New Scientist NL · Wetenschap

UN report: Return to 1,5°C warming possible, but unlikely

A UN report states that it is possible to reduce global warming to 1,5°C above pre-industrial levels by the end of the century, despite the expected overshoot of this limit. However, experts consider this scenario highly unlikely.

The UN Environment Programme (UNEP) confirms in a report that global warming will likely exceed the 1,5°C limit. Although the report outlines a scenario where temperatures could fall below this limit again by 2100, many experts do not consider this scenario the most likely.

The 1,5°C target, set in the Paris Agreement, already seemed unattainable in 2015. The UNEP report is an official confirmation that this limit will be widely exceeded. Nevertheless, some are not giving up on the target, emphasizing that 1,5°C remains the goal, but the approach must change.

If the 1,5°C limit is exceeded, severe consequences are expected, such as increasing food and water insecurity, health problems, and dangers to homes and infrastructure. Some consequences will be irreversible, meaning a return to 1,5°C will not equate to a return to the world as it was before.

The scenario for returning to 1,5°C requires a rapid reduction in CO₂ emissions and large-scale CO₂ removal from the atmosphere. Warming must be limited to a maximum of 1,8°C to prevent cascading effects. To achieve this, global emissions must be halved by 2035, which currently seems unlikely.

In addition to emission reductions, large-scale carbon removal is necessary, possibly a factor of 100.000 more than currently. Inexpensive methods like tree planting are limited by land availability, and direct air capture of CO₂ is very expensive. Experts deem this technically and financially possible, but politically unrealistic, and advocate for adaptation to at least 2°C warming.

Earth scientists are less optimistic, stating that there are no concrete plans for large-scale CO₂ removal. They advise adapting to a warmer and more dangerous world. Recent emission scenarios show that only a few models consider a return to 1,5°C before 2150 possible, while current policies lead to approximately 3°C warming in 2100.

The idea of first exceeding the 1,5°C limit and then returning is seen as a possible 'plan B' for the continued failure of climate policy. Despite the unlikelihood of success, experts emphasize that efforts to limit temperature are crucial. Every fraction of a degree avoided and every adaptation measure can save lives and limit losses.

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