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Global warming
Global warming is the increase in the average temperature on Earth. Scientists identified this phenomenon half a century ago. They alerted all stakeholders: the climate on Earth is gradually warming. The climate challenge is the most important challenge to be addressed in the very coming years. Solutions exist and an increasing number of enterprises and citizens is already acting .
The greenhouse effect
Global warming is the result of the greenhouse effect. What is it exactly?
Every day, the Earth receives heat and light from the sun’s rays, without which life would be impossible. The majority of these rays are radiated back to space1. In the upper atmosphere, certain gases act to retain the quantity of heat necessary for life. This fragile balance has protected us for thousands of years and allows life to exist on Earth.
The main greenhouse gases are carbon dioxide (CO2) and methane (CH4). When they reach the high layers in the atmosphere, these gases create a film that retains the heat of the sun instead of allowing it to escape: this is the greenhouse effect.
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Source : GIEC http://www.ipcc.ch
For thousands of years, the curve relating to the concentration of greenhouse gases in the atmosphere has always perfectly matched the average temperatures observed. When the industrial revolution started, humans began to produce vast quantities through their activities and, subsequently, an increase in the average temperature was observed. It has now been established that the concentration of these gases in the atmosphere is the cause of the increase in the temperature.
Picture source: An Inconvenient Truth – Al Gore
The current disturbances in this mechanism and the resulting increase in the temperature are transforming the entire planet into a gigantic greenhouse.
The origins of the warming and the greenhouse gases
No-one is contesting the fact today: it is human activity that is causing the global increase in temperatures. In 2004, there were 28 billion tons worth of greenhouse gas emissions in the world, 77 % of which was carbon dioxide and 14 % methane. The origin of these gases is mainly agriculture (14 %), deforestation (18 %) and energy production for transport (14 %), electricity (25 %) and industry (10 %). It is important to note the major impact of road transport (10 % of total emissions), which has increased by 26 % since 19901 in Europe, and the energy consumed by homes (10 % of total emissions), which are typically the uses on which we can have an impact.
The temperature has increased at a more rapid rate during the past few years: it is during the past 14 years that the 10 annual highest average temperatures have been recorded (with a record in 2005).
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