London, Dec 2 : Two researchers have theorized that even if humans turn to clean energy to reduce carbon emissions, the planet might carry on warming anyway due to the heat released into the environment by their ever-increasing consumption of energy.
According to a report in New Scientist, the contentious possibility has been raised by Nick Cowern and Chihak Ahn of the School of Electrical, Electronic and Computer Engineering at Newcastle University, UK.
They argue that human energy consumption could begin to contribute significantly to global warming a century from now.
Cowern and Ahn considered an emissions scenario proposed by James Hansen of the Goddard Institute for Space Studies in New York, and others.
Under this scenario, which envisages greenhouse gases being cut significantly through phasing out coal over the next 40 years, Cowern and Ahn calculate that the greenhouse effect will start to diminish by 2050, stabilising the climate.
But things may not go according to plan.
The energy that humans generate and consume ultimately ends up being dissipated into the environment as heat.
This input is relatively small today but might become significant in the next century, according to Cowern and Ahn.
Their calculations show that if global energy use increases at about 1 per cent per year, slower than in the recent past, then by 2100, the heat dissipated could become significant enough to cancel out the benefits of cuts in emissions.
According to Jonathan Gregory, a climate expert at the University of Reading, UK, Cowern and Ahn's argument is logical.
"Human energy dissipation is currently small compared with other factors, but you can imagine it becoming much bigger," he said.
The researchers said that being aware of this potential problem should inform what types of clean energy are adopted.
They said that one of the best types of clean energy is solar power.
But, Cowern and Ahn also point out that solar cells tend to absorb more energy from the sun's rays than Earth's surface does, some of which ends up warming the local environment.
One way round this could be to develop solar cells which absorb only the most energetic frequencies in the sun's rays, according to the researchers.