According to most estimates, rangeland ecosys tems occupy about 50% of the earth's terrestrial surface. By itself, this estimate implies range lands are important to humans, but their impor tance extends far beyond their global dominance. Globally, rangelands provide about 70% of the forage for domestic livestock. For many societies, livestock are critical to sur vival. Rangelands also provide a host of ecosystem services technology or other land types cannot provide. Among the most important of these services is climate regulation, or the ability to sequester and store greenhouse gases such as carbon dioxide. The ability of any rangeland to provide any ecosystem service is dependent, primarily, upon the rangeland's condi tion. Degraded rangelands are poor providers of ecosystem services, regardless of the commodity. In crop or forest ecosystems, managers can overcome inherent biophysical limitations with additions of water, fertilizer, cultivation, or new plant species. Rangeland managers typically lack those options. In general, management is concentrated on affect ing changes in soils and vegetation through the application of disturbances, such as fire or grazing. The primary input for rangeland managers is intellectual capital, whether it is in the form of livestock management practices based on research conducted at a nearby experiment station, experi ence handed down across generations, or other forms of local knowledge. Because rangeland managers have a lim ited ability to manage inputs, they are more dependent on environmental conditions. In particular, rainfall (amount and timing) governs rangelands, and managers' success or failure is determined by their ability to respond to, rather than create, conditions. Any change to the environment affecting rainfall, or how soils and plants process water, will have a dominant influence on productivity, stability, and profitability. The interaction between scientists and managers is critical to understanding and managing the relationships critical to healthy rangeland ecosystems. While scientists uncover new relationships governing ecosystem behavior, managers are ultimately responsible for implementing prac tices to ensure continued heath of the systems they manage. One of the most important scientific contributions of the past decade is an enhanced understanding of earth's climate system and human impacts on climate. Through a collab orative effort, scientists have communicated the links between humans and climate. Policy makers and the public are generally aware that humans have an influence on climate?an influence that is likely to increase in the immediate future. There is a recent consensus on the need