The study, which was presented to the American Meteorological Society and published in the scientific journal, Geophysical Research Letters, indicates the probability of hurricanes hitting the United States increases dramatically during low points of the 11-year sunspot cycle, such as we are currently experiencing.
Sunspots have long been implicated in the global climate. During periods of high sunspot activity, which occurred throughout the Medieval Warm Period, global temperatures rose. During the low points in sunspot activity, such as in the Little Ice Age, temperatures declined.
How does this affect hurricanes? Well, years with few sunspots and above-normal ocean temperatures, as is the case now, spawn a less stable atmosphere and, consequently, more hurricanes. When that happens, the differential creates more atmospheric instability and stronger storms, energizing what might otherwise remain tropical storms into hurricanes. Years with more sunspots but still above-normal ocean temperatures yield a more stable atmosphere and thus fewer hurricanes.
So here's the breakdown in numbers...
- The chance of at least one hurricane hitting the United States spikes to 64 percent in the lowest sunspot years, compared to only a 25 percent chance in peak sunspot years.
- Chances of three or more hurricanes hitting the United States increase from 20 percent to 40 percent in years when sunspots are in the lowest 25 percent, compared with years when they're in the highest 25 percent.