Look guys, 3% of 0.04% of a gas is causing ice to melt, not the actual mantle heating 70% of the earth's surface.
The hole was accidentally discovered about 10 years ago when an ocean science vessel was idling off the coast of Oregon waiting for a storm to pass.
They were directly above the subduction zone where the Pacific and North American plates pass over and under each other. They detected a plume of bubbles on the sea floor, deployed a robot to investigate, and discovered that fresh water was pouring up through the hole with the velocity of a fire hose.
Subsequent investigations have concluded that the water is coming from the actual slip zone where the two plates pass, and where the temperature is 300-500 degrees F.
They measured the temp of the out flowing fresh water at 16 degrees F higher than the ambient sea water.
This hole is claimed to be one of a kind, but there is no way to confirm that - there could be thousands of holes like this spread around the globe, or thousands of acres of super heated sea floor. Combine the heat source of those holes, hydro thermal vents, sea floor spreading, and normal ocean volcanic activity, and you have measurable heating of the ocean coming straight from the Earth's mantle.