Submitted by Coconspiritors t3_10oecsw in explainlikeimfive
There’s another eli5 asking why certain regions have more than rain than others. One of the answers referenced that these regions have more rain due physical conditions.
Why can’t we do this intentionally?
Removing mountains or adding them is the sort of thing that would be necessary to alter rain patterns, and the amount of effort needed to do so is incredible. It's just not seen as practical to go "We'll move mountains and build new ones" or "We'll have to remove mountains" especially when you might also have to change the geography of neighboring regions as well.
There's a few reasons I can think of:
Economically, wouldn’t it be more viable long term that the costs associated with droughts, flooding etc. If you could dictate an areas weather, or increase probabilities, why wouldn’t it be seen in a good light?
The sorts of changes needed are WAY more expensive than you're thinking.
The sheer amount of material involved is far, FAR too large for this to be practical.
Let's take a single mountain. I'll use Mount Diablo, a small mountain near my home in the San Francisco Bay Area.
Mount Diablo is roughly a (right circular) cone with a base radius of about 5 kilometers and a height of about 1 kilometer. (It's actually taller than this in terms of height above sea level, but here I'm just going to count its size starting at the surrounding land where the slopes fade into the background.)
The formula for the volume of a cone, then, gives us V = (1/3)Ah, where A is the area of the base and h is the height. That's (1/3)(pi * (5 km)^(2))(1 km) = about 26 cubic kilometers of rock. That's enough to blanket the entire state of California in a few inches of gravel, which should give you an idea of just how much material we're talking about here.
It's made mostly of sandstone, with some inclusions of denser rocks like basalt, so let's estimate a density of about 2.5 grams per cubic centimeter (a bit higher than the density of sandstone). 26 cubic km times 2.5 grams per cm^3 is 6.5 x 10^13 kg.
Okay, that's a big number. How big is that?
Well, it turns out to be approximately a quarter of all Earth moved by all humans worldwide every year. If we combined the entire earthmoving capacity of all of humanity, we could move four Mount Diablos each year, to the exclusion of literally every other construction project ever undertaken by mankind. (We'll set aside the fact that the actual logistics of this would be impossible, since you'd also have to be carting all that rock away, and the fact that we're cutting through hard bedrock and not soft soil.)
And to cut a pass through a mountain range, you need far more than that. A typical mountain range is something like 20 or 30 peaks "thick", and those peaks are typically quite a bit taller than Mount Diablo. Even just building a road through such places is a pretty serious engineering task; destroying the mountains entirely would be the greatest engineering task ever undertaken by mankind by a huge margin.
In general, with questions like this, it's worth just doing some back-of-the-napkin calculations to see roughly how large the thing you're trying to do is. Even if I didn't have all that info available, I could say something like:
Good answers. But worth highlithing that there is geo engineering or climate engineers that could actually modify some parameters in the environment. As an example, some countries are able to induce rain, by dissipating very fine particles in the sky (please dont think that plane contrails are involved!).
An issue is that we cant really understand full effect of implementing this regularly or at large scale. For example, you could make it rain in some regions, but how would this affect other regions, what damage could it result in in the environment, or how could it backlash. Lots of ethic questions involved.
I think you’re significantly underestimating the effort that would be required to relocate the Rocky Mountains and Sierra Nevada mountain ranges.
China has or had a desertification problem because the communist government decided to use cloud seeding to control weather patterns, but they didn't actually know what they were doing, so large areas of the country turned to desert because they were no longer getting their natural amount of rain.
Others have pointed out the size of the project and its likely unintended effects, but just to round it out, I'll add that engineering is about accomplishing a given goal as efficiently as possible.
So, let's say you want to move a mountain in order to get more water to a city. Let's look at a few options:
Even the "hard" options in that list, like desalination or moving the city, are significantly easier than moving the mountain. Throw in the climate effects, and there you go.
It's not just that it's unfeasible, though it certainly is. It's also not needed.
Short answer, no. Not economically viable. Theoretically possible? Maybe. The unimaginable costs associated with terraforming swaths of earth to the point it had a noticeable effect on regional weather patterns make this not an economically viable solution.
It's a bunch of factors combined. The terrain is part of it, but the elevation the terrain sits at is also a huge factor. Other factors include latitude, and also neighboring terrain features like how far to the ocean, where the mountains are, the nature and type of prevailing wind patterns. You can possibly build up an artificial mountain, but not a mountain range, and you're not moving oceans around.
Likely the best you can do is pick a perfect spot for an island and build it. Or you can dig canals and mess around with water flow. You have places like the Salton Sea and the current condition of the Aral Sea which are results of man-made water infrastructure.
We should seriously nuke the Sahara desert and cause the Mediterranean Sea to pour into the North African desert. If we had more water in the region, we could have better temperature controls.
If you want your roof to be warm in the winter (for melting snow, etc), make sure its black.
If you want your roof to be cooler in the summer, make it white. Why don't we do this? Fashion, and the desire to make sure someone will be willing to buy the house a few years in the future.
I live in tornado country, and I've seen a DOT structure that is thick steel-reinforced concrete in a dome shape. Its the shape that is the most resistant to high winds.
Why aren't houses shaped like this? https://www.thestructuralengineer.info/storage/news/562/featured_image/1160/665e96c29d55b13435d7a8d39deafe53_XL.jpg
And just what do you think is going to happen to weather patterns when you start removing and building new mountains?
All you're going to do is move the location of the weather somewhere else. And that will effect the weather all across the world.
You might be able to make a small local change, but you could screw up the weather for a much larger area.
That's all assuming it was even something that humans could do in the first place.
Thank you, I didn’t understand the numbers behind this, but I get it now
I want to take another approach here.
There are some changes we can make to geography that are cost effective.
Forestry and agriculture changes can make effective changes to microclimate.
If we plant trees alongside a river in an area that was formerly cropland along the river, we MAY reduce evaporation of the river water by giving it shade.
If we plant crops known for stabalizing soil, we may be able to reduce desertification in some instances.
The trick is to tailor your solution to fit your problem.
I live in an area where dykes were build to change tidal floodplains into agricultural areas. I'm sure it changed the microclimate over the last 300 years.
The number of places where this can be helpful is low.
Many places people want to change climate there is no cost effective solution.
So many unintended consequences when you are changing places that have developed over thousands of years regarding ecology and plant and animal species. Do you really want to cause species to go extinct?
cost effectiveness. - there are less expensive ways to approace the problem.
Thank you. What are the fields of study that investigate these geographical solutions?
This from world economic forum in 2019 - Here’s how we can use agriculture to fight climate change suggests a starting place for reading.
Another large scale kind of project we have data for is when we have made things like dams for power or flood control. The lakes created have big effects on climate.
This resource - takes the position that hydro dams are to be avoided (which I disagree with) but also raises questions that every project should consider. Someone at National Geographic also has the opinion that dams are bad but again it seems to me that dams give us another lever to adjust to reduce problems like flooding / agricultural water use / drought.
Mammoth-Mud-9609 t1_j6e2jbc wrote
Theoretically you could do this but the amount of effort involved is huge and you may end up changing the weather over a much larger area than you were hoping for.