The Climate Clock tracks the amount of time remaining before the carbon budget estimated by the IPCC to limit global warming to 1.5ºC runs out. Put differently, the Clock shows how much time is left before 1.5 degrees of global warming is "locked-in." The clock is updated yearly based on global emissions trends.

Data for the deadline is sourced from the Mercator Research Institute on Global Commons and Climate Change. The MCC’s carbon clock assumes an average annual rate of 42.2 Gt of carbon emissions in order to calculate the time remaining on the clock. However, if rates of global emissions continue to rise, our carbon budget will run out even faster. If we cut the rate of global carbon emissions, time on the clock would hypothetically begin to increase.