UNIT 8 Biology and Geology 4. Secondary education Ecosystems III: ecological balance THE GREENHOUSE EFFECT UNIDAD 7 The greenhouse effect UNIT How the natural greenhouse effect occurs Solar radiation hits the Earths surface. The Earth reflects a large part of this solar radiation. Part of the radiation reflected by the Earth is returned to space. Another part of the radiation is absorbed or retained by the atmosphere due to the action of certain gases, such as CO 2 and H 2 O vapour. Biology and Geology 4. Secondary education UNIDAD 7 The greenhouse effect UNIT How the increase in the greenhouse effect occurs Solar radiation hits the Earths surface. The Earth reflects a large part of this solar radiation. Part of the radiation reflected by the Earth is returned to space. Pollution, together with the progressive disappearance of forests, causes greater retention of the radiation, which leads to an increase in the temperature of the planet. Biology and Geology 4. Secondary education