In 1975, the MBL's Ecosystems Center was established, with George Woodwell as director. The original research focus was on the global carbon cycle, an emphasis maintained today. The Ecosystems Center has a year-round staff of more than 40 scientists who study a variety of ecosystems and their responses to human activities and environmental changes. The center is located in Woods Hole yet has a global reach, with active research sites in the Arctic tundra; in forest, coastal and marine sites in New England, Sweden and Brazil. The Ecosystems Center is home to two of the 26 U.S. Long Term Ecological Research (LTER) sites: Toolik Lake, Alaska; and Plum Island, Massachusetts. Scientists in the Ecosystems Center study the effects of forest clearance and land-use change on atmospheric chemistry, watershed processes and coastal ecology, the global-scale anthropogenic enrichment of the nitrogen cycle, and ecosystem responses to global warming. The interim director of the Ecosystems Center is Anne Giblin. Former directors of the Center who are still active on the scientific staff are Jerry Melillo, who studies the biogeochemistry of terrestrial ecosystems, and John Hobbie, a microbial ecologist. The Ecosystems Center is founded on a vision of collaborative, interdisciplinary science; shared lab facilities and instrumentation; and a long-term, large-scale, systems-wide view of ecosystem processes. The Josephine Bay Paul Center for Comparative Molecular Biology and Evolution was founded at the MBL in 1997 and is currently directed by David Mark Welch. By comparing diverse genomes, scientists at the center are elucidating the evolutionary relationships of biological systems, and describing genes and genomes of biomedical and environmental significance. Microorganisms found in a wide range of ecosystems, including the human microbiome, are studied. Mitchell Sogin, the Bay Paul Center's founder, also founded two courses at the MBL: the Workshop in Molecular Evolution; and Strategies and Techniques for Analyzing Microbial Population Structures. In 2003-2004, Sogin launched the International Census of Marine Microbes, a global effort to describe the biodiversity of marine micro-organisms. Early results from this census in 2006 revealed some 10 to 100 times more types of marine microbes than expected, and the vast majority are previously unknown, low-abundance microorganisms now called the “rare biosphere.” Other Bay Paul Center projects are focused on microbes that live in extreme environments, from hydrothermal vents to highly acidic ecosystems, which may lead to a better understanding of life that could exist on other planets.