A new study reveals that waste heat is a major source of national warming besides the greenhouse effect.
The study was published in Earth's Future, a journal of the American Geophysical Union. It was led by John Murray from the Open University in Milton Keynes, England and the lead author of the study and co-authored by Douglas Heggie of the University of Edinburgh.
The waste heat discharges when people use energy. This includes the clean energy. Murray said that this is a major source of climate change that has not been looked at. He further said that any kind of energy consumption generates heat.
The researchers focused on UK and Japan. They compared the national temperatures in the United Kingdom and Japan with global temperature trends and with energy consumption from 1965 to 2013. They discovered that for both countries the waste heat explains national climate variations. The national temperatures trace better with energy use than with the global temperature trends.
Murray stated that the data indicates a correlation between a temperature drop in the U.K. and the current economic recession, which has caused a drop in energy use there. They also found Japan's steadily growing energy consumption corresponds to the worldwide increase in carbon dioxide levels.
According to the researchers, Japan has the 8th highest mean energy consumption around the world. Meanwhile, the U.K. has the 13th. Both Japan and the U.K. are rather extreme cases and Japan has a warmer climate. The U.K. is cold enough to require indoor heating for about six months each year. It also has more cloud cover than in Japan. These clouds hold waste heat closer to the ground, where it can raise the temperature.