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- Yale Program on Climate Change CommunicationScientific research for climate change
- Yellowstone to Yukon Conservation InitiativeNorth American non-profit organisation
- YelpDirectory service and online review forum
- Yokkaichi asthmaLung disease caused by air pollution in Japan
- Yosemite Valley RailroadThe Yosemite Valley Railroad (YVRR) was a short-line railroad that operated in California
- Yugoslavia and weapons of mass destructionIn the late 1940's, Josip Broz Tito leader of Yugoslavia from 1945 to 1980, decided it was
- Yuvelis Morales BlancoColombian environmental activist and Goldman Prize winner