IIASA scientists contribute to a new UNEP report, emphasizing the need for urgent climate action

Maintaining the possibility of achieving the Paris Agreement goals hinges on significantly strengthening mitigation this decade to narrow the emissions gap. Prepared with the help of IIASA scientists*, the UNEP Emissions Gap Report 2023: Broken Record – Temperatures hit new highs, yet world fails to cut emissions (again), finds that global low-carbon transformations are needed to deliver cuts to predicted 2030 greenhouse gas emissions of 28% for a 2°C pathway and 42% for a 1.5°C pathway.

“There is no person or economy left on the planet unhit by climate change, so we need to stop setting unwanted records on greenhouse gas emissions, global temperature highs, and extreme weather,” said Inger Andersen, Executive Director of UNEP. “We must instead lift the needle out of the same old groove of commitments, not action, and start setting other records: on cutting emissions, on green and just transitions, and on climate finance.”

Key findings

The report finds that global greenhouse gas (GHG) emissions increased by 1.2% from 2021 to 2022 to reach a new record of 57.4 Gigatonnes of Carbon Dioxide Equivalent (GtCO₂e). GHG emissions across the G20 increased by 1.2% in 2022. In addition, the emissions trends reflect global patterns of inequality. Because of these worrying trends and insufficient mitigation efforts, the world is on track for a temperature rise far beyond the agreed climate goals during this century.

“The report reiterates that climate action this decade is critical to keep the Paris Agreement’s long-term temperature goal in reach,” highlights Matthew Gidden, a senior research scholar at IIASA and one of the chapter co-leads of the report. “Even the most optimistic projections reflect the fact that the world is significantly behind on the promise of limiting global warming to 1.5°C. Countries need to come to the table with more ambitious near-term climate pledges and back them up with credible climate policies.”

In percentage terms, the world needs to cut 2030 emissions by 28% to get on track to achieve the 2°C goal of the Paris Agreement, with a 66% chance, and 42% for the 1.5°C goal. If all conditional NDCs and long-term net zero pledges were met, limiting the temperature rise to 2°C would be possible.

“The report highlights that net zero pledges alone are insufficient and strong evidence toward their implementation is needed,” states Joeri Rogelj, another senior research scholar at IIASA and a chapter co-lead of the report. “It is clear that the G20 countries are not reducing their emissions at a pace consistent with the set targets and even in the most optimistic scenario the likelihood of limiting warming to 1.5°C is only around 14%”. At the same time, the coal, oil, and gas extracted over the lifetime of producing and planned mines and fields (as of 2018) would emit over 3.5 times the carbon budget available to limit warming to 1.5°C, and almost the entire budget available for 2°C.

Future pathways

The report calls for all nations to immediately and stringently deliver economy-wide, low-carbon transformations, with a focus on the energy transition.

Countries with greater capacity and responsibility for emissions – particularly high-income and high-emitting countries among the G20 – will need to take more ambitious and rapid action. As low- and middle-income countries already account for more than two thirds of global GHG emissions, meeting development needs with low-emissions growth is a priority in such nations – backed by financial and technical support from wealthier nations.

“The report emphasizes that the low-carbon energy transition poses economic and institutional challenges for low- and middle-income countries, as well as provides significant opportunities. Such transitions can help to provide universal access to energy in such countries and lift millions out of poverty,” says Narasimha Rao, a senior research scholar at IIASA and a chapter co-lead. “As renewables get cheaper, the associated energy growth can be met efficiently and equitably with low-carbon energy, ensuring not only the increased quality of life, but also green jobs and better air quality”.

COP28 and the Global Stocktake

The first Global Stocktake (GST) concluding at COP28 will inform the next round of NDCs that countries should submit in 2025 with targets for 2035. Global ambition in the next round of NDCs must bring GHG emissions in 2035 to levels consistent with the below 2°C and 1.5°C pathways, while compensating for excess emissions until levels consistent with these pathways are achieved.

The preparation of the next round of NDCs offers the opportunity for low- and middle-income countries to develop national roadmaps with ambitious development and climate policies, and targets for which finance and technology needs are clearly specified. COP28 should ensure that international support is provided for the development of such roadmaps.

Carbon dioxide removal

The report finds that delaying GHG emissions reductions will increase future reliance on carbon dioxide removal from the atmosphere. Carbon dioxide removal is already being deployed, mainly through afforestation, reforestation, and forest management. Current direct removals through land-based methods are estimated at 2 GtCO₂e annually. However, least-cost pathways assume considerable increases in both conventional and novel carbon dioxide removal – such as direct air carbon capture and storage.

Achieving higher levels of carbon dioxide removal remains uncertain and has associated risks: around land competition, protection of tenure and rights and other factors. Novel carbon dioxide removal methods are associated with different types of risks, including that the technical, economic, and political requirements for large-scale deployment may not materialize in time as well as sustainability concerns around energy, land use, and water requirements.

*The report was prepared with significant contributions from IIASA scientists, including Joeri Rogelj, Narasimha Rao, and Matthew Gidden as chapter co-leads, Jarmo Kikstra, Setu Pelz, and Gaurav Ganti as contributing authors, and Shonali Pachauri as a member of the Steering Committee.