Residential energy use represents roughly one-fifth of annual greenhouse gas emissions in the United States. A team of researchers led by McGill University has used data from 60 million individual American households to look into how carbon emissions caused by household energy use vary by race and ethnicity across the country. Paradoxically, this first national level analysis found that even though energy-efficient homes are more often found in Caucasian neighbourhoods, carbon emissions from these neighbourhoods are higher than in African American neighbourhoods.