This chapter assesses trends in greenhouse gas (GHG) emissions up to and including 2021. It analyses global emissions by gas, country, household and sector, providing the current and historical context for subsequent chapters on country pledges and mitigation pathways. There are both short- and long-term influences on GHG emissions. In the short term, abrupt geopolitical and economic events such as the COVID-19 pandemic and the war in Ukraine can lead to significant but temporary changes in annual emissions. In the long term, structural shifts in technologies, production and investment decisions, as well as economic and climate policies, play an important role. One aim of this chapter is to provide both short- and long-term perspectives on trends in global GHG emissions.