There are many different ways of quantifying the broad goal of "avoidance of dangerous human interference with the climate system", including targets for global temperature rise, radiative forcing, greenhouse gas (GHG) concentrations, GHG emissions in par
Mickael R. Raupach,Ian N. Harman,Josep G. Canadell. Global climate goals for temperature, concentrations, emissions and cumulative emissions. 2011-01-01.