What is happening to the planet's climate? Greenhouse gases (GHGs) are water vapour, carbon dioxide, methane, nitrous oxides, ozone, etc. They are produced naturally in the atmosphere and are essential for life on Earth . They absorb part of the Sun's radiation and ensure a moderate average temperature of around 14 °C on the Earth's surface. (7) Without them, this temperature would be -18 °C. However, human activities are excessively increasing the concentration of these gases in the atmosphere. As a result, the average temperature of the planet is increasing rapidly. This process is called global warming. It has serious ef fects: (8) The polar ice caps are melting. As a result, sea levels are rising and could exceed one metre by the end of the centur y, f looding the lowest coastal areas. It is causing climate change: the average temperature i s r i sing and extreme weath er e vent s such as heat waves, droughts, hurricanes and strong storms are becoming more frequent and severe. The need to address the climate emergency In 2021, NASA warned that the last eight years were the warmest since modern temperature records began . To slow down climate change, international summits are held regularly, with mixed results. The main objective is to reach agreements to limit GHG emissions and slow down global warming. Since the adoption of the United Nations Framework Convention on Climate Change in 1992, two of the most important agreements have been : 7. The greenhouse effect Radiation absorbed by GHGs that warms the lower layers of the atmosphere. Around 30 % of the solar radiation that reaches the Earth's surface is reflected back into space. Radiation absorbed by the Earth and the Ozone layer Greenhouse gases 8. Change in the average global temperature compared to the period 1850-1900 (beginning of industrialisation) COMMUNICATION Find information about one of the climate summits and discuss its results with the class. Summarise the main concepts of climate and its factors. Explain the relationship between global warming and climate change. Are they the same? Think about and write down one action you can take to help reduce climate change. K E Y Q U E S T I O N S The Kyoto Protocol (1997) Industrialised countries agreed to reduce their GHG emissions. The Paris Agreement (2015) Signed by 195 countries. It established a longterm plan to prevent the average temperature from rising over 2 °C above pre-industrial levels, with an aim of no more than 1.5 °C. 15
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