It's cold out there - blame global warming.

Weather experts say global warming not only warms the world, it also brings colder extreme weather.

"It means a higher risk of more extreme weather like freezing winter, snowstorms and scorching hot in the coming five decades," Kuang Yaoqiu, professor with Guangzhou Institute of Geochemistry under the Chinese Academy of Sciences, told China Daily yesterday.

Beijing, at 39 degrees north latitude, has witnessed its coldest morning in almost 40 years and its biggest snowfall since 1951. Britain is suffering through its longest cold snap since 1981 and the freezing cold is gripping millions in the deep south of the US.

According to the latest data from the National Meteorological Center, many provinces and municipalities in North China have suffered record cold temperatures since late last year with Altay, Northwest China's Xinjiang Uygur autonomous region, hit by the largest snowfall in half a century.

Kuang said human activities are concentrated north of the equator, which quickens the global warming process in the northern hemisphere.

The heated air, carrying the greenhouse gas carbon dioxide, rises and circulates to the southern hemisphere.

As the air loses its heat high in the atmosphere, the dense air, loaded with carbon dioxide, sinks and brings cold air from the upper atmosphere with it.

"And the cold air causes the south part of the Earth to become colder," Kuang said.

When carbon dioxide builds up in the south, the process reverses, with cold air descending on the northern hemisphere.

In 2008, CO2 levels in the atmosphere stood at 387 parts per million (ppm). The present goal, set at the Copenhagen climate summit, is to stabilize world gas emissions at or below 450 ppm, which would prevent a rise in average global temperatures of no more than 2 C.

"So far, the temperature in China's southern regions is 2 to 4 degrees above the average, while in the north it is 2 to 4 degrees below," said Wang Yongguang, the National Meteorological Center's chief forecaster.

Since the 1980s, global warming has played a major role in China, Wang said.

The national forecaster said yesterday on its website that the temperature will increase from Thursday but a new cold wave will bring gales and precipitation to most parts of the country from Saturday to next Monday.

The continuous freezing conditions since last week have left one person dead and at least 276 injured or sick, according to the Ministry of Civil Affairs.

Many counties in Europe and North America have also suffered from the freezing cold.

A five-day heavy snowfall claimed 27 lives in Ukraine at the end of last year, the local health ministry said in a statement, Xinhua reported.

Heavy snowfall and plummeting temperatures wreaked travel chaos across the UK with up to 50 cm of snow, and the cold spell is likely to continue into late January, local media reported.