The National Research Council issued a report on June 20, detailing its findings of the effect of tax policy on greenhouse gas emissions. According to the report, current Federal tax expenditures and subsidies, including those focused on energy, have a limited effect on U.S. greenhouse gas levels. The report took into account both energy related tax policies, such as tax credits and renewable energy and transportation fuel taxes, and broad-based tax policies that may have indirect effects on emissions, such as incentives for investment and machinery. While the report found that the current policies are a poor tool for decreasing greenhouse gas, it did not offer recommendations for other specific changes to the tax code. Rather, it found that the most efficient way to achieve climate change goals is to create a market price for carbon dioxide and other greenhouse gases through a direct tax or regulatory policies.