My read suggests that OP is probably less interested in increasing evaporation overall (though it would increase) than controlling where the water enters the atmosphere. There are places that are dry only because there happens to be a mountain in between them and the ocean, for example. Moving the water a long way is something we already know how to do (think oil pipelines, but containing salt water instead of hydrocarbon slurry). If it scales, this could make a substantial difference to such places.
Downside is that weather is the output of an insanely complex set of interconnecting natural systems and cycles. Making changes to the climate of a region this way will have unforeseeable side-effects over vast distances. Given the likely cost laying pipe over a mountain or whatever, I doubt many governments will be willing to take the risk of their big expensive weather-modification project provably messing up rainfall patterns or creating geologic instability or something in another state or country and having choose between paying enormous damages or eating their sunk construction costs. Most likely they would be unable to make that decision in a timely manner and default to doing both in the long run.
Then again, fracking, so I might be wrong about that.
I’ve gone into clarifications, as well as running numbers on example build-outs and yields, in the comments below. I just wanted to make a particular point here, though: the difference between “Unintended Consequences” and “Unforeseeable Side-Effects”.
When I build a bridge to ease traffic, and it leads to suburban sprawl, that’s both unintended and unforeseen. When my country’s coal particulate drops, because of clean-air regulations, and this removes sulfur and dust that was helping to cool the Earth, we have an unintended consequence: increased global warming, somewhat. Yet! This consequence was not unforeseen. We can use our knowledge of science, along with careful simulation, modeling, prototypes, staged roll-out, user feedback, community engagement, … to avoid the unforeseen. Even when our actions have a few side-effects we didn’t intend.
And, in particular, the claim that consequences are unforeseeABLE is bold. That would require “weather is beyond our ken, forever.” Instead, weather modeling has improved radically with artificial intelligence, and we are roughly accurate with hurricanes a week in advance, and google does ‘now-casting’, which has historically been the hardest part of forecasting weather, while long-term models tend to average-out any slight perturbations nicely. SO! Weather is complex, and our actions will always have side-effects which were not included in our hopes—hence, un-intended. Yet, we have the power to test, empirically, and study, to avoid the unforeseen. I wake in cold sweats for the Unforeseeable.
claim that consequences are unforeseeABLE is bold. That would require “weather is beyond our ken, forever.”
Maniac Extreme type argument on a minor semantic point.
We can make some pretty good guesses, but right now we have no effective means to fully and accurately predict the long-term and long-distance meteorological, geological, and hydrological side effects of a project that results in a moderate-to-major change in the annual rainfall of a region. There will be consequences that we are unABLE to forsee. Some of those consequences could be large, some could be negative. Some could be both, maybe we don’t get either.
Oh, my apologies—I am happy to concede that “currently unforeseeable” is a reasonable limitation in complex systems; I hadn’t noticed that qualifier.
And, if you had asked me four years ago “Might our weather models miss some catastrophic downstream consequence, which negates the potential value of returning jungle (now pasture) back to jungle, and preventing California droughts?” I would have given it a decent chance, which would negate the more intrusive, all-or-nothing interventions.
Yet—weather modelling is improving rapidly, with neural networks. Google is able to do “now-casting”, which forecasts local weather condition at small time scales. That sort of modelling was previously out-of-bounds, because it requires much smaller & more numerous voxels and turbulence could throw everything off due to local traffic conditions or a factory being shut down for maintenance. The fact that we have now-casting, among other steady improvements, lowers my assessment of a catastrophic blunder. Especially if we roll-out in a place like California, such that we return water to its state in the 1960s, which obviously would not be catastrophically disruptive.
So, it’s true that science misses catastrophe some times, and weather is complex, while very recent improvements in modelling reduce the risk of catastrophic disruption, especially when returning water to climate-change-parched regions, recently wet.
Fracking has a clear connection between action and reward.
Oil company uses fracking → it’s super effective → oil company pumps oil → oil sells at a high price. Then the oil company makes some political donations and the government is encouraged to allow it despite any damages to less politically connected people’s property (contaminated groundwater, microearthquakes or even the possibility that fracking causes this. This is why fracking is banned in certain states and many EU countries)
Desalination has similar action → reward mapping, as long as the water can be produced for a price that it is profitable to sell the water, it’s worth doing.
This proposal just generally increases rainfall in the area it’s done in. But a lot of the water will just fall on barren desert, and the rainfall is inconsistent, and it’s hard to tell how much of the rain is from the seawater evaporation. And it can’t be excluded as a good—you can’t deny water to people not paying the subscription fee.
Yes! Only 11,000 years ago, the solar intensity over the Sahara was 7% greater (Milankovitch, natch!) which caused about 10% more convection of air over land… from the humid Mediterranean! That’s just a 10% boost, but it was enough to cross a ‘threshold’ of humidity, when clouds can actually form, and rain can actually fall. There’s still moisture above the desert—it’s just never dense enough to come back to Earth!
So, the Sahara got 10% more moisture, which let a few plants grow… and plants are darker than desert rock, so they created a steeper gradient of heating every morning—the green inland regions got hot and humid fast, air rising, which pulled MORE sea-breeze and humidity deep inland! It’s a feedback loop, which was how the Sahara was green for thousands of years, covered in laurel forests and grasslands, in cycles stretching back tens of thousands of years.
The Point: if we add just a little bit more water, we can get a feedback loop, just like our geological past. We’re on the threshold of rain-formation humidity.
I’m missing numbers here. How much water could you evaporate, compared to the amount of sea water that evaporates every day?
My guess is this would be (pun not intended) a drop in the ocean.
My read suggests that OP is probably less interested in increasing evaporation overall (though it would increase) than controlling where the water enters the atmosphere. There are places that are dry only because there happens to be a mountain in between them and the ocean, for example. Moving the water a long way is something we already know how to do (think oil pipelines, but containing salt water instead of hydrocarbon slurry). If it scales, this could make a substantial difference to such places.
Downside is that weather is the output of an insanely complex set of interconnecting natural systems and cycles. Making changes to the climate of a region this way will have unforeseeable side-effects over vast distances. Given the likely cost laying pipe over a mountain or whatever, I doubt many governments will be willing to take the risk of their big expensive weather-modification project provably messing up rainfall patterns or creating geologic instability or something in another state or country and having choose between paying enormous damages or eating their sunk construction costs. Most likely they would be unable to make that decision in a timely manner and default to doing both in the long run.
Then again, fracking, so I might be wrong about that.
I’ve gone into clarifications, as well as running numbers on example build-outs and yields, in the comments below. I just wanted to make a particular point here, though: the difference between “Unintended Consequences” and “Unforeseeable Side-Effects”.
When I build a bridge to ease traffic, and it leads to suburban sprawl, that’s both unintended and unforeseen. When my country’s coal particulate drops, because of clean-air regulations, and this removes sulfur and dust that was helping to cool the Earth, we have an unintended consequence: increased global warming, somewhat. Yet! This consequence was not unforeseen. We can use our knowledge of science, along with careful simulation, modeling, prototypes, staged roll-out, user feedback, community engagement, … to avoid the unforeseen. Even when our actions have a few side-effects we didn’t intend.
And, in particular, the claim that consequences are unforeseeABLE is bold. That would require “weather is beyond our ken, forever.” Instead, weather modeling has improved radically with artificial intelligence, and we are roughly accurate with hurricanes a week in advance, and google does ‘now-casting’, which has historically been the hardest part of forecasting weather, while long-term models tend to average-out any slight perturbations nicely. SO! Weather is complex, and our actions will always have side-effects which were not included in our hopes—hence, un-intended. Yet, we have the power to test, empirically, and study, to avoid the unforeseen. I wake in cold sweats for the Unforeseeable.
Maniac Extreme type argument on a minor semantic point.
We can make some pretty good guesses, but right now we have no effective means to fully and accurately predict the long-term and long-distance meteorological, geological, and hydrological side effects of a project that results in a moderate-to-major change in the annual rainfall of a region. There will be consequences that we are unABLE to forsee. Some of those consequences could be large, some could be negative. Some could be both, maybe we don’t get either.
Oh, my apologies—I am happy to concede that “currently unforeseeable” is a reasonable limitation in complex systems; I hadn’t noticed that qualifier.
And, if you had asked me four years ago “Might our weather models miss some catastrophic downstream consequence, which negates the potential value of returning jungle (now pasture) back to jungle, and preventing California droughts?” I would have given it a decent chance, which would negate the more intrusive, all-or-nothing interventions.
Yet—weather modelling is improving rapidly, with neural networks. Google is able to do “now-casting”, which forecasts local weather condition at small time scales. That sort of modelling was previously out-of-bounds, because it requires much smaller & more numerous voxels and turbulence could throw everything off due to local traffic conditions or a factory being shut down for maintenance. The fact that we have now-casting, among other steady improvements, lowers my assessment of a catastrophic blunder. Especially if we roll-out in a place like California, such that we return water to its state in the 1960s, which obviously would not be catastrophically disruptive.
So, it’s true that science misses catastrophe some times, and weather is complex, while very recent improvements in modelling reduce the risk of catastrophic disruption, especially when returning water to climate-change-parched regions, recently wet.
Fracking has a clear connection between action and reward.
Oil company uses fracking → it’s super effective → oil company pumps oil → oil sells at a high price. Then the oil company makes some political donations and the government is encouraged to allow it despite any damages to less politically connected people’s property (contaminated groundwater, microearthquakes or even the possibility that fracking causes this. This is why fracking is banned in certain states and many EU countries)
Desalination has similar action → reward mapping, as long as the water can be produced for a price that it is profitable to sell the water, it’s worth doing.
This proposal just generally increases rainfall in the area it’s done in. But a lot of the water will just fall on barren desert, and the rainfall is inconsistent, and it’s hard to tell how much of the rain is from the seawater evaporation. And it can’t be excluded as a good—you can’t deny water to people not paying the subscription fee.
My guess would also be that if there is airflow over the ocean the air would hold most of the water you could hope for with such an approach.
Yes! Only 11,000 years ago, the solar intensity over the Sahara was 7% greater (Milankovitch, natch!) which caused about 10% more convection of air over land… from the humid Mediterranean! That’s just a 10% boost, but it was enough to cross a ‘threshold’ of humidity, when clouds can actually form, and rain can actually fall. There’s still moisture above the desert—it’s just never dense enough to come back to Earth!
So, the Sahara got 10% more moisture, which let a few plants grow… and plants are darker than desert rock, so they created a steeper gradient of heating every morning—the green inland regions got hot and humid fast, air rising, which pulled MORE sea-breeze and humidity deep inland! It’s a feedback loop, which was how the Sahara was green for thousands of years, covered in laurel forests and grasslands, in cycles stretching back tens of thousands of years.
The Point: if we add just a little bit more water, we can get a feedback loop, just like our geological past. We’re on the threshold of rain-formation humidity.