Over-reliance on biomass-based carbon removal technologies could increase climate and food security risks
An international team of researchers highlighted the inherent risk of relying too much on carbon removal technologies to limit climate change in a new study just published in Nature.
To limit global warming to within 2°C above pre-industrial levels, many are putting their hopes on the world’s abundant supply of biomass – materials like wood and wood residues, energy crops, and agricultural remnants – to deploy large-scale bioenergy with carbon capture and storage (BECCS), the use of which is also assumed to increase considerably in the future. The problem with this strategy, however, is that the detrimental effects of climate change on crop yields may reduce the capacity of BECCS and threaten food security, thus creating an unrecognized positive feedback loop on global warming.
In their study, the research group comprising researchers from IIASA, Fudan University in Shanghai, China, and several other institutions around the world, endeavored to quantify the strength of this feedback by taking a closer look at the nexus of climate change, agriculture, bioenergy, and carbon removal technologies. IIASA provided the core model that enabled the study, along with the associated expertise and feedback in designing the study itself.
Using the shared socioeconomic pathways of climate mitigation, the researchers designed a number of scenarios in which the deployment of large-scale mitigation technologies and BECCS starts in different decades, from 2030 to 2100, and further considered technical solutions to food shortages including cropland expansion, nitrogen fertilizer intensification, nitrogen use efficiency enhancement, afforestation, and international food trade. The feedback on future climate change and food shortages caused by reduced BECCS potential was quantified using an Earth System model and as a function of the delayed mitigation.
The simulation results showed that the feedback of biomass-based carbon removal technologies could have a significant impact on the long-term trend of future climate change. Owing to the negative impact of climate change on crop yields, the potential of BECCS decreases over time, which could lead to failure to achieve the 2°C goal of the Paris Agreement and threaten global food security. For example, when large-scale mitigation and BECCS are delayed from 2040 to 2060, the reducing yields of agricultural residue for carbon removal technologies could in turn increase global warming from 1.7°C to 3.7°C by 2200. Of this 2°C increase, 0.8°C is attributable to the loss of BECCS capacity caused by the feedback that had been ignored so far, while the remaining 1.2°C are attributed to the delayed mitigation itself.
Furthermore, this would be accompanied by a decline in global average daily food calories per capita – in other words, the total calorie supply available for human consumption divided by the total number of population using it – from 2100 to 1500 kilo calories per day. Notably, the responses of food supply to climate change vary from region to region.
The results further indicate that when climate mitigation is delayed from 2040 to 2060, the number of developing countries that see a domestic food supply gap would increase from 81 to 90 in 2100. As the food gap in 2100 would remain negative in developed countries, the export of food crops like wheat, rice, and maize from regions like China, Europe, and North America to other regions would reduce the fraction of people threatened by hunger. The projected export of crops, however, would be many times larger than the current levels for these regions, meaning that the increase in the scale of food trade could be too large to be plausible. As a result, early climate mitigation or regional population migration might be the only solution to satisfy food demand if the projected food trade failed to be achieved. If carbon removal technologies relying on biomass could however be widely deployed in the short term, there is still hope to alleviate both global warming and a food crisis.
“Although in our study we focused on only one carbon removal technology – BECCS – and showed how it will likely be limited because of harmful climate feedbacks, it is entirely possible that other technologies have similar limitations,” notes IIASA researcher, Thomas Gasser, one of the study authors. “Therefore, over-reliance on such unproven technologies when designing climate policies means taking the risk of simply failing to reach one's goal. The solution may be to diversify the technologies (to spread the risks out), but primarily it is to rely on conventional mitigation approaches, that is, to lower energy demand and consumption, and develop a sustainable clean energy supply.”
Reference
Xu, S., Wang, R., Gasser, T., Ciais, P., Peñuelas, J., Balkanski, Y., Boucher, O., Janssens, I.A., et al. (2022). Delayed use of bioenergy crops might threaten climate and food security. Nature DOI: 10.1038/s41586-022-05055-8
About IIASA:
The International Institute for Applied Systems Analysis (IIASA) is an international scientific institute that conducts research into the critical issues of global environmental, economic, technological, and social change that we face in the twenty-first century. Our findings provide valuable options to policymakers to shape the future of our changing world. IIASA is independent and funded by prestigious research funding agencies in Africa, the Americas, Asia, and Europe. www.iiasa.ac.at
JOURNAL
Nature
ARTICLE TITLE
Delayed use of bioenergy crops might threaten climate and food security.
ARTICLE PUBLICATION DATE
7-Sep-2022
Climate change puts availability of vital
renewable energy source at risk,
research reveals
Climate change is putting the availability of biomass fuels and technologies – a vital alternative to fossil fuels – at risk, according to new research.
Peer-Reviewed PublicationClimate change is putting the availability of biomass fuels and technologies – a vital alternative to fossil fuels – at risk, according to new research.
The study has found that as temperatures rise, the window of opportunity to maximise the use of biomass from plants, wood and waste as a renewable energy source and an alternative to petrochemicals is closing.
Published in Nature and led by researchers at the universities of York and Fudan in China, the study investigated the sustainability of biomass exploitation.
The researchers found that if urgent action is not taken to reduce fossil fuels in favour of bioenergy and other renewables, climate change will decrease crop yields, reducing the availability of biomass feedstocks. Reducing food production is also likely to incentivise cropland expansion, increasing greenhouse gas emissions from land use change and further accelerating the rate of climate change, the researchers say.
Co-author of the paper, Professor James Clark from the Department of Chemistry, said: “Biomass fuels and feedstocks offer a renewable source of energy and a viable alternative to petrochemicals, but the results of our study act as a stark warning about how climate change will put their availability at risk if we continue to allow global temperatures to rise.
“There is a tipping point where climate change will severely impede our ability to mitigate against its worst effects. Biomass with carbon capture and storage including the manufacture of bio-based chemicals must be used now if we are to maximise its advantage.”
In the latest report by the Intergovernmental Panel on Climate Change (IPCC) and in many assessments of climate mitigation, bioenergy with carbon capture and storage (BECCS) has been highlighted as a crucial element of the strategy for meeting the target of 2 °C or 1.5 °C warming set out in the Paris Agreement.
The researchers used global data to model the responses of crop yields to rising average temperatures, atmospheric CO2 concentration, nitrogen fertilisation intensity and precipitation. They found that if a switch to BECCS is delayed to the second half of this century, biomass production would be largely reduced by climate change, resulting in a failure to achieve the 2 °C goal and jeopardising global food security.
For example, when BECCS is delayed from 2040 to 2060, the researchers found reduced yields of agricultural residue for biomass technologies would decrease the capacity of BECCS and increase global warming from 1.7 to 3.7 °C by 2200, with a decline in global average daily crop calories per capita from 2.1 million calories to 1.5 million calories.
The researchers calculate that in this scenario the scale of the food trade would need to increase by 80% from 2019 levels in order to avoid severe food shortages in many parts of the developing world worst affected by climate change.
Professor Clark added: “If negative-carbon mitigation technologies relying on biomass could be widely deployed in the short term, there is still hope that we can alleviate global warming and a global food crisis.”
This research was carried out by an international team of scientists in the UK, China and Spain. Delayed use of bioenergy crops might threaten climate and food security is available here.
JOURNAL
Nature
ARTICLE TITLE
'Delayed use of bioenergy crops might threaten climate and food security'
ARTICLE PUBLICATION DATE
7-Sep-2022
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