The primary tool has been the use of snow machines to provide adequate cover: according to figures from the Austrian cableways association, investments in these totalled EUR 800 million in the five years following 2008.2 As a result, snow is guaranteed on 70% of the slopes in Austria. However, as temperatures (or humidity, or both) increase, so do the volumes of water and energy required, and the costs. As described in OECD (2007), there is also a technical limit because the machines generally require a temperature below -2 °C to be effective.