The past 12 months have been cooler than previous years but longer-term trends show the world is still warming due to climate change, the World Meteorological Organisation said Tuesday.

"The global temperature is likely to rank around the 10th warmest year" on record, WMO Director General Michel Jarraud told a press briefing.

"The trend for warming is still very much there," he said, noting that all the years that have been warmer than 2008 have been during the last 12 years.

The slight dip in 2008 was explained by the moderate-to-strong La Nina that developed in the latter half of 2007, he said.

The effects of El Nino and La Nina -- respectively the warming and related cooling of Pacific sea surface temperatures -- are felt in many parts of the globe. They have been blamed for a lengthy drought in Australia, flooding in the Horn of Africa and Bolivia, and more severe winter monsoons in South Asia in 2006-2007.

Jarraud said both phenomena should be "neutral" in 2009 and should not have a discernible impact on climate.

But he voiced concern that ice in the Arctic Sea dropped to its second-lowest level during the melt season since satellite measurements began in 1979. He noted that 2008 saw many devastating floods, droughts, heatwaves and storms, most notably Cyclone Nargis which devastated Myanmar in May.

He added that it was too early to give any forecasts for 2009 but cited the most recent report from the UN's Intergovernmental Panel on Climate Change (IPCC) which predicted a 0.2 percent rise in temperature over the next decade.

Earlier this year the WMO said that the ozone hole over Antarctica and the South Pacific was larger in 2008 than the previous year but is not expected to reach the size seen two years ago.