GOTHIC, Colo. (AP) - It's been 30 years since much of the world learned that global warming had arrived, but climate isn't the only thing that's changing: Nature itself is too.

That's the picture painted by interviews with more than 50 scientists and an Associated Press analysis of data on plants, animals, pollen, ice, sea level and more. It's been 30 years since much of the world learned that global warming had arrived.

On June 23, 1988, NASA scientist James Hansen testified before Congress, explaining that heat-trapping gases spewed by the burning of fossil fuels were pushing temperatures higher. One biologist says nature is extremely sensitive to temperature and that dramatic changes are happening right in front of us.

Evidence is in the blueberry bushes in Henry David Thoreau's Walden Pond, the dwindling population of polar bears of the Arctic and the dying corals worldwide.