NomadPatriot wrote:let's calculate then!
One acre-foot of water (the amount of water covering 1 acre to a depth of 1 foot) equals 326,000 gallons or 43,560 cubic feet of water, and weighs 2.7 million pounds. so 1 inch would be 326,000 / 12 = 27,166 gallons per 1 acre of water that is 1 inch deep
the pacific ocean is roughly 63,000,000 acres.
The Pacific Ocean is
quite a lot larger than that: 162 million square kilometers, or 40 billion acres in area.
(There are 2.59 square kilometers to a square mile, which would be pretty close to your 63 million number, is that what you meant?)
63,000,000 acres x 27,166 gallons per 1 inch of an acre of water = 1,711,458,000,000 gallons
so 1.7 trillion gallons of water per 1 inch of depth in the pacific ocean..
So, your estimate here needs to increase by a factor of about 635.
for perspective. .Lake Michigan holds 1,000,000,000,000,000 gallons , 1 Quadrillion gallons of water..
1,000,000,000,000,000 gallons ( 1 lake Michigan) divided 1,711,458,000,000 gallons ( 1 inch of Pacific ocean water ) = 584
so lake Michigan would hold 584 inches of the pacific ocean..
So, when you do this calculation, you would actually get 584 / 635 = 0.9 feet.
But actually this calculation based on areas is not really correct. Neither the Pacific Ocean nor Lake Michigan have a uniform depth, so it is better to think about this in terms of volumes -- how many Lake Michigan's worth of water in total does the Pacific Ocean have? The volumetric ratio of the Pacific Ocean to Lake Michigan is 134k. That means we should really divide by the average depth of the Pacific Ocean (a little over 13000 feet), for an average height decrease of about 0.1 feet, or about an inch (assuming the water removed was uniformly distributed across the ocean).
if you created a 1 lake Michigan inland anywhere on the planet.. & filled it with cleaned desalinated distilled ocean water.. ocean levels in the pacific would drop 48 feet..
Since the ocean is fully connected, you can't just remove water from the Pacific without having the displacement compensated by the rest of the ocean. Since the volume of the ocean in total is about twice the volume of the Pacific, the actual sea level decrease would be only about half an inch.
But what's special about Lake Michigan in particular? Does that amount of water correspond to what we actually need to consume?
I don't know exactly how much water Americans use on average when all direct and indirect uses are accounted for, but let's take
this estimate of 300 gallons per family per day, or something like 100 gallons per person. For 325 million people in the US, that corresponds to 0.12 cubic kilometers of water consumed per day, or 45 cubic kilometers per year. The volume of Lake Michigan is about 5000 cubic kilometers (I used that number above), so it would take about 100 years for the US to consume a Lake Michigan's worth of water.
So if in fact we did take an inch off sea level and desalinate it, we'd have enough water for 200 years alone, and that's ignoring all of the other existing freshwater sources, so presumably it's more than enough. Thus it's not practical to assume that water desalination is a solution to rising sea levels (which are projected to rise by several feet this century). Furthermore, water doesn't just disappear when we consume it. Eventually a big chunk of the water will make it way back to the ocean after we've consumed it, due to evaporation and runoff.
Posted: Tue Jun 25, 2019 12:00 am