To avoid the worst consequences of climate change, the world must balance carbon emissions with carbon stocks by 2050. But even if we reach the goal, a lot depends on how much we release in the meantime. Ten years ago, the term "net zero" was arcane jargon. Today, it is a key target in the fight against climate change and a well-known point of discussion around the world.

The concept is simple. In words Intergovernmental Panel on Climate Change (IPCC) : "Net zero emissions of carbon dioxide (CO ₂ ) are achieved when anthropogenic CO2 emissions are globally balanced by anthropogenic CO removal ₂ during a certain period. (James Dinneen, more at newscientist.com)