The science of climate change - The Greenhouse Effect & Global Warming
The Science of Climate Change
The surface temperature of the Earth is regulated by a blanket of greenhouse gases which trap heat within the atmosphere. Short wavelength solar radiation penetrates the atmosphere and warms the surface of the planet. Some of this energy is re-emitted at longer, infrared wavelengths which, had there been no atmosphere, would escape to space leaving the surface of the planet cool. Certain gases, the greenhouse gases, within the atmosphere, absorb or reflect this infrared radiation trapping heat thereby keeping the Earth’s surface warm. This is known as the greenhouse effect because of its similarity to the workings of a greenhouse.
The warming effect of this blanket of gases is essential to life because without it the average temperature at the surface of the Earth would be around -18 degrees Celsius. The greenhouse effect ensures that the current global mean surface temperature (GMST) is around 15 degrees Celsius.
Global Warming
The issue of Global Warming has increasingly received media attention in the last few years. This is due to the now widely accepted concept of global warming through anthropogenic (human) activities. Since the Industrial Revolution we have been burning fossil fuels in combustion processes to generate power. This includes electricity generation, gas to heat our homes and oil in most forms of transportation that we use.
CO2 is the biggest contributor to global warming but other gases such as methane and nitrous oxide also build up in the atmosphere. Each gas has a different effect on global warming as some stay in the atmosphere much longer than CO2 and also, due to higher concentrations, can have an increased effect. Each gas has a different Global Warming Potential (GWP). GWP is based on effect compared with CO2, usually over a 100 year period, so if CO2 has a GWP of 1 then methane has a GWP of 23 which means that, for the same amount released, methane is 23 times more potent a greenhouse gas than CO2. In this way greenhouse gas emissions can be shown in terms of carbon dioxide equivalent (CO2e).
