This implies an upper limit to the release of tropical land carbon of <200 PgC over the 21st century (assuming tropical warming of <4°C , and no CO 2-fertilization), which translates to dCO 2/dt <0.5 ppm yr–1.Boreal forest dieback is not expected to change the atmospheric CO 2 concentration substantially because forest loss at the south is partly compensated by: (i) temperate forest invasion into previously boreal areas; and (ii) boreal forest gain at the north (Friend et al., 2014; Kicklighter et al., 2014; Schaphoff et al., 2016)