New Delhi, Sept. 2 -- The world is likely to cross the 1.5degC global warming threshold by the end of this decade, according to a new United Nations Environment Programme (UNEP) report, marking a major setback to the temperature goal agreed under the 2015 Paris Agreement. The report, however, says the threshold should not be treated as a point of no return and calls for countries to limit how far temperatures rise beyond 1.5degC, shorten the period of excess warming and eventually bring global temperatures back below the level. Without stronger action, current policies could result in warming of about 2.6degC above pre-industrial levels by 2100.
UNEP's report, Limiting Overshoot, says human-caused warming is already approaching 1.4degC above pre-industrial levels, with global temperatures rising at roughly 0.25degC per decade. If that trend continues, the 1.5degC mark could be reached around the end of the 2020s.
The Paris Agreement calls on countries to keep long-term warming below 1.5degC while pursuing efforts to limit it to well below 2degC. The new report acknowledges that preventing the 1.5degC threshold from being crossed is no longer realistic, but says it remains possible to return below it later.
Under the most optimistic pathway, involving full implementation of countries' current climate plans and additional net-zero commitments, warming would peak at about 1.8degC, with a possible range of 1.7degC to 2.2degC, before declining. The report describes this as an "overshoot, peak and decline" pathway. Under current policies, the projected 2100 warming is about 2.6degC, with a range of 1.9degC to 3.6degC. "1.5 target is still the goal. But now we need to approach it differently from above," UNEP Executive Director Inger Andersen said.
Crossing 1.5degC would not cause an immediate global climate collapse, but the report says risks would increase with every additional fraction of a degree and every year spent at higher temperatures. Expected consequences include more severe heatwaves, floods and other extreme weather, damage to ecosystems, declining food and water security, health impacts, economic losses and rising risks for low-lying coastal areas and small island states.
The report also warns that prolonged warming increases the possibility of irreversible tipping points, including the destabilisation of the Greenland and West Antarctic ice sheets, degradation of the Amazon rainforest and disruption of the Atlantic Meridional Overturning Circulation, a system of ocean currents that helps regulate climate.
The warning comes days after a glacial collapse and flash flood in Nepal that killed 1,127 people and left thousands missing. Climate scientist Richard Betts of the University of Exeter said such events are expected to become more common as warming increases.
Reducing emissions quickly is central to limiting the peak. UNEP also points to methane and other short-lived pollutants as important targets in the near term. Every five years of delay in cutting emissions could add at least 0.1degC to peak warming, according to report co-author Joeri Rogelj of Imperial College London.
Countries will also need stronger adaptation measures because some damage cannot be avoided. The report describes this period as one of "coping and containment", with greater risks of deaths and illness, food shortages, water stress, economic disruption and species loss.
Returning below 1.5degC would eventually require removing carbon dioxide from the atmosphere as well as cutting fossil fuel emissions. The report says planting trees alone could reduce global temperatures by no more than about 0.1degC, meaning other carbon removal methods would be needed.
UN Secretary-General António Guterres said recent heatwaves, wildfires and deadly floods offer a warning of what could lie ahead. "We must make the overshoot above 1.5 degrees as small and short as possible," he said, calling for greater ambition in climate action.
Published by HT Digital Content Services with permission from Millennium Post.