The season for Atlantic tropical storms is considered to be from June through November. But in 2005, Tropical Storm Zeta, the final storm of the season, formed in late December and lasted into January 2006. It is tempting to attribute the increase in storm activity to rising global temperatures. This may be the case, but the situation is more complicated. There have been cycles of storm intensity and frequency in the past. The 1930s through the1950s were a period of greater storm activity. This was followed by several decades of relative calm and then the period of increased activity that we are currently experiencing. These cycles are due to changes in rainfall, ocean currents, and salinity. So there are two tendencies, one cyclical and the other long-term. Even if storm activity ebbs and flows as it has in the past, warmer oceans are likely to result in more storms and more intense storms. The quiet parts of the cycle will not be as calm as in the past. The active periods are likely to be worse. People in some parts of the world are in particular danger from storms in combination with rising sea levels. The Gulf of Mexico and the Bay of Bengal are places where relative sea level is rising most rapidly. They are also subject to frequent tropical storms.