Complex sentence: The North American Environmental Atlas is a project of the Commission for Environmental Cooperation, a trilateral international organization created by Canada, Mexico and the United States under the North American Agreement on Environmental Cooperation (NAAEC).
Split into simpler sentences: The North American Environmental Atlas is a collaborative project of government agencies in Canada, Mexico and the United States. It is coordinated by the Commission for Environmental Cooperation, a trilateral international organization created under the North American Agreement on Environmental Cooperation (NAAEC).