How do greenhouse gases cause climate change?

Most greenhouse gases (carbon dioxide, methane, nitrous oxide, chlorofluorocarbons (CFCs) and others) are naturally produced by the earth’s ecosystem and are essential to maintaining its temperature by absorbing and emitting radiation in the atmosphere. However, an excess of greenhouse gases leads to a phenomenon known as radiative forcing, whereby heat that would normally leave the earth becomes trapped, causing the atmosphere to warm up. By examining ice cores which contain bubbles of the earth’s atmosphere dating back thousands of years, IPCC scientists have shown that greenhouse gases have increased ‘markedly as a result of human activities since 1750 and now far exceed pre-industrial values’. CO₂ levels are now the highest they have been for over 650,000 years, due to an increase of around 30% in the last 50 years, and there is over twice as much methane in the atmosphere now as there was in pre-industrial times.

Данный текст является ознакомительным фрагментом.