Temporary carbon sequestration cannot prevent climate change

Storing carbon in biosphere sinks can reduce atmospheric CO₂ concentrations in the short term. However, this lowers the concentration gradient between the atmosphere and the oceans and other potential carbon reservoirs, and consequently reduces the rate of CO₂ removal from the atmosphere. If carbon is released again from that temporary storage, subsequent atmospheric CO₂ concentrations will, therefore, be higher than without temporary carbon storage. It is thus important to analyse whether temporary carbon storage in biosphere sinks can mitigate climate-change impacts. To analyse that, climate-change impacts need to be quantified explicitly. Impacts can be quantified: [(1)] as the instantaneous effect of increased temperature [(2)] through the rate of temperature increase [(3)] as the cumulative effect of increased temperatures. The analysis presented here shows that temporary carbon storage only reduces climate-change impacts related to the cumulative effect of increased temperature and could even worsen impacts mediated via the instantaneous effect of temperature or the rate of temperature change. This applies under both high and low greenhouse-gas emission scenarios. Because temporary carbon storage improves some, but worsens other, climate-change impacts, it achieves very little on average. For greenhouse mitigation, it is, therefore, not warranted to provide policy incentives for temporary carbon storage.