The Paris Agreement aims to limit global warming to 1.5°C – 2°C by the end of the century. However, if carbon emissions are not significantly reduced in the coming years, the scenarios show that the limit value will be exceeded. Future carbon-removal technologies could help us to keep with the Paris goal. Yet, they are quite uncertain. One such technology, highlighted in the latest IPCC report, is "bioenergy with carbon capture and storage" (BECCS). However, uncertainties on the potentials, and possible negative effects on biodiversity, land use and water conservation tend to discourage policymakers.
The LSCE researchers and their partners therefore wanted to know how global warming would affect the potentials and efficiency of BECCS technology implemented in the future, based on the re-use of current crop residues for power production followed by CO2 capture and storage.
Indeed, if global warming proceeds without any significant mitigation actions, agricultural yields will decline, leading to:
- the decrease in biomass stocks for BECCS technology from agricultural residues;
- the expansion of land cultivated for food production;
- increased greenhouse gas emissions due to land use change.
And yet, the decrease in the mitigation potential of BECCS technology under the effect of global warming is not taken into account by current economic models, which are used to evaluate the effectiveness of the commitments of the countries that signed the Paris Agreement.
To remedy this, the researchers developed several scenarios for implementing large-scale mitigation technologies with BECCS by decade, from 2030 to 2100, and considered several options to address food scarcity:
- expansion of cropland;
- intensification of nitrogen fertilization;
- improved nitrogen use efficiency;
- afforestation;
- international food trade.
They also determined the yield of crops intended for bioenergy by considering different factors:
- temperature during the growing season;
- atmospheric CO2 concentration;
- intensity of nitrogen fertilization;
- precipitation.
This enabled them to estimate the impact on mitigation timing of the effectiveness of BECCS technology. The result: the potential of BECCS technology is diminishing over time as crop production is negatively affected by climate change, making the 2°C target for 2100 harder to reach and posing a threat to global food security.
If global warming would exceed the 2.5°C threshold in case of late mitigation, even temporarily, it will be even more difficult to reach the long-term goal of 2°C.
In the event that BECCS implementation is delayed from 2040 to 2060, global warming would increase from 1.7°C to 3.7°C by 2100, accompanied by a decrease in the global average daily caloric intake per capita, from 2.1 to 1.5 megacalories. In addition, the number of countries with a food deficit will increase from 81 to 90 by 2100.
While such technologies are being considered on a large scale, the researchers recommend deploying them in the short term to hopefully mitigate global warming and the coming food crisis.
This study was conducted by Fudan University (Shanghai, China), in collaboration with the LSCE.