In an annual update on global-warming pollution, the UN Framework Convention on Climate Change (UNFCCC) said that, compared with the benchmark year of 1990, the 41 industrialised countries it monitors trimmed their emissions by 3.3 percent by the end of 2004.

But this was mainly due to the slump in the former Soviet bloc economies in the 1990s, which forced the closure or overhaul of thousands of power stations and factories that spewed out carbon dioxide.

Because of that historic change, countries in eastern and central Europe had a decrease in emissions from 1990-2004 of 36.8 percent. But from 2000-2004, they in fact increased their pollution by 4.1 percent as their economies emerged from the post-Soviet crash.

In contrast, the other industrialised countries saw an increase in pollution of 11 percent from 1990-2004. From 2000-2004, the increase was two percent.

The UNFCCC's executive secretary, Yvo de Boer, called on the world to heed the top scientific body on global warming, the Intergovernmental Panel on Climate Change (IPCC).

"It's telling us is that we need to act on climate change very urgently or else it's going to get very expensive. It's showing us that by the middle of the century, emissions probably need to be reduced by 60 or 80 percent, at least by industrialised countries," he told a press conference.

De Boer added, though: "The encouraging thing is that some of the political signals in fact are going in that direction."

The new report applies to so-called Annex 1 countries of the UNFCCC, the offshoot of the famous 1992 Rio Summit on the planet's environmental future and parent of the Kyoto Protocol for curbing greenhouse gases. Annex 2 parties are developing countries and the poorer ex-Soviet republics.

The report showed:

-- the United States remains by far the world's biggest polluter.

Of the 17.931 billion tonnes emitted by Annex 1 countries in 2004, 39.4 percent was emitted by the US alone. With 7.067 billion tonnes, the United States accounts for nearly a quarter of the global total of greenhouse-gas pollution, i.e. from Annex 1 and Annex 2 countries together.

Under the Kyoto Protocol, which President George W. Bush abandoned in 2001 because of what he cited as its cost to the US economy, the United States pledged to reduce its emissions by six percent by 2012 compared to 1990.

In 2004, it was 21.1 percent above the benchmark year, the UNFCCC said. The increase from 2000 to 2004 was 1.3 percent.

-- The Kyoto Protocol ratifiers have pledged to cut emissions by on average five percent by 2012 compared with 1990. In 2004, they were 15.3 percent below the 1990 level, although this figure masks the effects of the economic post-Soviet slump in eastern and central Europe and some hugely varying performances.

Japan, for instance, pledged a cut of six percent by 2012, yet in 2004 it already had an increase of six percent over 1990. Spain is pegged to a rise of only 15 percent by 2012 but in 2004 was already 49 percent over the 1990 target.

De Boer was upbeat, though, holding up the performance of Britain and Germany as countries whose economies have expanded but whose emissions have fallen sharply.

"It is possible to decouple economic growth and climate change," he said.

-- Emissions by Annex 1 countries from agriculture fell by 20 percent from 1990-2004 and from industry by 13.1 percent. But pollution by transport rose by 23.9 percent, reflecting that reductions in this sector "seem to be especially hard to achieve," the UNFCCC said.

De Boer pointed out that the 2004 figures do not take into account the effects of the Kyoto Protocol, which took effect in February 2005.

That treaty includes an array of market incentives, including a market in carbon emissions and credits for transferring cleaner technology to poorer countries. Already, 1.4 billion tonnes of carbon would be eliminated by Kyoto countries by 2012 under this credits scheme, he said.

Greenhouse gases are so called because, as in a stuffy greenhouse, they linger invisibly in the air. Instead of letting solar radiation bounce back into space, the gases trap it, thus warming Earth's surface.

Scientists say there is mounting evidence that the world's climate system is starting to be affected by the warming and are demanding quick, deep cuts in the gases to avert what could be a catastrophe.

The big culprits for this carbon-based pollution are oil, gas and coal -- the fossil fuels on which today's prosperity was built and on which every economy still depends.

Curbing the pollution carries an economic and thus political cost, because it requires users of these fuels to be more efficient or switch to cleaner alternatives.

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