Tree rings could finally settle what Al Gore could not: the debate on whether global warming is making hurricanes stronger.

Several studies made since early 2005 have linked global warming to the increasing occurrence and strength of hurricanes like Katrina over the last decade. But these conclusions have been debated because they relied on potentially flawed data.

The issue could finally be resolved using the technique developed by researchers from the University of Tennessee: measuring different isotopes of oxygen present in the rings. Big hurricanes produce large amounts of precipitation with lower oxygen isotope composition compared with the isotopes in dew or smaller storms.

By looking at older trees, the researchers have been able to create a record of hurricane activity in the Southeastern US dating back 220 years, more than double the current record. In fact, the study suggests that data up to 500 years can be accessed in future studies.

The research could help create a reliable record of hurricanes, including frequency and intensity, that goes beyond the records kept by the National Oceanic and Atmospheric Administration's Atlantic (NOAAA) in its hurricane database. NOAA 's records stretch back to the last 100 years. But because storm data from more than 20 years ago are not very accurate, researchers cannot make a credible baseline that accurately compares storm frequency and strength over time.

Dendroclimatology is the science of extracting past climate information from trees. Tree ring information can reconstruct climate conditions at the trees' growing site for certain seasons back to thousands of years. It's possible to reconstruct records much older than the oldest living trees, either by using dead trees that are still in place or trees that were cut and used for building long ago.