New Estimates Say Earth's Oceans Smaller Than Once Believed

Velcroman1 writes with this snippet from Fox News: "Using lead weights and depth sounders, scientists have made surprisingly accurate estimates of the ocean's depths in the past. Now, with satellites and radar, researchers have pinned down a more accurate answer to that age-old query: How deep is the ocean? And how big? As long ago as 1888, John Murray dangled lead weights from a rope off a ship to calculate the ocean's volume — the product of area and mean ocean depth. Using satellite data, researchers from the Woods Hole Oceanographic Institute set out to more accurately answer that question — and found out that it's 320 million cubic miles. And despite miles-deep abysses like the Mariana Trench, the ocean's mean depth is just 2.29 miles, thanks to the varied and bumpy ocean floor."

Comments

Re:What were the earlier estimates?

[mister_playboy]

The article specified the earlier (but still recent) estimate with weird units:

320 million cubic miles + 5 Gulf of Mexicos

and

320 million cubic miles + 500 Great Lakes(s)

How about some metric figures?

[Edisman]

For all you metric fans out there, the volume 320 × 10^6 cubic miles is approx. 133.4 × 10^7 cubic km with an average depth of 3.69 km.

Re:How about some metric figures?

[BerryMadness]

Seriously... miles?

I know. Everyone knows that you are supposed to use miles for length and gallons for volume.

Re:How about some metric figures?

[Pharmboy]

To quote: "The U.S. system of units is similar to the British Imperial system.[4] Both systems derive from the evolution of local units over the centuries, as a result of standardization efforts in the United Kingdom; the local units themselves mostly trace back to Roman and Anglo-Saxon units."

And from the metric system article:
"The metric system is an international decimalised system of measurement, first adopted by France in 1791"

I am pretty sure our old outdated American system of units predates the metric system of measuring units. And you seem to be misunderstanding the Mendenhall Order. "In 1866 the Congress passed a law which allowed, but did not require, the use of the metric system. Included in the law was a table of conversion factors between the traditional and metric units" This just establishes official translation between the two methods that already existed. While the "official" standards of the system has drifted some over the years, " The Mendenhall order amounted to a formal announcement of a change that had already occurred (Mendenhall 1893)." That doesn't change the fact that the pound, pint, peck, etc. were in use in the US for at least a full century before France adopted the metric system.

Re:Evaporation?

[Vinegar Joe]

earth will become one giant desert

Raise worms
Produce spice
Profit!

Re:Evaporation? Bleeding off Hydrogen

[thms]

Yes, IIRC by the same mechanism Venus has a lot of relatively heavier elements (Carbon, Oxygen, Sulfur), but barely any Hydrogen if you compare it to Earth and count the oceans as part of the atmosphere.

Water (gas) is split by solar radiation higher up, and the light hydrogen is carried upwards, and some of these particles bump into each other and often enough these bumps add up to escape velocity for one particle. Supposedly solar winds also play a significant role, and as Mars and Venus don't have a magnetic field anymore to protect them, over the eons all the hydrogen was lost. One more factor for the Drake Equation!

Re:Paging Captain Nemo

[DamienNightbane]

The title "20,000 Leagues Under the Sea" refers to the distance traveled, not the depth.

Re:What were the earlier estimates?

[Dthief]

Its ok, its from FoxNews, so you are better off not RTFA

Re:I estimate

[daem0n1x]

For the 640 billion people who have no idea what the fuck a mile is, here is your public translation service. The ocean's volume is about 1300 million cubic kilometres, and the average ocean depth is about 3.7 Km.

Re:I wonder

[zippthorne]

I know it's got the word, "sounder" in it, but the lead weights *are* the depth sounder, it's got nothing to do with sonar. A depth sounder is like a plumb line, except it's wet, and much longer.

Re:What were the earlier estimates?

[amRadioHed]

I believe those are football pitches actually.

Re:Is that so hard?

[Anonymous Coward]

That's not insightful, that's nonsense. It's just "look what the stupid treehuggers have forced us into, hurting their own cause with their idiocy" strawman baloney. If you look at a map of the oil rigs in the gulf of Mexico like this one, you can see that the area is pretty well saturated with rigs. This rig was so far out simply because they're following the oil further and further out to sea. So, please stop spreading lies implying that this is all somehow the fault of stupid hippies who forced the poor defenseless oil companies to drill in unsafe locations.

Re:I wonder

[totally bogus dude]

http://www.essortment.com/hobbies/depthsoundersh_secb.htm

In past times, ascertaining the water depth involved a difficult process called "sounding," which was done by throwing a weighted line over the side in an attempt to find the bottom. This line, called a "lead line" was knotted in increments that allowed the user to measure the water's depth in feet or more commonly, in "fathoms" a nautical unit of measure equal to 6 feet. Using a lead line from a moving vessel was of course problematic, and subject to inaccuracies. The user had to stand on the bow of the ship or boat and toss the line, wait until the lead weight hit the bottom, and then haul in the line and count the number of knots that were submerged. All the while the vessel was still moving and the bottom contour could, of course, have already changed by the time the sounder called out the depth to the captain.

Today's electronic depth sounders have changed all of this. Depth sounders provide instant and continuously updated readings of the water depth as a vessel speeds along. Depth sounders work by the principle of "sonar." A sound signal is emitted from the bottom of the hull and this signal travels through the water until it reaches the bottom and then bounces back, to be picked up by the depth sounder's receiver. Since sound waves travel at a known rate, the depth can be determined by calculating the amount of time it takes for the sound waves to hit the bottom and return to the vessel. This is all done automatically and instantaneously by the instrument.

So it was called sounding before we had sonar, and it's just a coincidence that the term "sound" is involved.