The average latitude at which cyclones are their most intense has been moving closer and closer to the poles since 1980.
This phenomenon could cause regions closer to the equator to have a reduced risk of experiencing a cyclone, but the risk is increased in coastal regions, an NOAA Headquarters news release reported.
Most coastal cities are not prepared for devastating cyclones.
This migration towards the poles is occurring at different rates depending on the region. The highest rate of migration has been observed in the southern Pacific and South Indian Oceans, but a migration has not been seen at all in the Atlantic.
The researchers believe their method of looking at where the cyclone started is more accurate than past studies.
"Historical intensity estimates can be very inconsistent over time, but the location where a tropical cyclone reaches its maximum intensity is a more reliable value and less likely to be influenced by data discrepancies or uncertainties," Jim Kossin, the paper's lead author, who is a scientist with NOAA's National Climatic Data Center currently stationed at the NOAA Cooperative Institute for Meteorological Satellite Studies at the University of Wisconsin-Madison, said in the news release.
Other studies are also showing an expansion of the tropics over the past 30 years.
"The rate at which tropical cyclones are moving toward the poles is consistent with the observed rates of tropical expansion," Kossin said. "The expansion of the tropics appears to be influencing the environmental factors that control tropical cyclone formation and intensification, which is apparently driving their migration toward the poles."
Poleward migration and expansion of the tropics show similar variability, suggesting they are connected.
"Now that we see this clear trend, it is crucial that we understand what has caused it - so we can understand what is likely to occur in the years and decades to come," Gabriel Vecchi, scientist at NOAA's Geophysical Fluid Dynamics Laboratory and coauthor of the study, said in the news release.
