It is well known that CO₂ emissions drive climate change, which emphasizes the need to reduce them. But even people who have worked in the green industry for many years can still be confused about how far emission reductions need to go in the future. Here, we introduce the important concept of the global carbon budget, which is defined as the amount of CO₂, measured in GtCO₂ or PgC, that we can emit while keeping global warming below a specific target. Global warming is an important one-dimensional indicator of climate change. It refers to the change in global mean surface temperature relative to pre-industrial levels. So how do scientists know the remaining carbon budget? Scientists use Earth system models, which are more or less digital versions of the Earth inside a computer, to simulate future global warming under different levels of CO₂ emissions. It has been shown that there is a near-linear relationship between cumulative emissions and increases in global mean surface tempera...
Evidence-based insights on carbon dioxide removal, carbon markets and climate science—with a focus on China.