Global warming is likely to breach the 1.5C threshold within the next few years, sooner than previously expected, according to a new United Nations report led in part by climate scientist Kristie Ebi.
The UN Environment Programme said the world was no longer on course to keep the rise in average temperatures below the limit set out in the Paris Agreement, warning that every additional fraction of a degree would intensify the risks to people and ecosystems.
Ms Ebi, one of the report’s lead authors, discussed the findings in an interview with CBS News as scientists urged governments to accelerate cuts in greenhouse gas emissions.
UN report warns of global warming overshoot
The report, titled Limiting Overshoot, examines what could happen if temperatures temporarily rise above 1.5C before eventually falling back below it.
It says the most optimistic scenario would see warming peak at about 1.8C above pre-industrial levels. Most other projected pathways would result in a higher peak, the report states.
UNEP said the best remaining option was an “overshoot, peak and decline” pathway, involving immediate and sustained emissions reductions followed by a long-term reduction in atmospheric carbon dioxide.
Such a route would require steep cuts in greenhouse gases, including methane, alongside the carefully governed removal of carbon dioxide from the atmosphere. The report stressed that carbon removal could not replace continued reductions in emissions.
The agency said a higher peak temperature, or a longer period above 1.5C, would increase the likelihood of irreversible changes in major ice sheets, the Amazon rainforest and ocean circulation systems.
It also warned of worsening extreme weather, ecosystem loss and growing damage to health, food supplies, water resources, infrastructure and economies. Low-lying coastal cities and small island states face particular risks, it said.
UNEP said returning below 1.5C remained technically possible, but years of delayed action meant that some losses and lasting changes were now unavoidable even under the most ambitious pathway.
The agency called for mitigation and adaptation measures to be advanced together, with countries most responsible for historical emissions expected to move fastest and provide greater support to vulnerable nations.
The report’s publication comes after repeated warnings that the Paris Agreement’s temperature goal is slipping out of reach. The UN said crossing the threshold should not be treated as a reason to abandon efforts, but as a signal that immediate action is needed to limit how high temperatures rise and how long they remain elevated.
