ISSUES

Climate Change

Climate is 'the average state of weather' and is fairly stable and predictable. However, while it is always changing, it is now expected to change much more dramatically. The term "climate change" now often refers to changes in modern climate, due to the rise in average surface temperature known as 'global warming'. Often the terms "global warming" and "climate change" are used interchangeably, We try and distinguish the two - that everybody agrees that global warming is occurring, but there is more uncertainty about what climate changes there may be ahead and what are causing them.

What causes 'Climate Change'?

Climate changes can result from interaction of the atmosphere and oceans. Possible examples of climate change include stronger El Nino's making some parts of world - eg Africa drier and other parts wetter, Gulf Stream moving, Melting Glaciers and Rising Seas. It is the biggest threat to the natural world and will have huge implications for the way we live our lives. See information.

But what is causing these elements to alter so much? The answer that most scientists in most countries agree with is the rise in carbon dioxide emissions since the beginning of the industrial revolution. We now have about 388 parts per million (ppm) of C02 in the atmosphere (388 = 0.4%).

How is it that a few trace gases, called Greenhouse Gases, can have such a profound effect?

CO2, water vapor (H2O ), methane (CH4), and nitrous oxide (NO2), all act as effective global insulators. They allow incoming visible light from the sun to penetrate the earths atmosphere. But trap like a blanket the energy radiated back to space from the earth. This phenomenon, the same principle as creates a warm atmosphere in a greenhouse, is what makes the earth habitable for life. Check out the explanation Of the small proportion of "trace gases" making up only 1% atmosphere, water vapour accounts for about 60% of GHG effect, C02 about 25%. But we cant do anything about the water vapour.

Is it caused by human activity?
The proportion of the anthropogenic effect (derived from human beings) that is caused by C0₂ is..about 60+ %. The UNFCCC uses the term "climate change" for human-caused change, and "climate variability" for other changes. Many use the term "anthropogenic climate change" for human-induced changes.

There may well be an iterative reaction between C0₂ and global warming - that it is not merely that C0₂ is promoting global warming, but that the global warming is encouraging evaporation of C0₂ from oceans and soils. And then there is the role of water vapour that may be having even more compound effects.

Climate Change