Even if it is possible to reverse the rise of global temperatures after a temporary overshoot of 1.5°C, some climate damages inflicted at peak warming, including rising sea levels, will be irreversible, according to a new study published today in Nature.

The study is the culmination of a three-and-a-half-year project, backed by the European innovation fund HORIZON2020, looking at so-called ‘overshoot’ scenarios where temperatures temporarily exceed the Paris Agreement’s 1.5°C limit, before descending again by achieving net-negative CO2 emissions.

“This paper does away with any notion that overshoot would deliver a similar climate outcome to a future in which we had done more, earlier, to ensure to limit peak warming to 1.5°C,” explains Carl-Friedrich Schleussner, Integrated Climate Impacts Research Group Leader in the IIASA Energy, Climate, and Environment Program and scientific advisor at Climate Analytics, who led the study. “Only by doing much more in this critical decade to bring emissions down and peak temperatures as low as possible, can we effectively limit damages,” he adds.

It matters how high and for how long we let temperatures rise

The paper highlights that if we were to exceed 1.5°C there are clear benefits to reversing warming by acting to achieve net negative emissions globally. Achieving long-term temperature decline could lower sea level rise in 2300 by about 40 cm compared to a situation in which temperatures merely stopped rising.

“Until we get to net zero, warming will continue. The earlier we can get to net zero, the lower peak warming will be, and the smaller the risks of irreversible impacts,” notes study co-author Joeri Rogelj, professor of climate science and policy and Director of Research of the Grantham Institute at Imperial College London and senior research scholar in the IIASA Energy, Climate, and Environment Program. “This underscores the importance of countries submitting ambitious new reduction pledges, or so-called Nationally Determined Contributions (NDCs), well ahead of next year’s climate summit in Brazil.”

Full carbon dioxide removal capacity needed to hedge against higher warming

The study emphasizes that while there are still pathways open to limiting warming to 1.5°C or lower in the long run, there is a need to ‘hedge’ against higher warming outcomes if the climate system warms more than median estimates. To do this, ambitious emissions reductions need to go hand in hand with scaled and environmentally sustainable carbon dioxide removal technologies. A ‘preventive capacity’ of several hundred gigatons of net removals might be required.

“There’s no way to rule out the need for large amounts of net negative emissions capabilities, so we really need to minimize our residual emissions. We cannot squander carbon dioxide removal on offsetting emissions we have the ability to avoid,” commented study coauthor Gaurav Ganti, research assistant at IIASA and a research analyst at Climate Analytics.

“Our work reinforces the urgency of governments acting to reduce our emissions now, and not later down the line. The race to net zero needs to be seen for what it is – a sprint,” Schleussner concludes.

Adapted from a press release prepared by Climate Analytics. Read the original article here.

Reference
Schleussner, C-F., Ganti, G., Lejeune, Q., Zhu, B., Pfleiderer, P., Prütz, R., Ciais, P., Frölicher, T.L., Fuss, S., Gasser, T., Gidden, M.J., et al. (2024). Overconfidence in climate overshoot. Nature DOI: 10.1038/s41586-024-08020-9  

News

SDGs

30 October 2024

Three pathways to achieve global climate and sustainable development goals

Sustainable lifestyles, green-tech innovation, and government-led transformation each offer promising routes to make significant progress towards the UN Sustainable Development Goals (SDGs) and the Paris Agreement, according to a new study by the Potsdam Institute for Climate Impact Research (PIK), to which IIASA scientists contributed. Contrary to the belief that the path to sustainable development is increasingly out of reach, the results show that humankind has a variety of pathways to depart from its current unsustainable trajectory.
Melting polar ice caps with large cracks

24 October 2024

2024 UNEP Emissions Gap Report: Immediate action essential to keep 1.5°C target alive

Governments worldwide must urgently commit to reducing annual greenhouse gas emissions by 42% by 2030 and 57% by 2035 in their next Nationally Determined Contributions (NDCs) to avoid surpassing the Paris Agreement’s 1.5°C global warming target, warns a new report released by the UN Environment Programme (UNEP) today.
CircEUlar

09 October 2024

The CircEUlar project: bridging business practices and consumer behaviours in circularity

Last month, CircEUlar had its third in-person consortium meeting hosted by the University of Groningen at the, very appropriately named, House of Connections. Twenty-eight CircEUlar members from across 12 research organizations met over three days of collaborative working. The meeting was also an opportunity for T6 Ecosystems, University of Groningen and CircEUlar’s sister-project CircoMod, to design, plan and deliver a stakeholder workshop, "Towards Net-Zero through a Circular Economy: the consumer and business perspectives".