AP: As the world’s biggest greenhouse gas producer, China was widely seen as an obstacle in the Copenhagen climate summit last year. But while negotiations inched forward, Beijing poured $34.6 billion into clean energy in 2009, nearly double the U.S. investment. Now, with the Asian giant hosting meetings this week ahead of the next major climate conference in Cancun, China has seized the high ground, touting its green credentials publicly and even lecturing rich nations. Its …