As a result of the campaign lake levels are now controlled to close to that of natural fluctuations.
Yet the academy's report tells us that we do not know how much effect natural fluctuations in climate may have had on warming.
But the scientists added that last year's warm temperatures appeared to have been linked, at least in part, to natural fluctuations.
The new study suggests that natural fluctuation can also lead to elevated scores.
My money is on the natural fluctuations, but I can't prove that.
But natural fluctuations in fish stocks can pose a problem for wild salmon fishing.
Some scientists continue to argue that natural climatic fluctuations may be responsible for the rise.
The changes being measured also appeared to be happening at rates far faster than natural fluctuations, they said.
It was simply a natural fluctuation for which they seized credit.
Time and again, the boom never seems to happen, or some natural fluctuation occurs that had nothing to do with the event.