Climate variability and tropical cyclone activity Tropical climate has received increased attention over the last 40 years mainly because of the El Niño Southern Oscillation (ENSO) phenomenon and the Madden Julian Oscillation (MJO) and their associated impacts on a local regional and global scale. While the MJO is the most prominent disturbance that operates on the subseasonal time scale (less than 90 days but longer than 10 days) the ENSO is a powerful interplay between the tropical ocean and atmosphere on interannual time scales with a preferred recurrence interval of 2 7 years. Studies show that MJO and ENSO can have a profound effect on global weather systems such as shifting tropical cyclone (TC) formation location altering frequency of occurrence storm tracks landfall locations intensity and lifespan in various ocean basins. There are at least two types of El Niño: the Eastern Pacific and Central Pacific types which modulate regional TC activity in a different manner. In addition to ENSO other climate modes that also influence TC activity on the interannual time scale include the North Atlantic Oscillation Pacific Meridional Mode and Atlantic Meridional Mode. On a longer time scale TC activity is modulated by the decadal to interdecadal oscillations in the Atlantic and Pacific. Aside from TCs the aforementioned climate modes also alter precipitation and temperatures variations resulting in drought flooding extreme cold or warm conditions and public health issues in many parts of the world. TC attributes are projected to change over the next 50 100 years under an anthropogenic warming scenario although uncertainty remains