system
Given the following post, respond as if you're commenting on Reddit:
human
Does the moon's effect on tides consume energy and does it mean the moon is decelerating? If so, how fast?

Hopefully the title requires no further clarification.
gpt
Yes, kinetic energy in the earth-moon system is being lost through tidal friction.  The system's angular momentum must be conserved and this happens by slowing the rotation of the earth and orbital speed of the moon.  In other words, both the day and the month are gradually increasing.  The longer month also means that the moon is moving away from the earth.  

Another way to think of it is that some of the earth's spin is being used to push the moon into a higher orbit.  The end-game would be when the length of the day and the month become equal and the earth always keeps the same side facing the moon in the same way that the moon already keeps the same side facing the earth.  Once this happened there would be no more changing tides on earth due to the moon, though there would still be tides (about half as strong) due to the sun.

From memory, this end-game is not predicted to happen until the earth is at least twice as old as it already is and, by that time, the sun will have expanded massively and possibly consumed both the earth and the moon.