What is the Greenhouse Effect?

The Greenhouse Effect is the blanketing effect created by greenhouse gases, which stops the Earth from having an average temperature below zero. The Enhanced Greenhouse Effect is where the problems start. Since the Industrial Revolution, humans have been increasing the quantity of greenhouse gases in the atmosphere, leading to more heat
being trapped, and the Earth¹s average temperature gradually rising. An increase of approximately 0.6C over the 20th century has already been recorded, and, according to the Intergovernmental Panel on Climate Change (IPCC), an increase of 1.4 to 5.8C is predicted for the next century. For the climate implications of this, see below.

The Earth's temperature has always fluctuated (which is why it is very difficult to calculate how much of the current change in temperature has been caused by humans, and how much has been caused by natural fluctuations). However the chairman of the IPCC warns that "if actions are not taken to reduce the projected increase in greenhouse gas emissions, the Earth¹s climate is likely to change at a rate unprecedented in the last 10,000 years."

What are greenhouse gases?

Greenhouse gases, in order of the ones having the most to least impact on the climate, are: water vapour, carbon dioxide, ozone, CFCs, methane and nitrous oxide. Humans aren't significantly changing water vapour levels in the atmosphere, but water vapour has a high heat absorbing capacity, and a change in temperature is likely to affect water vapour levels in the atmosphere, which could affect the climate. CFCs deplete ozone in the stratosphere and the ozone layer. When found in the troposphere, ozone is a greenhouse gas. Climate change and the hole in the ozone layer are otherwise unrelated problems.

So how will the climate change?

Global warming tends to get referred to as "climate change" these days, because global warming tends to make it sound like everything is going to get pleasantly warmer, and we will get more nice sunny days. In reality, the climate system is incredibly complicated, and the warming is likely to shift wind and pressure patterns, with diverse effects across the planet. The IPCC has predicted that rainfall will become less frequent and more intense, and that extreme weather events will increase in frequency. Which means more large storms, more tropical cyclones, more floods and more landslides. Australia is likely to experience a "more El Niño-like average state" which means yet more droughts. The IPCC states that poorer countries are much more vulnerable to climate change, because they don¹t have the resources to adapt.

Give me more!

Detailed information on the science of climate change is available on the following sites:

The Australian Bureau of Meteorology - www.bom.gov.au
The World Meteorological Organisation - www.wmo.ch
The Environment Protection Authority - www.epa.vic.gov.au

Information from the IPCC on the science of climate change, impacts, adaptation, vulnerability and mitigation are all available from - www.ipcc.ch