Читать книгу Neutral Life: - John Hartas - Страница 3

Global Warming and Carbon Footprint

This section gives an overview of two sorts. Firstly, to remind the reader, in layperson’s terms, of how the greenhouse effect works. This includes a short discussion of how greenhouse gases affect the Earth’s temperature, and information on the nature of the human effect on this process. Secondly, to describe the nature of an individual’s or organisation’s contribution to emissions (their ‘carbon footprint’), and to explain the process of calculating this.

Greenhouse Effect

Figure 1. The Greenhouse Effect.

Fig. 1 is a familiar diagram of the greenhouse effect: the basic mechanism through which global warming is taking place. When light from the Sun hits the Earth, some of it is reflected back as infra-red radiation. This reflected radiation comes into contact with gases in the atmosphere. Some gases – ‘greenhouse gases’ – reflect some of that radiation back down to Earth again. This means some heat, which would otherwise have left the atmosphere, is sent back to Earth and warms the surface further.

Greenhouse gases make up much less than 1% of the atmosphere, and human activity is responsible only for a tiny fraction of that: nearly all of the greenhouse effect is perfectly natural. If there were no greenhouse gases in the atmosphere at all, the surface of the Earth would be at a temperature around -18 C [Ref. 1]. By comparison, human beings are having only a tiny effect, but what we are adding is enough to increase the temperature of the Earth by anything between 1.1 to 6.4 C over the 21st Century [Ref. 2]. Immediate consequences of this are well known: retreating glaciers causing rising sea levels, extinction of many species, expanding deserts and reduced agricultural capacity causing food shortages.