The second "State of the Climate Cycle Report" (SOCCR2) aims to elucidate the fundamental physical, chemical, and biological aspects of the carbon cycle and to discuss the challenges of accounting for all major carbon stocks and flows for the North American continent. This assessment report has broad value, as understanding the carbon cycle is not just an academic exercise. Rather, this understanding can provide an important foundation for making a wide variety of societal decisions about land use and natural resource management, climate change mitigation strategies, urban planning, and energy production and consumption. To help assure the quality and rigor of SOCCR2, this report provides an independent critique of the draft document.