On the other hand, our weather has always been "chaotic". In fact, the weather forecasting models were what was used as the basis for defining "chaotic" in a mathematical sense. Basically, it means that very minor changes in the input parameters can produce large changes in the output parameters that are not necessarily predictable.
Mathematically "chaotic" systems are usually characterized by plots of their parameters tending to cluster or show time paths in one area of a graph for a while, then suddenly switch to doing that in a different area of the graph, maybe switching back and forth for reasons not readily apparent.
So, what this report is describing is more a matter of whether we will do one of those parameter cluster/path shifts. There have been many in Earth's history. Humans have benefited greatly from the last one, which produced a short warm period in a more steady era of cold (ice ages). In fact, we should probably have shifted back to an ice age already, or in the near future, if we had not already messed with out climate.
So, while we still don't understand how climate actually changed from ice age to short interglacial periods and back, many times in the last few million years, it appears that we have already messed with that cycle enough to preclude its continuation, and are probably embarking on some different shift in the climate cycles as we go into the future.
By the way, please don't be fooled by the folks who point to the Milankovitch (Orbital) Cycles as the full explanation of the ice age cycles. Those appear to be significant drivers, but the periods and temperature parameters do not match sufficiently to just predict ice ages like clockwork. What we seem to have had was a chaotic response of Earths climate to those orbital parameter cycles. Other things that we are still trying to understand, such as major heat transport pattern shifts in ocean currents, trade winds, etc. seem to be hugely important to changing climate rapidly when they shift in a manner that is "sudden" on the scale of geological history.