Lombardo comments about now scientists finally agree that temperatures have climbed in the last century. He explains that the effects more perceptible are in the melting of sea ice, causing the retreat of glaciers. Lombardo points out that CO2 level has risen as well, which facilitates the sun’s rays penetrate in the atmosphere, creating the “greenhouse effect”. He concludes saying that these theories are accepted, the trend is that temperatures will continue to increase, and there has to be a pact all over the world to reduce the burning of fossil fuels. On the other hand, Wong says that these theories have been criticized in many spheres. Some critics points out that this period of heating global that is not but a natural cycle of the Earth