A new UN report has acknowledged what has been clearly evident for some years - that there is no way for the world now to contain the global rise in temperatures to within 1.5 degree Celsius from pre-industrial times. The report by UN Environment Programme (UNEP) says the main question now is whether humans are able to take adequate action that minimises the 'overshoot' beyond 1.5 degree Celsius, and enables a return to the 1.5 degree Celsius warming range after some time. But even in the best case scenarios the temperature rise is expected to go up to at least 1.8 degree Celsius before declining. Most other pathways project peak temperatures to exceed 2 degree Celsius over pre-industrial times. "We are at a point where there are no plausible scientific pathways left that keep temperatures below 1.5 degree Celsius," the report said. Explained | ‘Failure to meet climate targets does not make multilateral processes irrelevant’: Why COP matters This is the first time that an authoritative report has acknowledged that a breach of the 1.5 degree Celsius threshold is now inevitable. Most other reports and analyses, including those by the Intergovernmental Panel on Climate Change (IPCC), have always offered a narrow, though ever-shrinking, window of opportunity to keep temperature rise within this limit. The 1.5 degree mark is an arbitrarily decided threshold. In terms of climate change impacts, there is nothing new that suddenly becomes possible once this threshold is crossed. But science says that climate impacts that are already unfolding - extreme weather events, flooding, droughts, heatwaves, and others - are expected to become more severe and frequent as warming increases. The main goal of global climate action, as embedded in the 2015 Paris Agreement, is to keep the rise in temperatures to well below 2 degree Celsius compared to pre-industrial average, and strive to limit it to 1.5 degree Celsius. The 1,5 degree Celsius threshold for annual averages has already been breached once, in 2024, the warmest year ever recorded, in which the average temperature happened to be 1.55 degree Celsius above pre-industrial times. Monthly averages have topped the 1.5 degree limit several times, particularly between July 2023 and December 2024, when every month, except one, was at least 1.5 degree Celsius warmer than the corresponding monthly average of pre-industrial times. However, when scientists talk about 1.5 or 2 degree Celsius temperature thresholds, they refer to long-term temperature trends, and not individual year aberrations that can be caused by some abnormal event. The record temperature in 2024, for example, was significantly influenced by the El Nino event. The following year, 2025, the warming came down to 1.45 degree Celsius. The UNEP report, however, warns that the world is now entering an era where annual average temperatures would be consistently higher than 1.5 degree Celsius. Must Read | Highway to ‘climate hell’: What breaching the 1.5 degree Celsius warming threshold could mean "The IPCC said we may cross 1.5 around 2035, however this year’s Indicators of Global Climate Change report estimates only around three years before the 1.5c carbon budget is used up if emissions continue at current levels," it says. It says that a return to 1.5 degree Celsius warming levels was uncertain, even if earnest efforts are made. "Even if a return to below 1.5 degree Celsius is secured, many nations and communities will face irreversible losses and permanently changed conditions," the report says. Ajay Mathur, former director general of International Solar Alliance and a former climate negotiator for India, said the recent disaster in Nepal was another grim reminder of the kind of risks that are likely to get enhanced if temperatures are allowed to continue to rise. The Nepal flash floods, most likely caused by a large chunk of glacier breaking off and getting into a stream, is still being analysed but scientists agree that climate change has a significant role to play in causing such events. "The disaster in Nepal reminds us with horrific clarity that an 'overshoot in temperature' carries a human cost measured in lives lost and communities shattered," Mathur said. "As the UNEP report highlights, delayed ambition is no longer just a failure of policy - it is an active contributor to ecological destabilization. The Paris Agreement succeeded in bending the emissions curve from a pre-Treaty path of nearly 4 degree Celsius to roughly 2.8 degree Celsius under current levels of climate action being undertaken by countries. However, in a fragmented world, our response cannot be incremental. We need urgent, targeted climate finance and unified global action to protect those on the frontlines of a rapidly warming planet," he said. The UNEP report says the return pathway towards 1.5 degree Celsius threshold would be heavily dependent on the success of carbon dioxide removal (CDR) technologies, which have had limited impact till now. "CDR will be needed in addition to, not instead of, sustained reductions in greenhouse gas emissions. Even optimistic CDR scaling is unlikely to lower temperatures more than a few tenths of a degree this century," it says.
