Negative emissions technologies and practices could challenge global resource supply and environmental limits
Greg Rau
in earlier works–could become the main constraint to the scale-up of bio-
logical CDR, which would imply a substantial increase (≤70%) in the global
demand for essential nutrients. This could potentially lead to conflicts with
the food system–beyond land competition53,91
—and certain technological
sectors dependent on these materials. Nutrient recovery remains challen-
ging in BECCS scenarios, as fertilizer-derived nutrients are either immo-
bilized in biomass ash or lost through run-off92. By contrast, applying
biochar to agricultural soils may reduce the demand for mineral fertilizer
inputs, since the nutrients contained in biochar are gradually released and
taken up by crops93
.
Finally, we show that the fire risk—projected to increase by up to 50%
within this century69
—jeopardizes the permanence of the carbon seques-
tered in forests, causing the GGR efficiency of forestation to drop over time.
Moreover, the formation of fine particulate matter during fire events could
lead to substantial health effects at the regional level—an effect not captured
by previous studies37–42. Thus, our analysis suggests that, contrary to pre-
vailing trends94,95, we should not view forestation as a no-regret fungible