Rich cities around the world are largely responsible for greenhouse gas emissions, says a new study. The study measures emissions based on the use of goods and services, such as food, clothing and electronics, by people living inside cities. It includes the impact of trade of such goods between points of production and use. This is a change from traditional measures, which look at emissions from production of goods. When measuring these gases based on consumption, rather than manufacturing, the biggest emitters are mainly cities in North America and Europe. The study found their emissions were 60 percent higher than currently estimated. Researchers shared this information this month at a United Nations climate conference in Edmonton, a city in Alberta, Canada. About 750 city leaders, university researchers and scientists from 80 countries took part. They discussed the latest climate research and what local governments can do to fight climate change.