Geographer Looks Back at Human History to Understand How We Got to 7 Billion and Counting

Environmental geographer Ruth DeFries is a pioneer in the study of how humans have transformed the surface of the Earth. Using satellite data, she explores how changes in Earth’s vegetation can affect climate, ecosystems and the relative ability of humans and other species to survive on this planet.

Her new book, The Big Ratchet: How Humanity Thrives in the Face of Natural Crisis, takes the very long view of human history, describing how, for at least 10,000 years, we have continually created new technologies that have allowed our numbers to grow.


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New Hope for Hair Lossvideo icon

Medical Center researchers have identified the immune cells responsible for destroying hair follicles in people with alopecia areata, a common autoimmune disease that causes hair loss.


Shift in Arabian Sea Plankton May Threaten Fisheries

A growing “dead zone” in the middle of the Arabian Sea has allowed plankton uniquely suited to low-oxygen water to take over the base of the food chain.

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What kind of bird is that? Snap a picture and find out. Computer science researchers created Birdsnap, an electronic guide for identifying birds.
Columbia's Leadership in Climate Research