Acknowledgements The material acknowledged below is Proprietary and used under licence, see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following: Figur
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5 The contemporary Arctic climate There is a remarkable seasonality in the Arctic climate. For example, the flow in some of the great rivers of Russia and North America that empty into the Arctic Ocean almost stops in winter (Figure 21). During May, ice in the rivers starts to break and in June there is a rapid flood of fresh water followed by a
4 The end of the last ice age: the Holocene I have already noted that the great ice sheets took about 100,000 years to form and only about 10,000 years to decay. So what happened at the end of the last ice age? Figure 15 shows the EPICA ice core CO2 concentration and air temperature for the most recent 20 000 years, which is within the last ice
3.2 The past temperature of the planet Measuring the concentration of lead in the ice is called a direct measurement: the ice sample is melted and the water produced contains a very small but readily measured quantity of lead dust. A very accurate set of scales would be needed to measure it, but it is a directly measured quantity. There are also many indirect measurements that can be made using proxy data. The concept for using proxies is both simple and brilliant: one measured property allows inference about other states o
1 A climate change icon The polar bear has become an international climate change icon. But how much is known about this bear, its habitat and life? This unit will talk about the role of language, but by way of introduction how about the name of this bear? To me it is the polar bear; to a German it is an Eisbär (ice bear) and to a French person it is an ours blanc (white bear). In these three examples the bear is referred to as polar, white, or an ice bear – eminently sensible. The Latin name for th
Introduction The scientific theory of plate tectonics suggests that at least some of these Arctic lands were once tropical. Since then the continents have moved and ice has changed the landscape. This unit will concentrate on evidence from the last 800,000 years using information collected from ice cores from Greenland and Antarctica, and will use this evidence to discuss current and possible future climate. The cores show that there have been nine periods in the recent past when large areas of the Earth
6.1 ‘I’, ‘we’ or ‘they’? We must abandon the conceit that individual, isolated, private actions are the answer. They can and do help. But they will not take us far enough without collective action. (Al Gore, 2007) There are some things that we can do as individuals: making this an energy-efficient house and making smart transport choices. Then there a 5.3 Moving towards a sustainable carbon footprint So far, you've been considering reductions in average individual or household carbon footprints by 20% to 30% or more. But it is becoming increasingly clear that this will not be enough. As I mentioned in Section 4, developed countries, like Britain, Germany and America, will have to reduce their CO2e emissions by 60% to 80% or more by 2050 to prevent climate change running out of control, while at the same time allowing the growing populations of Africa, India and China to r 2.2.4 Identifying the carbon heavyweights I've focused on two studies of the carbon footprint of UK individuals and households, but there are many others (e.g. WWF, 2006; Goodall, 2007 and Marshall, 2007a). 2.2 The carbon footprint of UK individuals and households The simplest way of calculating the average (mean) carbon footprint of an individual living in the UK can be obtained by dividing total UK annual CO2 emissions by the number of people in the country. Using the official government information in Figure 3(a), this produces a mean footprint 1.2 Individual and household carbon footprints I'll be referring mainly to the carbon footprint arising directly and indirectly from the activities of individuals and households. The carbon footprint of individuals and households is important because they are ultimately the main consumers of the energy, food and other goods and services that produce those emissions. Look at Author(s): 1.1.1 Carbon dioxide and other greenhouse gases Carbon dioxide (CO2) is used as the basis for the carbon footprint because it is by far the main contributor to the enhanced greenhouse effect from human activity (mainly burning fossil fuels, clearing forests and making cement). So, often only CO2 is counted in the carbon footprint. However, for a more complete measure of the carbon footprint the other human-generated greenhouse gases are converted into a CO2 equivalent (in kilograms or tonnes CO2e Learning outcomes By the end of this unit you should be able to: Understand the problem of green-house gas emissions; Explore what you can do as an individual or household to lighten those emissions; Identify how much you would need to reduce your carbon footprint to achieve an environmentally ‘sustainable’ level of emission. Introduction This unit focuses on the problem of greenhouse gas emissions, especially carbon dioxide, and explore what you can do to lighten those emissions to help reduce the rate of climate change. You will assess your ‘carbon footprint’ and see what actions you and, if relevant, other household members could take to lighten that footprint. You will also better understand which actions are more and less effective, and the scope and limits of what individuals can do at the personal and household leve Acknowledgements The content acknowledged below is Proprietary (see terms and conditions). This content is made available under a Creative Commons Attribution-NonCommercial-ShareAlike 2.0 Licence Grateful acknowledgement is made to the following sources for permission to reproduce material in this unit: References 2.8 End of unit question 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’. What is th 2.6.2 The role of modelling studies State-of-the-art models are designed to simulate the workings of the climate system (in so far as this is currently understood), and include the ‘internal’ interactions that generate short-term natural variability in the real world. They provide modellers with a means of carrying out ‘virtual’ experiments on the climate system. In the present context, an important aim of these experiments is to identify the ‘signal’ of a human influence on climate, so studies typically involve ‘ 2.6.1 Weighing up the evidence: the full cast of suspects Figure 36 (again adapted from the TAR) takes your thoughts on Question 11 on a stage. It gives estimates of the cumulative effect since pre-industrial times of the various climate change agents, with the contributions expressed in terms of radiative forcing. Note that the figure also includes yet another device for communicating the IPCC's confidence in a particular finding – an indication of the ‘level of scientific understanding’ that accompanies each estimate. This reflects the autho 2.6 An evolving consensus on attribution 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 2.2.2), and quite another to establish with a given level of confidence that it has been caused by (i.e. can be attributed to) human activity – specifically, the increase in greenhouse gas concentrations and associated radiative forcing since pre-industrial times (reviewed in Sec
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Question 12
