Carbon dioxide (CO2) is a gas essential for life—animals exhale it, plants sequester it. It exists in Earth’s atmosphere in comparably small concentrations but is vital for sustaining life. CO2 is also known as a greenhouse gas (GHG)—a gas that absorbs and emits thermal radiation, creating the ‘greenhouse effect’. Along with other greenhouse gases, such as nitrous oxide and methane, CO2 is important in sustaining a habitable temperature for the planet: if there were absolutely no GHGs, our planet would simply be too cold. It has been estimated that without these gases, the average surface temperature of the Earth would be about -18 degrees celsius.

Emissions from a number of growing economies have been increasing rapidly over the last few decades.

If we look at temperature trends which extend back to 1850, we see that temperatures then were a further 0.4 degrees colder than they were in our 1961-1990 baseline. Overall, if we look at the total temperature increase since pre-industrial times, this therefore amounts to approximately 1.2 degrees celcius. We have now surpassed the one-degree mark, an important marker as it brings us more than halfway to the global limit of keeping warming below two degrees celsius.

Read the full article on greenhouse gases by Hannah Ritchie and Max Roser at Our World in Data