Sea levels this year posted a record high, making low-lying coastal populations ever more vulnerable to extreme weather like super-storm Haiyan, the UN said Wednesday.
"Although individual tropical cyclones cannot be directly attributed to climate change, higher sea levels are already making coastal populations more vulnerable to storm surges. We saw this with tragic consequences in the Philippines," he said.
"Global sea level reached a new record high during March 2013," the WMO said in its report.
At 3.2 mm (0.12 inches) per year, the current average rise is double the 20th-century trend of 1.6 millimetres (0.06 inches) per year, it said.
The WMO said that in 2012, concentrations of greenhouse gases hitd a new high of 393.1 parts per million, a rise of 2.2 parts per million over the previous year and an increase of 41 percent since the start of the Industrial Revolution in 1750.
"We expect them to reach unprecedented levels yet again in 2013. This means that we are committed to a warmer future," Jarraud declared.
The agency said the first nine months of 2013 tied with 2003 as the seventh warmest such period since modern data collection began in 1850.
Global land and ocean surface temperature of about 0.48 degrees Celsius (0.86 degrees Fahrenheit) above the 1961-1990 average.