Gore says that after tripling the world's population from 2.3 billion to about 9 billion with the onset of the baby boom, "we are witnessing a collision between our civilization and the earth. It also introduces a misconception of disagreement over the science of global warming, in which opponents "reposition global warming as a theory rather than a fact" and links the issue to technological advances. Gore argues that the United States and China are using old, dirty, polluting technologies. Although many Americans believe there is an ultimatum in which one must choose between the economy and the environment, data illustrating the percentage change in market capitalization over the period 2003-2004 shows that cars that doing well around the world belong to companies that build energy-efficiently