SANTA BARBARA, Calif., April 19, 2013 /PRNewswire-USNewswire/ -- As another Earth Day rolls around, a California organization reminds us that population growth is still the fundamental environmental problem. "The consequences of that growth are all around us—loss of open space, air and water pollution, traffic congestion, and never-ending sprawl," said Jo Wideman, executive director of Californians for Population Stabilization (CAPS). "Habitat loss due to population growth is the greatest threat to wildlife." Since the first Earth Day in 1970, world population has nearly doubled to 7 billion, and the U.S. population, driven by immigration, has grown from 203 million to 316 million. According to Census Bureau projections, the nation's population will exceed 420 million by 2060, but that does not include the increase in immigration that would be wrought by the new immigration bill in the Senate. "It is extremely unfortunate that none of the analysis on the Gang of Eight's immigration bill has focused on its implications for population growth and the environment," Wideman said. "The bill provides more visas for legal immigration, and the amnesty will provide incentives for more illegal immigration." California has some of the most varied wildlife habitat on earth, boasting more endemic species than any other state, but rapid population growth imperils this extraordinary biodiversity. Over one-fourth of California's plants are extinct, rare, endangered, or threatened, and over 150 animals are listed as threatened or endangered. The founder of Earth Day, the late Sen. Gaylord Nelson often drew the links among population, immigration, and the environment. He stated, "In this country, it's phony to say 'I'm for the environment but not for limiting immigration.'" The late David Brower, the Sierra Club's first executive director and a CAPS Advisory Board member, noted, "Overpopulation is perhaps the biggest problem facing us, and immigration... has to be addressed."