Carbon dioxide levels are now 50% higher than during the pre-industrial era

This huge leap in CO2 emissions, a heat-trapping gas that is the primary driver of global heating, has quickly pushed the world into conditions not seen in 4m years, according to the National Oceanic and Atmospheric Administration (Noaa), which also takes measurements at Mauna Loa.

The epochal change in our atmosphere, due to the burning of coal, oil and gas to power our cars, trucks, houses and factories, has already caused severe heatwaves and worsening floods, droughts and storms. These impacts will become catastrophic should global heating advance further, beyond 1.5C above the pre-industrial era, scientists say.

The new study, which looks at the ongoing impact of CO2 as well as methane, nitrogen oxide and aerosols, like sulfur or soot, found that there is a two-thirds chance of temporarily going above 1.5C if emissions cuts are left until 2029. Scientists have said global emissions must be slashed in half this decade, and zeroed out by 2050, if the world is to have a chance of avoiding dire climate consequences.