New research has identified the conditions under which global warming could be limited to 1.5°C by 2100, keeping in line with targets set by the Paris Agreement.
Led by Joeri Rogelj, energy research fellow at the International Institute for Applied Systems Analysis (IIASA) in Austria, a team of researchers used six different computer models to model five different socioeconomic scenarios and their effect on warming.
Their study, published on Monday in Nature Climate Change, found that all scenarios that limited global average temperature rise to 1.5°C included reduced energy use, a shift towards low-carbon energy sources and away from fossil fuels and removal of carbon dioxide from the atmosphere.
“One of the goals of the Paris Agreement is to limit warming to 1.5°C, but scientific studies mainly looked at the question of limiting warming to 2°C,” said study author Rogelj. “This study now fills this gap and explores how climate change by the end of the 21st century can be brought in line with 1.5°C of warming.
Rogelj added that although individual studies have previously explored this question, the new study “is the first to use a broad and diverse set of models.”
The authors said the paper is also the first to examine the ways socioeconomic factors, including inequalities, international cooperation and energy demand, could affect the possibility of meeting climate goals.
The researchers call the five scenarios modelled Shared Socioeconomic Pathways (SSPs). In pathways that successfully limited warming, greenhouse gas emissions peaked at 2030, with zero net greenhouse gas emissions reached between 2055 and 2075. Energy efficiency measures in successful pathways reduced energy demand, which was of particular importance in scenarios with continued economic and population growth.
Successful scenarios also showed a significant shift away from fossil fuel dependence, with renewable energy sources comprising at least 60% of the energy mix by mid-century and oil being phased out by 2060. Additionally, successful pathways required removal of CO2 from the atmosphere through negative emissions technologies, such as reforestation and bioenergy with carbon capture and storage (BECCS).
IIASA Energy Program Director and study co-author Keywan Riahi highlighted the value the SSPs provide, saying they have “helped to systematically explore conditions under which such extreme low targets might become attainable.”
Riahi said the assessment highlights the crucial role sustainable development plays in achieving “extreme low climate change targets.” He added that issues such as “fragmentation and pronounced inequalities” would likely be accompanied by “low levels of innovation and productivity,” making the 1.5°C target difficult to achieve.
Although the authors said their work serves as a good “starting point,” they emphasised the need for additional research and hope other climate change researchers will use the 1.5°C scenarios created as part of their study.
The authors noted there are still some unanswered questions about their findings. The scenarios modelled in the study consider economic and technological feasibility, but could not account for issues such as international cooperation and social acceptability, which “can have a large effect on feasibility,” according to the researchers.
“How to transform the model results into a viable society transformation remains the elephant in the room,” Dr Glen Peters, a senior researcher at the CICERO Center for International Climate Research in Norway, told Carbon Brief. He added that if any of the “core building blocks” required by the successful scenarios are not met, the 1.5°C target will quickly become “infeasible.”
The study’s authors urged policy advisors to take these types of issues into consideration, and said that additional research could “help policy-makers to understand the real-world implications of these scenarios.”