ByJohn S. McClenahen The Washington-based Worldwatch Institute, an environmental activist group, is clearly discouraged by what it sees around the world: a thinning Arctic ice cap and rising growth in the use of fossil fuels, just to cite two examples. But, significantly, the group doesn't do a big blame number on industry; it saves that for politicians. Indeed, the institute's year 2001 annual report, released this week, stresses that industry is one key to environmental progress. It approvingly relates that last year, William Clay Ford, chairman of Ford Motor Co., Dearborn, Mich., raised questions about the long-term future of the internal-combustion engine and personal autos as his company accelerated efforts to develop new transportation technologies. Also, three oil companies announced they were moving "beyond petroleum" to a broader range of energy investments, notes the report.