According to a new research, heat generated in large cities from human activities affects temperatures in places located thousands of miles far and not just the cities themselves.

The study showed that the heat generated in mega cities affected had a significant impact in temperatures of distant places, warming some places while cooling others. Scientists at the National Center for Atmospheric Research (NCAR) in the US found evidence proving that heat generated from buildings, cars, and other sources in major Northern Hemisphere affect large areas of northern North America and northern Asia.

Researchers said that the study explains why some of the places in the region are experiencing warmer winters than usual. They said that temperatures in some places increased as much as 1 degree Celsius and on the other hand, the waste heat from cities also cooled some areas in Europe by 1 degree Celsius. They estimated that the net effect on global temperature is just 0.01 degrees Celsius as waste heat is only about 0.3 per cent of the heat transported by forces.

Study researcher Aixue Hu, of NCAR said, "The burning of fossil fuel not only emits greenhouse gases, but also directly affects temperatures because of heat that escapes from sources like buildings and cars. Although much of this waste heat is concentrated in large cities, it can change atmospheric patterns in a way that raises or lowers temperatures across considerable distances."