The world's ocean surfaces had their warmest summer temperatures on record, the US national climatic data centre said today.

Climate change has been steadily raising the earth's average temperature in recent decades, but climatologists expected additional warming this year and next due to the influence of El Niño.

Ocean surface temperatures were the warmest for any August since record keeping began in 1880. For the June to August summer months, average ocean surface temperatures rose to 16.9C (62.5F), which is 1.04F above the 20th century average, said the report from the climate centre, which is a branch of the National Oceanic and Atmospheric Administration.

The world's combined average land and ocean surface temperatures were the second warmest on record for August, and the third warmest for the summer months.

"During the season, warmer-than-average temperatures engulfed much of the planet's surface," the centre said. Australia and New Zealand had their warmest August since records began.

However, central Canada and the United States were the exceptions, with unusually cool temperatures. "In some areas, such as the western United States, temperatures were much cooler than average," the report said.

The unusually warm summer temperatures for much of the world's oceans were due to El Niño, the periodic warming of the Pacific. If El Niño strengthens, global temperatures are likely to set new records, the report said. So far, 2009 has been the fifth warmest year on record.

Some scientists have suggested that, the effects of El Niño, coupled with warming due to climate change could well make the coming decade the hottest in human history.

Nasa predicted at the start of this year that 2009 and 2010 could see the setting of new global temperature records.

The report also noted the continuing retreat in Arctic sea ice over the summer. Sea ice covered an average of 6.3m sq kilometres (2.42m sq miles) during August, according to the national snow and ice data centre. That was 18.4% the 1979-2000 average.