Lets say the ocean would freeze if heat from the mantle stopped flowing-is that right or wrong?

No, the flux of heat from the interior of the Earth is something like 50 milliwatts per square meter. The air-sea flux of energy is on the order of 100 watts per square meter, thousands of times bigger. The oceans would not freeze if the geothermal flux became zero.

EDIT for Crash: So you're saying if the oceans were not the oceans, but were instead solid rock, then it would be warmer at the bottom? But the oceans ARE the oceans, they are not solid rock, so doesn't make your entire argument irrelevant? Or am I missing something? Why not extend your geothermal temperature gradient up into the atmosphere, too?

Another EDIT for jim m: You said

"These answers are missing the point of the question. I don't why asimple question should be so hard to answer. Some amount of heat is flowing from the mantle and I just want to know how much."

If you want to know how much you'll actually have to READ the answers, rather than complaining about them--I gave you the number almost immediately after you asked the question.

Oh dear, it seems we have a new jim troll, past freezes of the planet are linked to drops in Co2, while there are thermal vents that do indeed heat water, average temperatures in the depths of the ocean are just above freezing (2-3c) so compared to average surface temperatures, it should not be that difficult to see where the majority of warming is coming from. Just as if you take away that large ball of hydrogen in the sky for a few months, in say the Northern or Southern Winters near the Poles, the surface also gets very cold.

As others have already tried to explain to you in the previous spins on this question, geothermal has only a small effect on atmospheric temperature and that effect has always been there.

5km of oceanic mantle rock does not suddenly decide it's going to be less insulating, take a geology class, but please make sure the teacher is not jim z as he will start in on his alternative theories on the origin of oil and you will learn nothing.

Mike : Not really sure how a magnetic field stops radiation, the atmosphere does that, the magnetic field stops the solar wind which is charged particles not radiation. Without a magnetic field we would (given millions of years) lose our atmosphere as the solar wind would literally blow it away, as it has done on Mars.

http://science.nasa.gov/science-news/science-at-na...

Actually The increase of heat as you go deeper into the earth has been established.

Its called The geothermal gradient & away from hot spots like tectonic plate boundaries it averages about 25c per kilometer of depth.

The average depth of the Earths oceans is 4.3k which @ 25c per k = around a 100c temperature increase.

The deepest part of the ocean, the challenger deep near Guam is a little over 11k deep. If it weren't for the heat transfer effect of ocean waters the temperature of earth & rock at that depth should be 275c+.

So heating from the mantle is not as insignificant as some would like you to believe.

wrong. there would be no more geological activity, no new rock formed and no continental drift as plates would stop being subducted. that means no more earthquakes, and eventually no more earth as all the rock would be eroded away and not replaced through tectonic uplift etc. unless this influenced the tilt on the earths axis it shouldn't lead to a freeze.

If the core of the Earth turned solid the magnetic field would die . Then the Earth

would get the Suns radiation will crisp the Earth.

Whew! Did Jimmy the egghead Hansen come and give a speech at your place? If this is not from him, don't give him any more ideas. It is baloney.