Short answers, pulled from the story.
Climate change increases tropical cyclone intensity by warming ocean temperatures, which provides more energy to developing storms. Between 1979 and 2017, the proportion of Category 3 and higher cyclones increased globally, and with 2 degrees Celsius of warming, an additional 13 percent of cyclones are projected to reach Category 4 or 5 strength.
Yes. The Clausius-Clapeyron relation shows that warming air holds roughly 7 percent more water vapor per degree Celsius, and every model assessed in a 2019 review projected future rainfall rate increases. A 2019 study found that climate change already raised rainfall from hurricanes Katrina, Irma, and Maria by 4 to 9 percent, with future increases of up to 30 percent projected.
Most climate models project a decrease in the total global frequency of tropical cyclones, not an increase. A 2020 paper comparing nine high-resolution models found robust frequency decreases in the Southern Hemisphere. Observations show little change in overall global frequency, though the North Atlantic and central Pacific have seen increases while the western North Pacific and southern Indian Ocean have seen decreases.
Between 1982 and 2019, the number of cyclones in the Arabian Sea increased by 52 percent and the number of very severe cyclones rose by 150 percent. The total duration of cyclones grew by 80 percent, while the duration of very severe cyclones increased by 260 percent.
There is documented poleward expansion in the latitude where tropical cyclones reach maximum intensity, which may be associated with climate change. In the North Pacific, an eastward expansion has also been observed. Between 1949 and 2016, tropical cyclone translation speeds slowed globally, though the extent to which climate change caused that slowdown remains uncertain.
In 2005-39 percent of Americans believed climate change contributed to hurricane intensity. By September 2017, following a particularly active hurricane season, that figure had risen to 55 percent. The destruction from major Atlantic hurricanes including Katrina, Wilma, and Sandy drove substantial growth in public and media interest in the climate-hurricane relationship.