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

What were the earlier estimates?

[cytoman]

Using satellite data, researchers from the Woods Hole Oceanographic Institute (WHOI) set out to more accurately answer that question -- and found out that it's 320 million cubic miles.

So, what were the earlier estimates? I'm on Slashdot => I did not RTFA.

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)

Re:What were the earlier estimates?

[Jenming]

I wonder if you need to correct for the oil if you use the Gulf of Mexico units. Or perhaps it just counts for that date.

Re:What were the earlier estimates?

[maxume]

1 cubic mile is about 26 billion barrels.

Re:What were the earlier estimates?

[miggyb]

How many Libraries of Congress would that be?

Re:What were the earlier estimates?

[Scaba]

How many Libraries of Congress would that be?

About 12 million football fields worth.

Re:What were the earlier estimates?

[hey!]

I'm an American; I need that expressed in football fields.

Oddly enough, so does the rest of the world, although their "football field" has an area of 71.4 ares instead of 53.51 ares.

Re:What were the earlier estimates?

[amRadioHed]

I believe those are football pitches actually.

Evaporation?

[cytoman]

Do they consider the effect of evaporation? Earth loses some of its atmosphere to space constantly and it's not too improbable that some water vapor is also lost in this way...

Re:Evaporation?

[Narcocide]

Don't panic, it's not very fast, but we DO need to encase it, ourselves and the sun in a giant Dyson Sphere soon to mitigate the problem.

Re:Evaporation?

[Vinegar Joe]

earth will become one giant desert

Raise worms
Produce spice
Profit!

Re:Evaporation?

[w0mprat]

While it's true we lose some gas at the top of our atmosphere, earth is probably sufficiently large that we have a net growth due to meteorite bombardment. (By every measure I've heard of the earth is supposedly getting heavier). We may take on extra H2O from water ice in meteroids?

Well it was more volumous...

[MyLongNickName]

Well, it was more volumous. But all those sponges soaked up so much.

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?

[Red Flayer]

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.

Yes, but that's meaningless to most people, it's a VLN without context. For all you fans of real, visceral numbers you can relate to, that volume (1.33 x 10^9 km^3) is approximately equal to the amount of water in the earth's oceans.

Hope that helps you to understand the magnitude of the number. Glad to be of service.

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?

[camperdave]

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

It wouldn't be so much of a problem to deal with your backward measurements, except you have so many of them: Furlongs, inches, yards, feet, leagues, gauges, links, rods, chains, fathoms, hands, nails, and who knows how many more. Why even your "mile" comes in geographical, international, survey, telegraph, tactical, and three different nautical flavours (admiralty, international, and US). An ounce of gold is heavier than an ounce of feathers, but a pound of gold is lighter than a pound of feathers. It's insane!

The really sad part of it all is that all your measurements are based on the metric standards anyways. So why not save your sanity and convert fully?

Re:How about some metric figures?

[viking80]

Well, if you put all the water after each other, it would reach from here to the moon and back. maybe that helps us grasp such a big number...

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:How about some metric figures?

[Anonymous Coward]

The really sad part of it all is that all your measurements are based on the metric standards anyways. So why not save your sanity and convert fully?

You are really clueless if you can't think of all the obstacles. MPH and how you measure your fat ass or assess the temperature are the least of the concerns. There are also matters of "hard" vs "soft" conversion. A "soft" conversion would be taking a standard unit wrench set (1/16" increments, e.g.) and numerically translating that to metric values. Easy and it can be done exactly and it is 100% compatible in both directions. It is also 100% fucking stupid as it creates a 3rd tool standard that is identical to an existing standard in all but name only. Buying a metric set of tools is easy. Many sets in the states will have both. What is difficult is all the associated hardware you must work with. At our small company, we retire a machine after - ohhhhh - maybe 20 to 30 years of work. So the machines we just bought that aren't 100% metric or are mixed are likely to be that way for decades. Consider other areas like building codes specifying 6" of insulation or 2x4s (~1.5" x ~3.5"). Again, we don't want "soft" conversions but rather the "hard" conversions that share an existing standard. Going metric would involve at least approving whatever the European equivalents would be. I hope nobody dies because of it! All our air water electrical conduit is in inches. I have never even seen pipe or conduit options in a metric size - that I recall. So very much of the imperial system is ingrained into everything we do.

What would be nice is if the pro-metric crowd would address the tough issues, seek parity where equivalents can be used, and - lastly - realize that this is a 100 year project where the 'hearts and minds' are the last thing you need to worry about. You can sell people on simplicity but you need to make a good case for it. Lastly - and I always say this - if the pro metric crowd cared about standards, they would ditch the French language. The sooner it is dead, the better. We don't need it.

Paging Captain Nemo

[schmidt349]

2.29 miles isn't even 1 league! I thought the ocean was 20,000 leagues deep!

Re:Paging Captain Nemo

[DamienNightbane]

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

Re:Is that so hard?

[DamienNightbane]

There are tons of places off the coasts that are far shallower with lots of oil. They couldn't drill in those spots because the government wouldn't let them, thus forcing them to drill in the more risky deep ocean wells where gas likes to freeze and make your rigs explode.

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:Wait, so what's your point?

[AuMatar]

The point is that accurate information about the Earth's oceans would be more valuable, and we're spending that kind of money to image another planetrary body. I'm not in 100% agreement, but his argument is sound.

Re:I wonder

[rm999]

Did you read the first sentence?
"Using lead weights and *depth sounders*"

That is what they used to do. But it only samples a tiny bit of the ocean and is biased towards certain parts of the ocean, like shipping channels. As the article says, the depth of the ocean is not very smooth, so non-global estimates won't be accurate.

Where do that start measuring?

[Itninja]

Do they include the extreme edge of the oceans (i.e. beaches) where the 'depth' is only a few millimeters? Or do they go out to sea a standard distance before they start measuring?

Global warming?

[sharkey]

We must stop global warming!! Our oceans are getting smaller, we, um, need to, uh, what?

Re:Global warming?

[Vinegar Joe]

Have Al Gore hop in the water at Coney Island and the global sea level will rise 26.58mm.

Smaller than expected.

[fahrbot-bot]

Having lived their entire lives without seeing the ocean, two old women take a trip to the Pacific coast. Upon arriving on the beach, one looks out toward the horizon and says to the other, "That's funny, I thought it would be bigger."

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 estimate

[ascari]

640 billion people? I suppose new estimates say Earth's population is larger than once believed...

Re:I estimate

[c6gunner]

Maybe FOX got it from a real news source, but I don't trust FOX.

That just means you're being brainwashed by a different news sources. You shouldn't trust ANY of them.

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:I estimate

[arielCo]

640 B should be enough for any planet.
* ducks *

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.

Re:I estimate

[mldi]

I don't trust any of them, but sometimes at least their sources check out. With Fox, there isn't even that decency.

Do you do regular fact checks on them, CNN, MSNBC, etc, and compare? What's your source? Making a wild claim out of the blue never helps a cause (even if it's about Fox news).