We hear a lot about global warming these days – increasing temperatures that result from higher concentrations of greenhouse gases in the atmosphere which trap heat emitted from the Earth’s surface. But the planet is heating up for another reason, namely that all of the energy that we use that is generated from non-renewable sources eventually ends up being dissipated as heat. The problem is neatly presented in a recent essay in New Sciensist, Issue 2702 [4 April 2009] by astrophysicist Eric Chaisson from Tufts University, Massachusetts, USA. The second law of thermodynamics tells us that energy eventually tends to dissipate into heat and so everything we do that utilises energy ends up generating heat that can nothing but warm the planet. Currently, this kind of heat input to the Earth system has only increased the temperature of the biosphere by 0.1 degrees Celsius but as energy use soars in the future a 3 degrees Celsius rise within 300 years is not unlikely – on top of “ordinary” global warming this is a significant amount. However, there is a way out of this problem, namely to generate energy from renewable sources. This works because energy from renewable sources is already accounted for in the global thermal budget, for example solar energy already warms the Earth so if we use some of it to generate electricity which then ends up dissipating as heat we’re not adding more heat to the system. This is another good argument for increasing our use of renewable energy sources (along with the fact that this would reduce greenhouse gas emissions) and it turns out that there’s is loads of power available in this way (there is ~7000 more power in the sunlight arriving on Earth as the current power consumption of all humans). It almost seems like a no-brainer to me.
Tim O'Hare 