As the strength of hurricanes continues to increase with global warming, two US researchers have now proposed expanding the scale for assessing hurricanes. A category 6 should be considered beyond the current categories 1 to 5 on the so-called Saffir-Simpson scale, according to a study by Michael Wehner from the Lawrence Berkeley National Lab and James Kossin from the University of Wisconsin. The aim: A more precise identification of storm intensity and better ways of informing and warning the population.