POLICYFORUM T

remendous progress has been made in understanding the functioning of the Earth system and, in particular, the impact of human actions ( 1). Although this knowledge can inform management of spe-cifi c features of our world in transition, soci-eties need knowledge that will allow them to simultaneously reduce global environ-mental risks while also meeting economic development goals. For example, how can we advance science and technology, change human behavior, and infl uence political will to enable societies to meet targets for reduc-tions in greenhouse gas emissions to avoid dangerous climate change? At the same time, how can we meet needs for food, water, improved health and human security, and enhanced energy security? Can this be done while also meeting the United Nations Mil-lennium Development Goals of eradicating extreme poverty and hunger and ensuring ecosystem integrity? Answering these questions will require reorientation toward new research that bet-ter allows science and society to address the needs of decision-makers and citizens at global, regional, national, and local scales ( 2). We will have to meet a twofold challenge: (i) develop strategies to respond to ongoing global change while meeting development goals and (ii) deepen knowledge of the func-tioning of the Earth system and its critical thresholds ( 3). Promoting sustainable devel-opment requires research on a wide range of social, economic, cultural, institutional, and environmental issues ( 4). Given that sustainable development is no longer pos-sible without addressing interactions with global change dynamics ( 5), we focus here on an important dimension of this larger sus-tainability agenda: the need to broaden and deepen Earth system research to encompass the intersection of global environmental change and sustainable development. Grand Challenges A great deal of collaborative international research on global environmental change is coordinated through four Global Environ