We are examining ecosystem processes at local, regional, and global scales with complex numerical models that run on platforms ranging from desktop computers to our large Linux computing cluster. We simulate ecosystems around the globe from tropical forests to tundra, and natural vegetation to intensively managed agroecosystems. We are addressing questions of global importance such as: What will happen to the services that ecosystems provide as land use changes (e.g., how large scale deforestation affect rainfall both locally and in remote regions)? What will global climate change do to crop yields and how might the Midwest corn-soybean region adapt? What happens to the functioning of the Midwest agroecosystems when some of the corn and soybean is replaced with biofuel crops? What are the consequences of the ‘greening’ of the Arctic regions as a result of climate change?