The Earth is on track to break through the critical 1.5°C global warming threshold within the next few years, according to a new United Nations report. Even in the most optimistic scenario for cutting emissions, the report found, the planet's average temperature is expected to reach 1.8°C above pre-industrial levels before global temperatures begin to fall.
The document, titled "Limiting Overshoot," concludes that international action to curb greenhouse gases has not moved fast enough to prevent the climate safety threshold set out in the Paris Agreement from being breached in the near term. The Paris Agreement, signed by nearly 200 countries in 2015, set 1.5°C above pre-industrial levels as the target limit for global warming.
No safe scenario above 1.5°C
The report states that there is no benign or safe scenario for life on Earth once warming passes 1.5°C. Every fraction of a degree beyond that mark is expected to bring significant impacts on people, the economy and the planet's ecosystems, it says.
The study warns of a sharply increased risk of crossing so-called tipping points in the global climate system. These include the destabilization of the West Antarctic and Greenland ice sheets, a slowdown of the Atlantic Meridional Overturning Circulation, and large-scale degradation of the Amazon rainforest.
Melting ice and rising seas
Among the risks highlighted, the report projects that global glaciers could lose more than a quarter of their mass by 2100 under warming scenarios of up to 3°C. That loss would raise sea levels by 9 to 12.5 centimetres and permanently threaten freshwater supplies in many parts of the world.
Small Island Developing States and low-lying coastal cities face flooding, saltwater contamination of agricultural water reservoirs, and even partial or total submersion of their territories as sea levels rise, according to the report.
Food, health and oceans at risk
Without effective adaptation measures, the report's projections point to a drop of up to 14% in global food production by 2050.
Rising temperatures are also expected to bring more frequent and severe heatwaves, an increase in diseases linked to malnutrition, and a greater likelihood that pathogens will spread through new transmission routes, the report says.
Warming oceans, combined with falling oxygen levels and rising acidity, could make survival harder for marine life, the report adds, with direct consequences for fishing communities that depend on those resources.
Inger Andersen, Executive Director of the UN Environment Programme, said there were no good outcomes if the world stayed above 1.5°C. She said extreme heatwaves happening around the world were already showing that climate impacts would be faster, more severe and longer lasting, costing more lives and causing even greater disruption.
What can still be done
Despite the alarming outlook, the United Nations stresses that the future is not predetermined, and that limiting long-term warming to 1.5°C remains achievable if the world urgently follows a path of "overshoot, peak and decline."
The strategy calls for keeping the peak temperature as low as possible and shortening the period during which the Earth remains above the climate safety limit.
For that return path to succeed, the report calls for immediate action, including a sustained reduction in carbon dioxide and short-lived pollutants, particularly methane. Cutting methane emissions from the fossil fuel, waste and agriculture sectors is described as the most effective short-term tool for slowing global warming and reducing temperature peaks.
The report also says renewable energy sources need to expand to make up between 60% and 70% of the electricity generated worldwide by 2030, in line with the international goal of tripling global renewable energy capacity agreed at the COP28 climate summit. COP28, held in Dubai in 2023, brought together nearly 200 countries under the UN climate process.
Another recommendation is the use of Carbon Dioxide Removal technologies and methods, alongside traditional reforestation and geological storage techniques, to offset residual emissions and achieve net negative emissions.
Finally, the report says countries with the greatest responsibility for global warming and the greatest financial capacity should lead the way on emissions cuts and help fund adaptation efforts in the most vulnerable nations.
Andersen said now was the time to redouble efforts on climate action. She said the world could, and must, take the right path by cutting greenhouse gas emissions, strengthening resilience and adaptation, and ensuring that any rise above 1.5°C was as small and as brief as possible.
