Tropical cyclones (TCs) are one of the most destructive natural phenomena on Earth in terms of human-life and eco-nomic losses. It is currently a matter of prodigious public and scientific interest how TC activity has changed and will change in a warming climate. This special issue focuses on a challenging subject raised in the Intergovernmental Panel on Cli-mate Change (IPCC) report and numerous research papers. Determining the response of TC activity to climate change is com-plicated by inherent natural variability. A portion of the detected trends in TC activity likely results from natural variability, but separating that portion is difficult due to limited historical records. Thus, understanding natural variability is critical to the projection of TC activity in a warming climate. In addition, understanding natural variability is also essential for sea-sonal forecasting.