MercoPress. South Atlantic News Agency

2004, fourth warmest year on record.

Greenhouse gases and to a lesser extent the El Niño current in the Pacific contributed to making 2004 the fourth warmest year on Earth since temperature measurements began worldwide at the end of the 19th century, revealed NASA scientists.

James Hansen, a climatologist at NASA's Goddard Institute for Space Studies, said there had been a strong warming trend over the past 30 years that had been shown to be due mainly to increasing greenhouse gases. Warmest years were 1998, 2002 and 2003, NASA said on its website. In 2004, the average global temperature was 14C, or 0.48C warmer than any year between 1951 and 1980, Mr Hansen said. Regions with the highest rise in average temperatures last year were Alaska, the Caspian Sea region and the Antarctic Peninsula.

Solar heat trapped by the accumulation of greenhouse gases ? especially carbon dioxide spewed out by cars and industries ? and the warming effect of the El Niño current could make 2005 approach the record warmth of 1998, NASA said. Scientists said the warming trend was already significant enough to permanently make seasons warmer.

NASA determines planetary cooling or warming by measuring the temperature at numerous spots around the world, at ground level and over the oceans, from orbiting satellites.

The issue of global warming is controversial, especially in the US, but the President Bush Administration opposes mandatory curbs on the emission of greenhouse gases such as carbon dioxide. Researchers agree it is one of the main causes of global warming.