Consensus Report

Limiting the Magnitude of Climate Change (2010)


Each report is produced by a committee of experts selected by the Academy to address a particular statement of task and is subject to a rigorous, independent peer review; while the reports represent views of the committee, they also are endorsed by the Academy. Learn more on our expert consensus reports.

Advancing the Science of Climate Change

Adapting to the Impacts of Climate Change

Informing an Effective Response to Climate Change

A five-video series on the America's Climate Choices project

Meeting internationally discussed targets for limiting atmospheric greenhouse gas concentrations and associated increases in global average temperatures will require a major departure from business as usual in how the world uses and produces energy, finds this new report from the national Research Council. This report from the America's Climate Choices suite of studies recommends that a U.S. policy goal be stated in terms of a budget for cumulative greenhouse gas emissions over the period 2012 2050. With only so much to "spend" during this period, the nation should act now to: (1) take advantage of key near-term opportunities to limit greenhouse gas emissions and to create new and better emission reduction opportunities for the longer term; (2) create a national policy framework within which actors at all levels can work toward a common goal; and (3) develop policy mechanisms durable enough to persist for decades but flexible enough to adapt to new information and understanding.

The report concludes that a carbon pricing system (either cap-and-trade, taxes, or a combination of the two) is the most important step for providing needed incentives to reduce emissions. There is also a need, however, for complementary policies aimed at ensuring rapid progress to: increase energy efficiency; accelerate the development of renewable energy sources; advance full-scale demonstration of nuclear power and carbon capture and storage systems; and retrofit or replace existing emissions-intensive energy infrastructure. Research and development of new technologies that could help reduce emissions further in the long term also should be strongly supported.

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Key Messages

  • Efforts to limit greenhouse gas emissions are already underway across the U.S. -- by state and local governments, businesses, non-governmental organizations, and individual households. However, we currently lack a framework of national goals and policies to help assure that everyone (not just these early actors) is working towards coherent national goals.
  • Limiting climate change is a global effort that will require significant reductions of greenhouse gas emissions by countries around the world. U.S. action alone is not sufficient, but is clearly necessary -- both to directly contribute to global efforts, and to enhance our leverage in encouraging other countries to take strong action.
  • Other key considerations in designing and implementing our nation's response strategy include the need to: a) allow a continued role for leadership by state and local-level governments, which are offering a valuable 'laboratories' for policy experimentation, and will be needed to help implement new federal policies; b) consider potential equity implications when designing and implementing climate change limiting policies, with special attention to disadvantaged populations; and c) craft policies that are both durable over the long-term, and have the capacity to evolve in response to new scientific, technological, and economic developments.
  • The Panel thus concludes that country needs to get started now in aggressively pursuing available emission reduction opportunities, and also needs to invest heavily in R&D aimed at creating new emission reduction opportunities.
  • The Panel's analyses suggest that meeting a budget in this range will require a major departure from "business as usual" in how we produce and use energy. Within the electric power and transportation sectors, essentially all available options for reducing greenhouse gas emissions (e.g., for energy efficiency, low-carbon electricity production, low-carbon fuels) will need to be deployed at levels near the maximum extent of what is technically possible. These technical potential estimates (from the National Research Council's study - America's Energy Future) are based on highly optimistic assumptions however; and it is likely that new, additional options will be needed to get the job done at a reasonable cost.
  • The most effective policy strategy for the United States is to pursue is a strong, economy-wide carbon pricing system (in form of cap-and-trade, taxes, or some combination), along with a portfolio of complementary policies aimed at ensuring rapid progress in the following key areas: a) promoting widespread implementation of existing technologies for energy efficiency and low-carbon energy sources (such as renewables); b) advancing full-scale demonstration of carbon capture and storage and new-generation nuclear power, to determine whether these are truly feasible as major parts of our nation's future energy system; and c) accelerating the retirement and replacement of existing GHG-intensive equipment and infrastructure.
  • This report recommends a U.S. policy goal stated as a budget for cumulative greenhouse gas emissions over the period 2012 - 2050. The panel does not recommend a specific budget number but (as a benchmark for assessing the magnitude of the challenge) suggests an illustrative budget range of 170 - 200 gigatons CO2-equivalents, derived from recently published studies of the Energy Modeling Forum ( Business-as-usual with regard to energy use and production would consume this budget well before 2050.