Denis Hayes is president and chair of the Earth Day Network, which this week is launching an Earth Day 2000 campaign focusing on global warming and energy use. Hayes was the national coordinator for the first Earth Day in 1970 and now earns his keep as president of the Bullitt Foundation in Seattle. Grist, not incidentally, is a project of the Earth Day Network. Sunday, 18 Apr 1999 EN ROUTE TO BOSTON Roll out of bed at 4:30 am, Seattle time. Round up some files to review for a speech at Harvard tomorrow. Write a couple real letters and reply …