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Climate Change Briefing Cover image National Assembly for Wales, Rogers Stirk H

Climate Change Briefing Cover image National Assembly for Wales, Rogers Stirk Harbour & Partners. Debating chamber natural ventilation funnel with mirrored reflector. Sustainable strategies and renewable energy systems were implemented throughout the building. Photo Richard Bryant/Arcaid.co.uk 1 About this Document This is the first of six components of Climate Change T ools, a package of guidance developed by the RIBA to encourage architects to engage with the issue of climate change and to deliver low-carbon new buildings and low-carbon refurbishment of existing buildings. This Climate Change Briefing sets the scene; the other elements of this package of guidance are: A Carbon Literacy Briefing, about the carbon dioxide emissions associated with energy use in buildings Principles of Low Carbon Design and Refurbishment Low Carbon Standards and Assessment Methods Low Carbon Design T ools Low Carbon Skills and T raining Each guide summarises its subject and provides links to other sources of more detailed information. 2 Introduction Climate change brought about by man-made emissions of greenhouse gases has been identified as the greatest challenge facing human society at the beginning of the twenty- first century. The United Nations Intergovernmental Panel on Climate Change (IPCC) has suggested that human society could eventually be reduced to a few isolated groups eking out an existence near the poles. Even though this scenario may seem implausible, we must all consider the potential consequences of not taking action to mitigate the risk. ‘We are currently in a twilight war against climate change; we have identified the enemy, we are marshalling our forces and we are skirmishing. But within 15 years we will be in all out war against climate change and it will influence everything we do.’ Colin Challen, MP, Chair – All Party Parliamentary Climate Change Group Every individual, every industry and every profession will have a part to play in meeting the challenge. Each person in the UK is responsible for around 10 tonnes of greenhouse gas emissions per year. Stabilising global greenhouse gas (GHG) emissions at a sustainable level would involve reducing UK GHG emissions to two tonnes per person per year. This briefing: Explains the basic mechanisms and likely effects of climate change Summarises international and UK GHG emissions reductions targets Explains the contribution of buildings to the UK’s national GHG emissions, and the effect of growth and replacement rates Sets out the RIBA’s key climate change policies and its expectations of members for the buildings that they design and specify. The Mechanisms of Climate Change The Greenhouse Effect The complex mechanisms of climate change involve the balance of carbon in the atmosphere, in the oceans and in all living things. The main mechanism is the greenhouse effect, by which levels of greenhouse gases in the atmosphere affect the heat balance of the earth. The process is summarised in Figure 1. Of the radiation from the sun arriving at the earth, approximately 30% is reflected by the atmosphere or by the earth’s surface. The radiation that is absorbed by the earth’s surface warms it, supporting life. In doing so, this radiation is converted into heat, causing the emission of longwave radiation from the earth into the atmosphere. Some of this radiation passes through the atmosphere Figure 1 The mechanism of global warming. Source: Okanagan University College, University of Oxford, EPA, IPCC, Philippe Rekacewicz 3 and is lost in space; the remainder is trapped by greenhouse gas molecules, warming the atmosphere and the earth’s surface and causing more longwave radiation. The major greenhouse gases are carbon dioxide, nitrous oxide and methane. As the concentration of greenhouse gases in the atmosphere increases, more longwave infrared radiation from the earth’s surface is absorbed, further warming both the atmosphere and the earth’s surface. Global temperatures are rising because of the increasing concentration of greenhouse gases, particularly carbon dioxide, in the atmosphere. The concentration of carbon dioxide in the atmosphere increased from approximately 280 parts per million by volume in the pre-industrial era to 380 parts per million in 2007. It is projected to increase to over 500 parts per million by 2050. Global T emperatures Figure 2 illustrates the trend in global average surface temperature since 1860. The significant increase in temperatures during the century is attributed primarily to the burning of fossil fuels, releasing carbon that has been locked into the earth’s crust for millions of years. There is an overwhelming scientific consensus that climate change is taking place as a consequence of man-made greenhouse gas emissions. Many of our day to day activities create emissions of greenhouse gases – running our buildings, travelling, extracting resources, manufacturing products. A recent report by the IPCC confirms that global greenhouse gas emissions increased by 70% and carbon dioxide emissions by 80% between 1970 and 2004, in line with world- wide economic growth, and predicts that emissions will continue to increase over the next several decades1. Feedback Effects There are some damping mechanisms in the natural carbon cycle: for example, when there is more carbon dioxide in the atmosphere, more of it dissolves in the oceans. Also, as temperatures rise, trees grow faster, converting more atmospheric carbon dioxide into solid carbon (wood). However, another consequence of the warming process appears to be the melting of glaciers and polar ice caps. This reduces the reflectivity of the earth, increasing the proportion of incoming solar radiation that is absorbed into the earth’s surface, re-radiated as longwave radiation and then trapped by greenhouse gases in the atmosphere. Some scientists believe that this positive feedback process may lead to runaway warming, resulting in catastrophic climate change. Figure 2 The trend in global average temperatures since 1860. Source: School of Environmnetal Sciences, Climatic Research Unit, University of East Anglia, UK, 1999 1 Climate Change 2007: Mitigation of Climate Change, Working Group III Contribution to the Fourth IPCC Assessment Report, UNIPCC, 2007 2 Stern Review: The Economics of Climate Change, Cambridge University Press, 2007 4 The Effects of Climate Change The effects of climate change are complex. They include: Increased average temperatures Rising sea levels (because of the melting of glaciers and of polar ice caps) Increased precipitation More frequent extreme weather events. Figure 3 illustrates the possible secondary effects of climate change, including impacts on human health, agriculture, forestry, water resources, coastal areas and species and their habitats. The effect on human society is also likely to be significant; a recent report The Economics of Climate Change2 (also known as the Stern Review) considered the economic costs and impacts of climate change and the costs and benefits of action to reduce greenhouse gas emissions. The Stern Review concluded that the benefits of strong, early action considerably outweigh the costs: ‘Climate change presents a unique challenge for economics: it is the greatest and widest ranging market failure ever seen. The evidence shows that ignoring climate change will eventually damage economic growth. Our actions over the coming few decades could create risks of major disruption to economic and social activity, later in this century and the next, on a scale similar to those associated with the great wars and the economic depression of the first half of the twentieth century... T ackling climate change is the pro-growth strategy for the longer term. The earlier effective action is taken, the less costly it will be. At the same time, given that climate change is happening, measures to help people adapt to it are essential. The less mitigation we do now, the greater the difficulty of continuing to adapt in the future.’ Figure 3 Source: United States Environmental Protection Agency (EPA), Philippe Rekacewicz UK after Climate Change? Rising sea levels are a particular danger: some scientists predict that much low-lying land could be flooded during this century, including entire countries such as Bangladesh, some island nations and many of the world’s coastal cities. The scientific consensus suggests that sea levels may rise by 1-3 metres this century, but some estimates predict much greater rises, possibly as much as 50 metres. The map above shows the impact of a 10 metre rise in sea levels across the UK. Source: Geomantics 5 Political Action to Address Climate Change Mitigation and Adaptation Action to address climate change falls into two categories: mitigation policies are designed to reduce greenhouse gas emissions to slow down or stop climate change; adaptation policies are designed to adjust society to cope with climate changes that are already happening or are likely consequences of current GHG emissions. Contract and Converge One approach to reducing GHG emissions, as recommended by climate change scientists including the IPCC, is known as ‘contraction and convergence’. This involves emissions from industrialised nations reducing (contracting) and emissions from all nations converging to an overall target. The target would be set to stabilise emissions at a sustainable level, and the convergence process would promote equitable distribution of the benefits associated with the energy use giving rise to the emissions. T o achieve this equitable distribution, each of us in the UK would need to reduce our average annual carbon dioxide emissions from 10 tonnes uploads/Geographie/ ccbriefing-guide.pdf