UN Says Breaching 1.5C Warming Limit Is ‘Imminent and Unavoidable’

For the first time, the UN has declared that exceeding the Paris Agreement’s 1.5C warming limit is “imminent and unavoidable.” “We are now saying this window has closed, but we can open it again by making the overshoot as brief as possible,” UN Environment Program Executive Director Inger Andersen said on a call with reporters. “This is about how to find a way back as shortly and as quickly as possible with as limited an overshoot as possible.” CNN reports: Past reports have examined the distance between countries’ emissions reduction commitments and what it would take to limit global warming to 1.5 C above preindustrial levels. However, this year’s report redefines the gap. Instead, it examines new emissions overshoot scenarios, and what it would take to limit peak warming to just 1.7 to 1.8 degrees C before bringing temperatures back down to 1.5 C through emissions cuts and the use of carbon removal technologies.

The report makes clear that every additional fraction of a degree of warming above 1.5 C “raises the risk of irreversible changes including in ice sheets, permafrost carbon, ocean circulation, and coral systems, along with devastating human impacts.” Each added fraction of a degree of warming can have an “immense” impact “as measured in terms of damage, cost and loss of lives,” said climate scientist Michael Mann of the University of Pennsylvania. Mann was not involved in producing the UNEP report.

According to the UNEP, which is based in Nairobi, the lowest overshoot scenario would keep peak warming to between 1.7 and 1.8 degrees C and return global average temperatures to at or below 1.5 C by 2100. However, to follow such a pathway, global greenhouse gas emissions would need to be slashed by far more than anything currently on the table at the upcoming COP31 talks. This would require an 18% cut by 2030, 45% by 2035, and 69% by 2040, relative to 2025 levels.

Meeting this lowest-possible overshoot scenario would require a tripling of renewable electricity capacity by 2035, and dramatic cuts to fossil fuels, including the phaseout of coal by 2040, the report states. In addition, there would need to be a major scaling up of carbon removal technologies, which so far have not been proven to work at such a large scale. In stark contrast to these figures, the fulfillment of existing emissions reduction pledges would only yield a 5-to-8% emissions cut by 2030 and an 11-to-15% reduction by 2035, the report found. This would be associated with a peak warming of about 2.6 degrees C.

If countries simply follow their current policies, then warming could reach a peak of about 2.8 C. That estimate has increased since last year, in part because of the withdrawal of the United States from the Paris Agreement and retraction of its emissions reduction commitments, the report states. Even the scenario that assumes countries meet their existing reduction commitments, and nations with net-zero pledges succeed in fulfilling them, still brings warming to a peak of 2.1 C.

Read more of this story at Slashdot.