The phrase "upward slope" refers to a situation where something is gradually increasing or becoming higher over time.
Sentences with «upward slope»
The second test was a hill climb — actually a fairly gentle upward slope of snow with a bit of ice. (extremetech.com)
So in my view, rather than a constant upward slope toward «truth,» human history actually made a downward slope into sin and ignorance. (redeeminggod.com)
Of course, the ride is going to bumpy and it won't at all look like a gradual upward slope. (thebalance.com)