It shows when the world or a country needs to stop emitting CO2. In the Paris Agreement, the countries of the world promised to limit global warming to "well below 2 °C" and to "pursue efforts" to limit it to 1.5 °C. The Intergovernmental Panel on Climate Change (IPCC) has calculated how much CO2 humanity can still emit to reach these goals. This is the world’s "CO2 budget".