阅读理解
With the possibility that the United States may be withdrawing from the confines of the Kyoto Protocol by the end of this year, it behooves responsible citizens of the world to examine the past and present implications of the international treaty. The 1992 Kyoto Protocol, signed by 174 of the world's nations, ambitiously sought to reduce worldwide emission levels by the year 2000, aiming to restore them to 1990 levels so as to slow global warming and begin the slow process of eradicating pollution. It has thus far not been entirely successful, with its noble goals overly vague, resulting in international willingness to comply with its provisions, but lacking a structured method by which to achieve them. Harsh criticism of the Kyoto Protocol often involves the relatively short-term nature of the project. By trying to achieve such spectacular environmental goals in such a short span of time, it has been argued that an impossibly difficult challenge has been undertaken. Finding the task impossible, the nations of the world may soon discard the wider goal of reducing pollution along with the protocol itself. Further, the commitments made by the industrialized nations, such as the United States, Britain and France, are vastly different from those agreed upon by the developing nations, such as Brazil and China, with the industrialized signatories agreeing to be bound by more concrete, stated plans and goals. This disparity in commitment has been viewed as a necessity, however. Developing nations argue that their more industrialized, wealthier counterparts achieved their power and status by utilizing methods of development that resulted in pollution, and that they have a right to take their turn at using those methods. Also, it has been stated that the richer nations are those who can afford to immediately change their methods of production to comply with the goals of the Kyoto Protocol, while the other nations would find it virtually impossible to change their ways without seriously disrupting their economies. Whatever one's stance, it is almost universally agreed upon that the Kyoto Protocol is a step in the right direction, in theory and philosophy, at the very least. The reality of practical application and implementation, however, is a very different story. With the possibility of a United States withdrawal looming, it must be considered that if the world's wealthiest and most powerful nation finds it impossible to reasonably comply with the protocol, then perhaps a more conservative and manageable plan must be considered.
单选题6.The second sentence in paragraph 3 implies that______.