Brrr, it’s getting cold outside. And Julia Butterfly, the 25-year-old who’s been stationed for two years in a redwood slated for logging by the Pacific Lumber Co., is hinting that it may be time for her to end her protest and come down before winter hits full on in Northern California. Of course, she’d only touch ground if it were certain that the tree, which she calls “Luna,” were guaranteed protection. She said yesterday that negotiations were underway with the timber company to spare the 600-year-old giant redwood, as well as a 200-foot buffer around it. “I’d like to spend Christmas with my family,” she said.