This Report (SAP 4.2) focuses on the thresholds of Climate Change in Ecosystems. As defined in this Synthesis and Assessment Report, 'an ecological threshold is the point at which there is an abrupt change in an ecosystem quality, property, or phenomenon, or where small changes in one or more external conditions produce large and persistent responses in an ecosystem'.Ecological thresholds occur when external factors, positive feedbacks, or nonlinear instabilities in a system cause changes to propagate in a domino-like fashion that is potentially irreversible. This report reviews threshold changes in North American ecosystems that are potentially induced by climatic change and addresses the significant challenges these threshold crossings impose on resource and land managers. Sudden changes to ecosystems and the goods and services they provide are not well understood, but they are extremely important if natural resource managers are to succeed in developing adaptation strategies in a changing world. The report provides an overview of what is known about ecological thresholds and where they are likely to occur. It also identifies those areas where research is most needed to improve knowledge and understand the uncertainties regarding them. The report suggests a suite of potential actions that land and resource managers …

The National Climate Assessment (NCA) Report Series summarizes regional, sectoral, and process-related workshops and discussions being held as part of the third NCA process. This workshop focused on techniques for quantitatively valuing climate impacts and adaptation in the context of the upcoming NCA. The workshop was held in Arlington, VA on January 12-13, 2011. Volume 8 of the NCA Report Series summarizes the discussions and outcomes of this workshop.

This document is intended to assist Federal agencies with analyzing cumulative effects during the NEPA process. It outlines general principles, common cumulative effects assessment methodologies, and resources for additional information and background data.

The report provides the status and trends of biodiversity offset and compensatory mitigation programs by geographical region. It summarizes the total active programs and developing activities, and broad metrics like total known payments and land area protected. It also analyzes the characteristics of offset programs and looks at recent developments in nascent and existing programs in the region.

On May 22, 2010, President Barack Obama announced the creation of the National Commission on the BP Deepwater Horizon Oil Spill and Offshore Drilling: an independent,nonpartisan entity, directed to provide a thorough analysis and impartial judgment. The President charged the Commission to determine the causes of the disaster, and to improve the country’s ability to respond to spills, and to recommend reforms to make offshore energy production safer. This report is the result of an intense six-month effort to fulfill the President’s charge. The Commission’s report offers the President, policymakers, industry, and the American people the fullest account available of the largest oil spill in U.S history: the context for the well itself, how the explosion and spill happened, and how industry and government scrambled to respond to an unprecedented emergency.