Can Internal Variability Explain Trends in the Latitude of Lifetime Maximum Intensity?

Past studies have shown significant poleward trends in the latitude at which tropical cyclones reach their lifetime maximum intensity, especially in the Northwest Pacific basin. Given the brevity of the historical record, it remains difficult to separate the forced trend from internal variability of the climate system. A recently developed tropical cyclone downscaling model is used to downscale the 1000 years of the CESM2 pre-industrial control period. It is found that observed trends in the latitude at which tropical cyclones reach their lifetime maximum intensity in the Northwest Pacific basin is very likely to be forced. Further analysis of the downscaled tracks shows that internal variability has significant control on the latitude of tropical cyclone genesis, and a lesser, but still important influence on the motion of tropical cyclones.