U.S. Reaches Lowest Greenhouse Gas Emissions in Three Decades, Largely Due to Pandemic Way of Life U.S. Reaches Lowest Greenhouse Gas Emissions in Three Decades, Largely Due to Pandemic Way of Life Comments Off on U.S. Reaches Lowest Greenhouse Gas Emissions in Three Decades, Largely Due to Pandemic Way of Life Greenhouse gas emissions in the United States are on track for the largest reduction on record, according to a new study. An analysis by the research firm BloombergNEF estimated that greenhouse gas emissions in 2020 will be 9 percent lower than in 2019, which is the biggest yearly drop to date. The unexpected decrease is largely due to a stunted transportation sector at the hands of the COVID-19 pandemic.