This study explores the causal relationship between carbon dioxide (CO2) emissions, renewable and nuclear energy consumption and real GDP for the US for the period 1960-2007. Using a modified version of the Granger causality test, we found a unidirectional causality running from nuclear energy consumption to CO2 emissions without feedback but no causality running from renewable energy to CO2 emissions. The econometric evidence seems to suggest that nuclear energy consumption can help to mitigate CO2 emissions, but so far, renewable energy consumption has not reached a level where it can make a significant contribution to emissions reduction. (C) 2010 Elsevier Ltd. All rights reserved.