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5 Human influence?

Evidence suggests that global temperature is beginning to rise. There are several factors that could cause this. Only one is affected by human activity.

Click on 'View document' to view a chart showing the rates of energy gain and loss by the Earth's surface and atmosphere

5.1 Pollution and loss of biodiversity

Unfortunately, halting the disappearance of species cannot be achieved simply by measures such as putting fences around special habitats and asking people not to pick the flowers or disturb the breeding birds. Many species are vanishing because of pollution. You probably have a good understanding of the meaning of this term, but it is variously defined. The Open University has a course on environmental control and public health, in which pollution is defined as the introduction into th
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4.5 Global climate change

I would like to turn now to the possible consequences of our use of energy for global climate change. Our pattern of energy use relies heavily on burning carbon-based fossil fuels, releasing carbon dioxide which spreads evenly around the globe and builds up slowly in the atmosphere. Carbon dioxide is a greenhouse gas, which means that it has the potential both to warm the atmosphere and to change our global climate. It is not the only greenhouse gas but is the most important of those e
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2.1 Environment and technology

A central concern of environmental studies is the relationship between technology and our environment: how people use technology to transform materials into forms which can meet our needs and wants. In the process of doing this we inevitably change the environment which provides these materials but which also supports all life.

A few moments ago I went to my fridge and took some milk out to add to a cup of coffee. I used this common example of a modern domestic appliance without a secon
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6.1 Introduction

The international level can be viewed as an arena of politics in its own right and not just as a context for states and other actors. If we think of the international world in this way, how should relations between states, and other actors on the international stage, be constructed? To what extent should those relations be regulated? We can ask whether relations between states, and states' policy making, should be dictated by allegedly universally shared human rights principles, or by other o
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2.1 Issues of responsibility

The aftermath of the 2004 Indian Ocean tsunami saw an unprecedented aid effort to assist the affected regions. In the early days after the disaster, pledges of financial assistance from overseas governments were often outstripped by the generosity of their own populaces. This was a case when ordinary people around the world saw and were moved by the tragic circumstances of others far away (Rose, 2006), and they responded with gifts of money and provisions, and even with offers of their own sk
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Module team

The Open University course team

Course Team Chair of Production

Gillian Rose, Professor of Cultural Geography

Course Team Chair of Presentation

Chris Brook, Senior Lecturer in Geography

External Assessor

Peter Jackson, Professor of Human Geography, University of Sheffield

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2.2 The purpose of this activity

For these short video extracts we have chosen to focus on two main viewpoints. Try not to look beyond the outline of the debate, for we are not expecting you to come to a conclusion about who is right and who is wrong – the issues are far too intricate for that. All you need to do is to recognise what the issues are and to be able to identify what arguments each side puts forward in support of its case.

The key skill being developed is identifying the arguments used by various individ
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1.6 Defining global markets

Global markets for manufactured goods, as opposed to, say, primary commodities such as oil and timber, arose largely in the second half of the twentieth century as trade between countries intensified. The lowering of transport costs and the relative fall in trade barriers enabled firms in one country to compete wit
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1.1 Aim

The activities and resources in this section engage you in an interdisciplinary investigation of your personal ecology by looking at a range of temporal, spatial, and organisational scales – from the personal to the global, from the short term to the long term. The aim is to gather evidence to he
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2.4 Oral and written communication

Humans use language to communicate. This is an obvious statement, but what is language and how do we use it? Language is basically a set of symbols with associated meanings. These symbols are delivered using a set of rules for stringing the symbols together to generate additional meaning. Humans use mostly sounds to represent these symbols, although as an Italian I can communicate common meanings by only using a range of hand gestures! We string together phonetic sounds to make words, and we
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1.1 Aim

This study unit introduces you to the proposition that our mental models change through learning, and
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5.1 Sudden changes

The third category of thermal effects identified in Section 2 are those associated with sudden changes. Here are some technically important examples where things change suddenly at a particular temperature:

  • Pure water boils at 100 °C (at atmospheric pressure).<
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4.4 Summary of Section 4

  • Thermal energy is a random thing, so any group of particles possessing it will have a distribution of kinetic energies.

  • The fraction of particles with energy greater than an amount E1 is proportional to exp(−E1/kT).

  • Thermally activated rates follow Arrhenius's law and are characterised by an activation energy.

  • Diffusion in solids and electrical conduction i
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4.3.3 Getting at the activation energy

The final trick I want to show you with Arrhenius's law is how to extract the constants r0 and Ea from experimental data. If the Arrhenius equation (Section 4.3.1) is ‘turned inside out’ by taking natural logarithms of both sides it becomes:


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4.2 Energy distribution

Atoms without much thermal energy will not be doing very much. Consider fifty million million million (50 × 1018) silicon atoms, bonded into a single massive network; I've chosen silicon, but any elemental solid would do. It will be a speck just large enough to be seen without a microscope. You know that if it is heated it will expand, at some stage it will melt and then eventually it will vaporise – that is because thermal energy effectively ‘rattles it to bits’. Having the
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4.1 Characteristics of processes activated by thermal energy

This is a long section and needs to be studied carefully. Keep your eye on the overall goal of seeking useful thermal effects on which to base devices.

This section continues the discussion of heat at an atomic level. You will need this background to appreciate the characteristics of processes activated by thermal energy – for example, the softening of glass in a gas flame, the diffusion of atoms through solids, the electrical conductivity of ceramics, and many chemical reactions. Suc
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3.3 Thermal stresses

When the temperature of an object increases (say, by ΔT) it expands. According to the linear model of thermal expansion the length increase is described by

What if there is a temperature change, but some constraint prevents the proper thermal size changes? The constraint
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2.2 Thermal effects in outline

Temperature is, of course, the measure of ‘thermal’ conditions. Nowadays it is measured by thermometers and expressed as a number on an agreed scale. Some features of thermometers and of their use are discussed in Thermometers and process control

The theoretical construct of temperature relates it to the kinetic energies of atoms. This gives clear insights into the way temperature affects the behaviour of materials. Energy is given to things to make them hot and taken
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4.3.2 Propagation

Once a small number of chains have been started, propagation involves successive addition of monomer units to achieve chain growth. At each step the free radical is regenerated as it reacts with the double bond. So in the case of styrene the propagation step is

The free radical can also add on in a
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