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What positive effect (if any) does frozen water have for Earth life? Or, would life have developed if water didn’t become solid till, say, -100 degrees Centigrade? We would have really cold rainstorms but I can’t think of anything that would be detrimental to life.
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How did ancient cultures explain the fact that water turns into this solid thing when it gets cold enough? I’m thinking of places where the four-element theory of matter was the latest in peer-reviewed publications. I assume ice is still considered water, but did anyone propose a reason for it to become solid instead of getting colder and colder while staying a liquid? Did they know about salt lowering the freezing temperature? What was the reasoning for why that happened? Surely somebody thought about these things rather than just say that’s the way things are.
I should amend the qualifier “ancient” to mean all time periods before the atomic theory of matter was known. Wikipedia says roughly before 1800.
Water filling cracks in rock, then freezing helps break it into smaller pieces, speeding erosion and the creation or renewal of soil. Same with glacial activity.
Also, snow and ice forming on mountains, etc. create a reservoir of fresh water that is delivered slowly as it melts, leveling out the wet-to-dry cycles downstream.
Ice is less dense than liquid water, meaning that it floats on the top of ponds, lakes and rivers. This allows aquatic life to continue to exist in liquid water during the winter. The life cycles of fish, plants etc underwater are probably very affected by this, and the adaptations (or lack thereof) of different species will have resulted in their geographic distributions. Life would, I think, be quite different if water never froze.
Weather would be a heck of a lot more variable, because water serves as a heat-buffer at its melting point:
What with your typical enzymatic reaction slowing down by a factor of 2 for each 10°C shift in temperature, the lower temperatures would require metabolic adaptation.
More to the point, the layer of floating ice insulates the water below and keeps it from cooling down as much. If the water stayed liquid, it could mix freely and exchange more heat with the atmosphere, so it would end up cooling to pretty much the same temperature as the air: i.e., much colder than it does when protected by a layer of ice.
Frozen water increases surface albedo, which in turn cools the climate. Of course, this can be carried too far.
But latent heat and water’s high specific heat don’t have anything to do with freezing. That just represents the energy difference between the two phases. In our water-never-freezes model, there’s no reason to assume this would change. I mean, there’s nothing special about the fact that at two different energy levels, one is water and the other is ice.
Yes, and if the phase doesn’t change at a particular temp, there won’t be any large energy uptake or release at that temp. It’d take 1 cal for 1 g of water to go from -0.5°C to 0.5°C, rather than the 79.6 cal it takes to melt 1 g of ice in our everyday world.
IIRC, the Greeks conceived of their four elements as combinations of heat and moisture. ThusL
Fire – hot and dry
Water – cold and wet
Air – hot and wet (this was Greece, right by the sea)
Earth – cold and dry.
In that conceptual framework, they probably assumed that freezing removed the moisture from the water, turning from cold and wet to cold and dry and thus a solid like earth. If asked where it went, they would probably say into the hot and wet air (and it would come back from that).
It explained things pretty neatly (if incorrectly).
Another effect on life: permafrost. In very cold northern climates, plant growth is limited by frozen ground, which makes it very difficult for roots to grow, animals to burrow, respiration to take place, dead material to decompose, etc. If water never froze, I suspect we’d see a lot more plants and biodiversity in the arctic regions than we do right now.
But to address the overall question: I don’t think a lack of ice would prevent life from forming. After all, the current evolutionary theories put the development of life in either intertidal beaches or deep-sea vents. Neither of those are affected by ice in any way. However, the lack of ice could limit the number of environments that animals could cope with.
I think weather extremes would be particularly significant, with bigger swings between hot/cold and dry/wet seasons due to the lack of ice and snow to moderate temperature changes and store water for later release. A lot of land-based life would probably have to operate more like desert life does - short bursts of life at opportune seasons, with long periods of dormancy to survive the extremes.
Taller and more durable mountain ranges (due to decreased erosion) would also contribute to extremes. As air rises over mountains, it dumps moisture and leaves the other side dry. South America is a great example, where you go from a drenched rain forest on one side of the Andes to extreme deserts on the other side.
life may very well have developed with water having different physical characteristics though it likely would not be life as we know it which developed which our current situation.
Thanks, this is an interesting explanation. Do you have a cite for the idea that they thought the four elements were one level up from the two more basic elements of heat and moisture?
Here’s a chart in Wikipedia, though you can find it in any source discussing the concepts. It says the concept comes from Aristotle.
The earliest Greek philosophers held that there was just one basic element, that transformed into different forms. The first philosopher, Thales, taught that this basic substance was water. It seems more than likely that he came to this conclusion because he saw water can indeed quite easily transform into both a solid and a gas (along with the fact that water is necessary for all life).
Over the next few generations, several alternatives to water as the basic substance were put forward by other philosophers, for various reasons: the indefinite (Anaximander); air (Anaximenies); earth (Xenophanes); and fire (Heraclitus). All of these ideas seemed to have both advantages and disadvantages. Eventually Empedocles attempted to get teh best of all these theories by proposing that there are four basic elements, earth, air, fire, and water, which do not themselves transform, but rather mix together in different proportions to form all the different sorst of substance we find around us. Aristotle took over this theory and popularized it, adding the stuff about the opposed pairs of qualities (hot-cold, wet-dry).
As far as life is concerned, there are a lot of advantages to the water-storing feature of frozen water on mountains and in glaciers.
If the Earth’s temperature range included the freeze point, we’d get those benefits. That wold be true whether ice froze at 0C or -100C. But if we assume the Earth’s temperature range is the same as it really is, but water froze at -100C, then we’d not get those benefits.
Oceanic life would be mostly unaffected, but a lot more of the dry land would be uninhabitable by our typical flora and fauna. There’d be a lot more deserts.
As mnemosyne said:
The point is not that water freezes. But water is one of the few (or the only?) common molecule that is less dense frozen than as a liquid. If water was a typical substance, the oceans could easily freeze solid during a prolonged winter. As it is, ice is effectively insulation preventing the deeper levels of water from freezing quickly. Almost all life that we know of requires some permanent source of liquid water.