Banking heavily on bioenergy with carbon capture and storage (BECCS) to keep average global warming under 1.5°C could put more than 50% of the world’s population into high water stress by the end of the century, with South America and southern Africa in line to suffer the worst.
“The water needed to irrigate enough energy crops to stay under the 1.5°C limit would leave 4.58 billion people experiencing high water stress by 2100—up from 2.28 billion today,” reports New Scientist, citing a study just published in the journal Nature Communications.
“That is 300 million more people than a scenario in which BECCS isn’t used at scale and warming spirals to a devastating 3°C.”
The findings are particularly alarming given that BECCS plays a significant role in most Intergovernmental Panel on Climate Change scenarios for avoiding an increase of more than 1.5°C of warming.
Explaining that high water stress is felt “when the ratio of water demand to supply is more than 40%,” New Scientist notes that the “upper-end projection of 4.58 billion affected people assumes a total of six million square kilometres of crops grown for BECCS, limited use of sustainable water, and a global population reaching nine billion by 2100.”
The science news outlet adds that, in this scenario, new BECCS crop plantations would “expand to previously unstressed parts of the world,” with water supplies in both South America and southern Africa greatly affected.
The new study is the latest red flag against plans that lean heavily on BECCS to soak up emissions, with previous studies warning that the necessary dedication of land would ravage biodiversity and food production.
Lead author Fabian Stenzel of the Potsdam Institute for Climate Impact Research said the “takeaway message” of his team’s report is that policy-makers must take side effects into better account.
“To limit all the trade-offs that we might face in terms of climate change and climate change mitigation, it’s really important to look at the holistic Earth system,” he said.
Stenzel conceded that some form of negative emissions will be needed to prevent dangerous levels of warming because, he said, “as humanity, we are stupid and slow.” But, he added, BECCS should only be used alongside other approaches, like reforestation and upping soil carbon sequestration.