COPENHAGEN, Denmark - This decade is on track to become the warmest since records began in 1850, and 2009 could rank among the top-five warmest years, the U.N. weather agency reported yesterday on the second day of a pivotal 192-nation climate conference.

Only the United States and Canada experienced cooler conditions than average, the World Meteorological Organization said, although Alaska had the second-warmest July on record.

In central Africa and southern Asia, this will probably be the warmest year, but overall, 2009 will "be about the fifth-warmest year on record," said Michel Jarraud, secretary-general of the WMO.

The agency also noted an extreme heat wave in India in May and a heat wave in northern China in June. It said that parts of China experienced their warmest year on record and that Australia so far has had its third-warmest year. Extremely warm weather was also more frequent and intense in southern South America.

This decade "is very likely to be the warmest on record, warmer than the 1990s, than the 1980s and so on," Jarraud told a news conference, holding a chart with a temperature curve pointing upward. The second-warmest decade was the 1990s.

The current decade has been marked by dramatic effects of warming.

During the 2007-09 period, the summer melt reduced the Arctic Ocean ice cap to its smallest extent ever recorded. In that period, researchers found that Antarctica was warming more than previously believed. Almost all glaciers worldwide are retreating.

Meanwhile, such destructive species as jellyfish and bark-eating beetles are moving northward out of normal ranges, and seas expanding from warmth and glacier melt are encroaching on low-lying island states.

If 2009 ends as the fifth-warmest year, it would replace 2003. According to NASA and scientists in Britain, other years since 1850 that had a notable increase in warming have been 1998, 2005, 2006, and 2007. NASA said the differences in readings among these years were so small as to be statistically insignificant.

The U.N. agency reported that the global combined sea-surface and land-surface temperature for the January-to-October period this year was estimated at 0.79 degrees Fahrenheit above the 1961-90 annual average of 57.2 degrees Fahrenheit. Final data will be released early in 2010.

Negotiators at the two-week climate talks in Copenhagen turned yesterday to "metrics," "gas inventories," and other technicalities, as delegates worked to craft a global deal to rein in carbon dioxide and other greenhouse gases and stem climate change.

Governments, meanwhile, jockeyed for position leading up to the finale late next week, when more than 100 national leaders, including President Obama, will converge on Copenhagen for the final days of bargaining.

Preliminary drafts circulated at the conference yesterday showed marked differences between rich and poor countries over how to structure a final agreement. A leaked Danish document that was submitted before the conference came under heavy criticism from climate activists as an attempt by rich countries to exclude them from the bargaining.

"As the talks ramp up and big players put forward their proposals for the deal, it is vitally important that vulnerable countries are part of the debate," Oxfam spokesman Antonio Hill said.

U.N. climate chief Yvo de Boer played down the document, saying it was an "informal paper" and not a formal text for the conference.

The Copenhagen talks are aimed at prodding both large and small countries to provide some measure of reducing carbon emissions.

The European Union has pledged to reduce greenhouse-gas emissions by 20 percent by 2020, and is considering raising that to 30 percent if other governments also aim high.

The United States has offered a 17 percent reduction in emissions from their 2005 level, comparable to a 3 to 4 percent cut from 1990 levels.