For the second year in a row, Angela Merkel, the first woman to become chancellor of Germany, ranks No. 1 on our list of the World's 100 Most Powerful Women. She continued to impress the world with her cool leadership at two back-to-back summits. First, she stuck to her principles, getting G-8 leaders to agree to significant cuts in carbon emissions, among other things. Merkel later corralled European Union countries into an agreement on a treaty to replace the E.U. constitution. Meanwhile, China's vice premier, Wu Yi (No. 2), continues to help lead a government that oversees an economy whose...