This study shows that urban land uses generate an average of 58 times more greenhouse gases per acre than the production of California's leading crops. This means that conserving farmland by preventing its development is an effective strategy for alleviating climate change. The study found that emissions from seven crops grown on four million acres of the state’s farmland – including rice, tomatoes, lettuce, almonds, wine grapes, corn and alfalfa – averaged 0.89 tons of CO2 equivalent per acre, while those from residential, commercial and industrial land uses in 13 California cities averaged 51 tons per acre.