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Huge Pool of Ice-Free Water Discovered Under Greenland Ice
The BBC reports that researchers have discovered a huge pool of meltwater beneath Greenland's ice sheet, trapped "in the air space between particles of ice, similar to the way that fruit juice stays liquid in a slush drink."
From the article, based on research published in Nature Geoscience (abstract): "The scientists say the water is prevented from freezing by the large amounts of snow that fall on the surface of the ice sheet late in the summer. This insulates the water from the air temperatures which are below freezing, allowing the water to persist as liquid all year long. Other researchers believe this discovery may help explain disparities between projections of mass loss by climate models and observations from satellites."
We're not very good at looking through solid substances yet. Not only don't we know what's under the Greenland ice, we don't even know what's under many of our cities. For example, construction of the Thessaloniki metro recently discovered an entire Roman city center buried beneath the modern-day city center. In limited cases you can find some of this kind of stuff with ground-penetrating radar, but in general mapping out stuff that's covered by solid dirt/ice/etc. is not easy, even in the 21st century.
10 PRINT CHR$(205.5+RND(1)); : GOTO 10
...said the physics teacher.
Under pressure, the freezing point of water is lowered. The more pressure, the lower the ice point. To demonstrate:
Assume that a container is indestructible (let's say, a sphere with a perfect seal). It is full of water with no gas in solution or loose in bubbles or anything like that. Just pure water. Now, stick it in a deep freeze. Wait.
Water has the odd property of expanding at around 4C at normal (sea level) pressure. By the time it freezes at 0C under those same pressure conditions, it has expanded to fill 1/8 more volume than it did as a liquid. This is why icebergs float. This is why distilled water ice cubes also float. The liquid water does its thing and... you know the rest. Titanic.
The water in the sphere is prevented from freezing for the simple reason that it has nowhere to go. It has no space to expand into. If it cannot expand, it cannot freeze. How low can you go? I have no idea, having no access to magnetocaloric equipment. But I daresay, you wouldn't meet the conditions required to get the volume of water to contract to the point where it can solidify in the available space, outside of a suitably equipped laboratory or in the shadow of an outer planet.
Further reading suggests temperatures approaching/lower than about 70K (-203C) to achieve this. Further reading.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
it's not true that subsurface water in the Arctic ocean isn't freezing: it is, continually. What salinity does is disrupt the phase equilibrium between liquid and solid so the water phases between solid and liquid at a faster rate than the liquid phasing to solid, ergo the mass remains a liquid. That's only considering salinity. Absent pressure at depth, the entire ocean would be a block of ice right now, but see my other post in this thread (here) as to the other reason the Arctic ocean is liquid.
Political debates have me rolling my eyes so much I think I got optical whiplash. I should sue. - Foamy The Squirrel
There's lots of fresh water on the planet (including all the fresh water stored as ice). The problem is getting to a place where it's useful. Most places have to make do with the fresh water that's available locally. A notable exception being Southern California which imports water from the north and from the Colorado River. I doubt you'll find knowledgeable people saying fresh water would be completely gone (except perhaps for some overtaxed aquifers). Instead they are saying there will be more demand for fresh water than there is supply available to fill that demand in the future. Getting fresh water from Greenland to any place useful would be difficult and expensive.
No, they believe they know *something*: That the planet *is* warming at an alarming rate, and that human produced CO2 is the forcing factor. Basically all the data collected to date corroborates this, and so that much is considered settled. The exact *implications* of those facts is still very much up in the air. We know the ice caps will melt, that's firmly within the error bars on the model. The exact speed at which it happens, the implications thereof, and the various confounding factors that may arise along the way, *that* is all still very much under examination.
Consider an example - we have a pretty good model of gravity - so if I throw a baseball with a given speed and direction we can model the exact parabolic path it would follow in a vacuum, and that will give us a pretty good idea of where it will land. For a better model we'll have to factor in air resistance and wind velocity, which will give us a much more accurate guess, but still not be perfectly accurate. Then we'd need to factor in any spin on the ball. We could find the exact local gravity (which fluctuates by almost 1% over the Earth's surface) and get even more accurate. If we had a sufficiently detailed weather model (or a large sealed room) we could factor in the fluctuations in air velocity over the course of the balls path. We could even model the exact surface features of the ball and how they influence it's movement as the air drags across it. It *still* wouldn't be completely accurate, but would probably be accurate to within some fraction of an inch. Provided I don't hit a passing bird and totally disrupt the prediction (a totally unexpected major confounding factor) For most purposes though that initial "ball in a vacuum" estimate, with sufficient error bars, is perfectly servicable.
With climate science we're still kind at the level of trying to take the ball's spin into account. There are lots of variables still not understood, and there may even be some giant major confounding factors that end up giving us a "get out of jail free" card. (Aliens swoop in to save us? Rush Limbaugh's head implodes and sucks all the excess hot air out of the world?) The core of the matter though is that, to the limits of our current understanding we are actively creating a situation that is going to have a really drastic impact on our planet's ability to continue supporting us, and the sooner we start facing the problem the cheaper and less severe it will be to make sure we can still support at least a couple billion people by the end of the century. We could have started changing our behaviors 50 years ago to almost completely avoid it, but back then all we had was a crude theory easily dismissed by vested interests. Now we're starting to see the first obvious (to the layman) undeniable signs that the theory was correct, and have fleshed it out to be ever more accurate. Yet people still want to deny that our actions are causing a problem.
Look at it this way - if I were to propose that we restructure our society because in the next fifty years some major confounding factor will be discovered in our theory of gravity that will allow for cheap and simple levitation, you would think I was nuts. Yet when people say we should continue on with business as usual because surely some unexpected confounding factor in climate science will make everything okay, somehow that's okay?
--- Most topics have many sides worth arguing, allow me to take one opposite you.