea of green cornfields which (I have to believe) send lots and lots of moisture into the atmosphere, where it must have some impact on weather conditions. How was that weather different before there were all those cornfields, when the land was primarily covered with grasses of one type or another? Has anyone researched or modeled this phenomenon?
My guess would be that any difference was more likely to be in relative humidity rather than actual temperature. But, I don't really know and that's why I'm asking.
During the summer, the Midwest is a seemingly endless sea of green cornfields which (I have to believe) send lots and lots of moisture into the atmosphere, where it must have some impact on weather conditions. How was that weather different before there were all those cornfields, when the land was primarily covered with grasses of one type or another? Has anyone researched or modeled this phenomenon?
My guess would be that any difference was more likely to be in relative humidity rather than actual temperature. But, I don't really know and that's why I'm asking.
What neuron said. The hypothesis was known as Rain follows the plow and has been discredited.
posted by 0xFCAF at 3:39 PM on October 25, 2010 [1 favorite]
posted by 0xFCAF at 3:39 PM on October 25, 2010 [1 favorite]
before there were all those cornfields, when the land was primarily covered with grasses of one type or another?
FWIW, corn is a grass of one type or another.
posted by jon1270 at 4:43 PM on October 25, 2010 [2 favorites]
FWIW, corn is a grass of one type or another.
posted by jon1270 at 4:43 PM on October 25, 2010 [2 favorites]
Peter Andrews of Australia (of Natural Sequence Farming) wrote about how vegetative cover effects climate in Beyond the Brink. Allan Savory (Holistic Management) also discusses the relationship between climate and vegetation. Basically, perennial vegetative cover is best for stabilizing the climate. The problem I see with corn production and climate issues is the fact that the soil in those areas is almost always left bare for half the year.
posted by sk932 at 4:55 PM on October 25, 2010
posted by sk932 at 4:55 PM on October 25, 2010
The difference in the midwest was probably less corn vs grass, and more whatever the weather impact is of heavy irrigation. That's a lot of extra transpiration at times of the year when there would have been a lot less.
posted by Forktine at 5:59 PM on October 25, 2010
posted by Forktine at 5:59 PM on October 25, 2010
Best answer: The big difference between then and now is irrigation. A lot of those fields are getting "rain" a lot more often and a lot more regularly than that land did in the old days, because the farmers irrigate.
And in some parts of the midwest the water they're using is fossil water left over from the last ice age.
Some of that water runs off but most of it evaporates, so it's true that there's more water respiring now than used to be the case. But I don't think anyone really understands weather well enough to know what consequences that has. And I don't think there are adequate historical records to determine it empirically.
posted by Chocolate Pickle at 6:00 PM on October 25, 2010
And in some parts of the midwest the water they're using is fossil water left over from the last ice age.
Some of that water runs off but most of it evaporates, so it's true that there's more water respiring now than used to be the case. But I don't think anyone really understands weather well enough to know what consequences that has. And I don't think there are adequate historical records to determine it empirically.
posted by Chocolate Pickle at 6:00 PM on October 25, 2010
Separating the effects of agriculture from the effects of fossil fuel emissions, deforestation, wildlife depletion, and cow farts is pretty hard. I'd say just jump in and start studying paleoclimatology, or pick a specific region (Fertile Crescent, Amazonia, etc) that might illuminate the issue and start reading.
Plus, is your question about the time before "we farmed the land" or about the time before "there were all those cornfields"? Two very different ideas, separated by about six or seven thousand years.
posted by General Tonic at 6:14 PM on October 25, 2010
Plus, is your question about the time before "we farmed the land" or about the time before "there were all those cornfields"? Two very different ideas, separated by about six or seven thousand years.
posted by General Tonic at 6:14 PM on October 25, 2010
Corn is a kind of grass. Basically it's super-grass, genetically modified beyond recognition over thousands of years to be exactly the sort of thing humans wanted it to be.
The fact that grain = grass is why the US prairies make such great farmland for corn and wheat.
posted by Sara C. at 7:14 PM on October 25, 2010
The fact that grain = grass is why the US prairies make such great farmland for corn and wheat.
posted by Sara C. at 7:14 PM on October 25, 2010
Well, there's this study which concludes the heavy agriculture on the great plains is making the summers cooler and wetter downwind in the midwest - mainly due to the increased irrigation from fossil water.
posted by ArkhanJG at 4:33 AM on October 26, 2010 [1 favorite]
posted by ArkhanJG at 4:33 AM on October 26, 2010 [1 favorite]
Response by poster: Plus, is your question about the time before "we farmed the land" or about the time before "there were all those cornfields"?
The latter, actually. Thanks for making the distinction.
The rest of the story: I am in the midst of writing a creative non-fiction piece about an ancestor who, in the mid-1840s, was one of the early farmers in a particular West Central Illinois location. I have been able to find a bit of information about how the land looked at that point in time. As part of my "scene-setting", I am seeking information how it might have felt in contrast to today (largely because a high percentage of this ancestor's descendants still live in that area and might well be intrigued by the juxtaposition).
posted by John Borrowman at 7:26 AM on October 26, 2010
The latter, actually. Thanks for making the distinction.
The rest of the story: I am in the midst of writing a creative non-fiction piece about an ancestor who, in the mid-1840s, was one of the early farmers in a particular West Central Illinois location. I have been able to find a bit of information about how the land looked at that point in time. As part of my "scene-setting", I am seeking information how it might have felt in contrast to today (largely because a high percentage of this ancestor's descendants still live in that area and might well be intrigued by the juxtaposition).
posted by John Borrowman at 7:26 AM on October 26, 2010
This is purely anecdotal, but I grew up in high plains farm country near the west end of the Ogallala aquifer. At that time (60s, early 70s), agricultural production was slowly shifting to more and more irrigated corn (from mostly sugar beets and pinto beans, with a lot of wheat country to the north and south). Back in the 60s and 70s, the summer humidity was always fairly low, maybe 15% - 30% on average.
By the time I moved away (late 70s), humidity in the summer was noticeably higher, and over the years as I've returned for visits, the humidity has always been very noticeable - maybe 50% - 60% on average.
As I said, purely anecdotal, but long time residents all acknowledge it, with a general air of "you can't put that much water onto crops day in and day out without it going somewhere."
posted by nonliteral at 9:22 AM on October 26, 2010
By the time I moved away (late 70s), humidity in the summer was noticeably higher, and over the years as I've returned for visits, the humidity has always been very noticeable - maybe 50% - 60% on average.
As I said, purely anecdotal, but long time residents all acknowledge it, with a general air of "you can't put that much water onto crops day in and day out without it going somewhere."
posted by nonliteral at 9:22 AM on October 26, 2010
So you just want to know what the weather in a very specific part of the country was like for a certain group of years? Why not consult old weather records?
If you can't find official scientific records, check archives for diaries kept by local residents. A lot of people in the 19th century kept diaries wherein they mentioned the weather a lot. I remember reading Laura Ingalls Wilder's journal of her trip from North Dakota to Oklahoma with her husband and young daughter in the 1890's and being seriously disappointed that she spent half the time talking about weather and what they ate. I'm sure there's an 1840's Illinois equivalent.
posted by Sara C. at 9:23 AM on October 26, 2010
If you can't find official scientific records, check archives for diaries kept by local residents. A lot of people in the 19th century kept diaries wherein they mentioned the weather a lot. I remember reading Laura Ingalls Wilder's journal of her trip from North Dakota to Oklahoma with her husband and young daughter in the 1890's and being seriously disappointed that she spent half the time talking about weather and what they ate. I'm sure there's an 1840's Illinois equivalent.
posted by Sara C. at 9:23 AM on October 26, 2010
High-sulphur coal burned in Michigan causes acid rain in Vermont, not in Michigan.
These kinds of local changes don't actually tend to be local. An increase in water vapor transpired (I used the wrong word before) in the mid-West isn't going to have a substantial affect on the weather in that area, because most of that water vapor will get blown to the east by prevailing winds. But it might have affected the weather in New York and Pennsylvania quite a lot.
posted by Chocolate Pickle at 12:33 PM on October 27, 2010
These kinds of local changes don't actually tend to be local. An increase in water vapor transpired (I used the wrong word before) in the mid-West isn't going to have a substantial affect on the weather in that area, because most of that water vapor will get blown to the east by prevailing winds. But it might have affected the weather in New York and Pennsylvania quite a lot.
posted by Chocolate Pickle at 12:33 PM on October 27, 2010
Hmm. . . an interesting and relevant study just released in Nov. 2010:
Researchers can't go back in time to revisit old fields in their pristine state, but a University of Missouri graduate student did perhaps the next best thing, using a detailed computer model to simulate, year-by-year, the effects of 100 years of farming on claypan soils.
Grad Student Simulates 100 Years of Farming to Measure Agriculture's Impact on Land and Water Quality
posted by General Tonic at 9:40 AM on November 5, 2010
Researchers can't go back in time to revisit old fields in their pristine state, but a University of Missouri graduate student did perhaps the next best thing, using a detailed computer model to simulate, year-by-year, the effects of 100 years of farming on claypan soils.
Grad Student Simulates 100 Years of Farming to Measure Agriculture's Impact on Land and Water Quality
posted by General Tonic at 9:40 AM on November 5, 2010
This thread is closed to new comments.
Back in Devonian time (around 400 million years ago), plants evolved seeds. Prior to that they reproduced with spores, which required them to be near water, so most of the earth was barren. With seeds, plants quickly overtook all of the earth's surface. The effect on the climate was dramatic, with much more rainfall and erosion. CO2 levels dropped, causing global cooling which caused a mass extinction.
The American West was settled in the 1800s largely due to the widespread belief, which largely came from land speculators, that tilling the soil would cause rain to fall. Alas, it does not.
posted by neuron at 3:33 PM on October 25, 2010 [5 favorites]