The global average temperature is set to rise to at least 1.2 to 1.3 degrees Celsius above pre-industrial levels over the next five years, a World Meteorological Organization (WMO) official said on Monday, close to a limit adopted in a global treaty.
The prediction comes as governments are due to meet in New York for the UN Climate Action Summit to build on their pledges from the 2015 Paris Agreement, which aims to cap the global temperature rise at 1.5 degrees.
The agreement, adopted by almost 200 nations, set a goal of limiting warming to "well below" a rise of 2C above pre-industrial times while "pursuing efforts" for the tougher 1.5C goal.
A rise of 2C is expected to wipe out more than 99 percent of coral reefs and melt most of the sea ice in the Arctic.
"Basically we are on track to reach at least 1.2- 1.3 degrees centigrade (above pre-industrial levels) over the next five years," said Omar Baddour, WMO senior scientific officer, in response to a Reuters question at a Geneva news conference.
"It needs drastic actions," he added.
The comments came after the UN agency released a report on Sunday showing that the period from 2015 to 2019 was set to be the warmest five-year period on record, rising by 0.2 degrees Celsius over 2011-2015.
"Not only are these statistics alarming they dispel any false sense of security that maybe we will muddle through this," said Maxx Dilley, director of the climate prediction and adaptation division of the WMO, told journalists.
"There is going to have to be a dramatic scale up in the level of ambition and as well as in the level of actual follow through on the current policies that are intending to address this," he added.
The WMO report also showed record carbon dioxide and other greenhouse gases in the atmosphere recorded over the same period, with the pace of carbon dioxide growth up 20 percent versus the last five-year assessment.
There is a lag in the period that the world's climate responds to carbon dioxide and other gasses, meaning that the emissions produced today can affect temperatures 20 years later, Dilley added, locking in the warming trend.