Basics of Sustainability. Climate Change

Transcription

1 Basics of Sustainability 2 Climate Change 1

2 Contents Page Aims. 2 Introduction. 3 Causes of Climate Change: Natural and Human Influences. 3 The Impacts of Climate Change.. 4 Mitigating Climate Change... 5 Adaptation... 5 Conclusion.. 6 Bibliography and Further Reading.. 6 Aims By reading this section, you should be able to: Understand what constitutes the generally adopted definition of climate change. Understand how natural and human factors influence climate change. Realise the impacts of climate change on the Earth, ecosystems and humanity. Recognise that we all have a part to play in changing behaviors for energy usage and consumerism. 2

3 Introduction After years of debate, an overwhelming majority of governments, scientists, businesses, institutions and communities now acknowledge that climate change, caused and/or exacerbated by human activity, is occurring and unarguably represents the greatest global environmental challenge of our time. Weather changes are defined by hourly or daily changes in temperature, precipitation (rain, hail, sleet and snow) and wind, whereas climate change refers to an identifiable change in the climate (temperature, wind and precipitation) that persists for an extended period, typically decades or longer. Causes of Climate Change: Natural and Human Influences Natural and human factors both affect the global climate and, by extension, sea levels and the concentration of carbon dioxide (CO 2 ) in the atmosphere. The average global temperature is currently in the region of 15 C, though geological and other scientific evidence suggests that this average may have been as high as 27 C and as low as 7 C in the past. The Earth s climate has changed many times in response to natural causes. These have included changes in solar output that can vary global temperature; volcanic activity where particulates and gases released into the atmosphere from eruptions block solar radiation, therefore cooling the Earth; or cycles relating to the Earth's orbit around the sun. There is substantial and conclusive scientific evidence that human activities, primarily the burning of fossil fuels but also changes in land use, including agriculture and deforestation, are driving climate change. The greenhouse effect is one of the main factors determining the temperature of the Earth. This is the phenomenon by which certain gases - so-called greenhouse gases (GHGs) - in the atmosphere trap heat that would otherwise escape to space, thereby keeping the planet warm. Whilst the Earth's atmosphere has always contained GHGs which have caused warming, such as CO 2, human activities are changing the strength of the greenhouse effect by increasing the proportion of GHGs in the air. For example, CO 2 concentration in the atmosphere has increased by about 43% since the beginning of the industrial revolution, from 280 then to about 400 parts per million (ppm) now. Records from ice cores confirm without doubt that current CO 2 concentration is far higher than for at least the past 800,000 years (and some studies suggest this could extend as far back as 20 million years) and that the additional CO 2 in the atmosphere today has a chemical fingerprint that links it to fossil fuels. Levels of other GHGs, such as methane and nitrous oxide, have also increased significantly since pre-industrial times - again driven by human contributed emissions from fossil fuel burning, forest clearance and agriculture. Human activity has caused depletion of natural resources such as trees, gas, oil and minerals. These resources, once used or destroyed, are difficult or indeed impossible to replace. The disappearance of the rainforest is especially significant as more than 20% of the world s oxygen is produced in the Amazon rainforest. 3

4 The Impacts of Climate Change Climate change triggers some processes which exacerbate warming, and other effects which mitigate it. The balance between these positive and negative feedbacks is a major cause of uncertainty in climate predictions. Evidence from direct measurement of surface air temperatures and subsurface ocean temperatures, from phenomena such as increases in average global sea levels, retreating glaciers, as well as changes to physical and biological systems indicates that climate change has, and will continue to have, numerous impacts. Sea levels have risen by approximately 20cm between 1870 and 2004 understood to be caused mainly by the expansion of warming oceans but also the melting of ice sheets and sea ice. Records show Arctic sea ice has thinned by 40% in recent decades during summer and autumn. There are, however, anomalies in some years, parts of the Antarctic actually appear to be getting colder, and there are discrepancies between trends in surface temperatures and those in the troposphere (the lower portion of the atmosphere). Melting sea ice causes a vicious cycle in terms of warming, as less ice means more solar radiation is absorbed instead of reflected, leading in turn to greater seaice melt. Rising sea levels are threatening low-lying countries such as Bangladesh and the Maldives, and hundreds of millions of people could be at greater risk as a consequence of flooding. Most glaciers in temperate regions of the world and along the Antarctic Peninsula are in retreat, often leading to the formation of lakes in the space once occupied by glaciers. Almost all glacial lakes in the Himalayas are dammed by glacial debris, which is structurally weak and prone to collapse caused by flooding, rockslides or avalanches. The impact of flooding further down a valley is the loss of human life and livestock and devastation to cultivated land, as well as to dwellings and infrastructure. The potential impacts of climate change on a human level are huge, with predicted freshwater shortages, sweeping changes in food production conditions, and increases in deaths from floods, storms, heat waves, droughts and other natural hazards; a phenomena that is now being labelled as Global Weirding. Developing countries, which are less equipped to deal with the effects and are generally in locations that are more vulnerable to a changing climate, will feel the impact more than developed countries. Plant and animal species extinctions are predicted as habitats change faster than species can adapt, and the World Health Organization has warned that the health of millions could be threatened by increases in malaria, water-borne diseases and malnutrition. 4

5 Fig. 1: Effects of climate change The economic costs Rising Temperatures Rising sea levels and flooding and ocean acidification impacting on marine life Plant & animal habitat changes, species become extinct Health malnutrition, famine, increases in malaria and waterborne diseases The Effects of Climate Change Glaciers retreating leading to formation of lakes and flooding Extreme weather storms, drought, heatwaves & floods Mitigating Climate Change Climate change cannot be prevented. The reduction of greenhouse gases in the atmosphere is dependent upon the chemical and physical processes that remove each gas. For some of these gases, such as methane, their concentrations decrease almost immediately in response to a reduction in emissions. CO 2 on the other hand, can actually continue to increase for centuries even with reduced emissions, though this is no reason to continue emitting CO 2 at the current unsustainable levels. Coupled with this, the rising global temperature will lead to a slow warming of the oceans, which will affect ice packs, sea levels and thermal currents such as the Gulf Stream. Therefore adaptation is unavoidable and necessary. The average global temperature is expected to increase by a further 0.6 C by the end of the 21 st Century relative to As a planet we need to reduce our reliance on fossil fuels and their greenhouse gas by-products or improve the capability of carbon sinks to absorb these gases from the atmosphere. Deforestation is part of this problem due to the reduction of plants and forests and their natural absorption of CO 2. Adaptation So how do we adapt to the challenges presented by the changing climate? Can we minimise its impact on our activities now and in the future? From a construction perspective this will encompass how we design and construct new buildings and, perhaps 5

6 more importantly, how we address the retrofitting and refurbishment of the existing building stock. Adaptation involves a revision in our approaches to energy generation and consumption for both homes and industry; methods of how we transport materials/goods and people; agricultural management; forestry management for carbon capture; and waste management. This can embrace behavioural change, such as turning off electronic equipment and lights that are not needed to reduce our power consumption, much of which is generated by GHG emitting fossil fuels, through to the specification of construction techniques and products that minimise carbon in manufacture (called embodied carbon) and transportation. Conclusion Whether or not you subscribe to the school of thought that understands climate change as being a consequence of human activity, or to that which sees it as a natural process (or indeed the fact that it can be attributed in part to both), there is irrefutable proof that it is happening, and happening at a rate unseen at any point in the Earth s history. We need to be aware of the implications of climate change on our own and others way of life. Failure to react and adapt will have significant consequences with regard to the increased frequency of extreme weather events such as storms, drought and flooding, as well as rising sea levels that will reduce land mass and displace millions of people. The effect will be to compress an ever-growing population into a smaller space and place greater pressure on food and water supplies that will themselves be disrupted by a changing climate. Every government in the world and an overwhelming majority of scientific institutes and businesses acknowledge the threat and the need for action, but it is down to us all to change our behaviour to either be part of the solution or part of the problem. Bibliography and Further Reading Metz, B., Davidson, O.R., Bosch, P.R., Dave, R. Meyer, L.A. (2007) IPCC Intergovernmental Panel on Climate Change. Mitigation of Climate Change Cambridge: Cambridge University Press Parry, M.L., Canziani, O.F., Palutikof J.P., et al (2007) IPCC Intergovernmental Panel on Climate Change. Impacts, Adaptation and Vulnerability Cambridge: Cambridge University Press Rana, B (2000) Hazard Assessment of the Tsho Rolpa Glacier Lake and Ongoing Remediation Measures Journal of Nepal Geological Society 2000, Vol.22, pp Solomon, S., Qin, D., Manning, D., Chen,Z., et al (2007) IPCC Intergovernmental Panel on Climate Change. The Physical Science Basis Cambridge: Cambridge University Press Stern, N (2006) The Economics of Climate Change. London: HM Treasury 6