On an early lesson in the sequence ralating energy, work, combustion and renewable energy (the sun) , I try to convey the idea of our survival as a specie relates to the temperature of our environment. The problem with burning (combustion) and the generation of chemical species such as carbon oxides and water vapor, the so-called "greenhouse gases" that tends to prevent the heat generated in our atmosphere to be radiated out, towards the space . If the heat is kept in the atmosphere, the temperature of the environment will keep up increasing at the speed much higher than our bodies can evolve as to survive the increase , threatening our survival as a specie.