Introduction

This article is the first in a series of articles which will take the reader on an alphabetic journey on global warming, commencing with A for Amazon.

The phrase global warming is a term that has been in common usage for some time and usually refers to the warming of Earth's atmosphere, and which also implies a manmade or human influence.

Earth's atmosphere is comprised of many gases, oxygen, nitrogen, carbon dioxide and water vapour to name a few. These gases are collectively called greenhouse gases and they keep the Earth's temperature at a comfortable 15 degrees Celsius, without them Earth would be a chilly - 18 degrees Celsius. Since pre-industrial times, usually taken to be around 1750 we know from ice core records that Co2 levels were around 280 ppm, that's 280 parts of Co2 per million parts of air. As industrialisation got underway mankind started to farm the land more intensely than ever before, deforest for agriculture and settlements, and later since around 1850 or so, burn fossil fuels for energy and transport which have added considerably to greenhouse gas levels, particularly Co2.

This has resulted in Co2 levels increasing to around 385 ppm, an increase of around 37% over pre-industrial levels mainly as a result of burning fossil fuels.

How do we know this? Well, data from ice core records that go back at least 650,000 years now show us that Co2 levels have fluctuated naturally during this time between 280 and 300 ppm. Co2 levels have also been measured accurately from the top of Mauna Loa Volcano in Hawaii since 1958, and results show an increase in Co2 levels from 315 ppm to 385 ppm since that time. Therefore Co2 now stands at 85 ppm more than it has been for at least 650,000 years of Earth's history. It is a known scientific fact that higher levels of greenhouse gases will lead to higher temperatures, and this appears to be occurring now. The world has warmed by an average of 0.74 degrees during the last 100 years or so.

As a result of this warming, polar ice has started to decrease and melt, and so are Earth's land based glaciers. This in turn is causing sea levels to rise which is putting low lying islands at risk of flooding or total submersion. This will eventually threaten more and more of the worlds coastal cities and regions.

As Earth's atmosphere starts to warm, the warming itself may cause further positive feedback mechanisms to kick in. A warmer atmosphere holds more water vapour, which is itself a powerful greenhouse gas. This will in turn cause further warming, and so on.

Melting ice means that more sunlight is absorbed by the surrounding "darker" water and land, meaning further warming, and more melting ice. Methane deposits currently held in a frozen but stable state under the sea and under the permafrost maybe released as the oceans warm and permafrost melts, which will cause further warming as methane is a potent greenhouse gas etc etc.

Page 1 of 2 :: First | Last :: Prev | 1 2 | Next