Concentrations of the major greenhouse gases, CO2 , CH4 , and N2 O, continued to increase despite the temporary reduction in emissions in 2020 related to measures taken in response to COVID-19. 2020 was one of the three warmest years on record. The past six years, including 2020, have been the six warmest years on record. Temperatures reached 38.0 °C at Verkhoyansk, Russian Federation on 20 June, the highest recorded temperature anywhere north of the Arctic Circle. The trend in sea-level rise is accelerating. In addition, ocean heat storage and acidification are increasing, diminishing the ocean’s capacity to moderate climate change.