• What are the consequences of the anthropogenically accelerated nitrogen cycle?

• Can we quantify the interactive roles of increasing carbon dioxide, the changing nitrogen cycle, and land use in terms of present and future terrestrial carbon storage?

• How will the role of marine ecosystems change with future changes to ocean circulation, temperature, and nutrient/toxic inputs?

• What are the current budgets for the sources and sinks of biogenic greenhouse gases, especially methane and nitrous oxide?

• How is current environmental change, including land-use change, fertilization, and atmospheric nitrogen deposition, affecting the sources and sinks for these gases?

• How might the sources and sinks change in the future with changing land management, climate, and chemical inputs?

• As global use of anthropogenic nitrogen increases, is there potential for nitrous oxide emission or methane consumption to change rapidly?

• What changes are occurring to the atmosphere-ecosystem exchange of reactive trace gas species (nitric oxide, ammonia, nonmethane hydrocarbons, dimethyl sulfide)?

• What biological and pyrogenic processes control these exchanges, and how might they change in the future?

• What is the role of changing biogenic trace gas emissions in the changing photochemistry of the troposphere and stratosphere?

• Aerosols have become a major issue in climate: what role do sulfur and organic compounds from biogenic sources, dust from agriculture and other soil disturbances, and biomass burning play in global aerosol forcing?

Multiple Stresses Imperative

Understand the responses of ecosystems to multiple stresses.

Multiple Stresses Questions

• How do multiple global changes interact to produce ecosystem responses?

• What are the interactions of changing land use, climate, nutrient and toxic inputs, and hydrology on ecosystems and their ability to produce goods and services?

• What are the required data sets, theory, and models needed to understand the regional coupling of physical and chemical climate, land use, and ecosystems?

• Can we develop the science needed to manage regional systems subject to multiple stresses to provide ecosystem goods and services while maintaining ecological integrity?