Boysen Potentials, consequences and trade-offs of terrestrial (CDR): Strategies for #climate engineering
https://t.co/knfig3fTn9 Abstract For hundreds of years, humans have engineered the planet to fulfil their need for incre- asing energy consumption and production. Since the industrial revolution, one conse- quence are rising global mean temperatures which could change by 2◦C to 4.5◦C until 2100 if mitigation enforcement of CO2 emissions fails.To counteract this projected glo- bal warming, climate engineering techniques aim at intendedly cooling Earth’s climate for example through terrestrial carbon dioxide removal (tCDR) which is commonly per- ceived as environmentally friendly. Here, tCDR refers to the establishment of large-scale biomass plantations (BPs) in combination with the production of long-lasting carbon products such as bioenergy with carbon capture and storage or biochar. This thesis examines the potentials and possible consequences of tCDR by ana- lysing land-use scenarios with different spatial and temporal scales of BPs using an advanced biosphere model forced by varying climate projections. These scenario simu- lations were evaluated with focus on their carbon sequestration potentials, trade-offs with food production and impacts on natural ecosystems and climate itself. Synthesised, the potential of tCDR to permanently extract CO2 out of the atmos- phere is found to be small, regardless of the emission scenario, the point of onset or the spatial extent. On the contrary, the aforementioned trade-offs and impacts are shown to be unfavourable in most cases. In a high emission scenario with a late onset of BPs (i.e. around 2050), even unlimited area availability for tCDR could not reverse past emissions sufficiently, e.g. BPs covering 25% of all agricultural or natural land could delay 2100’s carbon budget by no more than two or three decades (equivalent to ≈550 or 800 GtC tCDR), respectively. However, simultaneous emission reductions and an ear- lier establishment of BPs (i.e. around 2035) could result in strong carbon extractions reversing past emissions (e.g. six or eight decades or ≈500 or 800 GtC, respectively). In both cases, land transformation for tCDR leads to high “costs” for ecosystems (e.g. biodiversity loss) and food production (e.g. reduction of almost 75%). Restricting the available land for BPs by these trade-off constraints leaves very small tCDR poten- tials (well below 100 GtC) despite a near-future onset (in 2020). Similarly, simulated tCDR potentials on dedicated BP areas defined in a commonly used and published low emissions scenario stay below the aimed values using current management practices. Some potential may lie the reduction of carbon losses from field to end-products, new management options and the restoration of degraded soils with BPs. This thesis contradicts the assumption that tCDR could be an effective and envi- ronmentally friendly way of complementing or substituting strong and rapid mitigation efforts. -- You received this message because you are subscribed to the Google Groups "geoengineering" group. To unsubscribe from this group and stop receiving emails from it, send an email to [email protected]. To post to this group, send email to [email protected]. Visit this group at https://groups.google.com/group/geoengineering. For more options, visit https://groups.google.com/d/optout.
