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Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Wed May 23, 2012 10:17 am
by 500pesos
solseed.eric wrote:
"We may think that ice forests are a laughable idea now but life will find a way to make them eventually and then vacuum forests and then the huge surface area of the outer icy worlds of Sol will be open to them."
I very much doubt this. The only way there would be what us humans perceive as 'ice forests' is on a planet where water exists only in solid form (that covers the 'ice' part) but life has developed based on a different chemical substance which on that planet (because of its gravity and temperature) is liquid, off the top of my head, say, ammonia. Theoretically it could be possible. Not on Earth though.
Now, plants - and not any old sort of bacteria and the like - living in vacuum I find this extremely highly improbable to ever develop, for biological reasons, no matter how many gazillions of aeons go by. Were it otherwise, the universe around us would be teaming with vegetation (it obviously ain't).
Also, life existed for (only) 600 million years on Earth you say, which you find it "a blink of an eye in cosmic terms". That may be so, as I cannot say for how long this universe intends to exist in the future. In our planet's existence terms though, Earth will remain in a state where it can sustain life as we know it only for approximately another 600 million years, so, only for another blink of an eye... There's not enough time for anaerobic forests to start on this planet and populate the solar system.
Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Thu May 31, 2012 9:57 pm
by solseed.erid
500pesos wrote:The only way there would be what us humans perceive as 'ice forests' is on a planet where water exists only in solid form (that covers the 'ice' part) but life has developed based on a different chemical substance which on that planet (because of its gravity and temperature) is liquid, off the top of my head, say, ammonia. Theoretically it could be possible. Not on Earth though.
Now, plants - and not any old sort of bacteria and the like - living in vacuum I find this extremely highly improbable to ever develop, for biological reasons, no matter how many gazillions of aeons go by. Were it otherwise, the universe around us would be teaming with vegetation (it obviously ain't).
Also, life existed for (only) 600 million years on Earth you say, which you find it "a blink of an eye in cosmic terms". That may be so, as I cannot say for how long this universe intends to exist in the future. In our planet's existence terms though, Earth will remain in a state where it can sustain life as we know it only for approximately another 600 million years, so, only for another blink of an eye... There's not enough time for anaerobic forests to start on this planet and populate the solar system.
500pesos, I believe you are showing a lack of imagination. We don't see the universe as teaming with vegetation because 1) it is young, 2) we haven't looked very far, 3) vacuum and ice forests are not in the adjacent possible of ocean life.
1) The galaxy is less than three times as old as the Earth. The first generation of stars were without heavy elements so they couldn't spawn life. The second generation were probably heavy element poor and so may not have been able to do any better. Sol is the first generation of stars to be able to support life. Even if the big rip is only 20 billion years away that allows Sol's biosphere about 30 times the time since the Ediacaran explosion to develop before the end. Granted it has to survive the end of Sol but for that it only has to manage to travel to another star in less than 5 billion years which should be easy.
2) Just because ice and vacuum forests are not visible to us doesn't mean they don't exist or won't exist somewhere in the galaxy. As already pointed out, the galaxy is young. It is often pointed out that aliens capable of FTL, if they exist, would be obvious because they would be everywhere by now. It would be tremendous coincidence if they arrived in the vicinity of Earth for the first time in the same century or even million years that we developed the technology to recognize them. But that point doesn't stand up when you are talking about life spreading through the galaxy. Given that the galaxy spins once every quarter billion years, it would be reasonable to assume that vacuum life, once it starts spreading could take a billion years to spread through the galaxy. If the possibility of life is only 5 or 10 billion years old then it would not be a coincidence if vacuum forests spread to our solar system in the same billion years that we developed the technology to detect it.
3) Life developed in the oceans of Earth within a few hundred million years of their formation but took billions of years to colonize intermittently wet land, let alone dry land. It was not in the adjacent possible for ocean life to colonize the high Arctic. But once ocean life colonized wet land, within a few hundred million years it had also colonized deserts and created tundra. Ice forests may or may not yet be in the adjacent possible of naturally evolving life, vacuum forests are definitely not. But given a few more hundred million years even naturally evolving life, may open up a lot of adjacent possible to which it currently does not have access. Add to that, that life now includes humans and artificially enhanced evolution (breeding and genetic engineering) and the next 600 million years (barring something like human-caused destruction of the biosphere) will be a lot longer in terms of evolutionary potential than the last 600 million.
As for the idea that life needs a different chemical basis to survive ice or vacuum. Again you need more imagination. Water can be kept liquid at low temperatures with pressure and dissolved substances; water can be kept warm, even in the vacuum of space with insulation. It may be that life will develop a new chemical basis in order to make the jump, but that basis could be developed by substitution over time. a) Add a small percentage of ammonia or alcohol to the cytoplasm in order to survive a little below zero, b) adapt metabolism to the presence of these substances in the cytoplasm, repeat step a) and b) a few times and you are no longer water based. I am not saying that is how it will go, I am just saying that given a chance, life will find a way.
All the salt in the oceans
Posted: Tue Jun 12, 2012 1:08 pm
by neufer
http://earthobservatory.nasa.gov/IOTD/view.php?id=78250 wrote:
<<Salinity—the amount of dissolved salt in the water—is critical to so many aspects of the ocean, from circulation to climate to the global water cycle. For the past year, NASA and Argentina’s Comisión Nacional de Actividades Espaciales (CONAE) have been making comprehensive observations of sea surface salinity from space. Launched on June 10, 2011, the Aquarius mission is slowly compiling a more complete picture of the salty sea and how it varies.
The map above shows salinity near the ocean surface as measured by the Aquarius instrument on the Satélite de Aplicaciones Científicas (SAC)-D satellite. The data depicted shows average salinity from May 27 to June 2, 2012, in a range from 30 to 40 grams per kilogram, with 35 grams being the average. Lower values are represented in purples and blues; higher values are shown in shades of orange and red. Black areas occur where no data was available, either due to the orbit of the satellite or because the ocean was covered by ice, which Aquarius cannot see through.
As oceanographers have known for many years—but now can “see”—the Atlantic Ocean is saltier than the Pacific and Indian Oceans. Rivers such as the Amazon carry tremendous amounts of fresh runoff from land and spread plumes far into the sea. And in the tropics—particularly near the Pacific’s Inter-Tropical Convergence Zone—extra rainfall makes equatorial waters somewhat fresher.
Near most coastlines and inland seas in the map, waters appear much fresher or saltier than in open-ocean locations. Look, for instance, at the Red Sea and the Mediterranean for saltier waters; significantly fresher waters appear in the Black Sea, in the icy high latitudes, and around the many islands and peninsulas of Southeast Asia. Indeed, runoff from rivers and melting ice does make water fresher, and strong evaporation and other processes do make the Red and Mediterranean Seas saltier. But mostly those extreme salinity measurements around the coastlines are a distortion of the satellite signal.
Technically, Aquarius measures the emissivity or “brightness temperature” of the surface waters, notes Gary Lagerloef, Aquarius principal investigator, based at Earth and Space Research in Seattle. Land masses have a higher emissivity than the ocean, so any measurement close to land tends to be skewed by its brightness. Over time, the Aquarius research team should be able to calibrate the measurements and develop mathematical tools to better distinguish the salt signal. But for now, the measurements are so new that the team is still working on the big picture of ocean salinity.
Aquarius is the first NASA instrument specifically designed to study surface ocean salinity from space, and it does so at a rate of 300,000 measurements per month. It uses three passive microwave sensors, called radiometers, to record the thermal signal from the oceans' top 10.1 millimeters (0.4 inches). “An overarching question in climate research is to understand how changes in the Earth’s water cycle—meaning rainfall and evaporation, river discharges and so forth—ocean circulation, and climate link together,” said Lagerloef. Most global precipitation and evaporation events take place over the ocean and are very difficult to measure. But rainfall freshens the ocean’s surface waters, and Aquarius can detect these changes in saltiness. “Salinity is the variable we can use to measure that coupling. It’s a critical factor, and it will eventually be used to improve climate forecasts.”>>
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Jerry: (Crying) What--what is this salty discharge?
Elaine: Oh my God. You're crying.
Jerry: This is horrible! I care!
Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Wed Jun 05, 2013 8:49 pm
by JFB
The diameter of the Earth is 12,755 KM and the narrative accompanying the graphic says that the sphere of water is 700KM. If that were so then 18.22 of these water spheres would line up side by side across the earth's diameter. Clearly the scale of the Water sphere is wrong by a factor of 2x. Its shown covering 1/3 of the continental US, which is 4,828 KM across.
Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Wed Jun 05, 2013 9:17 pm
by BMAONE23
JFB wrote:The diameter of the Earth is 12,755 KM and the narrative accompanying the graphic says that the sphere of water is 700KM. If that were so then 18.22 of these water spheres would line up side by side across the earth's diameter. Clearly the scale of the Water sphere is wrong by a factor of 2x. Its shown covering 1/3 of the continental US, which is 4,828 KM across.
Take another look, the write-up actually states that the ball of water would have a Radius of 700k
The radius of this ball would be only about 700 kilometers, less than half the radius of the Earth's Moon
This would give a diameter of 1,400K and would be 1/3 of 4,200k close enough to 4,828K
Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Thu Jun 13, 2013 5:00 pm
by Galaxian
Chris Peterson wrote:drollere wrote:a sphere 1400 kilometers in diameter of water. ok ... now let's calculate how much trash, garbage, polluted runoff and sewage is dumped into it each year by 7 billion humans. maybe you can tint it brown in proportion. blue is much too optimistic.
That works out to each person on the planet having their own little cube of water about 600 meters on a side.
Only if you execute every other life-form on the planet, which is quite possibly a bad idea. Humans need to give some of those 216,000,000 cubic metres of water to fishes, vegetables, ducks (I *like* duck, it's tasty), veni... sorry, deer, crabs, kangaroos and other edibles. Even if Man exterminates all the non-useful beasties, the ones that aren't nice to eat and don't go well in curries, I'd think most of that cube would be used to keep non-humans alive.
You need more food than human to feed a human.
I'd think people would be lucky to have more than 1000 cubic metres of water each.
As 1 m3 is a ton, that comes to about a thousand tons of water each.
So, even with extremely high estimated usage by other buggers sharing the planet we each still have a swimming pool to drink.
No need to panic, then.
"The Martian Way" by Isaac Asimov. While I think it would be a capital offence to even think of messing with The Rings, for they are a thing of beauty and wonder, Saturn has *many* blobby bits floating around doing no good to no one. That short story should be required reading at every meeting of "environmentalists" and other tree-huggers on this planet. Before they start bleating about a paucity of clean water.
The very idea is laughable.
What we do have is a failure of imagination, a failure of courage and a failure of ability to do arithmetic.
[Sorry to revive a dead thread but I was busy in 2012 and missed this one and I'm too Green and Environmentally-aware to not be helpful.]
Re: APOD: All the Water on Planet Earth (2012 May 15)
Posted: Tue Jan 13, 2015 1:00 am
by Nitpicker
I too am sorry to revive an old thread, but after reading the whole thing, I am surprised that no one had already made the point that there is really quite a huge amount of water on Earth, in relation to the habitable volume of Earth. What the APOD really shows is that the total volume of Earth is so much (~600 times) bigger than the habitable volume of Earth. If we make the simple assumption that all of the Earth's water (1386 million km3) is habitable and make the further (even simpler) assumption that the lowest 1 km of atmosphere above the whole Earth's surface (510 million km3) is habitable, then (ignoring the volume of any subterranean habitable space, which I've just lumped in with the somewhat arbitrary habitable atmospheric volume), all of the Earth's water represents 73% of the habitable volume of Earth.
The fact is that sea levels are predicted to rise in the coming centuries, by amounts expected to cause all sorts of problems for humanity. This appears to be at odds with the notion that there isn't really that much water on Earth. I imagine that marine life might eventually benefit from the change. Change is good for life in general, but not necessarily for human life in particular.
