Eli5. Salt melts ice. Glaciers sit in an ocean of salt. Glaciers don’t melt.



Eli5. Salt melts ice. Glaciers sit in an ocean of salt. Glaciers don’t melt.

In: Earth Science

Salt doesn’t necessarily melt ice, it just lowers the freezing point of the water that composes the ice, meaning that water has to reach a lower temperature in order to freeze. My guess is that the oceans in the Arctic and Antarctic are so cold, that it negates the effect of the salt on the ice, but I’m not a scientist or anything

I think glaciers are melting. I was told it’s because of global heating but I think you’re on to something here


Salt is a solute, which when added to water (ice in this case) lowers its freezing point.

The freezing point of water is 0 degrees on Celsius scale. Addition of salt will lower its freezing point, to some negative temperature.

The geological locations where Glaciers exist, the temperatures are way below 0 degrees. So even though the freezing point of ice is lower, the temperature is still lower than the final freezing point of the salt-water solution, hence it tends to remain in the solid state.

Glaciers sit on land, not the ocean. When the end of a glacier reaches the ocean, parts of it break off and become icebergs, which eventually melt.

Only the very edge of glaciers touch ocean water. Glaciers are constantly melting into the ocean and forming farther up on land.


I think you mean icebergs?

Glaciers are rivers of ice. They don’t touch salt water as a general rule, except where the river meets the sea.

Icebergs are giant hunks of ice floating in the ocean.

Salt lowers the freezing point of water, which is why it can cause ice to melt. But it does not remove the freezing point altogether. At about 28.4F, saltwater will freeze. That is the point at which salt will no longer melt ice, and that is the temperature at which icebergs can survive in saltwater.

Salt causes water to melt at a temperature below the usual freezing point (32F/0C).

If it’s colder that that new freezing point, the ice stays frozen.

Salt doesn’t melt ice.
It changes the freezing point of the water.

So instead of water changing from liquid to solid at 0C, that number decreases. How much it decreases depends on how much salt you add. The actual scientific concept is called “freezing point depression” and you can calculate the exact new freezing point if you know how much salt is added, but it’s not very ELI5.

The reason it seems like it melts the ice is because most places don’t maintain a constant temperature of -20C, which is relatively easy to depress water to with icemelt pellets. So, the ice then melts because it isn’t cold enough for it to stay frozen with the newly depressed freezing point.

If you try using salt to melt ice in places where it’s freakishly cold, it doesn’t really work very well.

The glaciers exist in places (the Arctic and Antarctic), which are generally freakishly cold.

You have several misconceptions here. Salt doesn’t melt ice, it just lowers the freezing point of water so water has to be colder to freeze and ice will melt and colder temperatures. Also, glaciers are not on water. A glacier is, by definition, on land.

Now if you’re asking about sea ice, yes, salt in the ocean lowers the freezing point of the water slightly from 32 degrees F (0C) to about 28.5 F (-2C), but there’s still (for the time being) sea ice that’s below 28.5 degrees, so it doesn’t melt.

Glaciers sit on land. Land is made of dirt and rock. It doesn’t have much salt.

Now, icebergs which are in the water melt. That’s why the entire surface of the oceans isn’t covered in icebergs.

at 35g/kg salinity, the [Freezing Point Depression](https://en.m.wikipedia.org/wiki/Freezing-point_depression) effect of regular sea water is only a few degrees below normal freezing. if the seawater is cold enough the iceberg won’t melt and can last for years. this is no longer the case though for most areas with icebergs, due to climate change