They are elusive but have a huge impact on the ecosystem. According to a study by researchers from Switzerland and Austria, multi-year dry periods or “megadroughts” not only occur regularly, they have also become more frequent over the past 40 years. In the journal Science the team reports that these events now tend to be even drier, longer and hotter, cause more damage to vegetation and affect ever larger areas of land than in 1980. They have increased significantly in recent years in particular. However, some “paradoxical” droughts are still barely noticed, it is said.