This excellent response displays an in-depth analysis of the issue and superior facility with language.

While acknowledging that environmental problems are serious and of global dimensions, the essay explores the complexity of international cooperation. Such cooperation, the essay argues, runs into a variety of problems, and the writer offers persuasive examples to support that point:

-- the unwillingness of nations to "interfere" with other nations through political measures such as restriction of foreign aid

-- inadequate environmental regulations, which are caused both by "the differential impact of polluting activities" between countries and regions and by the difficulty of comparing the "long-term effects of polluting activities" with the more easily documented, short-term costs of reducing pollution.

The essay distinguishes itself in part by its excellent organization. The first paragraph analyzes the claim and announces the writer’s position; the second and third paragraphs provide clear examples supporting that position. The skillful use of a quotation from a business person vividly illustrates the economic impact of pollution controls. The last two paragraphs bring a sense of closure to the essay by continuing the theme announced in the first paragraph -- that cooperation must wait until more dire circumstances produce the political will necessary to reduce pollution.

The essay exhibits superior control of grammar and syntax, with only minor errors. Transitional phrases -- "because," "however," "for instance" -- help guide the reader through the argument. Also, effective sentence variety and the use of precise word choice help confirm the score of 6.