It's called black gives up a pawn for one tempo in compensation gambit. So in other words, dubious.
Which defense variation is this?

It gives black one tempo for a pawn. You need three tempo to justify a pawn investment. So really you will have barely enough compensation to last until white castles to which black will just be fighting in a pawn down middlegame.

If you're willing to spend a few dollars, there's an app on Android called Chess PGN Master Pro. It includes a very comprehensive opening tree that will name every opening and variation plus give you the Informant ECO opening code. Be sure to get the Pro key, which unlocks all the features. Compatible with most engines like Stockfish and Komodo. Can create databases. Reads SCID files, which SCID is a free data base app that can download TWIC, This Week In Chess, which are huge tournament game collections offered every week on Monday night of most current tournaments in the world.

This particular variation does not have a name. Since its only a few moves into the opening you have to figure it's not a great move. But you can also turn on Stockfish to help evaluate the position.

The begin of your line was a Caro-Kann.
However, as soon as you gave up 1 pawn.
You no longer was in a Caro-Kann.
For the Caro-Kann is not a gambit line.
The closest name I can find which might be similar to your position is called the Scandinavian Defense/Blackburne Gambit
The above line is the closest I could get to a name.
This is the Caro-Kann defense, but does anybody know what the variation is called?
Giving up material in exchange for development and two half-open files.