In a great opening paragraph, every sentence does significant work. Each sentence requires significant attention to tone, content, and language. The two anchors are your opening sentence and your thesis sentence, but these do not lie apart from one another or from the rest of the sentences. Like an interlocking framework, all the sentences work together; even a small shift in one sentence could affect all the others.
For example, let's stay with the paragraph on global warming.
"Not only has the United States failed to ratify the Kyoto Protocol and reduce the U.S. contribution to global warming, but existing U.S. standards for greenhouse gas emissions also have failed to encourage polluters to decrease levels of emissions. Emissions from factories, cars, and ? [research a third item] have been increasing dramatically every year in the United States [check facts and cite], while most other industrialized nations have been able to hold emissions fairly steady in at least one of these areas in the years since the Kyoto Protocol [check facts and cite]. These other nations--x, y, and z in particular--have succeeded primarily by enforcing strict emissions standards and by simultaneously demonstrating a commitment to improving the environment. The United States, in contrast, has pursued some policies that have encouraged additional air pollution, such as XXX. No organization has done more to publicize the U.S. role in global warming than ..., which has spent ... million dollars to convince me and millions of others that the United States should strengthen its emissions policies."
Again, note that the writer leaves some material for future research. Much of the content work can be performed later and added to the next draft. Just remember that when your research suggests an alteration in the argument, the argument should be changed accordingly.