Topic outline

  • General

  • Topic 1

    Introduction

    • This unit explores the topic of climate change and global warming. We will begin by exploring how the Earth’s global mean surface temperature is determined through a global “balancing act” of the rate...

  • Topic 2

    1 Global climate and the greenhouse effect

    • At the beginning of the 21st century, terms such as the ‘greenhouse effect’, ‘greenhouse gases’ and ‘greenhouse warming’ are printed or spoken thousands of times a week in the context of climate change...
    • The Sun is the ultimate source of energy for the Earth's climate. A planet such as the Earth will have a stable temperature as long as there is a balance between the rate at which energy comes in from...
    • Before we focus on the enhanced greenhouse effect, we need to refine the schematic representation in Figure 7 and draw in some of the other processes that influence the Earth's temperature – not only at...
    • Figure 12 incorporates the additional factors considered in Section 1.3, including the non-radiative energy transfers across the surface-air boundary (green arrow). Essentially a more detailed version...
    • Since its first major report in 1990, the IPCC has used the concept of ‘radiative forcing’ as a simple measure of the importance of a potential climate change mechanism. The basic idea is straightforward....
    • There is no doubt that CO2 is accumulating in the atmosphere. The record from Mauna Loa charts a continuing rise in CO2concentration since measurements began in 1958, when the level was 315 ppm; the value...
    • Figure 12 summarises the ways in which the Earth's surface and atmosphere gain and lose energy. The main points are as follows:
    • Information on the different albedos of various types of surface was given in Section 1.2.1. Given that information:

  • Topic 3

    2 What do we know about recent climate change?

    • Here are some quotes from the ‘Summary for Policymakers’ (SPM) included in the report from the scientific working group in the IPCC TAR (IPCC, 2001a):
    • To put the temperature records reported by the IPCC in context, we start with a longer-term geological perspective on the Earth's GMST.
    • For complex issues such as global climate change, there are many opportunities for scientists to take issue with the findings of their colleagues. They can disagree about the procedures for gathering data,...
    • At the time of writing (2006), debate about the ‘hockey stick’ reconstruction continues to rumble on. In this and other controversial areas, it is natural that scientists who are not part of the IPCC process...
    • The observed increase in GMST may be the key global indicator of greenhouse warming, but it is far from being the only tangible sign of climate change during the 20th century. This brings us back to the...
    • The fact that the Earth really is warming up now commands near-universal support. However, it is one thing to detect a global warming trend that appears to be unprecedented in the past millennium (Subsection...
    • Reconstructions based on direct temperature measurements (back to 1860) and proxy data (Box 7) reveal that the Earth's GMST varies naturally on many different time-scales: from year-to-year, over periods...
    • The writer and campaigner George Monbiot wrote the following (in The Guardian Weekly, 10 February 2000): ‘Every time someone in the West switches on a kettle, he or she is helpting to flood Bangladesh’....

  • Topic 4

    References and Acknowledgements