3. What have been the causes of global warming?
The causes of the natural global warming of Earth are due to the greenhouse effect of our atmosphere. The solar rays come from space, bounce off the surface of the planet and try to escape back to the cosmos, but a part is trapped by some gases in the atmosphere, with CO2 being the most important of them. Consequently, the greenhouse effect is produced, an acceptably uniform temperature condition, key to life on the planet. If this phenomenon does not happen, Earth would be an icy planet, probably uninhabited like most others, or at least not suitable for life as we know it.
The causes of anthropogenic global warming, that is, those caused by human activities, are due to the emission of greenhouse gases (GHGs), which add extra amounts of CO2 and other gases to the atmosphere. As the greenhouse effect increases, the atmosphere retains a greater quantity of solar rays and consequently increases the temperature in our planet.
GHG emissions have intensified since the beginning of the Industrial Revolution, in 1750, and especially since the 1950s. Most of this increase comes from the burning of fossil fuels, while another corresponds to the deforestation of woodlands and the intensification of agriculture and the livestock industry. The most important sources of GHG emissions are the burning of coal, gas and oil, used in industry and transport.
The CO2 represents only 0.04% of total gases in atmosphere, but, with such a small amount, has been responsible for maintaining life on Earth. It is the main greenhouse gas whose concentration recently broke a record by passing the threshold of 400 PPM, parts per million, for the first time since Homo sapiens appeared on Earth.Click edit button to change this text.