Significant digits isn't always the best way to denote a number and its accuracy. If a simulation says 552 +/- 100, then how would you write down the fact that the expectation is centered around 552 and there is an error of 100, using a single number?
The best you can do with a single number would be something like 6·10^2 tons, you also use 6 hectotons or 0.6 gigagram though people might find those a bit weird.
Or you could just denote its accuracy, which the original source likely does, but which news article inevitably fail to include (and subsequently fail to adjust the number of significant digits).
