Siberia warmed up by New York, say US scientists

But US academics claim major cities such as  New York, Paris, London and Tokyo are making the air slightly milder.

Heat from buildings and cars added to the warming effect of asphalt and roofs which absorb heat causes cities to be warmed than rural areas.

This has been well known but until now it was assumed this 'urban heat island' stayed close to the cities.

But no. A study suggests the heat rises almost a kilometre 'and then its energy changes the high-altitude currents in the atmosphere that dictate prevailing weather' reported AP, citing new research in the scientific journal Nature Climate Change.

'Basically, it changes the flow,' said Guang Zhang of the Scripps Institution of Oceanography in La Jolla, California, who conducted the research with Aixue Hu at the National Center for Atmospheric Research in Boulder, Colorado.

They claim Siberia - like northwestern Canada - is between 0.8C and 1C warmer in winter due to this urban heat impact. 

Zhang is quoted saying it 'may not be a bad thing' to warm Siberia a little. 

The findings have surprised experts who have called for more detailed research. 

'It's an interesting and rationally carried out study,' said David Parker, climate monitoring chief of the United Kingdom meteorology office.

'We must be cautious until other models are used to test their hypothesis'.