Global Heating Will Hit At Least 1.8C, UN Warns, and There Are 'No Good Outcomes'

The United Nations Environment Program has released a report warning that global temperatures will rise at least 1.8 degrees Celsius above preindustrial levels, surpassing the Paris Agreement's limit of 1.5C. This overshoot is deemed unavoidable, despite recent efforts to address human-caused climate change caused by fossil fuel combustion.

The report's authors assert that no positive outcomes exist beyond 1.5C. At 3C above preindustrial levels, glaciers could lose more than a quarter of their mass by 2100, elevating sea levels by up to 13cm. Agriculture may decline by up to 14% by 2050 without effective adaptation strategies. Human health, water sources, wildlife, urban areas, infrastructure, and economies could sustain significant damage, with some consequences becoming irreversible.

Some communities might need to relocate or alter their livelihoods. The report suggests an "overshoot, peak, and decline" pathway for limiting damage, which necessitates immediate and sustained reductions in greenhouse gas emissions, coupled with efforts to remove carbon dioxide from the atmosphere. Achieving net zero emissions—currently a politically contentious goal—is deemed an essential milestone that cannot be skipped.

Carbon dioxide removal through measures like establishing extensive forests must accompany, not substitute, substantial cuts in fossil fuel pollution. The authors emphasize that the global average temperature could revert to 1.5C this century only if warming remains below roughly 1.8C. Nonetheless, they caution that nature's ability to store carbon is uncertain and is likely to diminish as the planet warms.

Existing national policies project emissions to increase by at least 2.3C, yet limiting warming to 2C remains possible if nations fulfill their net zero emissions commitments by mid-century.