Desertification of North America (more specifically, the US)

I'm writing a novel set in an ecologically devastated future Earth, and currently, I'm tossing around the idea of the central United States (or former US by the time of the book) being mostly a desert wasteland populated only by small mining towns(pretty much the only thing that these areas are now good for is strip mining), survivalist enclaves, just plain stubborn people and whatnot. The coasts and areas surrounding the Great Lakes are still populated with large cities and massively developed areas, as they are the only place where water can reliably be obtained for a large population. (We can assume by the future year in this novel, desalinization is cheap and efficient.)

The question is, could this realistically happen? While my novel isn't trying to shoot for Hard Science Fiction (or speculative fiction ;] ), I would hate to see, if my novel ever makes it out, to have its own work page here on TV Tropes with tons of examples under the Did Not Do The Research section.

Um, not without some weird significant climate change that has never happened before. In the past when it has been hot enough that desert regions would start creeping up, the polar ice caps would melt and split the North America with a huge sea that took up most of that mid-west region. That and desert areas become deserts because they don't get much rain. With that kind of heat, there would be a lot of precipitation and therefore be just as likely to turn into rainforests in most places. It has to do with where the clouds go and where the mountains are.

I'm not an ecology expert, but this doesn't seem hugely unreasonable. Maybe for hard science fiction (pfft. ), but you could probably get away with it otherwise...

But wouldn't rainforests not form in the case of the central area becoming too polluted for plant life to form adequately? The world doesn't just suffer from global warming, it also suffers from pollution on a massive scale.

Not really because of one huge obstacle: The Southwest Monsoon.

The gist of it is, the Southwest Monsoon season is regular summer rains all over the Sierra Nevada, Basin and Range region, Rocky Mountains (even as far north as Southern Canada), and the western Great Plains.

How it works is seasonal wind shifts down south in Mexico caused by the heating of the Sonora and Mojave Deserts in May. The strongest seasons often correspond to some of the hottest years. (And the inverse is true, colder summers mean next to zero moisture in the region.)

Global warming predictions fail to account for this in the regions noted above. The monsoon season gets stronger or weaker depending on temperature. If the place warms significantly and makes the seasonal wind reversals stronger the monsoon rains become stronger and more frequent. (A similar effect happens in more traditional monsoon areas like Japan, Korea, China, Vietnam and India.)

Meaning at the most extreme end, the Western US would have some (more) very densely forested mountains and the foothills regions would be more covered by trees and scrubby plants. The grasslands wouldn't change much. They are very very drought hardy to begin with and not minding of heavier rain seasons.

Now if the region got COLDER in a more permanent sense...

Thank you for a very clear explanation, Tom. I have friends in Phoenix (Arizona, for those of you who aren't intimately familiar with US cities) who talk about "the monsoons", but I've never been there a the right time to experience them.

I guess if you had really really bad pollution then the rain would turn into acid rain and kill plants, but honestly it would have to be pretty ridiculous amounts that we still don't even come close to have enough constant acid rain everywhere so that the entire country turns into a desert.

^^ Just go there anytime between June 15 and September 12. (The Colorado monsoon lasts pretty much the same window give or take a few days.) It's highly probable at either end of the scale but July and August are effectively guaranteed.

Granted, during that time, it is obscenely hot in Phoenix, AZ. I go away for the Summer in May and when I come back in August, it's unbearable.

Another reason why the United States probably wouldn't be desertified as a whole (and one which I can attest to through personal experience) is the hurricane season. Almost every summer (barring major climatic cycles like El Nino), the American Southeast gets hit by several tropical cyclones (ranging anywhere from mild low-pressure systems to full-on hurricanes) that dump copious amounts of water all over the lower Mississippi watershed and the Appalachian Mountains. As a matter of fact, flooding was a major seasonal problem for the Tennessee River Valley up until the TVA built a large number of dams to control it. (As an added bonus, they also give us reservoirs during those occasional summer droughts and a convenient source of cheap hydroelectric power.) I'm not enough of a climate scholar to predict how a major shift might change that pattern, but I think major desertification of the area in less than a millennium is probably not that realistic an assumption (though I could be wrong).

Poor soil cultivation might cause some problems — and, in fact, it did cause quite a few, back when large-scale tobacco and cotton farming literally sucked all the nutrients out of the soil in large swathes of land — but good crop rotation practices (including planting nitrate-fixing crops like peanuts and soybeans) have largely mitigated that in recent years.

Its already happened once before. Remember, deserts can form in perfectly wet places for a variety of reasons. The two big human induced ones are soil salinity and the aforementioned dust bowl effect, in which destruction of native plant life causes accelerated erosion. Once the topsoil is lost or becomes too toxic to support most plant species, it is generally impossible to return the land to pristine conditions.

Other possible causes of future desertification include strip mining and oil shale exploitation, invasive species, and human manipulation of the weather (there's already talk of using cheap heat pumps powered by wave action to lessen hurricanes). A rogue genetic engineer could also wreak havoc using genetically modified bacteria (we are getting close to the point where garage scientists could cook up some nasty creepy crawlies). For example, it doesn't take all that much to modify common soil bacteria which are normally responsible for plant decay to produce alcohol. That sounds all well and good if you want some cheap booze, but what happens when you release the little buggers into the soil, and every single plant on Earth is killed by alcohol poisoning? (This nearly happened, by the way, due to the FDA being rather stupid about their approval process for genetically modified organisms).

The dust bowl phenomena didn't turn the entire continent into a desert.

There's no reason why you couldn't ramp things up. I can even see a plausible scenario - a combination of the ogallala reservoir collapsing (leading to a massive die-off of corn and wheat in the midland states), and the Canadians scaling up the rates at which they are depleting forests in Alberta for oil shale exploitation.

If you could contrive a way to get rid of all the top soil on the entire continent than maybe, but considering what we know about soil preservation now, it seems unlikely we could ever let that happen. not to mention that humans actually aren't everywhere, even though we sometimes think we are.

edited 3rd Jan '12 11:23:46 PM by NoirGrimoir

You're still going to not change much near the Rocky Mountains. Most of the plant life there is adapted to poor soils sometimes barely above that of broken rock and sand. (No really. The soil here near the mountains in Colorado is 80% clay, 15% rocks and 5% usable materials. On the mountains themselves it's like 80% rock, 18% clay and the rest usable. There's a lot of plants around here that wouldn't really care if The Dust Bowl On Steroids hit.)

edited 4th Jan '12 4:30:56 AM by MajorTom

Alright. The world I'm trying to paint is a cyberpunk-esque world in which Earth has become a polluted Crapsack World (for the record, this story isn't a Green Aesop, it's just a feature to make the world a darker place.

The majority of humanity lives in massive Wretched Hive cities (to get a good idea what they look like, think of the extended opening from Avatar or Blade Runner.) Unless if you are making tons of money, your choice of food extends to Soylent Soy, with real food being a luxury for rich people

Earth's fertile farmland is very rare, and the only reliable source of food is from offworld colonies. FTL travel is possible, but it's slow and expensive, jumps take months to complete, and travel length increases as you increase a ship's space for people and cargo.

So what would be more realistic then? I'm not trying to go for super realistic (evident since I have FTL travel), just something that isn't too far fetched.

Well in general most people buy into the whole Desert Punk future thing, so as long as you aren't concerned about accuracy, people will probably go with it.

Well, a good portion of the planned plot takes place in the Mega Cities, not in the wastelands, although the plot does dip in there from time to time, the events in the cities are what drive the plot.

I'm just trying to see if the concepts are at least somewhat accurate.

Since this is the future, you can take some liberties with what fucked up the climate. If you're very far into the future you might even be able to invoke another ice age, which could very well achieve your desired effect. Otherwise, just go with some sort of freak ecological accident. Since it's not the main focus of the story, you don't need to elaborate too much on it.