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Comment by 8bitsrule | Hacker News Reader

Why it matters:

The ice-water phase change absorbs much more heat than heating water by 1 degree. The energy required for that phase change, called the 'enthalpy of fusion', is 333.55 Joules/gram. This is huge compared to the energy required to heat 1g of water by 1 degree, 4.18 J.

In other words, the ice 'cold bank' is much more of a cushion for temperature change than water is. One metric ton of ice is one million grams. The phase change melt absorbs 333 million joules ... the energy in about 2.8 gallons of gasoline. Multiply that by 28 trillion.

The bank is emptying.

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The thermal mass in the ice water transition I suspect is tiny compared to the thermal mass of all the rock making up the crust, mantle, and core of the earth.

Obviously there is some thermal impedance to the deeper down rocks, but I still suspect the ice mass to be negligible.

Rock has about a quarter the specific heat of water (there are lots of kinds of rock, and it varies with temperature quite a bit.)

That's a quarter of the 4.18 J/g.K, not a quarter of the enthalpy of fusion.

> Obviously there is some thermal impedance to the deeper down rocks

Rock has very low thermal conductivity. That's one reason why land heats up at 2 to 3 times the rate of the surface of the oceans, so you go to the beach in summer.

Finally, experts in the field consider this (permanent ice melt) to be important. When you think they're wrong, surely the appropriate response is "what am I missing? What don't I understand?".

Heat is not 'banked' by the atmosphere though; it is radiated away. If that heat were not trapped phase changing water, a significant fraction would be radiated back into space.

Except for these "greenhouse gases" which reflect an annually increasing amount of radiation back to the planet?

Eventually Earth won’t support life at all anymore.

Yeah, but we have like a billion years or so until that happens (e.g. the sun turns red giant and boils the atmosphere away).

Life did pretty well even in the Paleocene-Eocene thermal maximum.

The life that we care about as people is the biosphere that supports people life. I am not being facetious, that's just part of how this conversation works. We have to assume some things are shared knowledge.

Except 50 million years ago we had +10 degrees Celsius increase in temperature and life on the planet was pretty good. We see mass extinctions during ice ages, not during hot spells.

This is left out of nearly every climate debate, which typically goes back in the last few hundred years rather than millions.

Example graph: http://jeremyshiers.com/blog/wp-content/uploads/2014/07/glob...

When I want to use a new material for my fancy microchip fab, I refer to jeremyshiers.com as an authority about why it will work

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