The discovery that volcanic emissions have cooled the Earth significantly during the past decade implies that the heating effect per ton of CO₂ is stronger than the estimate from a year ago.

In effect, our boat has been drifting slowly towards the waterfall, and we just discovered that one engine was on and trying to push us away for the past decade. That implies the current is faster than we thought.

The analogy is limited. The current in this case is the result of our greenhouse gas emissions, and we could reduce them greatly if we take bold measures.