Tropical storms and hurricanes are now reaching their peak intensity closer to the globe's poles at a rate of roughly 35 miles per decade, according to a new study.
The study, led by the National Oceanic and Atmospheric Administration (NOAA), and published in the journal Nature on Wednesday, says the rate at which tropical storms are moving toward the poles over the past 30 years as the earth's oceans have warmed has increased.
The report, published by three of the world's leading tropical weather experts, indirectly links man-made climate change and tropical storms, or hurricane behavior.
The report's authors say that the rate at which hurricanes are moving toward the globe's poles matches the rates at which the tropical region is expanding.
"The rate at which tropical cyclones are moving toward the poles is consistent with the observed rates of tropical expansion," Jim Kossin, scientist with NOAA, and the paper's lead author, said in a statement on Wednesday. "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."
That means that as the range of the tropics spreads, increasing heat in the mid-latitudes, the number of hurricanes moving toward the poles increase.
Still, while human-caused increases in greenhouse gases, ozone depletion and higher atmospheric pollution are causing the expansion of the tropics, scientists say, it is too early to tell if that directly impacts hurricane movement.
"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," says Gabriel Vecchi, a coauthor of the study.
The findings in the report may be the smoking gun connecting man-made climate change to hurricane, and tropical storm, activity, which has been largely disputed amongst lawmakers on Capitol Hill.