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Tornado outbreaks have been producing more tornadoes and more deaths in recent years, according to a new study.

Published in the online journal Nature Communications, the findings revealed tornado "clusters" are more dangerous now than they've been since at least 1954. Responsible for 79 percent of tornado fatalities in the eastern two-thirds of the U.S., these outbreaks often leave damage totals in the billions, the study also found.

"These discoveries suggest that the risks from tornado outbreaks are rising far faster than previously recognized," Joel Cohen, a mathematical population biologist and head of the Laboratory of Populations at Rockefeller University in New York and Columbia's Earth Institute, told Live Science.

(MORE: Texas Had Its Most Tornadic Year on Record in 2015)

Using NOAA tornado records from 1954 to 2014, the scientists studied events when at least six tornadoes rated EF1 or higher were spawned in a 6-hour span. In calculating the average number of tornadoes spawned by each of these clusters, the findings revealed an average of 15 twisters per outbreak from 2004 to 2014. In the 1950s, the average was just 10.

Included in their last decade of research was the 2011 Superoutbreak, when 349 tornadoes were spawned across the South and East, April 25-28, 2011.

As for whether or not climate change is fueling this rise, the jury's still out. The study acknowledges the fact that tornado counts have likely increased in recent decades because of better reporting techniques, as well as the increase in populated areas. But the study also notes that there is a correlation between the rise in tornadoes and the increase in events where the atmosphere is favorable for severe weather, which may be due to the changing climate.

Still, the authors of the study say there needs to be more research before any conclusions can be made about global warming's impact on these outbreaks.

"We want to know what in the climate system is driving these changes. Some have implicated climate change. We think such a conclusion is premature, and further study is needed," study co-author Michael Tippett told Live Science.

MORE ON WEATHER.COM: Tornadoes in the Plains, May 2015