Any sovereign nation should decide what it wants to do within its own borders. However, since what you do in your backyard affects your neighborhood, it's only fair to put up some common sense rules into place.
One simple thing to do is having countries agree to pay a "climate tax", with higher values for lower values of forest area as % of land.
But countries hardly agree on anything, measures are difficult and there's a lack of trust, not to start on how to set the values of thresholds.