evidence: In summary, neither our model projections for the 21st century nor our analyses of trends in Atlantic hurricane and tropical storm activity support the notion that greenhouse gas-induced warming leads to large increases in either tropical storm or overall hurricane numbers in the Atlantic. A recent study finds that the observed increase in an Atlantic hurricane rapid intensification metric over 1982-2009 is highly unusual compared to one climate model’s simulation of internal multidecadal climate variability, and is consistent in sign with that model’s expected long-term response to anthropogenic forcing. Studies of extreme precipitation events in Texas and tropical cyclone precipitation in Puerto Rico are suggestive of emerging anthropogenic influence on hurricane precipitation. The above climate change detection/attribution studies are not yet definitive for hurricane activity metrics, and more research is needed for more confident conclusions. A slowing of tropical cyclone propagation speeds over the continental U.S. has been found since 1900, but its cause remains uncertain. [...] Despite the difficulty in identifying a detectable influence of human-caused greenhouse gas increases on global tropical cyclone activity, greenhouse gas-induced climate change may have already caused changes in tropical cyclone activity that are not yet detectable due to their small magnitude compared to estimated natural variability, or due to observational limitations.