Global temperatures are on track to move beyond the crucial 1.5-degree Celsius warming threshold within the next few years, the United Nations Environment Programme (UNEP) has
warned, highlighting the growing threat to ecosystems, glaciers and vulnerable coastal communities.
The warning reflects the increasing likelihood that the target established under the 2015 Paris climate agreement will be temporarily exceeded. UNEP said the world must now concentrate not only on preventing further warming, but also on limiting the duration and scale of any period in which temperatures remain above 1.5C.
Returning global temperatures below the threshold remains technically achievable, the UN agency said, but described the prospect as highly uncertain. It would require countries to accelerate reductions in greenhouse-gas emissions while also expanding efforts to remove carbon dioxide that has already accumulated in the atmosphere.
The Paris Agreement calls for global warming to be kept well below 2C above pre-industrial levels, while pursuing efforts to limit the increase to 1.5C because each additional fraction of warming increases the severity of climate-related impacts.
UNEP said an "overshoot" of the 1.5C threshold is now extremely likely. The longer temperatures remain above that level, the greater the risks of permanent damage.
"Every year of delay and every fraction of a degree above 1.5C increases risks and makes recovery harder," the report said, warning that some losses could become irreversible even if global temperatures eventually decline.
Current policies point to much higher warming
The UN assessment also underlined the gap between governments' climate commitments and the emissions reductions needed to meet the Paris goals.
Even if countries fully deliver on their existing national climate pledges, global warming could peak at around 1.8C above pre-industrial levels, according to UNEP. The agency cautioned, however, that actual warming is likely to be higher if governments fail to implement their commitments in full.
Under policies that are currently in place, median global warming is projected to reach about 2.6C by the end of this century, UNEP said.
Such a trajectory would significantly increase the likelihood of more frequent and severe heatwaves, heavy rainfall, droughts and other extreme weather events, while placing additional stress on natural ecosystems and human settlements.
Carbon removal seen as increasingly important
UNEP said technologies and measures capable of removing carbon dioxide from the atmosphere will become increasingly important if global temperatures overshoot the 1.5C objective.
Carbon dioxide removal includes approaches such as restoring forests and creating new woodland, as well as other methods designed to capture and permanently store carbon.
However, the UN agency stressed that carbon removal cannot substitute for rapid reductions in emissions from energy, transport, industry and other major sources.
The report effectively leaves governments with a narrowing window in which to reduce the scale of the temperature overshoot. The sooner emissions fall, UNEP said, the greater the chances of limiting the duration and consequences of warming beyond the 1.5C threshold. Photo by Alisdare Hickson, Wikimedia commons.
