Greenhouse gases trap heat in the atmosphere by absorbing the sun’s infrared radiation without reflecting it back towards space. It is an entirely natural process. Oceans and ecosystems, mainly forests, can absorb the greenhouse gas and emit oxygen but by doing so, oceans acidify, destroying some of their inhabitants and reducing their ability to absorb more CO2. Deforestation also reduces the amount of greenhouse gases absorbed.
They are different gases that act as greenhouse gas; water vapour,
carbon dioxide (CO2), methane (CH4), nitrous oxide (N2O)
and fluorinated gases (HFCs, PFCs, SF6 – grouped under name ‘others’)
Numbers for USA, China, EU, India, Russia, Brazil and Japan
The main problem causing climate change is the level of greenhouse gases within the atmosphere.
Since the Industrial Revolution started back in about 1750, CO2 levels have increased by nearly 40% (2009) and methane by 150%.
The increase of the heat cannot be explained by a potential change in the sun activity as, on average, the amount of energy coming from the sun has mainly remained constant since 1750. If it was coming from the sun, heat would rise in all layers of the atmosphere. Today only the lower parts are warmer as greenhouse gas trap heat in the lower atmosphere. Climate models that include solar irradiance do not reflect the change we have witnessed for the past century. (NASA)
Which sectors pollute?
The sectors that contribute most greenhouse gas emissions include energy, farming and logging among others.
The global warming consequences include the melting of polar ice caps adn rising sea levels.
Other effects are ocean acidification, changes to plant growth and ozone layer depletion.
Actions taken so far
Some Fluorinated gases have been forbidden following Montreal protocol in 1987 to protect the ozone layer. The EU has submitted an amendment proposal in April 2015 to down the use of HFCs under this same protocol.
The leading industrialised nations have also set goals on reducing emissions.
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