The monetized cost to the U.S. of carbon dioxide emissions is on a steady rise, according to a review by a working group of 11 federal agencies. The assessment projects that in 2020, the cost per metric ton of CO2 will range from $12 to $129 depending on a variety of scenarios. An earlier assessment done in 2010 projected the costs in 2020 to be between $7 and $81 per metric ton of CO2. Required by federal executive order, the assessment serves as a guide to regulatory agencies in determining the costs and benefits of reducing CO2 emissions. The cost estimate of CO2 emissions considers the relative cost impacts of increased emissions on human health and agricultural productivity as well as flood damage and ecosystem loss.